JP6215472B2 - Measurement timing detector - Google Patents

Description

  The present invention relates to a measurement timing detection device that detects timing for measuring a force applied to a crank that rotates about a rotation axis.

  2. Description of the Related Art Conventionally, there is a device that is mounted on a human-powered machine such as a bicycle and calculates and displays information related to the traveling of the bicycle and information related to the movement of the driver. This type of device calculates and displays predetermined information by receiving data from a sensor provided on the bicycle. The information to be displayed includes a force (torque or the like) applied to the pedal by the driver.

  Also, this type of device may display the force applied to the pedal at predetermined angular intervals. For this purpose, it is necessary to detect the angle of the crank relative to the reference position. For example, in Patent Document 1, a magnet group 21 in which a plurality of magnets are arranged at intervals of 30 ° around the center C of the frame-shaped member 20 on the surface of an annular frame-shaped member 20 fixed to the side surface of a bicycle frame. And a magnetic sensor 22 that is fixed to the chain ring and rotates together with the crank, and describes that the magnetic sensor 22 detects the position of each magnet in the magnet group 21 to detect the angle. Yes.

  Japanese Patent Application Laid-Open No. H10-228561 describes that a crank rotation angle is detected by an angular velocity sensor 10 and acceleration sensors 11 and 12.

  That is, Patent Documents 1 and 2 detect the measurement timing for measuring the force applied to the pedal by detecting the rotation angle of the crank.

International Publication No. 2013/046472 JP 2014-8789 A

  In the case of the rotation angle detection device described in Patent Document 1, although the angle detection accuracy is high, the magnet arranged at the position to be the reference angle requires a magnet with high magnetic force, and thus costs are required because a plurality of types of magnets are used. It will be up.

  In addition, dust and the like are likely to intrude between the frame-shaped member 20 and the crank under an adverse effect that includes a lot of dust, earth and sand. Furthermore, since a magnet is used, there is a problem that sand iron or the like is likely to adhere and the durability is low.

  Since the pedaling state measuring apparatus described in Patent Document 2 uses an angular velocity sensor, there is a problem in that power consumption increases. It is known that an angular velocity sensor generally consumes more power than an acceleration sensor. Since a device attached to a bicycle or the like is driven by a battery or the like as a power source, low power consumption is desired.

  Therefore, in view of the above-described problems, an object of the present invention is to provide a measurement timing detection device capable of reducing cost and improving durability and reducing power consumption.

In order to solve the above problems, the invention described in claim 1 are each arranged at different distances from the crankshaft axis of rotation of the member that rotates in conjunction with the crank or the crank, the longitudinal direction of the crank A first acceleration sensor and a second acceleration sensor that detect acceleration in parallel directions, a reference position detector that detects that the crank is at a predetermined reference position, and a predetermined measurement at an appropriate angular position of the crank Determination of determining the next measurement timing of the measurement unit based on the output value of the first acceleration sensor and the output value of the second acceleration sensor, the detection result of the reference position detection unit, and the next measurement angle. and parts, a measurement timing detecting device characterized in that it comprises a.

The invention described in claim 11, detects the direction parallel to the longitudinal direction of the acceleration of the crank or the crank and different distances and arranged said crankshaft from said crank axis of rotation of the member that rotates in conjunction An acquisition step of acquiring an output value of the first acceleration sensor and an output value of the second acceleration sensor; a reference position detection step of detecting that the crank is at a predetermined reference position; and a predetermined angular position of the crank at a predetermined angular position. The next measurement timing of the measurement unit that performs measurement is based on the output value of the first acceleration sensor and the output value of the second acceleration sensor, the detection result of the reference position detection step, and the next measurement angle. a determination step of determining a measurement timing detecting method characterized by comprising a.

  According to a thirteenth aspect of the present invention, there is provided a measurement timing detection program that causes a computer to execute the measurement timing detection method according to the twelfth aspect.

  The invention described in claim 14 is a computer-readable recording medium in which the measurement timing detection program according to claim 13 is stored.

It is explanatory drawing which shows the whole structure of the bicycle which has a rotation angle detection apparatus concerning the 1st Example of this invention. It is explanatory drawing which showed the positional relationship of the cycle computer shown in FIG. 1, and a measurement module. FIG. 2 is a block configuration diagram of a cycle computer and a measurement module shown in FIG. 1. It is explanatory drawing of arrangement | positioning to the crank of the acceleration sensor shown by FIG. It is explanatory drawing about the acceleration which an acceleration sensor detects when a crank is stationary. It is explanatory drawing about the acceleration which an acceleration sensor detects when a crank is rotating. It is explanatory drawing of the determination method of a measurement timing. It is the table | surface explaining the offset of the acceleration sensor. It is explanatory drawing of the angle of a flame | frame. It is explanatory drawing of arrangement | positioning to the crank of the strain gauge shown by FIG. FIG. 4 is a circuit diagram of a measurement module strain detection circuit shown in FIG. 3. It is explanatory drawing of the force added to a right side crank, and a deformation | transformation. It is a flowchart of a process of the measurement module and cycle computer shown by FIG. It is a block block diagram of the cycle computer and measurement module concerning 2nd Example of this invention. It is explanatory drawing which showed the relationship between the acceleration of the longitudinal direction of a crank, and the acceleration of a transversal direction. It is the graph which showed the relationship between the acceleration of the longitudinal direction of a crank, the acceleration of a transversal direction, and the rotation angle of a crank. It is a block block diagram of the cycle computer and measurement module concerning the 5th Example of this invention. It is the graph which showed the output of the acceleration sensor before and behind giving LPF shown by FIG. It is the top view which showed the chain ring and crank concerning 6th Example of this invention. FIG. 20 is a plan view showing the crank shown in FIG. 19.

  Hereinafter, a rotation angle detection device according to an embodiment of the present invention will be described. In the rotation angle detection device according to an embodiment of the present invention, the first acceleration sensor and the second acceleration sensor are arranged on a crank attached to a rotation shaft or a member that rotates in conjunction with the crank, and the longitudinal direction of the crank The acceleration in the parallel direction is detected, and the reference position detector detects that the crank is at a predetermined reference position. The next measurement timing of the measurement unit in which the determination unit performs a predetermined measurement at an appropriate angular position of the crank, the output value of the first acceleration sensor, the output value of the second acceleration sensor, and the detection result of the reference position detection unit Next, it is determined based on the next measurement angle. In this way, the acceleration component of the centrifugal force in the longitudinal direction (detection axis direction) of the crank of the acceleration sensor can be calculated. Therefore, the next measurement timing (time until the next measurement timing) can be calculated based on the acceleration component of the centrifugal force and the next measurement angle. In addition, since the next measurement timing is determined based on the reference position, the offset of the measurement timing generated due to the characteristics of the acceleration sensor, the power supply voltage fluctuation, etc. can be taken into account, and the measurement timing can be calculated with high accuracy. . In addition, since no magnet is used, the cost can be reduced, and since it is not affected by dust or iron sand, durability can be improved. Further, since the angular velocity sensor is not used, the power consumption can be reduced.

  Further, the first acceleration sensor and the second acceleration sensor may be arranged at different distances from the rotation axis. By doing so, the next measurement timing can be determined by arranging the first acceleration sensor and the second acceleration sensor on one crank.

  Further, the determination unit calculates the rotation speed of the crank from the detection result of the reference position detection unit, and determines the next measurement timing as the output value of the first acceleration sensor and the output value of the second acceleration sensor, the rotation speed of the crank, It may be determined based on the next measurement angle. By doing so, it is possible to determine the measurement timing based on the rotation speed of the crank, and to calculate the measurement timing with high accuracy.

  The determination unit determines the next measurement timing based on the output values of the first acceleration sensor and the second acceleration sensor, the detection result of the reference position detection unit, and the next measurement angle. You may have a correction | amendment part which correct | amends the said measurement timing after the said next measurement timing after that. By doing so, it is possible to correct the measurement timing once determined due to a change in acceleration or the like, and it is possible to increase measurement timing determination accuracy.

  In addition, the determination unit may determine whether the measurement unit next time based on the plurality of output values of the first acceleration sensor and the plurality of output values of the second acceleration sensor, the detection result of the reference position detection unit, and the next measurement angle. The measurement timing may be determined. By doing in this way, the output value of a 1st acceleration sensor and the output value of a 2nd acceleration sensor are used in multiple numbers, For example, those average values can be used. Therefore, it is possible to make it less susceptible to the influence of noise or the like superimposed on the output of the acceleration sensor as compared with the case where it is determined only by the instantaneous output value.

  The determination unit calculates a crank rotation period based on the output value of the first acceleration sensor and the output value of the second acceleration sensor, and based on the rotation period, the detection result of the reference position detection unit, and the next measurement angle. Then, the next measurement timing of the measurement unit may be determined. By doing so, for example, when measuring at every 30 ° per round, the time until the next measurement can be calculated from the rotation period of the crank and 30 °. Therefore, the next measurement timing can be detected.

  In addition, the measurement unit performs a predetermined measurement at a timing corresponding to an angle obtained by dividing the crank m rotation by n equally (m and n are integers of 1 or more), and the determination unit performs the next measurement based on m and n. An angle may be obtained. By doing in this way, it can measure at equal intervals, for example, every 30 degrees.

  The determination unit may detect the measurement timing based on the reference position. By doing in this way, the reference | standard for detecting a measurement timing can be set.

  The reference position detection unit may include a detection unit that is fixedly disposed at a position corresponding to a specific rotation angle of the crank, and a detection unit that is disposed on the crank and detects the detection unit. Good. In this way, for example, by providing a magnetic sensor on the crank and providing a magnet on the bicycle frame, the position of the frame can be set as the reference position.

  A third acceleration sensor for detecting acceleration in a direction parallel to the short direction of the crank; a notification unit for notifying that the detection unit has detected the detected unit; and the first acceleration sensor or the second acceleration sensor. And a timing instruction unit that instructs the determination unit to acquire the output value of the first acceleration sensor or the second acceleration sensor and the output value of the third acceleration sensor. Then, the timing instruction unit causes the determination unit to acquire the output value of the first acceleration sensor or the second acceleration sensor and the output value of the third acceleration sensor based on the notification that the notification unit has detected the detected unit, and the reference position The detection unit may set the reference position based on the output value of the first acceleration sensor or the second acceleration sensor acquired by the determination unit and the output value of the third acceleration sensor. By doing in this way, the angle with respect to the perpendicular direction of the position where the to-be-detected part was provided can be calculated based on the gravitational acceleration applied to the crank from which the to-be-detected part was detected. Therefore, it is not necessary to investigate the angle in the vertical direction of the bicycle frame or to measure it with a protractor.

  Moreover, you may have the filter part which filters the output value of a 1st acceleration sensor and the output value of a 2nd acceleration, and the delay angle correction | amendment part which performs an angle correction process after a filter process is performed. By doing so, it is possible to remove acceleration components other than gravitational acceleration and acceleration of centrifugal force applied to the crank due to vibration and the like, and the detection accuracy of the next measurement timing can be improved. The delay generated by the filter process can be corrected by the delay angle correction unit.

  The rotation angle detection method according to an embodiment of the present invention includes a crank from a first acceleration sensor and a second acceleration sensor arranged on a member that rotates in conjunction with a crank or a crank attached to a rotation shaft in the acquisition step. The acceleration in the direction parallel to the longitudinal direction is acquired, and in the reference position detection step, it is detected that the crank is at a predetermined reference position. Then, in the determination step, the next measurement timing of the measurement unit that performs a predetermined measurement at an appropriate angular position of the crank is detected in the output value of the first acceleration sensor, the output value of the second acceleration sensor, and the reference position detection step. A determination is made based on the result and the next measurement angle. In this way, the acceleration component of the centrifugal force in the longitudinal direction (detection axis direction) of the crank of the acceleration sensor can be calculated. Therefore, the next measurement timing (time until the next measurement timing) can be calculated based on the acceleration component of the centrifugal force and the next measurement angle. In addition, since the next measurement timing is determined based on the reference position, the offset of the measurement timing generated due to the characteristics of the acceleration sensor, the power supply voltage fluctuation, etc. can be taken into account, and the measurement timing can be calculated with high accuracy. . In addition, since no magnet is used, the cost can be reduced, and since it is not affected by dust or iron sand, durability can be improved. Further, since the angular velocity sensor is not used, the power consumption can be reduced.

  Further, a rotation angle detection program that causes a computer to execute the rotation angle detection method described above may be used. By doing so, the acceleration component of the centrifugal force in the longitudinal direction (detection axis direction) of the crank of the acceleration sensor can be calculated using a computer. Therefore, the next measurement timing (time until the next measurement timing) can be calculated based on the acceleration component of the centrifugal force and the next measurement angle. In addition, since the next measurement timing is determined based on the reference position, the offset of the measurement timing generated due to the characteristics of the acceleration sensor, the power supply voltage fluctuation, etc. can be taken into account, and the measurement timing can be calculated with high accuracy. . In addition, since no magnet is used, the cost can be reduced, and since it is not affected by dust or iron sand, durability can be improved. Further, since the angular velocity sensor is not used, the power consumption can be reduced.

  The rotation angle detection program described above may be stored in a computer-readable recording medium. In this way, the program can be distributed as a single unit in addition to being incorporated in the device, and version upgrades can be easily performed.

  A bicycle 1 including a cycle computer 201 having a rotation angle detection device according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the bicycle 1 includes a frame 3, a front wheel 5, a rear wheel 7, a handle 9, a saddle 11, a front fork 13, and a drive mechanism 101.

  The frame 3 is composed of two truss structures. The frame 3 is rotatably connected to the rear wheel 7 at the rear end portion. A front fork 13 is rotatably connected in front of the frame 3.

  The front fork 13 is connected to the handle 9. The front fork 13 and the front wheel 5 are rotatably connected at the front end position of the front fork 13 in the downward direction.

  The front wheel 5 has a hub part, a spoke part, and a tire part. The hub portion is rotatably connected to the front fork 13. And this hub part and the tire part are connected by the spoke part.

  The rear wheel 7 has a hub part, a spoke part, and a tire part. The hub portion is rotatably connected to the frame 3. And this hub part and the tire part are connected by the spoke part. The hub portion of the rear wheel 7 is connected to a sprocket 113 described later.

  The bicycle 1 has a drive mechanism 101 that converts a stepping force (stepping force) by a user (driver) 's foot into a driving force of the bicycle 1. The drive mechanism 101 includes a pedal 103, a crank mechanism 104, a chain ring 109, a chain 111, and a sprocket 113.

  The pedal 103 is a part in contact with a foot for the user to step on. The pedal 103 is supported so as to be rotatable by a pedal crankshaft 115 of the crank mechanism 104.

  The crank mechanism 104 includes a crank 105, a crankshaft 107, and a pedal crankshaft 115 (see FIGS. 2, 4, and 10).

  The crankshaft 107 passes through the frame 3 in the left-right direction (from one side of the bicycle side to the other). The crankshaft 107 is rotatably supported by the frame 3. That is, it becomes the rotating shaft of the crank 105.

  The crank 105 is provided at a right angle to the crankshaft 107. The crank 105 is connected to the crankshaft 107 at one end.

  The pedal crankshaft 115 is provided at a right angle to the crank 105. The axial direction of the pedal crankshaft 115 is the same as that of the crankshaft 107. The pedal crankshaft 115 is connected to the crank 105 at the other end of the crank 105.

  The crank mechanism 104 has such a structure on the side opposite to the side surface of the bicycle 1. That is, the crank mechanism 104 has two cranks 105 and two pedal crankshafts 115. Therefore, the pedal 103 is also provided on each side of the bicycle 1.

  When distinguishing whether these are on the right side or the left side of the bicycle 1, they are described as a right crank 105R, a left crank 105L, a right pedal crankshaft 115R, a left pedal crankshaft 115L, a right pedal 103R, and a left pedal 103L, respectively. To do.

  The right crank 105R and the left crank 105L are connected so as to extend in opposite directions around the crankshaft 107. The right pedal crankshaft 115R, the crankshaft 107, and the left pedal crankshaft 115L are formed in parallel and on the same plane. The right crank 105R and the left crank 105L are formed in parallel and on the same plane.

  The chain ring 109 is connected to the crankshaft 107. The chain ring 109 is preferably constituted by a variable gear capable of changing the gear ratio. A chain 111 is engaged with the chain ring 109.

  The chain 111 is engaged with the chain ring 109 and the sprocket 113. The sprocket 113 is connected to the rear wheel 7. The sprocket 113 is preferably composed of a variable gear.

  The bicycle 1 uses the drive mechanism 101 to convert the user's stepping force into the rotational force of the rear wheels.

  The bicycle 1 has a cycle computer 201 and a measurement module 301 (see also FIG. 2).

  The cycle computer 201 is disposed on the handle 9. As shown in FIG. 2, the cycle computer 201 includes a cycle computer display unit 203 that displays various types of information and a cycle computer operation unit 205 that receives user operations.

  The various types of information displayed on the cycle computer display unit 203 include the speed of the bicycle 1, position information, the distance to the destination, the estimated arrival time to the destination, the travel distance since the departure, and the elapsed time since the departure. These are time, propulsive force, loss power, efficiency, etc. for each angle of the crank 105.

  Here, the propulsive force is the magnitude of the force applied in the rotation direction of the crank 105. On the other hand, the loss force is a magnitude of a force applied in a direction different from the rotation direction of the crank 105. The force applied in a direction different from the rotational direction is a useless force that does not contribute to the driving of the bicycle 1. Therefore, the user can drive the bicycle 1 more efficiently by increasing the propulsive force as much as possible and decreasing the loss force as much as possible. That is, these forces are loads applied to the crank 105 when the crank 105 rotates.

  The cycle computer operation unit 205 is shown as a push button in FIG. 2, but is not limited thereto, and various input means such as a touch panel or a plurality of input means can be used in combination.

  The cycle computer 201 also has a cycle computer wireless reception unit 209. The cycle computer wireless reception unit 209 is connected to the main body portion of the cycle computer 201 through wiring. Note that the cycle computer wireless reception unit 209 does not need to have a reception-only function. For example, you may have a function as a transmission part. Hereinafter, an apparatus described as a transmission unit or a reception unit may also have both a reception function and a transmission function.

  The measurement module 301 is provided on the inner surface of the crank 105, for example, and a human power (stepping force) applied by the user to the pedal 103 using a strain gauge 369 (see FIGS. 3 and 10) configured from a plurality of strain gauge elements. Is detected. Specifically, a propulsive force that is the rotational force of the crank 105 and serves as the driving force of the bicycle 1 and a loss force that is a force applied in a direction different from the rotational direction are calculated. The measurement module 301 also detects the measurement timing of propulsive force and loss force using an acceleration sensor 371 described later. That is, the detection (calculation) of the propulsive force and the loss force is a predetermined measurement according to the present embodiment.

  The measurement module 301 includes a magnetic sensor 373 that detects the approach of the magnet 503 provided on the frame 3 of the bicycle 1 (see FIG. 3). The magnetic sensor 373 detects the position of the magnet 503 by being turned on by the approaching magnet 503. That is, when the magnetic sensor 373 is turned on, the crank 105 is also present at the position where the magnet 503 is present. Therefore, the cycle computer 201 can obtain cadence [rpm] from the output of the magnetic sensor 373. That is, the measurement module 301 also has a cadence sensor function.

  FIG. 3 is a block diagram of the cycle computer 201 and the measurement module 301.

  First, the block configuration of the measurement module 301 will be described. As illustrated in FIG. 3, the measurement module 301 includes a measurement module wireless transmission unit 309, a measurement module control unit 351, a measurement module storage unit 353, a power sensor 368, an acceleration sensor 371, and a magnetic sensor 373.

  The measurement module wireless transmission unit 309 is a rotation angle of the crank 105 calculated based on the propulsive force and loss force calculated from the strain information by the measurement module control unit 351 and the measurement timing calculated (detected) from the output information of the acceleration sensor 371. In addition, the cadence calculated based on the output of the magnetic sensor 373 is transmitted to the cycle computer wireless reception unit 209.

  The measurement module control unit 351 comprehensively controls the measurement module 301. The measurement module control unit 351 includes a propulsive force calculation unit 351a, a measurement timing determination unit 351b, a reference angle detection unit 351c, a transmission data creation unit 351d, and a cadence calculation unit 351e.

  The propulsive force calculation unit 351a calculates the propulsive force and the loss force from the strain information output from the power sensor 368. A method for calculating the propulsive force and the loss force will be described later.

  The measurement timing determination unit 351b calculates (determines) the next measurement timing from the output value of the acceleration sensor 371 and the number of measurements n per m rounds, and controls the timing at which strain information is acquired. A method for calculating the measurement timing will be described later. In the present embodiment, the following description will be given with m = 1 and n = 12. Further, the measurement timing determination unit 351b acquires the output value of the acceleration sensor 371 at a predetermined sampling cycle (predetermined time interval) and stores it in an output value storage unit 357 described later. The predetermined sampling period is shorter than the measurement timing interval.

  The reference angle detection unit 351c detects whether or not the position of the crank 105 is at the reference position. The reference position is detected by receiving an output of an information signal indicating that the magnetic sensor 373 is turned on.

  The transmission data creation unit 351d includes the rotation angle of the crank 105 calculated from the propulsive force and loss force calculated by the propulsive force calculation unit 351a, the next measurement timing calculated by the measurement timing determination unit 351b, and the reference position, Transmission data is created from the cadence calculated by the cadence calculation unit 351e and output to the measurement module wireless transmission unit 309.

  When the cadence calculation unit 351e receives the output of the information signal indicating that the magnetic sensor 373 is turned on, the cadence calculation unit 351e performs the following operation. The cadence calculation unit 351e refers to the value of the counter that it has. Then, cadence is calculated from the counter value. Specifically, the time (cycle) [second] at which the magnetic sensor 373 is turned on is calculated by multiplying the count number (C) of the counter by one count interval (T). Then, cadence [rpm] is calculated by dividing 60 by this period. The counter may be externally provided as a timer or the like. Further, the cadence calculation unit 351e may obtain cadence by a method other than the above. In short, any other method may be used as long as it is obtained from the interval at which the magnetic sensor 373 is turned on.

  Various information is stored in the measurement module storage unit 353. The various types of information are, for example, a control program for the measurement module control unit 351 and temporary information required when the measurement module control unit 351 performs control. In addition to the information described above, the measurement module storage unit 353 also stores a reference angle storage unit 355 and an output value storage unit 357.

  The reference angle storage unit 355 is configured by a nonvolatile memory such as a flash memory, for example, and stores an angle with respect to the vertical direction of the frame 3 on which the magnet 503 is provided. As for the angle of the frame 3 with respect to the vertical direction, a value or the like actually measured using a protractor or the like is stored in advance by referring to a design drawing or specifications of the frame 3 in advance.

  The output value storage unit 357 is configured by, for example, a RAM (Random Access Memory), and stores a plurality of output values of the first acceleration sensor 371a and a plurality of output values of the second acceleration sensor 371b. For example, it is only necessary to store output values acquired at two or more sampling periods such as from the previous measurement timing calculation to the present (measurement timing calculation).

  The magnetic sensor 373 is switched ON / OFF when the magnet 503 approaches. When the magnetic sensor 373 is turned on, the magnetic sensor 373 outputs an information signal indicating that to the measurement module control unit 351.

  The acceleration sensor 371 is bonded to and integrated with the crank 105. The acceleration sensor 371 may be appropriately selected from known methods such as a capacitance type and a piezoresistive type. The acceleration sensor 371 includes a first acceleration sensor 371a and a second acceleration sensor 371b.

  In FIG. 4, the example of arrangement | positioning to the crank 105 of the acceleration sensor 371 in a present Example is shown. The acceleration sensor 371 is bonded to the inner surface 119 of the crank 105. The inner surface of the crank 105 is a surface on which the crankshaft 107 is protruded (connected), and is a surface (side surface) parallel to a plane including a circle defined by the rotational motion of the crank 105. Although not shown in FIG. 4, the outer surface 120 of the crank 105 is a surface on which the pedal crankshaft 115 is protruded (connected) so as to face the inner surface 119. That is, it is a surface on which the pedal 103 is rotatably provided. The upper surface 117 of the crank 105 is one of the surfaces extending in the longitudinal direction in the same direction as the inner surface 119 and the outer surface 120 and orthogonal to the inner surface 119 and the outer surface 120. A lower surface 118 of the crank 105 is a surface facing the upper surface 117. In this embodiment, the acceleration sensor 371 is described as being bonded to the inner surface 119 of the crank 105. However, the acceleration sensor 371 may be bonded to the outer surface 120, the upper surface 117, or the lower surface 118, or provided inside the crank 105. May be.

  The first acceleration sensor 371a and the second acceleration sensor 371b have a detection direction parallel to the longitudinal direction of the crank 105, that is, parallel to the central axis C1 of the inner surface 119 and provided at different distances from the center of the crank shaft 107. It has been. In the example of FIG. 4, the first acceleration sensor 371a is provided at a position closer to the center of the crankshaft 107 than the second acceleration sensor 371b. The first acceleration sensor 371a and the second acceleration sensor 371b have a detection direction that is parallel to the longitudinal direction of the crank 105. Further, the first acceleration sensor 371a and the second acceleration sensor 371b may not be provided on a straight line as shown in FIG.

  The detection result (output) of the acceleration sensor 371 is output to the measurement module control unit 351. At this time, analog information may be converted into digital information by an A / D converter (not shown).

  Here, a method of detecting the next measurement timing by the measurement timing determination unit 351b using the acceleration sensor 371 provided as shown in FIG. 4 will be described with reference to FIGS. FIG. 5 is an explanatory diagram for the acceleration detected by the acceleration sensor 371 when the crank 105 is stationary. The longitudinal direction in FIG. 5 is the longitudinal direction of the crank 105, and the direction toward the tip of the arrow indicates the direction from the crankshaft 107 toward the pedal crankshaft 115. Moreover, in the case of FIG. 5, it is in the state which has stopped at the position shifted | deviated from the perpendicular direction.

In the case of FIG. 5, since the crank 105 is stationary, no centrifugal force is applied, and only the acceleration of gravity is detected by the acceleration sensor 371 (FIG. 5A). However, since the detection direction of the acceleration sensor 371 is parallel to the longitudinal direction of the crank 105, the longitudinal component of the gravitational acceleration is actually detected (FIG. 5B). The longitudinal component of gravitational acceleration is expressed by the following equation (1). The first acceleration sensor 371a and the second acceleration sensor 371b detect the same value.

  Next, when the crank 105 rotates, it becomes as shown in FIG. Here, it is assumed that the first acceleration sensor 371a is provided at a distance r1 from the center of the crankshaft 107, and the second acceleration sensor 371b is provided at a distance r2 from the center of the crankshaft 107. Further, r1 <r2.

  When the crank 105 rotates, centrifugal force is generated in the longitudinal direction of the crank 105 (direction from the crankshaft 107 to the pedal crankshaft 115, that is, the normal direction of rotation of the crank 105) together with the gravitational acceleration. Join. The acceleration of the centrifugal force increases as the distance from the rotation center (center of the crankshaft 107) increases. Further, the acceleration (instantaneous acceleration) obtained by adding the gravitational acceleration and the acceleration of centrifugal force is added to the first acceleration sensor 371a, and the acceleration (acceleration of the gravity acceleration and the acceleration of centrifugal force) is added to the second acceleration sensor 371b. Instantaneous acceleration). As described above, since the detection direction of the acceleration sensor 371 is parallel to the longitudinal direction of the crank 105, the longitudinal component of the instantaneous acceleration is actually detected.

In the case of FIG. 6, if the angular velocity at the time of rotation is ω, the acceleration of the centrifugal force of the first acceleration sensor 371a is the following equation (2), and the acceleration of the centrifugal force of the second acceleration sensor 371b is the following equation (3). Respectively.

The instantaneous acceleration of the first acceleration sensor 371a is expressed by the following equation (4), and the instantaneous acceleration of the second acceleration sensor 371b is expressed by the following equation (5).

Therefore, the detection value (output value) of the first acceleration sensor 371a is expressed by the following equation (6), and the detection value (output value) of the second acceleration sensor 371b is expressed by the following equation (7).

Here, when a2-a1 is set, the acceleration component of gravity can be canceled. That is, the following equation (8) is derived from the equations (2), (3), (6), and (7).

When the equation (8) is transformed, the acceleration of the centrifugal force when the crank 105 in the second acceleration sensor 371b is rotating is expressed by the following equation (9).

Here, when the rotation speed of the crank 105 is R [rpm], the expression (3) is expressed by the expression (10).

Therefore, the rotation speed R is expressed by the following equation (11).

The expression (11) is expressed by the following expression (12) when the expression (9) is substituted.

When the expression (12) is expanded, the following expression (13) is obtained.

Since the part other than a2-a1 in the expression (13) is a constant, the expression (13) can be expressed as the following expression (14) when the calculation result of only the constant is K. The constant K may be stored in advance in a nonvolatile memory or the like in the measurement module control unit 351 and read when calculating the rotation speed R. That is, the rotation speed R is calculated by the measurement timing determination unit 351b by multiplying the output value of the first acceleration sensor 371a by the constant K from the output value of the second acceleration sensor 371b and the square root of the result.

  The time per rotation of the crank 105 (rotation cycle) can be calculated from the rotation speed R calculated by the equation (14). For example, when the rotation speed R is 90 [rpm], one round is 0.6667 seconds. Then, when measuring the propulsive force and loss force every 30 ° of one lap, since one lap is divided into 12 (m = 1, n = 12), the time from one measurement timing to the next measurement timing is 0. .0556 seconds (55.6 milliseconds). Therefore, for example, if the next measurement angle is 30 °, the time of measurement timing every 30 ° is calculated, and the time is set as a time indicating the next measurement timing in a timer (not shown) included in the measurement timing determination unit 351b. By doing so, the next measurement timing can be detected. This next measurement angle need not be calculated every time. In the case of dividing the m circumference (rotation) into n equal parts as in this embodiment, it can be obtained in advance by m / n.

  The above-described method is good when the crank 105 rotates at a constant speed, but in the case of the bicycle 1, the force applied to the pedal 103 by the driver often fluctuates, so that the crank 105 does not always rotate at a constant speed. Therefore, the time indicating the next measurement timing set in the timer is corrected before that time.

  An example is shown in FIG. In FIG. 7, the measurement timing is set every 30 ° of one round. The star in FIG. 7 is the reference position. It is assumed that (a) is 90 rpm, (b) is 91 rpm, and (c) is 92 rpm at three measurement timings (a), (b), and (c) immediately after the reference position.

  First, since it is 90 rpm at the time of (a), the timer is set to 55.5 milliseconds from the rotation period and the number of measurements and started. Then, the rotational speed R is calculated before (b), that is, before 55.5 milliseconds have elapsed. If the calculated result is, for example, 91 rpm, the timer is corrected to 54.9 milliseconds from the rotation period and the number of measurements. Then, the time of (b) is corrected to be shortened by 0.6 milliseconds, and when the timer times out after the corrected time elapses, the measurement timing determining unit 351b calculates the propulsive force and the loss force to the propulsive force calculating unit 351a. The propulsive force, the loss force, and the like are transmitted to the cycle computer 201 via the transmission data creation unit 351d and the measurement module wireless transmission unit 309.

  In (b), the propulsive force calculating unit 351a calculates the propulsive force and the loss force, and the next measurement timing is set to 54.9 milliseconds and started. Then, the rotational speed R is calculated before (c), that is, before 54.9 milliseconds elapses. If the calculated result is, for example, 92 rpm, the timer is corrected to 54.3 milliseconds from the rotation period and the number of measurements. Then, the time of (c) is corrected to be shortened by 0.6 milliseconds, and when the timer times out after the corrected time elapses, the measurement timing determining unit 351b calculates the propulsive force and the loss force to the propulsive force calculating unit 351a. The propulsive force, the loss force, and the like are transmitted to the cycle computer 201 via the transmission data creation unit 351d and the measurement module wireless transmission unit 309. This is repeated thereafter.

  Here, the timing for correcting the timer is, for example, about 95% of the time set in the timer. For example, when the timer is set at 55.5 milliseconds, correction processing is performed when 52.7 milliseconds have elapsed. If the timing for this correction is too late, the correction may not be in time. Of course, it is not limited to 95% and may be changed as appropriate. That is, after the next measurement timing is determined based on the output value a1 of the first acceleration sensor 371a, the output value a2 of the second acceleration sensor 371b, and the number of times of measurement n, until the next measurement timing. The next measurement timing is corrected.

  The output value a1 of the first acceleration sensor 371a and the output value a2 of the second acceleration sensor 371b used for calculating the rotation speed R are not limited to one acquired when calculating the measurement timing, and are used in a plural number. May be. For example, in FIG. 7, when the correction is performed before (b), the output value of the first acceleration sensor 371a and the second value sampled from (l), which is the measurement timing before (a), to just before the correction. The output value of the acceleration sensor 371b may be used. The plurality of output values can be used by calculating an average, for example. In this way, even if noise or the like is included in the output of the acceleration sensor 371, the influence can be reduced. When using a plurality of output values, it is necessary to store the output values in the output value storage unit 357 at predetermined time intervals shorter than the measurement timing, but only by storing the output values of the acceleration sensor 371 in a memory or the like. There is little power consumption because the arithmetic processing such as the above formula is performed only when the timer times out.

  However, if the period in which the plurality of output values a1 of the first acceleration sensor 371a and the plurality of output values a2 of the second acceleration sensor 371b are used is too long, fluctuations in the rotational speed R are difficult to detect. What is necessary is just to use the output value acquired within the time before about 2 sections. Of course, it is not limited to one or two sections, and may be changed as appropriate.

  By the way, the rotational speed R according to the above-described equation (14) may cause an error with respect to the actual rotational speed due to variations in characteristics such as temperature characteristics of the acceleration sensor 371 and fluctuations in the power supply voltage. Therefore, the measurement timing determination unit 351b performs correction using the cadence calculated from the detection interval of the magnet 503 by the cadence calculation unit 351e. This operation will be described with reference to FIG.

  FIG. 8 is a table showing cadence (number of rotations) at each measurement timing when the crank 105 rotates twice. In the table, a to l correspond to a, b, c, and l in FIG. 7, and d to k are codes given to measurement timings (every 30 °) sequentially counterclockwise from c in FIG. 7.

  The first rotation row in FIG. 8 shows the cadence by the acceleration sensor 371, that is, the rotation speed R calculated by the above-described equation (14), and the cadence calculated by the cadence calculation unit 351e, that is, the detection interval of the magnet 503. Is the number of revolutions calculated from As for the cadence by the acceleration sensor 371, the rotation speed R calculated at each measurement timing and the average value thereof are described as AVG. Since the cadence calculated by the cadence calculating unit 351e is calculated once per rotation, it is described in the AVG line.

  Since the cadence calculated by the cadence calculating unit 351e is the rotation speed calculated from the detection interval of the magnet 503, the accuracy is higher than the rotation speed R calculated by the above-described equation (14). Therefore, as described in the second rotation column of FIG. 8, the difference between the average value of the cadence by the acceleration sensor 371 of the first rotation and the cadence calculated by the cadence calculation unit 351e is taken, and the difference is used as an offset. This is reflected in the rotation speed R calculated at each measurement timing of the rotation. The second rotation row in FIG. 8 shows the cadence by the acceleration sensor 371, that is, the rotation speed R calculated by the above-described equation (14), and the cadence by the acceleration sensor 371 with the offset, that is, the corrected rotation speed. , Shows. In the example of FIG. 8, the offset is subtracted, but of course there is a case where the offset is added. That is, the measurement timing includes the output value of the first acceleration sensor 371a and the output value of the second acceleration sensor 371b, the cadence (the number of rotations of the crank 105) calculated by the cadence calculation unit 351e, and every 30 ° (next measurement angle). ) And is determined based on.

  The offset may be calculated not only for each rotation, but may be calculated only for the first time, and the calculated value may be used thereafter, or may be calculated once for a plurality of rotations.

  The cadence calculation unit 351e calculates cadence once per rotation from the detection interval of the magnet 503 as described above. The cadence calculation unit 351e calculates the cadence when it receives an output of an information signal indicating that the magnetic sensor 373 is turned on. Therefore, the position where the magnetic sensor 373 is turned on, that is, the position of the magnet 503 is determined. It becomes the reference position, and the above-described offset is calculated and addition / subtraction is performed when the reference position is detected. The average value of the rotational speed R calculated by the above-described equation (14) is calculated by storing the value calculated at each measurement timing in the measurement module storage unit 353 and at the reference position detection timing. Alternatively, the average value so far may be sequentially calculated at each measurement timing.

In addition, in order to detect the next measurement timing, the reference position is used as the starting angle as shown in FIG. Since the magnet 503 is provided on the frame 3 as described above, an angle θ ₀ with respect to the vertical direction of the frame 3 on which the magnet 503 is provided is used as a reference position as shown in FIG.

The angle θ _{0 of the} reference position is stored in the reference angle storage unit 355 in advance by, for example, referring to the design drawing or specification of the frame 3 or measuring in advance with a protractor or the like. Then, every time the magnetic sensor 373 detects the magnet 503, the reference timing detection unit 351c notifies the measurement timing determination unit 351b that the reference position has been detected, and the measurement timing determination unit 351b notifies the reference angle detection unit 351c of the notification. Then, the next measurement timing is detected by the method described above.

  That is, the magnet 503 functions as a detected unit and the magnetic sensor 373 functions as a detection unit, and the reference angle detection unit 351c, the measurement timing determination unit 351b, and the reference angle storage unit 355 function as a reference position detection unit.

  Note that the reference position is not necessarily an angle that matches the measurement timing that is every 30 ° when the front end of the crank 105 faces directly upward. Accordingly, the next measurement timing of the reference position is not a time corresponding to, for example, 30 °, but a time until an angle corresponding to the latest angle of every 30 ° is set. For example, when the reference position in FIG. 7 is 250 °, the time required for rotation by 20 °, which is the difference up to 270 °, which is the angle every 30 °, is calculated from the rotation speed R. And after 270 degrees, the time to the angle equivalent to the angle for every 30 degrees is set.

  Further, the rotation angle of the crank 105 can be calculated from the angle of the reference position and the angle of the measurement timing which are known in advance. For example, in the case of FIG. 7, if the reference position is 250 °, the angle of the measurement timing is every 30 °, so (a) is calculated as 270 °, (b) is 300 °, and (c) is calculated as 330 °. Is done.

  As is clear from the above description, the measurement module control unit 351 (measurement timing determination unit 351b, reference angle detection unit 351c, transmission data creation unit 351d, cadence calculation unit 351e) and measurement module storage unit 353 (reference angle storage unit) 355, output value storage unit 357), acceleration sensor 371 (first acceleration sensor 371a, second acceleration sensor 371b), magnetic sensor 373, and magnet 503 constitute the measurement timing detection device 310 according to the present embodiment. doing.

  That is, the measurement timing determination unit 351b (determination unit) determines the next measurement timing of the propulsion force calculation unit 351a that performs predetermined measurement 12 times while the crank 105 makes one rotation (one revolution). It is determined based on the output value a1 and the output value a1 of the second acceleration sensor 371b, the number of revolutions calculated from the reference position, and 12 times. Here, from 12 times per rotation, it can be detected that the angle of every 30 ° which is the next measurement angle has been reached. That is, in this embodiment, detection of a predetermined angle is converted into time and detected as measurement timing.

  In this embodiment, the magnetic sensor 373 and the magnet 503 are used as the detecting unit and the detected unit. However, the present invention is not limited to this, and can be installed on the crank 105 and the frame 3 such as an optical sensor or a mechanical sensor. Any sensor capable of detecting one rotation may be used.

  The power sensor 368 includes a strain gauge 369 and a measurement module strain detection circuit 365. The strain gauge 369 is bonded to the crank 105 and integrated. The strain gauge 369 includes a first strain gauge 369a, a second strain gauge 369b, a third strain gauge 369c, and a fourth strain gauge 369d (see FIG. 10 and the like). Each terminal of the strain gauge 369 is connected to the measurement module strain detection circuit 365.

  In FIG. 10, the example of arrangement | positioning to the crank 105 of the strain gauge 369 in a present Example is shown. The strain gauge 369 is bonded to the inner surface 119 of the crank 105.

  The first strain gauge 369a and the second strain gauge 369b have a detection direction parallel to the longitudinal direction of the crank 105, that is, parallel to the central axis C1 of the inner surface 119 and symmetrical to the central axis C1 of the inner surface 119. It is provided to become. The third strain gauge 369c is provided on the central axis C1, and the detection direction is parallel to the central axis C1, and is provided between the first strain gauge 369a and the second strain gauge 369b. The fourth strain gauge 369d is provided on the central axis C1 in the detection direction perpendicular to the longitudinal direction of the crank 105, that is, perpendicular to the central axis C1 of the inner surface 119.

  That is, the direction parallel to the central axis C1 (the longitudinal direction in FIG. 10) that is the axis extending in the longitudinal direction of the crank 105, that is, the direction parallel to the longitudinal direction of the crank 105 is the first strain gauge 369a, The detection direction of the strain gauge 369b and the third strain gauge 369c is the direction perpendicular to the central axis C1 (the lateral direction in FIG. 10), that is, the direction perpendicular to the longitudinal direction of the crank 105, and the detection direction of the fourth strain gauge 369d. It becomes. Accordingly, the detection directions of the first strain gauge 369a to the third strain gauge 369c and the fourth strain gauge 369d are orthogonal to each other.

  In addition, arrangement | positioning of the 1st strain gauge 369a thru | or the 4th strain gauge 369d is not restricted to FIG. In other words, other arrangements may be used as long as a parallel or vertical relationship with the central axis C1 is maintained. However, the first strain gauge 369a and the second strain gauge 369b are arranged symmetrically across the central axis C1, and the third strain gauge 369c and the fourth strain gauge 369d are arranged on the central axis C1, as will be described later. This is preferable because each deformation can be detected with high accuracy.

  In FIG. 10, the crank 105 is described as a simple rectangular parallelepiped, but the corner may be rounded or a part of the surface may be configured by a curved surface depending on the design or the like. Even in such a case, each deformation described later can be detected by arranging the strain gauge 369 so as to maintain the above-described arrangement as much as possible. However, the detection accuracy decreases as the relationship (parallel or vertical) with the center axis C1 is shifted.

  The measurement module strain detection circuit 365 is connected to the first strain gauge 369a, the second strain gauge 369b, the third strain gauge 369c, and the fourth strain gauge 369d, and outputs the strain amount of the strain gauge 369 as a voltage. The output of the measurement module strain detection circuit 365 is converted from analog information to strain information signals that are digital information by an A / D converter (not shown). Then, the strain information signal is output to the propulsive force calculation unit 351a of the measurement module control unit 351.

  An example of the measurement module strain detection circuit 365 is shown in FIG. The measurement module strain detection circuit 365 includes a first detection circuit 373a and a second detection circuit 373b that are two bridge circuits. On the first system side of the first detection circuit 373a, the first strain gauge 369a and the second strain gauge 369b are connected in this order from the power source Vcc. That is, the first strain gauge 369a and the second strain gauge 369b are connected in series with the power supply Vcc. On the second system side, the fixed resistor R and the fixed resistor R are connected in this order from the power source Vcc. On the first system side of the second detection circuit 373b, the third strain gauge 369c and the fourth strain gauge 369d are connected in this order from the power source Vcc. That is, the third strain gauge 369c and the fourth strain gauge 369d are connected in series with the power supply Vcc. On the second system side, the fixed resistor R and the fixed resistor R are connected in this order from the power source Vcc.

  That is, the two fixed resistors R are shared by the first detection circuit 373a and the second detection circuit 373b. Here, the two fixed resistors R have the same resistance value. The two fixed resistors R have the same resistance value as that before the compression or expansion of the strain gauge 369 occurs. The first strain gauge 369a to the fourth strain gauge 369d have the same resistance value.

  As is well known, the resistance value of the strain gauge 369 decreases when it is compressed, and increases when it is expanded. This change in resistance value is proportional when the amount of change is small. The detection direction of the strain gauge 369 is the direction in which the wiring extends, and as described above, the first strain gauge 369a, the second strain gauge 369b, and the third strain gauge 369c are parallel to the central axis C1, The fourth strain gauge 369d is in a direction perpendicular to the central axis C1. When compression or expansion occurs in a direction other than the detection direction, the strain gauge 369 does not change its resistance value.

  When the first detection circuit 373a using the strain gauge 369 having such characteristics is not compressed or expanded in the detection direction of the first strain gauge 369a and the second strain gauge 369b, the first detection gauge 369a and the first strain gauge 369a The potential difference between the potential Vab between the two strain gauges 369b and the potential Vr between the two fixed resistors R is almost zero.

  When the first strain gauge 369a is compressed and the second strain gauge 369b is expanded, the resistance value of the first strain gauge 369a decreases and the resistance value of the second strain gauge 369b increases. It becomes higher and the potential Vr does not change. That is, a potential difference is generated between the potential Vab and the potential Vr. When the first strain gauge 369a is expanded and the second strain gauge 369b is compressed, the resistance value of the first strain gauge 369a increases and the resistance value of the second strain gauge 369b decreases. The potential Vr does not change. That is, a potential difference is generated between the potential Vab and the potential Vr.

  When both the first strain gauge 369a and the second strain gauge 369b are compressed, the resistance value of both the first strain gauge 369a and the second strain gauge 369b decreases, so the potential difference between the potential Vab and the potential Vr is almost zero. It becomes. When both the first strain gauge 369a and the second strain gauge 369b are extended, the resistance value of both the first strain gauge 369a and the second strain gauge 369b increases, so that the potential difference between the potential Vab and the potential Vr is almost zero. It becomes.

  The second detection circuit 373b operates similarly to the first detection circuit 373a. That is, when the third strain gauge 369c is compressed and the fourth strain gauge 369d is expanded, the potential Vcd is increased, the potential Vr is decreased, and a potential difference is generated between the potential Vcd and the potential Vr. When the third strain gauge 369c is expanded and the fourth strain gauge 369d is compressed, the potential Vcd is decreased, the potential Vr is increased, and a potential difference is generated between the potential Vcd and the potential Vr. When both the third strain gauge 369c and the fourth strain gauge 369d are compressed and when both the third strain gauge 369c and the fourth strain gauge 369d are expanded, the potential difference between the potential Vcd and the potential Vr becomes almost zero. .

  Therefore, the first detection circuit includes a connection point between the first strain gauge 369a and the second strain gauge 369b where the potential Vab of the first detection circuit 373a can be measured, and a connection point between the two fixed resistors R capable of measuring the potential Vr. The output of 373a (hereinafter referred to as A output). The connection point between the third strain gauge 369c and the fourth strain gauge 369d that can measure the potential Vcd of the second detection circuit 373b, and the connection point of the two fixed resistors R that can measure the potential Vr are represented by the second detection circuit 373b. Output (hereinafter referred to as B output). The A output and B output become strain information.

  FIG. 12 shows a deformed state of the right crank 105R when a force (stepping force) is applied by the user. (A) is a plan view seen from the upper surface 117 of the right crank 105R, (b) is a plan view seen from the inner surface 119 of the right crank 105R, and (c) is seen from the end of the right crank 105R on the crankshaft 107 side. It is a top view. In the following description, the right crank 105R will be described, but the same applies to the left crank 105L.

  When a pedaling force is applied from the user's foot via the pedal 103, the pedaling force becomes a rotational force of the crank 105, a propulsive force Ft that is a tangential force of the rotation of the crank 105, and a normal direction of the rotation of the crank 105 And the loss power Fr. At this time, the deformation state of bending deformation x, bending deformation y, tensile deformation z, and torsional deformation rz occurs in the right crank 105R.

  As shown in FIG. 12A, the bending deformation x is a deformation in which the right crank 105R is bent so as to bend from the upper surface 117 toward the lower surface 118 or from the lower surface 118 toward the upper surface 117. Is a deformation caused by That is, distortion due to deformation generated in the rotation direction of the crank 105 (distortion generated in the rotation direction of the crank 105) is detected, and rotation direction distortion generated in the crank 105 can be detected by detecting the bending deformation x. As shown in FIG. 12B, the bending deformation y is a deformation in which the right crank 105R bends from the outer surface 120 toward the inner surface 119 or from the inner surface 119 toward the outer surface 120, and the loss force Fr. Is a deformation caused by That is, distortion caused by deformation generated from the outer surface 120 of the crank 105 to the inner surface 119 or from the inner surface 119 to the outer surface 120 (strain generated in a direction perpendicular to a plane including a circle defined by the rotational motion of the right crank 105R). Therefore, it is possible to detect the inward and outward strain generated in the crank 105 by detecting the bending deformation y.

  The tensile deformation z is a deformation that is caused by the right crank 105R being stretched or compressed in the longitudinal direction, and is caused by the loss force Fr. That is, the strain due to the deformation generated in the direction in which the crank 105 is pulled or pushed in the longitudinal direction (strain generated in the direction parallel to the longitudinal direction) is detected. The strain in the tensile direction can be detected. The torsional deformation rz is that the right crank 105R is deformed so as to be twisted, and is generated by the propulsive force Ft. That is, distortion due to deformation generated in the direction in which the crank 105 is twisted is detected, and distortion in the torsion direction generated in the crank 105 can be detected by detecting the torsional deformation rz. In FIG. 12, the deformation directions of the bending deformation x, the bending deformation y, the tensile deformation z, and the torsional deformation rz are indicated by arrows. However, as described above, each deformation may occur in the direction opposite to the arrow. .

  Therefore, in order to measure the propulsive force Ft, either the bending deformation x or the torsional deformation rz is measured, and in order to measure the loss force Fr, either the bending deformation y or the tensile deformation z is quantitatively detected. Good.

  Here, the measurement module strain detection circuit 365 is arranged as shown in FIG. 10 and connected to the first strain gauge 369a, the second strain gauge 369b, the third strain gauge 369c, and the fourth strain gauge 369d as shown in FIG. A method for detecting (measuring) the bending deformation x, the bending deformation y, the tensile deformation z, and the torsional deformation rz will be described.

  First, how each deformation is detected (measured) in the output A of the first detection circuit 373a will be described. In the bending deformation x, the right crank 105R is deformed from the upper surface 117 toward the lower surface 118 or in the opposite direction. When the right crank 105R is deformed from the upper surface 117 toward the lower surface 118, the first strain gauge 369a is compressed and thus the resistance value is decreased, and the second strain gauge 369b is expanded and the resistance value is increased. Therefore, the output A of the first detection circuit 373a is a positive output (the potential Vab is high and the potential Vr is low). Further, when the right crank 105R is deformed from the lower surface 118 toward the upper surface 117, the first strain gauge 369a is expanded and thus the resistance value is increased, and the second strain gauge 369b is compressed and the resistance value is decreased. Therefore, the output A of the first detection circuit 373a is a negative output (the potential Vab is low and the potential Vr is high).

  In the bending deformation y, the right crank 105R is deformed from the outer surface 120 toward the inner surface 119 or in the opposite direction. When the right crank 105R is deformed from the outer surface 120 toward the inner surface 119, since both the first strain gauge 369a and the second strain gauge 369b are compressed, the resistance value of both decreases. Therefore, the output A of the first detection circuit 373a is zero (there is no potential difference between the potential Vab and the potential Vr). Further, when the right crank 105R is deformed from the inner surface 119 toward the outer surface 120, both the first strain gauge 369a and the second strain gauge 369b are stretched, so that the resistance value of both increases. For this reason, the output A of the first detection circuit 373a is zero.

  The tensile deformation z is deformed so that the right crank 105R is stretched or compressed in the longitudinal direction. When the right crank 105R is extended, both the first strain gauge 369a and the second strain gauge 369b are extended, so that the resistance value of both increases. For this reason, the output A of the first detection circuit 373a is zero. Further, when the right crank 105R is compressed, both the first strain gauge 369a and the second strain gauge 369b are compressed, so that the resistance value of both decreases. For this reason, the output A of the first detection circuit 373a is zero.

  The torsional deformation rz deforms so that the right crank 105R is twisted. When the right crank 105R is twisted in the direction of the arrow in FIG. 12B, both the first strain gauge 369a and the second strain gauge 369b are stretched, so that the resistance value of both increases. For this reason, the output A of the first detection circuit 373a is zero. Further, when the right crank 105R is twisted in the direction opposite to the arrow in FIG. 12B, both the first strain gauge 369a and the second strain gauge 369b are expanded, so that the resistance value of both increases. For this reason, the output A of the first detection circuit 373a is zero.

  As described above, only the bending deformation x is detected from the A output. That is, the first detection circuit 373a is connected to the first strain gauge 369a and the second strain gauge 369b, and detects the rotational strain generated in the crank 105.

  Next, how each deformation is detected (measured) in the B output of the second detection circuit 373b will be described. In the bending deformation x, the right crank 105R is deformed from the upper surface 117 toward the lower surface 118 or in the opposite direction. When the right crank 105R is deformed from the upper surface 117 toward the lower surface 118, since the third strain gauge 369c and the fourth strain gauge 369d are only bent, the resistance value does not change because they are neither compressed nor expanded in the detection direction. Therefore, the B output of the second detection circuit 373b is zero. In addition, when the right crank 105R is deformed from the lower surface 118 toward the upper surface 117, the third strain gauge 369c and the fourth strain gauge 369d are only bent, so that the resistance value does not change because they are neither compressed nor expanded in the detection direction. Therefore, the B output of the second detection circuit 373b is zero.

  In the bending deformation y, the right crank 105R is deformed from the outer surface 120 toward the inner surface 119 or in the opposite direction. When the right crank 105R is deformed from the outer surface 120 toward the inner surface 119, the third strain gauge 369c is compressed and thus the resistance value is decreased, and the fourth strain gauge 369d is expanded and the resistance value is increased. Therefore, the B output of the second detection circuit 373b is a positive output (the potential Vcd is high and the potential Vr is low). Further, when the right crank 105R is deformed from the inner surface 119 toward the outer surface 120, the third strain gauge 369c is expanded and thus the resistance value is increased, and the fourth strain gauge 369d is compressed and the resistance value is decreased. Therefore, the output B of the second detection circuit 373b is a negative output (the potential Vcd is low and the potential Vr is high).

  The tensile deformation z is deformed so that the right crank 105R is stretched or compressed in the longitudinal direction. When the right crank 105R is extended, the third strain gauge 369c is extended and the resistance value is increased, and the fourth strain gauge 369d is compressed and the resistance value is decreased. Therefore, the B output of the second detection circuit 373b is a negative output. When the right crank 105R is compressed, the third strain gauge 369c is compressed and thus the resistance value is decreased, and the fourth strain gauge 369d is expanded and the resistance value is increased. Therefore, the B output of the second detection circuit 373b is a positive output.

  The torsional deformation rz deforms so that the right crank 105R is twisted. When the right crank 105R is twisted in the direction of the arrow in FIG. 12B, the third strain gauge 369c is expanded, so that the resistance value increases, and the fourth strain gauge 369d is not deformed in the detection direction, so the resistance value does not change. . Therefore, the B output of the second detection circuit 373b is a negative output. Further, when the right crank 105R is twisted in the direction opposite to the arrow in FIG. 12B, the third strain gauge 369c is expanded, so that the resistance value increases, and the fourth strain gauge 369d is not deformed in the detection direction, so that the resistance value is increased. Does not change. Therefore, the B output of the second detection circuit 373b is a negative output.

  As described above, the bending deformation y, the tensile deformation z, and the torsional deformation rz are detected from the B output. That is, the second detection circuit 373b is connected to the third strain gauge 369c and the fourth strain gauge 369d, and detects the inward / outward strain or tensile strain generated in the crank 105.

Then, from the A output of the first detection circuit 373a and the B output of the second detection circuit 373b, the propulsive force calculation unit 351a determines that the propulsive force Ft is the following equation (15) and the loss force Fr is the following (16). Each is calculated by an equation. The tensile deformation z is very small compared to the bending deformation y and can be ignored. That is, the values calculated by the equations (15) and (16) are values relating to the load applied to the crank 105 when the crank 105 rotates.

Here, A is the A output value at the time of calculating the propulsive force Ft (or loss force Fr), A0 is the A output value at no load, and B is B at the time of calculating the propulsive force Ft (or loss force Fr). The output value, B0 is the B output value when there is no load, p, q, s, u are coefficients, and are values calculated by simultaneous equations consisting of the following equations (17) to (20).

  Here, Am is an A output value when m [kg] is put on the pedal 103 with the angle of the crank 105 facing forward in the horizontal direction (a state where the crank 105 is horizontal and extends in the direction of the front wheel 5). Be is the B output value when the angle of the crank 105 is horizontally forward and m [kg] is placed on the pedal 103. Ae is an A output value when m [kg] is placed on the pedal 103 with the angle of the crank 105 being vertically downward (a state in which the crank 105 extends vertically and toward the ground). Bm is the B output value when the angle of the crank 105 is vertically downward and m [kg] is placed on the pedal 103.

  Since the coefficients p, q, s, u, and A0 and B0 are values that can be calculated or measured in advance, the propulsive force Ft can be calculated by substituting A and B into the equation (15).

  In the equation (15), the A output is corrected using the B output. In equation (16), the B output is corrected using the A output. Thereby, the influence of distortion other than the detection target contained in the 1st detection circuit 373a or the 2nd detection circuit 373b can be excluded. If the first strain gauge 369a and the second strain gauge 369b are not displaced in the crank direction (the direction parallel to the central axis C1), Ae = A0 and correction by the B output is not necessary.

  The arrangement of the strain gauges 369 and the configuration of the bridge circuit are not limited to the configurations shown in FIGS. For example, the number of strain gauges 369 is not limited to four, and the number of bridge circuits is not limited to one. In short, any configuration that can calculate the propulsive force Ft and the loss force Fr may be used.

  Next, the block configuration of the cycle computer 201 will be described. As illustrated in FIG. 3, the cycle computer 201 includes a cycle computer display unit 203, a cycle computer operation unit 205, a cycle computer wireless reception unit 209, a cycle computer storage unit 253, and a cycle computer control unit 251.

  The cycle computer display unit 203 displays various types of information based on user instructions and the like. In this embodiment, the propulsive force Ft and the loss force Fr are visualized and displayed. The visualization method may be any method, but based on the rotation angle of the crank 105 transmitted from the measurement module 301, for example, the propulsive force Ft and the loss when the rotation angle of the crank 105 is 30 °. The force Fr can be displayed as a vector. As other methods, for example, any method such as graph display, color-coded display, symbol display, and three-dimensional display may be used. Also, a combination thereof may be used.

  The cycle computer operation unit 205 receives a user instruction (input). For example, the cycle computer operation unit 205 receives a display content instruction from the user on the cycle computer display unit 203.

  The cycle computer radio reception unit 209 receives transmission data (propulsion force Ft and loss force Fr, rotation angle of the crank 105 and cadence) transmitted from the measurement module 301.

  Various information is stored in the cycle computer storage unit 253. The various information is, for example, a control program of the cycle computer control unit 251 and temporary information required when the cycle computer control unit 251 performs control. The cycle computer storage unit 253 has a RAM and a ROM. The ROM stores a control program and various parameters, constants, and the like for converting the propulsive force Ft and the loss force Fr into data that is visually displayed on the cycle computer display unit 203.

  The cycle computer control unit 251 comprehensively controls the cycle computer 201. Further, the measurement module 301 may be comprehensively controlled. The cycle computer control unit 251 converts the propulsive force Ft and the loss force Fr into data that is visually displayed on the cycle computer display unit 203.

  Next, processing of the measurement module 301 and the cycle computer 201 will be described with reference to FIG. The process of FIG. 13 may be executed by software (computer program) operating on a CPU built in the measurement module control unit 351 or the cycle computer control unit control unit 251 or may be executed by hardware. First, the process of the measurement module 301 is shown in FIG. In step ST11, the measurement timing is detected. That is, the values detected by the first acceleration sensor 371a and the second acceleration sensor 371b are acquired by the method described above. Then, the rotational speed R is calculated, the time from the rotational speed R to the next measurement timing is calculated and set in the timer, the time when the timer times out after correction is performed is the measurement timing detection. In this step, correction corresponding to the correction unit described above is also performed. That is, step ST11 functions as an acquisition process and an output process.

  Next, in step ST13, the measurement module strain detection circuit 365 is driven. That is, a power supply voltage is applied to the bridge circuit as shown in FIG.

  Next, in step ST15, the propulsive force Ft and the loss force Fr are calculated based on the output (A output, B output) from the measurement module strain detection circuit 365.

  Next, in step ST17, the transmission data creation unit 351d transmits the calculated propulsive force Ft, loss force Fr, rotation angle, and cadence as transmission data via the measurement module wireless transmission unit 309. The transmitted propulsive force Ft and loss force Fr, rotation angle, and cadence are received by the cycle computer radio reception unit 209 of the cycle computer 201. Note that the cadence need not be transmitted every time and may be transmitted once per rotation, so in the present embodiment, it may be transmitted once every 12 times.

  Details of the measurement timing detection process of FIG. 13A are shown in FIG. Although it is basically as described above, it is collectively shown in a flowchart. First, in step ST31, it is determined whether or not the reference position has been detected. If it is detected (YES), the process proceeds to step ST32. If not detected (NO), the process waits in this step.

  Next, in step ST32, based on the output value of the first acceleration sensor 371a and the output value of the second acceleration sensor 371b, the rotational speed R is calculated from the above-described equation (14).

  Next, in step ST33, a cycle of one rotation is calculated from the rotation speed R calculated in step ST32, a timer set value is calculated and set from the cycle, and the timer is started.

  Next, in step ST34, the rotational speed R is calculated before the set time of the timer set in step ST33.

  Next, in step ST35, it is determined whether or not timer correction is necessary. If necessary (YES), the process proceeds to step ST36, and if not necessary (NO), the process proceeds to step ST37. In this step, a cycle of one rotation is calculated from the rotation speed R calculated in step ST34, a timer set value is calculated from the cycle, and correction is necessary if the value is different from the value set in the timer in step ST33. to decide.

  Next, in step ST36, the timer set value is corrected. That is, a value based on the timer set value calculated in step ST35 is set in the timer.

  Next, in step ST37, it is determined whether or not the reference position has been detected. If it is detected (YES), the process proceeds to step ST38, and if not (NO), the process proceeds to step ST39. In this step, it is determined whether or not the offset calculation is performed at the reference position described above. Since the reference position often exists during the measurement timing, it is performed before the timer times out. Of course, when the reference position coincides with the measurement timing (for example, when the reference position has an angle of every 30 °), it may be performed in step ST39 described later.

  Next, in step ST38, an offset is calculated from the average value of the cadence (rotation speed) calculated by the cadence calculation unit 351e and the rotation speed R calculated at each measurement timing, and calculation (addition / subtraction) based on the offset is performed. .

  Next, in step ST39, it is determined whether or not the timer has timed out. If timed out (in the case of YES), the process returns to step ST33, and the operations after step ST13 in FIG. On the other hand, when the timeout does not occur (in the case of NO), the process returns to step ST37.

  Further, the cycle computer control unit 251 of the cycle computer 201 performs the process of FIG. In step ST71, when the cycle computer control unit 251 receives the propulsive force Ft, the loss force Fr, the rotation angle, or the cadence, an interruption is performed. That is, when the cycle computer control unit 251 detects that the cycle computer wireless reception unit 209 has received the propulsive force Ft, the loss force Fr, the rotation angle, or the cadence, the cycle computer control unit 251 interrupts the processing up to that point ( Interrupt) to start the processing from step ST73.

  Next, in step ST73, the cycle computer control unit 251 causes the cycle computer display unit 203 to display the propulsive force Ft, the loss force Fr, and the cadence for each rotation angle. The cycle computer display unit 203 displays the propulsive force Ft and the loss force Fr as a vector for each rotation angle of the crank 105, or displays a cadence value as a numerical value.

  For example, the magnitudes of the propulsive force Ft and the loss force Fr are displayed with arrows or the like at every predetermined rotation angle (30 °) of the crank 105.

  Next, in step ST75, the cycle computer control unit 251 stores the propulsive force Ft, the loss force Fr, and the cadence in the cycle computer storage unit 253 of the cycle computer storage unit 253. Thereafter, the cycle computer control unit 251 performs other processes until the interrupt of step ST51 is performed again.

  According to the present embodiment, the first acceleration sensor 371a and the second acceleration sensor 371b are arranged on the crank 105 attached to the crankshaft 107, detect accelerations a1 and a2 in a direction parallel to the longitudinal direction of the crank 105, The propulsive force calculation unit 351a measures the propulsive force and the loss force 12 times while the crank 105 rotates once. Then, the measurement timing determination unit 351b is calculated from the output value a1 of the first acceleration sensor 371a and the output value a2 of the second acceleration sensor 371b, and the period at which the magnetic sensor 373 detects that the crank 105 is at the reference position. The rotation speed R of the crank 105 is calculated based on the cadence and 12 measurement times within one rotation, and the next measurement timing of the propulsive force calculating unit 351a is calculated based on the rotation speed R and the 12 measurement times. To decide. By doing so, the acceleration component of the centrifugal force in the longitudinal direction (detection axis direction) of the crank of the acceleration sensor 371 can be calculated. Therefore, the rotation speed R can be calculated based on the acceleration component of the centrifugal force, and the rotation period is calculated from the rotation speed R to calculate the measurement interval per time, that is, the time until the next measurement timing. be able to. In addition, since the next measurement timing is determined from the cadence calculated based on the reference position, the offset of the measurement timing generated due to the characteristics of the acceleration sensor 371, power supply voltage fluctuation, etc. can be taken into account, and the measurement timing is accurately determined. It can be calculated well. In addition, since no magnet is used for angle detection itself, the cost can be reduced and it is not affected by dust or iron sand, so that durability can be improved. Further, since the angular velocity sensor is not used, the power consumption can be reduced.

  Further, since the angular velocity sensor is not used, the power consumption can be reduced. An angular velocity sensor, such as a gyro sensor, generally consumes more power than an acceleration sensor because a vibrator or the like must be constantly vibrated. Therefore, as in this embodiment, by detecting the rotation angle only with the acceleration sensor 371, the power consumption can be reduced and the driving time of the battery or the like can be extended.

  Further, since the power sensor 368 is operated when the detected rotation angle is an angle of every 30 °, the operation period of the power sensor 368 can be limited, and the power consumption can be further reduced.

  Further, the measurement timing determination unit 351b is calculated from the output value a1 of the first acceleration sensor 371a and the output value a2 of the second acceleration sensor 371b, and the period at which the magnetic sensor 373 detects that the crank 105 is at the reference position. Based on the cadence and the measurement count of 12, the measurement timing of the propulsive force calculation unit 351a is corrected before the next measurement timing determined. By doing so, it is possible to correct the measurement timing once determined due to a change in the rotational speed R or the like, and to increase the measurement timing determination accuracy.

  In addition, the measurement timing determination unit 351b detects a plurality of output values a1 of the first acceleration sensor 371a and a plurality of output values a2 of the second acceleration sensor 371b, and a period at which the magnetic sensor 373 detects that the crank 105 is at the reference position. The next measurement timing of the propulsive force calculation unit 351a is determined based on the cadence calculated from the above and the number of measurements 12 times. By doing in this way, the output value a1 of the 1st acceleration sensor 371a and the output value a2 of the 2nd acceleration sensor 371b can be used, and those average values can be used. Therefore, it is possible to make it less susceptible to noise or the like superimposed on the output value of the acceleration sensor 371 as compared with the case where the determination is made only with the instantaneous output value.

  In addition, the reference position detection unit that sets the reference position of the rotation angle of the crank 105 includes a magnet 503 that is fixedly disposed on the frame 3 and a magnetic sensor 373 that is disposed on the crank 105 and detects the magnet 503. Configured. By doing so, the cadence calculation unit 351e can calculate the cadence based on the detection interval of the magnet 503. In addition, a reference for detecting the measurement timing can be set. Further, the position of the frame 3 can be set as the reference position.

  In the above-described embodiment, the first acceleration sensor 371a and the second acceleration sensor 371b are disposed on one crank 105, but one acceleration sensor is provided for each of the cranks 105 on both sides, that is, the crank 105R and the crank 105L. May be arranged. In this case, the absolute value of the distance from the crankshaft 107 of each acceleration sensor may be the same. The distance from the crankshaft 107 may be expressed as a positive number for one crank and a negative number for the other crank. Further, the measured value a (a1 or a2) of the acceleration sensor on the side where the distance is expressed by a negative number may be expressed by multiplying by a negative number (-1).

  In the above-described embodiment, the crank 105 has an angle obtained by dividing one rotation (one revolution) into 12 equal parts. However, the angle is not limited to one rotation, and an angle obtained by equally dividing two rotations into 12 equal parts. Also good. Further, in the above-described embodiments, the measurement timings are equal intervals, but may not be equal intervals. If the output value a1 of the first acceleration sensor 371a, the output value a2 of the second acceleration sensor 371b, and the next measurement angle are known, the next measurement timing can be determined therefrom.

  Next, a rotation angle detection apparatus according to a second embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment, the angle of the frame 3 provided with the magnet 503 with respect to the vertical direction needs to be measured in advance using a protractor or the like by referring to the design drawing and specifications of the frame in advance. Then, the point which measures the angle with respect to the perpendicular direction of the flame | frame 3 is different, without requiring them.

  The configuration of this embodiment is shown in FIG. In FIG. 14, a third acceleration sensor 371c, an LED 374, and a setting unit 375 are added to FIG.

  Unlike the first acceleration sensor 371a and the second acceleration sensor 371b, the third acceleration sensor 371c has a detection direction in a direction parallel to the short direction of the crank 105 (a tangential direction of rotation of the crank 105). Further, the third acceleration sensor 371c is not an individual sensor, and one of the first acceleration sensor 371a and the second acceleration sensor 371b may be a biaxial acceleration sensor.

  The LED 374 is a light emitting diode that emits light in response to an information signal indicating that the magnetic sensor 373 is turned on. That is, the LED 374 functions as a notification unit that notifies that the magnetic sensor 373 (detection unit) has detected the magnet 503 (detected unit). Note that the notification unit is not limited to notification by display such as the LED 374 but may be notification by a buzzer or the like.

  The setting unit 375 is configured by, for example, a push button or the like, and can be operated by the user in accordance with lighting of the LED 374. The setting unit 375 functions as a timing instruction unit that instructs the measurement timing determination unit 351b to acquire the output value of the first acceleration sensor 371a or the second acceleration sensor 371b and the output value of the third acceleration sensor 371c.

  When the acceleration sensor 371 is arranged as in the present embodiment, the first acceleration sensor 371a and the second acceleration sensor 371b detect the longitudinal acceleration of the crank 105, and the third acceleration sensor 371c The acceleration in the short direction is detected. FIG. 15 shows an example in the case of gravitational acceleration G. As shown in FIG. 14, the longitudinal acceleration component can be detected by the first acceleration sensor 371a or the second acceleration sensor 371b, and the acceleration component in the short direction can be detected by the third acceleration sensor 371c.

  The relationship between the output values of these accelerations and the rotation angle of the crank 105 is as shown in the graph of FIG. From this graph, the acceleration in the short-side direction has a positive value when 0 ° ≦ θ <180 °, and a negative value when 180 ° ≦ θ <360 °. Therefore, the angle of the frame 3 can be detected by referring to both the acceleration in the longitudinal direction and the acceleration in the short direction.

  Specifically, when the crank 105 is rotationally moved to a position parallel to the frame 3, the magnetic sensor 373 detects the magnet 503. Then, an information signal indicating that the magnetic sensor 373 is turned on is output, and the LED 374 emits light. Therefore, the crank 105 is stopped at that position, and the setting unit 375 is operated. The measurement timing determination unit 351b acquires the gravitational acceleration when the setting unit 375 is operated, calculates the crank angle, that is, the angle of the frame 3, and stores the calculated angle of the frame 3 in the reference angle storage unit 355.

  That is, the setting unit 375 outputs the output value of the first acceleration sensor 371a or the second acceleration sensor 371b and the output value of the third acceleration sensor 371c based on the notification that the LED 374 (notification unit) detects the magnet 503 (detected unit). Is acquired by the measurement timing determination unit 351b. Then, the measurement timing determination unit 351b (reference position detection unit) sets the reference position based on the acquired output value of the first acceleration sensor 371a or the second acceleration sensor 371b and the output value of the third acceleration sensor 371c. doing.

  According to the present embodiment, the third acceleration sensor 371c that detects acceleration in a direction parallel to the short direction of the crank 105, the LED 374 that notifies that the magnetic sensor 373 has detected the magnet 503, and the first acceleration sensor 371a. Alternatively, a setting unit 375 that instructs the timing for acquiring the output value of the second acceleration sensor 371b and the output value of the third acceleration sensor 371c is provided. Then, the setting unit 375 instructs acquisition of the output value of the first acceleration sensor 371a or the second acceleration sensor 371b and the output value of the third acceleration sensor 371c based on the notification that the LED 374 detects the magnet 503, and the measurement timing. The determination unit 351b sets the reference position based on the output value of the first acceleration sensor 371a or the second acceleration sensor 371b and the output value of the third acceleration sensor 371c. By doing in this way, the angle with respect to the vertical direction of the said position is computable based on the gravitational acceleration added to the crank 105 by which the magnet 503 was detected. Therefore, it is not necessary to investigate the angle in the vertical direction of the frame 3 of the bicycle 1 or to measure it with a protractor or the like.

  In the second embodiment, the notification unit and the timing instruction unit are provided in the measurement module 301, but may be provided separately. For example, the cycle computer display unit 203 and the cycle computer operation unit 205 of the cycle computer 201 may also function.

  Next, a rotation angle detection apparatus according to a third embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In this embodiment, as shown in FIG. 17, the output of the acceleration sensor 371 is subjected to a low-pass filter (LPF) process, and the delay caused by the low-pass filter process is corrected by the measurement timing determination unit 351b2. That is, the LPF 372 functions as a filter unit.

  Since various vibrations are applied from the outside to a vehicle provided with a rotation angle detection device such as a bicycle, the acceleration sensor 371 often includes an acceleration component other than the acceleration component of gravity acceleration or centrifugal force in its output value. Accordingly, the output of the acceleration sensor 371 is subjected to low-pass filter processing using a digital filter such as an FIR (finite impulse response) filter or an IIR (infinite impulse response) filter with the LPF 372, thereby causing vibrations included in the output of the acceleration sensor 371. Remove noise components. Of course, an analog filter may be used instead of a digital filter.

  As shown in FIG. 18, since the output value subjected to the digital filter is a value delayed by a certain number of samples depending on the characteristics of the digital filter, the rotation of the crank 105 finally calculated from the measurement timing is output. It is necessary to correct the corner. Therefore, the measurement timing determination unit 351b2 corrects the rotation angle by performing an operation as shown in equation (23) described later. That is, the measurement timing determination unit 351b2 functions as a delay angle correction unit.

For example, when the acceleration of the centrifugal force of r [m] from the center of the crankshaft 107 is a _far [m / sec ² ] with an n-tap FIR filter and a sampling frequency fs [Hz], n / (2 × fs) [Sec] The rotation angle of the previous crank 105 is calculated.

Further, the acceleration a _{far from the} centrifugal force is expressed by equation (21) when the angular velocity is ω, and the angular velocity ω is expressed by equation (22).

Therefore, the correction may be made so that the calculated rotation angle is advanced by equation (23).

For example, in the case of the second acceleration sensor 371b, the acceleration a _{far from the} centrifugal force can be calculated by the equation (9) shown in the first embodiment. Of course, you may obtain | require from the 1st acceleration sensor 371a. In that case, it can be similarly obtained from the equations (7) to (6).

  Alternatively, in determining which half rotation of the crank 105 is in one rotation, the rotation acceleration is calculated by measuring the time between the half rotations, and the acceleration of the centrifugal force for correction is obtained from the value. You may do it. Then, during the half rotation, the acceleration of the centrifugal force calculated from the previous half rotation time is used.

  According to the present embodiment, there is an LPF 372 that performs filter processing on the first acceleration and the second acceleration, and a measurement timing determination unit 351b2 that performs angle correction processing after the filter processing is performed. In this way, acceleration components other than gravitational acceleration and acceleration of centrifugal force applied to the crank 105 due to vibration or the like can be removed, and the accuracy of estimating the next measurement timing can be improved. In addition, the measurement timing determination unit 351b2 can correct the delay generated by the filter processing.

  Next, a rotation angle detection apparatus according to a fourth embodiment of the present invention will be described with reference to FIGS. The same parts as those in the first embodiment described above are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, components that can detect the rotation angle of the crank 105 by detecting the acceleration in the longitudinal direction of the crank 105 in addition to the crank 105 will be described.

  FIG. 19 is a plan view showing the chain ring 109 and the crank 105A according to this embodiment, and FIG. 20 is a plan view showing the crank 105A shown in FIG.

  The crank 105A is attached to the chain ring 109 via a spider arm 77 described later. The chain ring 109 has two large and small sprockets (an example of a front chain wheel) 109a and 109b.

  The crank 105A extends radially from the crankshaft side, and has five spider arms 77 that can mount two large and small sprockets 109a and 109b at the tip, and a pedal crankshaft mounting hole 115a that is fixed to the crankshaft 107 and formed at the tip. And a crank arm 78. The crank 105A is an arm member having a plurality of arm portions extending radially from the crankshaft, and corresponds to a member that rotates in conjunction with the crank. At the tip of the spider arm 77, a sprocket mounting portion 77a having a through hole 77b through which a fixing bolt passes and two mounting surfaces 77c for mounting the sprockets 109a and 109b is formed.

  The large-diameter sprocket 109a has an annular gear member. The gear member is made of, for example, an aluminum alloy material. Gear teeth 86a with which the chain 111 is engaged are formed on the outer periphery of the gear member. The small-diameter sprocket 109b has an annular gear member. The gear member is made of, for example, an aluminum alloy material. Gear teeth 72a with which the chain 111 is engaged are formed on the outer periphery of the gear member.

  19 and 20, the spider arm 77 is formed integrally with the crank arm 78. However, the spider arm 77 is not limited thereto and may be a separate body.

  In the crank 105A having such a configuration, by providing an acceleration sensor on the spider arm 77, it is possible to calculate the next measurement timing and perform timer correction and offset calculation in the same manner as shown in the first embodiment. . One acceleration sensor may be disposed on the spider arm 77, the other may be disposed on the crank arm 78, or both may be disposed on the spider arm 77. However, as shown in the first embodiment, the detection axes of the two acceleration sensors are parallel to the longitudinal direction of the crank arm 78 and are provided on the same right or left side, The distance from the crankshaft center of the acceleration sensor needs to be different.

  In addition, you may arrange | position an acceleration sensor not only to the spider arm 77 but to the pedal crankshaft 115 (pedal shaft). In short, any crank or member that rotates in conjunction with the crank and that can detect the acceleration in the longitudinal direction of the crank is applicable. Here, the interlock means that the same rotation shaft as the crank rotates at the same rotation speed as the crank.

  According to the present embodiment, at least one acceleration sensor is arranged on the spider arm 77, the output value of the acceleration sensor, the output value of the acceleration sensor arranged on the other spider arm 77 or the crank arm 78, and m rounds. The next measurement timing is calculated based on the number of hits n. By doing so, the rotational angle of the crank arm 78 can be obtained even if the acceleration sensor is arranged on a part other than the crank arm 78, and the degree of freedom of the arrangement of the acceleration sensor is increased.

  In the four embodiments described above, the propulsive force, the loss force, and the rotation angle measured by the measurement module 301 are displayed in real time on the cycle computer display unit 203 of the cycle computer 201. However, the present invention is not limited to this. For example, the information output from the measurement module 301 to a recording medium such as a memory card, and the information recorded on the memory card later is read by a personal computer or the like, and the propulsive force and loss force are displayed in time series for each rotation angle of the crank 105. May be.

  In addition, the human-powered machine in the present invention refers to a machine driven by human power including a crank 105 (crank arm 78) such as a bicycle 1 or a fitness bike. In other words, any human-powered machine may be used as long as it is a machine that is driven by a human power equipped with the crank 105 (it is not always necessary to move locally).

  In addition, the measuring device in the present invention may be a part of the cycle computer 201 or may be another independent device. Further, it may be an aggregate of a plurality of devices physically separated. In some cases, a device other than the strain gauge 369 (measurement module strain detection circuit 365) and the acceleration sensor 371 may be a device in a completely different place through communication.

  Further, the present invention is not limited to the above embodiment. That is, those skilled in the art can implement various modifications in accordance with conventionally known knowledge without departing from the scope of the present invention. Of course, such modifications are included in the scope of the present invention as long as the configuration of the measurement timing detection apparatus of the present invention is provided.

1 Bicycle 3 Frame 77 Spider arm (member that rotates in conjunction with the crank)
105 Crank 107 Crankshaft (Rotating shaft)
310 Measurement Timing Detection Device 351 Measurement Module Control Unit 351a Propulsion Force Calculation Unit (Measurement Unit)
351b Measurement timing determination unit (determination unit, correction unit, reference position detection unit, delay angle correction unit)
351c Reference angle detector (reference position detector)
351e Cadence calculation unit (decision unit)
353 Measurement module storage unit 355 Reference angle storage unit (reference position detection unit)
371a First acceleration sensor 371b Second acceleration sensor 371c Third acceleration sensor 372 LPF (filter unit)
373 Magnetic sensor (detector)
374 LED (notification part)
375 Setting section (timing instruction section)
503 Magnet (Detected part)
a1 Output value of first acceleration sensor a2 Output value of second acceleration sensor ST11 Rotation angle detection (acquisition step, output step, first correction step)

Claims (13)

Arranged from crank or said of the crank member that rotates in conjunction with the crank shaft at different distances, respectively, a first acceleration sensor and the second acceleration sensor for detecting a direction parallel to the longitudinal direction of the acceleration of the crank ,
A reference position detector for detecting that the crank is at a predetermined reference position;
The next measurement timing of the measurement unit that performs predetermined measurement at an appropriate angular position of the crank, the output value of the first acceleration sensor and the output value of the second acceleration sensor, the detection result of the reference position detection unit, A determination unit for determining based on the next measurement angle;
Measurement timing detecting device characterized in that it comprises a. The determination unit calculates the rotation speed of the crank from the detection result of the reference position detection unit, and determines the next measurement timing as the output value of the first acceleration sensor and the output value of the second acceleration sensor, and the crank. Determined based on the number of rotations and the next measurement angle,
The measurement timing detection apparatus according to claim 1 . The determination unit determines the next measurement timing based on the output value of the first acceleration sensor and the output value of the second acceleration sensor, the detection result of the reference position detection unit, and the next measurement angle. 3. The measurement timing detection apparatus according to claim 1, further comprising a correction unit that corrects the next measurement timing between the determination of the first measurement timing and the next measurement timing. 4. The determination unit performs the measurement based on a plurality of output values of the first acceleration sensor and a plurality of output values of the second acceleration sensor, a detection result of the reference position detection unit, and the next measurement angle. measuring timing detection device according to any one of claims 1 to 3, characterized in that to determine the next measurement timing parts. The determination unit calculates a rotation period of the crank based on an output value of the first acceleration sensor and an output value of the second acceleration sensor, and detects the rotation period, a detection result of the reference position detection unit, and the next time. measuring angles and measurement timing detection device according to any one of claims 1 to 4, characterized in that to determine the next measurement timing of the measurement unit based on. The measuring unit performs the predetermined measurement at a timing corresponding to an angle obtained by dividing the m rotation by the crank into n equal parts (m and n are integers of 1 or more),
The determination unit obtains the next measurement angle based on the m and the n.
Measuring timing detection device according to any one of claims 1 to 5, characterized in that. The determination unit may measure the timing detection device according to any one of claims 1 to 6, characterized in that detecting the measurement timing based on the reference position. The detected position, wherein the reference position detection unit is fixed and arranged at a position corresponding to a specific rotation angle of the crank;
A detection unit disposed on the crank for detecting the detected unit;
The measurement timing detection apparatus according to claim 7 , comprising: A third acceleration sensor for detecting acceleration in a direction parallel to the short side direction of the crank;
A notification unit for notifying that the detection unit has detected the detected unit;
A timing instructing unit that instructs the determination unit to acquire the output value of the first acceleration sensor or the second acceleration sensor and the output value of the third acceleration sensor;
The timing instruction unit sends the output value of the first acceleration sensor or the second acceleration sensor and the output value of the third acceleration sensor to the determination unit based on the notification that the notification unit has detected the detected unit. Let's get
The reference position detection unit sets the reference position based on an output value of the first acceleration sensor or the second acceleration sensor acquired by the determination unit and an output value of the third acceleration sensor;
The measurement timing detection apparatus according to claim 8 . A filter unit that performs a filtering process on an output value of the first acceleration sensor and an output value of the second acceleration;
A delay angle correction unit that performs an angle correction process after the filter process is performed;
Measuring timing detection device according to any one of claims 1 to 9, characterized in that a. Crank or the output value from the first acceleration sensor that detects the direction parallel to the longitudinal direction of the acceleration of the crank of the crank located at different distances respectively from the rotation axis member that rotates in conjunction with the crank and the second An acquisition step of acquiring an output value of the acceleration sensor;
A reference position detecting step for detecting that the crank is at a predetermined reference position;
The next measurement timing of the measurement unit that performs a predetermined measurement at an appropriate angular position of the crank, the output value of the first acceleration sensor and the output value of the second acceleration sensor, the detection result of the reference position detection step, A determination process to be determined based on the next measurement angle;
Measurement timing detecting method characterized by comprising a. A measurement timing detection program that causes a computer to execute the measurement timing detection method according to claim 11 . A computer-readable recording medium storing the measurement timing detection program according to claim 12 .

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