WO2016009537A1

WO2016009537A1 - Rotation angle detection device

Info

Publication number: WO2016009537A1
Application number: PCT/JP2014/069081
Authority: WO
Inventors: 恭一寺尾; 秀人遠藤
Original assignee: パイオニア株式会社
Priority date: 2014-07-17
Filing date: 2014-07-17
Publication date: 2016-01-21

Abstract

Provided is a rotation angle detection device with which cost reduction is possible and for which durability can be improved, and with which power consumption can be reduced. A rotation angle estimation unit (351b), that is provided to a crank (105) which is attached to a crank shaft (107), acquires the output of an acceleration sensor (371) which detects acceleration in a direction parallel to the longitudinal direction of the crank (105) and acceleration in a direction parallel to the short direction of the crank (105). The rotation angle estimation unit calculates the center value of longitudinal-direction acceleration and short-direction acceleration from the newest output value of the acceleration sensor (371) and a previous output value of the acceleration sensor (371) equal to one turn of the crank (105), and by calculating the inverse tangent of the difference between such calculated value and the newest output value of the acceleration sensor (371), calculates the rotation angle of the crank (105).

Description

Rotation angle detector

The present invention relates to a rotation angle detection device that detects a rotation angle of a crank that rotates about a rotation axis.

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.

Further, Patent Document 2 describes that the rotation angle of the crank is detected by the angular velocity sensor 10 and the acceleration sensors 11 and 12.

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, under adverse effects such as dust and earth and sand, dust and the like are likely to enter between the frame member 20 and the crank. 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.

The pedaling state measuring device described in Patent Document 2 uses an angular velocity sensor, and thus has a problem of increasing power consumption. 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 rotation angle detection device capable of reducing cost and improving durability and reducing power consumption.

In order to solve the above-mentioned problem, the invention described in claim 1 is arranged on a crank attached to a rotating shaft or a member that rotates in conjunction with the crank, and the first in a direction parallel to the longitudinal direction of the crank. An acceleration sensor that detects acceleration and a second acceleration in a direction parallel to the short direction of the crank, and acquires the first acceleration and the second acceleration, and n at different times (n is an integer of 3 or more) An output unit that outputs information related to the current rotation angle of the crank based on the first acceleration and the second acceleration acquired twice, and a rotation angle detection device.

The invention described in claim 8 is disposed on a crank attached to a rotating shaft or a member that rotates in conjunction with the crank, and a first acceleration in a direction parallel to a longitudinal direction of the crank and a short direction of the crank An acquisition step of acquiring a second acceleration in a direction parallel to the current time, and the current acceleration based on the first acceleration and the second acceleration acquired n (n is an integer of 3 or more) times at different times in the acquisition step An output step of outputting information on the rotation angle of the crank.

The invention described in claim 9 is a rotation angle detection program that causes a computer to execute the rotation angle detection method according to claim 8.

The invention described in claim 10 is a computer-readable recording medium in which the rotation angle detection program according to claim 9 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 the graph which showed the relationship between the acceleration of the longitudinal direction of a crank when the crank is stationary, the acceleration of a short direction, and the rotation angle of a crank. FIG. 5 is a diagram showing a longitudinal acceleration and a short-side acceleration on a plane having axes orthogonal to each other when the crank is stationary. It is explanatory drawing about the acceleration which an acceleration sensor detects when a crank is rotating. FIG. 6 is a diagram showing a longitudinal acceleration and a short-side acceleration on a plane with axes orthogonal to each other when the crank rotates at a constant speed. FIG. 6 is a diagram showing a longitudinal acceleration and a short-side acceleration on a plane with axes orthogonal to each other when the crank is accelerated or decelerated. It is explanatory drawing of the method of calculating the rotation angle of a crank from the newest output value and the output value for 1 round of cranks. 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 explanatory drawing of the method of calculating the rotation angle of a crank from the newest output value concerning the 2nd Example of this invention, and two past output values. It is a block block diagram of the cycle computer and measurement module concerning 3rd Example of this invention. It is the graph which showed the measured value of the acceleration sensor at the time of stillness and rotation. It is a block block diagram of the cycle computer and measurement module concerning 4th 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. It is the top view which showed the crank shown by FIG.

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 one embodiment of the present invention, the output unit is disposed on a crank attached to a rotation shaft or a member that rotates in conjunction with the crank, and the first acceleration in a direction parallel to the longitudinal direction of the crank and Two accelerations are acquired from an acceleration sensor that detects a second acceleration in a direction parallel to the short direction of the crank. Then, based on the first acceleration and the second acceleration acquired n (n is an integer of 3 or more) times at different times, information on the current crank rotation angle is output. Thus, if a plurality of measured values (sensor output values) of the longitudinal acceleration and the short-side acceleration of the crank can be acquired, information related to the crank rotation angle such as the crank rotation angle can be output. . Therefore, 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 output unit calculates a center value of the acceleration in the longitudinal direction and the acceleration in the short direction based on the first acceleration and the second acceleration acquired n times at different times, and the center value and the first acceleration currently acquired Information on the rotation angle of the crank may be output based on the second acceleration. Thus, for example, the crank rotation angle can be calculated by calculating the arc tangent of the difference between the center value and the currently acquired output value.

Further, the output unit may calculate the center value of the acceleration in the longitudinal direction and the acceleration in the short direction based on the first acceleration and the second acceleration for one or more revolutions of the crank. By doing so, the amount of data increases and the calculation accuracy of the center value increases, so that the calculation accuracy of the crank rotation angle can also be increased.

Further, a reference position setting unit that sets a reference position for one turn of the crank may be provided, and the output unit may detect one turn of the crank based on the reference position set by the reference position setting unit. In this way, it is possible to easily detect one revolution of the crank.

In addition, the reference position setting unit may include a detected 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 detected unit. Good. In this way, for example, by providing a magnetic sensor in the crank and providing a magnet in the bicycle frame, one revolution of the crank can be detected.

The reference position setting unit may set the reference position based on the maximum value or the minimum value of the first acceleration. By doing so, it is possible to detect when the acceleration in the longitudinal direction is in the gravity direction or in the opposite direction, that is, in the vertical direction. Further, since the output value of the acceleration sensor for detecting the rotation angle of the crank can be used, there is no need to add another sensor or the like.

Further, a filter unit that performs a filter process on the acquired first acceleration and the second acceleration, and a delay angle correction unit that performs an angle correction process after the filter process is performed may be included. In this way, acceleration components other than gravitational acceleration and centrifugal force acceleration applied to the crank due to vibration or the like can be removed, and the accuracy of information related to the rotation angle of the crank can be improved. The delay generated by the filter process can be corrected by the delay angle correction unit.

In addition, the rotation angle detection method according to the embodiment of the present invention is arranged in a first step in a direction parallel to the longitudinal direction of the crank, which is arranged in the acquisition step and is arranged on a crank attached to the rotary shaft or a member that rotates in conjunction with the crank. The acceleration and the second acceleration in the direction parallel to the short side direction of the crank are respectively acquired from the acceleration sensor. In the output step, information on the current crank rotation angle is output based on the first acceleration and the second acceleration acquired n (n is an integer of 3 or more) times at different times in the acquisition step. Thus, if a plurality of measured values (sensor output values) of the longitudinal acceleration and the short-side acceleration of the crank can be acquired, information related to the crank rotation angle such as the crank rotation angle can be output. . Therefore, 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.

Also, a rotation angle detection program that causes a computer to execute the rotation angle detection method described above may be used. Thus, if a plurality of measured values (sensor output values) of the longitudinal acceleration and the short-side acceleration of the crank can be obtained using a computer, information on the crank rotation angle such as the crank rotation angle can be obtained. Can be output. Therefore, 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 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.

フレーム 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) 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 12).

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 converts the stepping force of the user into the rotational force of the rear wheel by such a drive mechanism 101.

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 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 12) configured by 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 rotation angle of the crank 105 using an acceleration sensor 371 described later.

Moreover, the measurement module 301 has 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 based on the propulsive force and loss force calculated from the strain information by the measurement module control unit 351, the rotation angle of the crank 105 calculated from the output information of the acceleration sensor 371, and the output of the magnetic sensor 373. The calculated cadence or the like is transmitted to the cycle computer radio 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 rotation angle estimation unit 351b, 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 rotation angle estimation unit 351b calculates (estimates) the rotation angle of the crank 105 calculated from the output information of the acceleration sensor 371 acquired at predetermined time intervals, and controls the timing at which strain information is acquired. A method for calculating the rotation angle of the crank 105 will be described later.

When the cadence calculating unit 351e receives the output of the information signal indicating that the magnetic sensor 373 is turned on, the cadence calculating 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.

The transmission data creation unit 351d generates transmission data from the propulsive force and loss force calculated by the propulsive force calculation unit 351a, the rotation angle of the crank 105 calculated by the rotation angle estimation unit 351b, and the cadence calculated by the cadence calculation unit 351e. Created and output to the measurement module wireless transmission unit 309.

The measurement module storage unit 353 stores various types of information. 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 an output value storage unit 355 and a tangent table unit 357.

The output value storage unit 355 is composed of, for example, a RAM (Random Access Memory), and stores the output value of the acceleration sensor 371. As the amount to be stored, the output value for one revolution of the crank 105 is stored in this embodiment. The memory capacity required for the output value storage unit 355 can be appropriately determined from the minimum rotation speed of the crank 105 and the sampling frequency at which the acceleration sensor 371 obtains the output value.

The sine table unit 357 is configured by a ROM (Read Only Memory), for example, and stores a correspondence table between the rotation angle and the tangent value tan θ.

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 the crank 105 and integrated. The acceleration sensor 371 may be appropriately selected from known methods such as a capacitance type and a piezoresistive type.

FIG. 4 shows an example of the arrangement of the acceleration sensor 371 in the present embodiment on the crank 105. 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 acceleration sensor 371 includes a direction parallel to the longitudinal direction of the crank 105 (a direction parallel to the central axis C1), a direction parallel to the short direction of the crank 105 (a direction perpendicular to the central axis C1), This is a two-axis acceleration sensor capable of detecting acceleration in the two axial directions. That is, both the first acceleration and the second acceleration can be detected. In this embodiment, a biaxial acceleration sensor will be described, but an acceleration sensor that detects acceleration in a direction parallel to the longitudinal direction of the crank 105 and acceleration in a direction parallel to the short direction of the crank 105 are detected. The structure which arrange | positions two acceleration sensors with the acceleration sensor to perform may be sufficient.

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 rotation angle of the crank 105 by the rotation angle estimation 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. The short direction in FIG. 5 is the short direction of the crank 105. 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. However, the acceleration sensor 371 detects the longitudinal direction component and the short direction component of the gravitational acceleration because the detection direction is a direction parallel to the longitudinal direction of the crank 105 and a direction parallel to the short direction. Is done.

Here, the detection value (output value) of the acceleration sensor 371 changes as shown in FIG. 6 depending on the angle of the position where the crank 105 is stationary. Therefore, if the acceleration in the longitudinal direction is the X axis and the acceleration in the short direction is the Y axis orthogonal to the X axis, the output value (X, Y) output from the acceleration sensor 371 is the X axis as shown in FIG. And a circle with a radius of 1 [G] centered at the intersection of the Y axis and the Y axis. In FIG. 7, from the graph of FIG. 6, if the state in which the crank 105 is facing directly upward is 0 °, 180 ° is obtained when (X, Y) = (1, 0), and (X, Y) = (− It is clear that 0 ° in the case of (1,0), 90 ° in the case of (X, Y) = (0,1), and 270 ° in the case of (X, Y) = (0, −1). is there.

When the crank 105 rotates, centrifugal force is generated in the longitudinal direction of the crank 105 (the direction from the crankshaft 107 to the pedal crankshaft 115, that is, the normal direction of the rotation of the crank 105). The acceleration of the rotational force is generated in the rotation direction 105 or the reverse direction of the rotation, that is, the tangential direction of the rotation of the crank 105. Therefore, as shown in FIG. 8, the acceleration of centrifugal force (centrifugal acceleration) and the acceleration of rotational force (rotational acceleration) are added together with the gravitational acceleration.

When the crank 105 rotates at a constant speed, the center of the circle shown in FIG. 7 is offset in the longitudinal direction by the acceleration of the centrifugal force as shown in FIG.

When the crank 105 is gradually accelerated from a stationary state and rotates at a constant speed, the circle shown in FIG. 7 is added with the acceleration of the centrifugal force and the acceleration of the rotational force, as shown in FIG. The center moves to the position of FIG. 9 while adding both offsets in the short direction. Further, when the crank 105 is gradually decelerated from the constant speed rotation and becomes a stationary state, the circle shown in FIG. 9 adds the acceleration of the centrifugal force and the acceleration of the rotational force as shown in FIG. 10B. The center moves to the position shown in FIG. 7 while offsets in both the longitudinal direction and the lateral direction are added. In addition, since Fig.10 (a) is acceleration and (b) is deceleration, the change of a transversal direction becomes reverse.

In this embodiment, the principle described above is used. That is, the output values (first acceleration and second acceleration) of the acceleration sensor 371 for one revolution of the crank 105 are acquired (sampled) at regular intervals and stored in the output value storage unit 355. The center value of the acceleration in the longitudinal direction and the acceleration in the short direction in the circumference is obtained, and the angle of the crank 105 at the latest output value is calculated from the center value and the latest output value (current output value). A specific example is shown in FIG. That is, based on the output values (first acceleration sensor and second acceleration) of the acceleration sensor 371 acquired n times at different times, the center value of the acceleration in the longitudinal direction and the acceleration in the short direction is calculated. Information on the rotation angle of the crank 105 is output based on the output values of the acceleration sensor 371 (currently acquired first acceleration and second acceleration).

In FIG. 11, points plotted on the XY plane are the output value of the acceleration sensor 371 and the latest output value of the acceleration sensor 371 for the past one round. The variation in the plot is due to the influence of noise such as vibration. The rotation angle estimation unit 351b estimates the center value (X _c , Y _c ) by obtaining an average value from the output values of the acceleration sensor 371 for the past one round. Then, an arctangent arctan ((Y ₀ -Y _c ) / (X ₀ -X _c )) is obtained based on the latest output value (X ₀ , Y ₀ ) and the center value (X _c , Y _c ). To calculate the angle θ.

Actually, the arc tangent calculation is not performed, and a tangent table unit 357 storing a tangent value of a predetermined angle such as every 30 ° is used. That is, when the tangent tan θ is obtained from X ₀ -X _c and Y ₀ -Y _c and the obtained tangent tan θ value is compared with the tangent table 375 to become the value of the tangent table 375 (or a close value). Suppose that the angle indicated by the value is detected.

In this embodiment, since one round is indicated by 360 °, there are a plurality of angles at which the tangent has the same value. For example, whether X ₀ -X _c is positive or negative, or Y ₀ -Y _{c is} positive. Negative information may be included in the tangent table unit 357, and these information may be compared together.

In this embodiment, the angle θ is output as information related to the rotation angle of the crank 105. However, the angle θ may be output, or a tangent value or X ₀ −X _c and Y ₀ −Y _c. May be output as information on the rotation angle of the crank 105, and the subsequent calculation may be performed at the output destination.

Here, in this embodiment, since the output value of the acceleration sensor 371 for one round is acquired as described above, it is necessary to detect one round. Therefore, a position (reference position) that is the starting point of one round is defined. In this embodiment, the magnetic sensor 373 and the magnet 503 used for cadence measurement are used. Since the magnet 503 is provided on the frame 3 as described above, one rotation can be detected when the rotation angle estimation unit 351b receives an information signal indicating that the magnetic sensor 373 is turned on. That is, the position of the magnet 503 becomes the reference position.

That is, the magnet 503 functions as a detected portion, the magnetic sensor 373 functions as a detecting portion, and the rotation angle estimating portion 351b functions as a reference position setting portion.

In the above description, the center value is calculated from the output value for one revolution of the crank, but it may be calculated from the output value of two or more turns. Further, the center value may be calculated once per round (or once per multiple rounds), or may be calculated every time the output value of the acceleration sensor 371 is obtained. That is, the center value may be calculated using the output value for the previous round of the previous week, and the current center value may be the center value calculated using the output value for the previous week. One round may be sufficient from an output value.

As is clear from the above description, the measurement module control unit 351 (rotation angle estimation unit 351b, transmission data creation unit 351d), measurement module storage unit 353 (output value storage unit 355, tangent table unit 357), acceleration sensor The rotation angle detecting device 310 according to the present embodiment is configured by the 371, the magnetic sensor 373, and the magnet 503.

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 has 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. 12 and the like). Each terminal of the strain gauge 369 is connected to the measurement module strain detection circuit 365.

FIG. 12 shows an example of the arrangement of the strain gauge 369 on the crank 105 in this embodiment. 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 that is the axis extending in the longitudinal direction of the crank 105 (the longitudinal direction in FIG. 12), 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 detection direction of the fourth strain gauge 369d in the direction perpendicular to the central axis C1 (the lateral direction in FIG. 12), that is, the direction perpendicular to the longitudinal direction of the crank 105. 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. 12, the crank 105 is described as a simple rectangular parallelepiped, but the corners may be rounded or a part of the surface may be formed of 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.

When the resistance value of the strain gauge 369 is compressed as is known, the resistance value decreases, and when the strain gauge 369 is expanded, the resistance value increases. 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. 14 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. 14A, 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. 14B, 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 caused by the right force 105R being stretched or compressed in the longitudinal direction and 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. 14, 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. 12 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).

Bending deformation y causes the right crank 105R to deform 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 deforms 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 twist 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. 14B, 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 twisted in the direction opposite to the arrow in FIG. 14B, 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.

Bending deformation y causes the right crank 105R to deform 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 deforms 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 twist 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. 14B, the resistance value increases because the third strain gauge 369c is expanded, and the resistance value does not change because the fourth strain gauge 369d does not deform in the detection direction. . 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. 14B, 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 (1) and the loss force Fr is the following (2). 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 (1) and (2) 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 (3) to (6).

Here, Am is an A output value when m [kg] is placed on the pedal 103 with the angle of the crank 105 facing forward in the horizontal direction (a state in which the crank 105 extends horizontally and 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 thrust Ft can be calculated by substituting A and B into the equation (15).

Also, in the equation (1), the A output is corrected using the B output. In equation (2), the A output is used to correct the B 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 wireless reception unit 209 receives transmission data (propulsion force Ft, loss force Fr, rotation angle and cadence of the crank 105) 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 processing of FIG. 15 may be executed by software (computer program) that operates 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 output value of the acceleration sensor 371 is acquired. Then, the tangent value is calculated by the method described above. Detailed processing in this step will be described later with reference to FIG. That is, step ST11 functions as an acquisition process and an output process.

Next, in step ST13, it is determined whether or not the rotation angle detected in step ST11 is an angle of every 30 °. If the angle is every 30 ° ３０ (in the case of YES), the process proceeds to step ST15; Returns to step ST11. Whether or not the rotation angle is an angle of every 30 ° can be determined by comparing the calculated tangent value with the value of the tangent table unit 357 as described above. In this step, the tangent value calculated in step ST11 is converted into an angle θ. That is, in step ST11, the tangent value is calculated, and if it is not determined that the angle is every 30 ° in this step, it is not converted into a rotation angle. That is, in this embodiment, step ST13 is also an output process. In this embodiment, every 30 ° is used, but of course, every other angle such as every 45 ° may be used.

Next, in step ST15, the measurement module strain detection circuit 365 is driven. That is, a power source voltage is applied to the bridge circuit as shown in FIG.

Next, in step ST17, the propulsive force Ft and the loss force Fr are calculated based on the outputs (A output and B output) from the measurement module strain detection circuit 365.

Next, in step ST19, 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.

In the process of step ST11 described above, as shown in FIG. 15B, in step ST31, output values (first acceleration and second acceleration) for one round are acquired from the acceleration sensor 371.

Next, in step ST33, a center value (X _c , Y _c ) is calculated from the output value acquired in step ST31.

In step ST35, an angle (tangent value) is calculated. X ₀ -X _c and Y ₀ -Y _c may be used instead of the tangent value.

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 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 rotation angle estimation unit 351b is disposed on the crank 105 attached to the crankshaft 107, and the acceleration in the direction parallel to the longitudinal direction of the crank 105 and the acceleration in the direction parallel to the short direction of the crank 105 are performed. The output value of the acceleration sensor 371 that detects the above is acquired. Then, the center value of the acceleration in the longitudinal direction and the acceleration in the short direction is calculated from the output value of the latest acceleration sensor 371 and the output value of the acceleration sensor 371 for one revolution of the past crank 105, and the calculated value and the latest value are calculated. The rotation angle of the crank 105 is calculated by calculating the arctangent of the difference from the output value of the acceleration sensor 371. Thus, if the center value can be calculated, the rotation angle of the crank 105 can be calculated from the arc tangent of the difference between the center value and the latest output value. Therefore, since no magnet is used for the angle detection itself, the cost can be reduced and it is not affected by dust or iron sand, so that the durability can be improved. Further, since the angular velocity sensor is not used, the power consumption can be reduced.

Also, since an angular velocity sensor is not used, it is possible to reduce power consumption. 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.

Also, since the acceleration sensor 371 is composed of a biaxial acceleration sensor, the number of parts can be reduced, which can contribute to cost reduction.

The correspondence between the angle θ and the tangent value is stored in the tangent table unit 357 in advance, and the measurement module control unit 351 (rotation angle estimation unit 351b) outputs the rotation angle of the crank 105 based on the tangent table unit 357. Therefore, it is not necessary to perform an arctangent calculation, and the processing of the calculation can be reduced.

In addition, the reference position setting unit that sets the reference position for one turn 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 in this way, one round of the crank 105 can be detected easily. Moreover, since it can serve as a cadence sensor, a dedicated sensor or the like is not required.

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

This embodiment has the same configuration as that of the first embodiment, but differs in the way of obtaining the center value when calculating the rotation angle of the crank 105. In the first embodiment, the center value is obtained from the output value of the acceleration sensor 371 for one revolution of the crank 105. However, in the present embodiment, at least at a different time in the past from the latest output value of the acceleration sensor 371. A center value is calculated from the output value of the acceleration sensor 371 acquired twice (see FIG. 16).

That is, a circle having a radius of 1 [G] is drawn from each of the three output values, and the overlapping point can be estimated as the center value (X _c , Y _c ). In the case of three points, the center value (X _c , Y _c ) can be obtained from the solution (X, Y) of the simultaneous equations by the following equations (7) to (9).

After obtaining the central value, the tangent value may be obtained in the same manner as in the first embodiment, and the rotation angle of the crank 105 may be obtained based on the tangent table unit 357.

It should be noted that the past output value of the acceleration sensor 371 is not limited to the same rotation as the latest output value of the acceleration sensor 371 (within one turn from the latest output value), and may be an output value one or more turns before. The output values of the past two acceleration sensors 371 may also have different rotations. Further, the center value may be obtained from the past three output values without including the latest output value of the acceleration sensor 371. In short, output values acquired at different times may be used.

According to the present embodiment, the rotation angle estimation unit 351b obtains the center value based on the latest output value of the acceleration sensor 371 and the output value of the acceleration sensor 371 acquired twice at different times in the past. The center value can be calculated with a smaller amount of data compared to obtaining the output value for one round. Therefore, the capacity of the output value storage unit 355 can be saved.

In the above-described embodiment, the output value of the acceleration sensor 371 has been described as three, but may be four or more as a matter of course.

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 magnetic sensor 373 is not connected to the rotation angle estimation unit 351b, and the magnetic sensor 373 and the magnet 503 are not used to detect the reference position. FIG. 18 is a graph of the output value (first acceleration) in the longitudinal direction of the acceleration sensor 371. 18A is a graph when the crank 105 is stationary, and FIG. 18B is a graph when the crank 105 is rotating. Since the centrifugal force is applied when the crank 105 rotates, an offset is applied to the curve.

As is apparent from FIG. 18, when the acceleration gradient is “0” and the value is the maximum value, the angle of the crank 105 is 180 ° (the direction of gravity, that is, the tip of the crank 105 faces directly below). Therefore, by detecting this, 180 ° can be set as the reference position.

In this embodiment, in order to calculate the inclination of acceleration, the difference between the previous measurement value and the current measurement value is calculated for the output value (first acceleration) in the longitudinal direction of the acceleration sensor 371. In addition, since the difference becomes “0” in actuality, a predetermined threshold value is provided, and when the difference is equal to or less than the threshold value, the maximum value may be determined. This process is performed by the rotation angle estimation unit 351b. That is, the rotation angle estimation unit 351b sets the reference position based on the maximum output value of the acceleration sensor 371.

According to the present embodiment, the reference position is the case where the output value of the acceleration in the longitudinal direction of the acceleration sensor 371 is the maximum value. In this way, it is possible to detect when the acceleration detected by the acceleration sensor whose detection direction is the direction parallel to the longitudinal direction is the gravity direction, that is, when it is the vertical direction. Further, since the output value of the acceleration sensor 371 for detecting the rotation angle of the crank 105 can be used, there is no need to add another sensor or the like.

In this embodiment, the minimum value may be used instead of the maximum value. In this case, the detected reference position is 0 ° (in the opposite direction to gravity, that is, the tip of the crank 105 faces directly above).

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 this embodiment, as shown in FIG. 19, the output of the acceleration sensor 371 is subjected to a low-pass filter (LPF) process, and the rotation angle estimation unit 351b2 corrects the amount delayed by the low-pass filter process. That is, the LPF 372 functions as a filter unit.

Since a vehicle equipped with a rotation angle detection device such as a bicycle is subjected to various vibrations from the outside, the acceleration sensor 371 includes an acceleration component other than gravity acceleration, acceleration component of centrifugal force, and acceleration component of rotation force in the output value. There are many. 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. 20, since the output value subjected to the digital filter is delayed by a certain number of samples depending on the characteristics of the digital filter, the finally calculated rotation angle of the crank 105 is corrected. There is a need to. Therefore, the rotation angle estimation unit 351b2 corrects the rotation angle by performing a calculation as shown in the equation (12) described later. That is, the rotation angle estimation unit 351b2 functions as a delay angle correction unit.

For example, when an n-tap FIR filter, sampling frequency fs [Hz], and angular velocity ω [rad / sec], the rotation angle of the crank 105 before n / (2 × fs) [sec] is calculated. Therefore, it may be corrected so that the calculated crank rotation angle is advanced by the following expression (10).

Here, when the angle is detected every certain time t [sec], the angular velocity ω is calculated by the following equation (11) from the calculated angle θ [rad] and the previously calculated angle θ ₋₁ .

Alternatively, the angular velocity ω may be calculated by the following equation (12) on the assumption that a round time t _r [sec] is measured and a constant angular velocity continues for the next round.

According to the present embodiment, there is an LPF 372 that performs filter processing on the output value of the acceleration sensor 371, and a rotation angle estimation 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 information regarding the rotation angle of the crank 105 can be improved. Further, the rotation angle estimation unit 351b2 can correct the delay generated by the filter processing.

Next, a rotation angle detection apparatus according to a fifth 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 longitudinal acceleration and the short-side acceleration of the crank 105 in addition to the crank 105 will be described.

FIG. 21 is a plan view showing the chain ring 109 and the crank 105A according to this embodiment, and FIG. 22 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.

21 and 22, the spider arm 77 is formed integrally with the crank arm 78, but is not limited thereto and may be a separate body.

In the crank 105A having such a configuration, by providing the spider arm 77 with the biaxial acceleration sensor, the rotation angle of the crank arm 78 can be calculated in the same manner as shown in the first embodiment. However, as shown in the first embodiment, the detection axis of the acceleration sensor needs to be parallel to the direction parallel to the longitudinal direction of the crank arm 78 and parallel to the short direction.

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, the biaxial acceleration sensor is arranged on the spider arm 77, and the information on the rotation angle of the crank arm 78 based on the current output value of the acceleration sensor and the past two or more output values. Is calculated. 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 six 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, but are not limited thereto. 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.

Further, the human-powered machine in the present invention refers to a machine driven by human power equipped with 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).

Also, the measuring device in the present invention may be a part of the cycle computer 201 or 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 rotation angle detection apparatus of the present invention is provided.

1 Bicycle 77 Spider arm (member that rotates in conjunction with the crank)
105 Crank 107 Crankshaft (Rotating shaft)
310 rotation angle detection device 351 measurement module control unit 351b rotation angle estimation unit (acquisition unit, output unit, reference position setting unit, delay angle correction unit)
353 Measurement module storage unit 371 Acceleration sensor 372 LPF (filter unit)
373 Magnetic sensor (detector)
503 Magnet (Detected part)
ST11 Rotation angle detection (acquisition process, output process)

Claims

A crank attached to a rotating shaft or a member that rotates in conjunction with the crank, and a first acceleration in a direction parallel to the longitudinal direction of the crank and a second acceleration in a direction parallel to the short direction of the crank. An acceleration sensor to detect,
The first acceleration and the second acceleration are acquired, and the current rotation angle of the crank is determined based on the first acceleration and the second acceleration acquired n (n is an integer of 3 or more) times at different times. An output unit for outputting information;
A rotation angle detection device comprising:
The output unit calculates a center value of the acceleration in the longitudinal direction and the acceleration in the short direction based on the first acceleration and the second acceleration acquired n times at different times, and acquires the center value and the current value. The rotation angle detection device according to claim 1, wherein information on the rotation angle of the crank is output based on the first acceleration and the second acceleration.
3. The rotation angle detection device according to claim 2, wherein the output unit calculates the center value based on the first acceleration sensor and the second acceleration sensor for one or more rounds of the crank.
A reference position setting unit for setting a reference position for one turn of the crank;
The output unit detects one revolution of the crank based on the reference position set by the reference position setting unit;
The rotation angle detection device according to claim 3, wherein
The detected position where the reference position setting section is fixedly disposed 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 rotation angle detection device according to claim 4, comprising:
The rotation angle detection device according to claim 4, wherein the reference position setting unit sets the reference position based on the acquired maximum value or minimum value of the first acceleration.
A filter unit that performs a filtering process on the acquired first acceleration and the second acceleration;
A delay angle correction unit that performs an angle correction process after the filter process is performed;
The rotation angle detection device according to claim 1, wherein the rotation angle detection device is provided.
The first acceleration in the direction parallel to the longitudinal direction of the crank and the second acceleration in the direction parallel to the short side direction of the crank are obtained by being arranged on a crank attached to the rotating shaft or a member that rotates in conjunction with the crank. An acquisition process to
An output step of outputting information on the current rotation angle of the crank based on the first acceleration and the second acceleration acquired n (n is an integer of 3 or more) times at different times in the acquisition step;
A rotation angle detection method characterized by comprising:
A rotation angle detection program for causing a computer to execute the rotation angle detection method according to claim 8.
10. A computer-readable recording medium in which the rotation angle detection program according to claim 9 is stored.