JP6373736B2 - Golf club fitting apparatus, method and program - Google Patents

Description

  The present invention relates to a golf club fitting apparatus, method, and program.

  Conventionally, various fitting methods for supporting selection of a golf club suitable for a golfer have been proposed. A typical fitting method is to make a golf club try a golf club, measure a swing motion during this time with a measuring device, and analyze the measured value to select an optimal golf club. At this time, what is used as a reference is an important factor for determining the quality of the fitting, and various standards have been proposed conventionally. For example, Patent Document 1 discloses a fitting method based on the bending rigidity of a shaft of a golf club.

JP 2013-226375 A

  By the way, in selecting a golf club, the ease of swing is a reference for one fitting, but it is not as good as easy to swing. For example, the lighter the golf club, the easier it is to swing, but the kinetic energy transmitted to the ball due to the collision with the golf club becomes smaller and the flight distance does not increase. However, if the golf club is too heavy, it will be difficult to swing and the flight distance will not increase.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a golf club fitting device, method and program capable of specifying the optimal swingability suitable for a golfer.

  As shown in FIG. 1, the present inventors generally indicate between a predetermined swing index such as a head speed and a torque exerted amount and a golf club swingability such as a weight of a golf club and a moment of inertia around a grip end. I found that there is a relationship. For example, as the golf club becomes heavier, the golf club cannot swing the golf club with the force of the golfer, and the head speed decreases. However, even if it is lighter than a certain level, the head speed reaches a peak (see FIG. 1A). This is because it cannot be shaken with a force more than a full swing. Or, as the golf club is heavier, the torque exerted amount during the swing increases, but when it becomes heavier than a certain level, the golfer reaches the limit, and the torque exerted reaches a peak (see FIG. 1B). That is, even if it is easier or more difficult to swing, if the golfer reaches the limit, the swing index will not increase. The first to ninth aspects of the present invention are inventions based on the findings.

  A golf club fitting device according to a first aspect of the present invention includes an acquisition unit, an index calculation unit, and an optimal index identification unit. The acquisition unit acquires a measurement value obtained by measuring swing motions of a plurality of golf clubs. The index calculation unit calculates a swing index that is an index characterizing the swing motion for each of the golf clubs based on the measurement value. The optimum index specifying unit specifies an intersection of the first regression line and the second regression line based on the swing index calculated by the index calculation unit, and swings the golf club at or near the intersection. An optimal index or an optimal index band that is an easy-to-swipe index indicating ease is specified. The first regression line is a regression line of the swing index in a certain region where the swing index is substantially constant with respect to the ease of swinging index. The second regression line is a regression line of the swing index in a proportional region where the swing index is approximately proportional to the ease of swinging.

  Here, the intersection index of the first regression line in the fixed region as shown in FIG. 1 and the second regression line of the swing index in the proportional region or the vicinity of the swing index is specified. This intersection is a point (change point in FIG. 1) corresponding to a golfer's limit at which the swing index does not grow even if it is easier or more difficult to swing. Therefore, here, an optimal swingability index that realizes an optimal swing index corresponding to the limit of the golfer is specified. That is, it is possible to identify the optimal ease of swinging that suits the golfer.

  A golf club fitting device according to a second aspect of the present invention is the golf club fitting device according to the first aspect, wherein the acquisition unit performs the swing operation of the golf club having an extremely small swing ease index. The measured first measurement value and the second measurement value obtained by measuring the swing motion of the golf club having an extremely large swing ease index are acquired. The optimum index specifying unit specifies the first regression line based on the swing index based on the first measurement value, and determines the second regression line based on the swing index based on the second measurement value. Specifying or specifying the first regression line based on the swing index based on the second measurement value and specifying the second regression line based on the swing index based on the first measurement value .

  As shown in FIG. 1, the swing index is divided into a proportional area proportional to the ease of swinging and a constant area that is substantially constant regardless of the ease of swinging, at a certain point. Therefore, usually, a measured value (first measured value) of a swing motion by a golf club having an extremely small swing ease index and a measured value (second measured value) of a swing motion by a golf club having an extremely large swing ease index. Always belongs to either a certain region or a proportional region. Here, based on the knowledge, one of the first regression line and the second regression line is identified based on the first measurement value, and the other of the first regression line and the second regression line is identified based on the second measurement value. Is done. As a result, the first regression line and the second regression line can be specified with a small number of trial hits.

  Note that the relationship between the swing index and the ease of swinging index is shown in FIG. And if a fixed area | region and a proportional area are specified based on the measured value in the area | region where such a change is gentle, there exists a possibility that the precision of an analysis may fall. However, here, as described above, since the measurement values by the extremely small golf club and the extremely large golf club having an extremely easy to swing index are used, such a problem can be avoided.

  A golf club fitting device according to a third aspect of the present invention is the golf club fitting device according to the first aspect or the second aspect, wherein the optimum index specifying unit is configured to measure the measured value by one golf club. The first regression line is specified as a straight line having a slope of zero through a point corresponding to the swing index.

  Here, the first regression line can be specified only by trial hitting of one golf club.

  A golf club fitting apparatus according to a fourth aspect of the present invention is the golf club fitting apparatus according to any one of the first aspect to the third aspect, wherein the optimum index specifying unit releases the cock during the swing operation. The second regression line is specified on the basis of a regression equation of the slope of the second regression line with at least one of timing and head speed at impact as an explanatory variable.

  The present inventors have found that the slope of the second regression line (proportional constant in the proportional region) correlates with the cock release timing during the swing operation and / or the head speed during the impact. Therefore, here, the inclination of the second regression line is calculated based on at least one of the cock release timing during the swing operation and the head speed during the impact. Therefore, the second regression line can be specified with a small number of trial hits.

  A golf club fitting device according to a fifth aspect of the present invention is the golf club fitting device according to the fourth aspect, wherein the optimum index specifying unit is the swing index based on the measured value of one golf club. The second regression line is specified as a straight line having the slope calculated based on the regression equation through a point corresponding to.

  Here, the second regression line can be specified only by trial hitting of one golf club.

  A golf club fitting device according to a sixth aspect of the present invention is the golf club fitting device according to any one of the first to fifth aspects, wherein the ease of swinging includes the weight of the golf club, At least one of a moment of inertia around the grip end of the golf club and a moment of inertia around the shoulder of the golfer is included.

  Here, the ease of swinging the golf club is evaluated based on at least one of the weight of the golf club, the grip end moment of inertia, and the moment of inertia around the golfer's shoulder.

  A golf club fitting device according to a seventh aspect of the present invention is the golf club fitting device according to any one of the first to sixth aspects, wherein the swing index includes a head speed, a torque output amount, an average At least one of torque, average power, and energy production is included.

  Here, the swing index is evaluated based on at least one of the head speed, the torque exerted amount, the average torque, the average power, and the energy exerted amount.

  A golf club fitting device according to an eighth aspect of the present invention is the golf club fitting device according to any one of the first to seventh aspects, and a plurality of fitting devices that match the optimum index or the optimum index zone. An optimum club specifying unit for specifying a golf club having a small swing inertia moment and a large grip end inertia moment from among the golf clubs is further provided.

  Here, it is possible to identify a golf club that can increase the head speed from among a plurality of golf clubs that match the optimal index or the optimal index band.

A golf club fitting method according to a ninth aspect of the present invention includes the following steps. Here, the same effect as the first aspect can be achieved.
(1) A step of measuring swing motions of a plurality of golf clubs using a measuring device.
(2) A step of calculating a swing index, which is an index characterizing the swing motion, for each of the golf clubs based on the measured value of the swing motion.
(3) Based on the calculated swing index, a first regression line of the swing index in a certain region where the swing index is substantially constant with respect to the swing ease index representing the ease of swinging of the golf club is specified. Step.
(4) A step of identifying a second regression line of the swing index in a proportional region where the swing index is substantially proportional to the swing ease index based on the calculated swing index.
(5) identifying an intersection between the first regression line and the second regression line, and identifying an optimal index or an optimal index band that is the index of ease of swinging at or near the intersection.

A golf club fitting method according to a tenth aspect of the present invention is the golf club fitting method according to the ninth aspect, and further includes the following steps. Here, the same effect as the eighth aspect can be achieved.
(6) A step of identifying a golf club having a small swing inertia moment and a large grip end inertia moment from a plurality of golf clubs that match the optimum indicator or the optimum indicator band.

The golf club fitting program according to the eleventh aspect of the present invention causes a computer to execute the following steps. Here, the same effect as the first aspect can be achieved. (1) A step of acquiring a measurement value obtained by measuring the swing motion.
(2) A step of calculating a swing index, which is an index characterizing the swing action, for each of the golf clubs based on the measured value.
(3) Based on the calculated swing index, a first regression line of the swing index in a certain region where the swing index is substantially constant with respect to the swing ease index representing the ease of swinging of the golf club is specified. Step.
(4) A step of identifying a second regression line of the swing index in a proportional region where the swing index is substantially proportional to the swing ease index based on the calculated swing index.
(5) identifying an intersection between the first regression line and the second regression line, and identifying an optimal index or an optimal index band that is the index of ease of swinging at or near the intersection.
program.

A golf club fitting program according to a twelfth aspect of the present invention is a golf club fitting program according to the eleventh aspect, and further causes a computer to execute the following steps. Here, the same effect as the eighth aspect can be achieved.
(6) A step of identifying a golf club having a small swing inertia moment and a large grip end inertia moment from a plurality of golf clubs that match the optimum indicator or the optimum indicator band.

  According to the present invention, an optimal swingability index that realizes an optimal swing index corresponding to a golfer's limit is specified. That is, it is possible to identify the optimal ease of swinging that suits the golfer.

The figure which shows the relationship between a swing parameter | index and a swing ease parameter | index. A figure showing a golf swing analysis system provided with a golf swing analysis device concerning one embodiment of the present invention. The functional block diagram of a golf swing analysis system. The figure explaining xyz local coordinate system on the basis of the grip of a golf club. (A) The figure which shows an address state. (B) The figure which shows a top state. (C) The figure which shows an impact state. (D) The figure which shows a finish state. The flowchart which shows the flow of a 1st conversion process. The flowchart which shows the flow of the process which derives the time of an address. The figure explaining a swing plane. The flowchart which shows the flow of a shoulder behavior derivation | leading-out process. The figure which illustrates a double pendulum model notionally. The flowchart which shows the flow of an parameter | index calculation process. Another diagram conceptually explaining the double pendulum model. The figure explaining the energy performance amount which is one of the swing parameters | indexes. First experimental data showing the relationship between the head speed and the golf club weight. Second experimental data showing the relationship between the head speed and the golf club weight. Third experimental data showing the relationship between the head speed and the golf club weight. 4th experimental data which show the relationship between a head speed and a golf club weight. The figure explaining an optimal index specific process. Contour map of head speed by simulation. FIG. 6 is a contour map of head speed according to another simulation. Furthermore, the contour map of the head speed by another simulation. Contour map of cock angle by simulation. The figure explaining the optimal club specific process.

  Hereinafter, a golf club fitting device, method, and program according to an embodiment of the present invention will be described with reference to the drawings.

<1. General configuration of golf club fitting system>
2 and 3 show an overall configuration of a fitting system (hereinafter, analysis system 100) including the fitting device 2 for the golf club 4 according to the present embodiment. The fitting device 2 is a device that supports selection of the golf club 4 suitable for the golfer 7 based on measurement data obtained by measuring the swing motion of the golf club 4 by the golfer 7. The swing motion is measured by the sensor unit 1 (measuring device) attached to the grip 42 of the golf club 4. The fitting device 2 constitutes an analysis system 100 together with the sensor unit 1.

  Hereinafter, after describing the configuration of the sensor unit 1 and the fitting device 2, the flow of the fitting process will be described.

<1-1. Configuration of sensor unit>
As shown in FIGS. 2 and 4, the sensor unit 1 is attached to the end (grip end) on the opposite side of the head 41 in the grip 42 of the golf club 4, and measures the behavior of the grip 42. The golf club 4 is a general golf club and includes a shaft 40, a head 41 provided at one end of the shaft 40, and a grip 42 provided at the other end of the shaft 40. The sensor unit 1 is configured to be small and light so as not to hinder the swing operation. As shown in FIG. 3, an acceleration sensor 11, an angular velocity sensor 12, and a geomagnetic sensor 13 are mounted on the sensor unit 1 according to the present embodiment. The sensor unit 1 is also equipped with a communication device 10 for transmitting measurement data from these sensors 11 to 13 to the external fitting device 2. In the present embodiment, the communication device 10 is wireless so as not to hinder the swing operation, but may be connected to the fitting device 2 in a wired manner via a cable.

The acceleration sensor 11, the angular velocity sensor 12, and the geomagnetic sensor 13 each measure grip acceleration, grip angular velocity, and grip geomagnetism in the xyz local coordinate system with the grip 42 as a reference. More specifically, the acceleration sensor 11 measures grip accelerations a _x , a _y , and a _z in the x-axis, y-axis, and z-axis directions. The angular velocity sensor 12 measures grip angular velocities ω _x , ω _y , and ω _z around the x axis, the y axis, and the z axis. Geomagnetic sensor 13 measures the x-axis, y-axis and z-axis direction of the grip geomagnetism m _x, m _y, a m _z. These measurement data are acquired as time-series data of a predetermined sampling period Δt. The xyz local coordinate system is a three-axis orthogonal coordinate system defined as shown in FIG. That is, the z axis coincides with the direction in which the shaft 40 extends, and the direction from the head 41 toward the grip 42 is the z axis positive direction. The x-axis is oriented as much as possible in the toe-heel direction of the head 41, and the y-axis is oriented as much as possible in the normal direction of the face surface of the head 41.

  In the present embodiment, measurement data obtained by the acceleration sensor 11, the angular velocity sensor 12, and the geomagnetic sensor 13 are transmitted to the fitting device 2 in real time via the communication device 10. However, for example, the measurement data may be stored in a storage device in the sensor unit 1, and the measurement data may be taken out from the storage device after the swing operation is finished and transferred to the fitting device 2.

<1-2. Configuration of fitting device>
The configuration of the fitting device 2 will be described with reference to FIG. The fitting device 2 installs the golf club fitting program 3 according to the present embodiment stored in a computer-readable recording medium 20 such as a CD-ROM or USB memory from the recording medium 20 to a general-purpose personal computer. It is manufactured by. The fitting program 3 is software for analyzing the swing motion based on the measurement data sent from the sensor unit 1 and outputting information that assists in selecting a golf club suitable for the golfer 7. The fitting program 3 causes the fitting apparatus 2 to execute an operation described later.

  The fitting device 2 includes a display unit 21, an input unit 22, a storage unit 23, a control unit 24, and a communication unit 25. These units 21 to 25 are connected via the bus line 26 and can communicate with each other. In the present embodiment, the display unit 21 is configured with a liquid crystal display or the like, and displays information to be described later to the user. In addition, a user here is a general term for the person who requires the result of fitting, such as golfer 7 himself or its instructor. The input unit 22 can be configured with a mouse, a keyboard, a touch panel, and the like, and accepts an operation from the user on the fitting device 2.

  The storage unit 23 is configured by a nonvolatile storage device such as a hard disk. The storage unit 23 stores the fitting program 3 and the measurement data sent from the sensor unit 1. The communication unit 25 is a communication interface that enables communication between the fitting device 2 and an external device, and receives data from the sensor unit 1.

  The control unit 24 can be composed of a CPU, ROM, RAM, and the like. The control unit 24 reads and executes the fitting program 3 in the storage unit 23 to virtually acquire the acquisition unit 24A, the index calculation unit 24B, the optimal index specifying unit 24C, the display control unit 24D, and the optimal club specifying unit 24E. Operate. Details of the operation of each of the units 24A to 24E will be described later.

<2. Fitting process>
Next, the flow of the fitting process for the golf club 4 by the analysis system 100 will be described. The fitting process according to this embodiment includes the following six steps.
(1) Grip acceleration a _x in the xyz local coordinate system, a _y, a _z, grip angular velocity ω _x, ω _y, ω _z and grip geomagnetism m _x, m _y, measuring step of measuring the measurement data m _z ( 2) First, the measurement data in the xyz local coordinate system obtained in the measurement process is converted into grip accelerations a _X , a _Y , a _Z and grip angular velocities ω _X , ω _Y , ω _Z in the XYZ global coordinate system. Conversion step (In the first conversion step, grip speeds v _X , v _Y , and v _Z in the XYZ global coordinate system are also derived.)
(3) The behavior of the grip 42 (grip angular velocities ω _X , ω _Y , ω _Z and grip velocities v _X , v _Y , v _Z ) in the XYZ global coordinate system is determined from the grip 42 in the swing plane P (described later). (4) Shoulder behavior deriving step for deriving a pseudo shoulder behavior of the golfer 7 in the swing plane P based on the behavior of the grip 42 in the swing plane P (4) 5) An index calculation step for calculating a swing index (in this embodiment, head speed) that characterizes the swing motion based on the behavior of the grip 42 and the pseudo shoulder behavior (6) The swing index calculated in the index calculation step Is plotted in a swing ease index-swing index plane, and an optimum index identifying step (7) for identifying an optimal swing ease index suitable for the golfer 7 (in this embodiment, the weight of the golf club 4). Optimum club identification process for identifying a golf club that can increase the head speed from among a plurality of golf clubs that match the optimum swing ease index identified in the suitable index identification process. explain.

  The XYZ global coordinate system is a three-axis orthogonal coordinate system defined as shown in FIG. That is, the Z-axis is a direction from the vertically lower side to the upper side, the X-axis is a direction from the back to the stomach of the golfer 7, and the Y-axis is parallel to the ground plane and goes from the ball hitting point to the target point. Direction.

<2-1. Measurement process>
In the measurement process, the golfer 7 swings the plurality of golf clubs 4 with the sensor unit 1 described above. In this embodiment, one extremely light golf club 4 and two extremely heavy golf clubs are tried. At this time, the difference in weight between the extremely light golf club 4 and the extremely heavy golf club 4 (the lighter of the two) is preferably 30 g or more, and more preferably 40 g or more. The difference in weight between two extremely heavy golf clubs 4 is preferably 5 g or more, and more preferably 10 g or more. For example, three golf clubs 4 such as 275 g, 315 g, and 325 g can be selected.

  In the present embodiment, the optimum weight of the golf club 4 is calculated as the optimum swinging ease index suitable for the golfer 7. Therefore, as the golf club 4 for trial hitting, it is preferable to prepare a golf club 4 that meets the wishes of the golfer 7 with respect to the specifications of the golf club 4 other than the weight such as length and balance. Further, if the golf club 4 in which various weight adjusting weights can be fitted to the head and / or the grip end of the golf club 4 is used, the golf club 4 having various weights for trial hitting can be easily obtained. Can be prepared.

Subsequently, the grip acceleration a _x in the swing plurality of golf clubs 4 as described above, the a _y, a _z, grip angular velocity ω _x, ω _y, ω _z and grip geomagnetism m _x, m _y, m _z Measurement data is measured by the sensor unit 1. This measurement data is transmitted to the fitting device 2 via the communication device 10 of the sensor unit 1. On the other hand, on the fitting device 2 side, the acquisition unit 24 </ b> A receives this via the communication unit 25, and stores it in the storage unit 23 for each golf club 4. In this embodiment, at least time-series measurement data from the address to the impact is measured.

  Note that the golf club swing operation generally proceeds in the order of address, top, impact, and finish. The address means an initial state in which the head 41 of the golf club 4 is arranged near the ball, as shown in FIG. 5A, and the top means the golf club 4 from the address, as shown in FIG. Is taken back and the head 41 is swung up most. As shown in FIG. 5C, the impact means a state at the moment when the golf club 4 is swung down from the top and the head 41 collides with the ball. The finish means as shown in FIG. It means a state in which the golf club 4 is swung forward after impact.

In the measurement step, it is preferable that each of the plurality of golf clubs 4 is subjected to trial hitting a plurality of times, preferably 5 times or more. In this case, an average value of measurement data obtained by one golf club 4 can be calculated and used for subsequent calculations. Also, in order to remove abnormal values due to miss shots, measurement errors, etc., the standard deviation σ of the measurement data is calculated, and the measurement data of all trial hits are preferably within the average value ± 1.65σ, more preferably the average value ± 1. It is preferable to obtain measurement data that falls within 28σ. Then, in order to perform the check, the control unit 24 calculates the standard deviation σ of the measurement data. When the value of σ does not satisfy the above conditions, a message for requesting addition or re-measurement is displayed. You may make it display on the part 21. FIG. Instead of the average value of the measurement data itself, the processing value calculated based on the measurement data (e.g., head speed V _h to be described later) may be calculated an average value of. Similarly, when calculating the average value of the processed values, it is possible to check the reliability of the data based on the standard deviation σ.

<2-2. First conversion step>
Hereinafter, the first conversion step for converting the measurement data of the xyz local coordinate system into the value of the XYZ global coordinate system will be described with reference to FIG. In the following, for the sake of simplicity, the processing based on the measurement data by one golf club 4 will be described, but actually, the following processing is performed on the measurement data for each golf club 4. The same applies to the subsequent second conversion step, shoulder behavior derivation step, and index calculation step.

Specifically, first, the acquisition unit 24A performs grip accelerations a _x , a _y , a _z , grip angular velocities ω _x , ω _y , ω _z and grips in the xyz local coordinate system stored in the storage unit 23. geomagnetic m _x, m _y, reads the measurement data of the time series of m _z (step S1).

Next, based on the time-series measurement data in the xyz local coordinate system read in step S1, the index calculation unit 24B derives the times t _i , t _t , and t _a of impact, top, and address ( Step S2). In this embodiment, the impact time t _i is first derived, the top time t _t is derived based on the impact time t _i , and the address time t _a is derived based on the top time t _t .

Specifically, the time when the increment of the grip angular velocity ω _x per sampling period Δt first exceeds the threshold of 300 deg / s is set as the temporary impact time. Then, the time at which the increment of the grip angular velocity ω _x per sampling period Δt exceeds 200 deg / s from the time when a predetermined time is passed from the time of the temporary impact to the time of the temporary impact is detected. The time t _i is set.

Next, the time before the impact time t _i and when the grip angular velocity ω _y is switched from negative to positive is specified as the top time t _t . The address time t _a is calculated according to the flowchart of FIG.

In subsequent step S3, the index calculation unit 24B calculates an attitude matrix N (t) at time t from the address to the impact. Assume that the posture matrix is expressed by the following formula. The posture matrix N (t) is a matrix for converting the XYZ global coordinate system at time t to the xyz local coordinate system.

The meanings of the nine components of the posture matrix N (t) are as follows.
Component a: Cosine of the angle formed by the X axis of the global coordinate system and the x axis of the local coordinate system Component b: Cosine of the angle formed by the Y axis of the global coordinate system and the x axis of the local coordinate system Component c: Overall Cosine of angle formed by Z axis of coordinate system and x axis of local coordinate system Component d: Cosine of angle formed by X axis of global coordinate system and y axis of local coordinate system Component e: Y of global coordinate system Cosine of angle between axis and y axis of local coordinate system Component f: cosine of angle between Z axis of global coordinate system and y axis of local coordinate system Component g: X axis of global coordinate system and local Cosine of angle between z axis of coordinate system Component h: Cosine of angle between Y axis of global coordinate system and z axis of local coordinate system Component i: Z axis of global coordinate system and z of local coordinate system Here, the vector (a, b, c) represents a unit vector in the x-axis direction, and the vector (d, e, f) represents a single vector in the y-axis direction. Represents a vector, the vector (g, h, i) represents a unit vector in the z-axis direction.

Further, the attitude matrix N (t) can be expressed by the following equation according to the concept of Euler angles in the ZYZ system. Here, φ, θ, and ψ are rotation angles around the Z axis, the Y axis, and the Z axis.

In calculating the posture matrix N (t) to the impact from the address, first, the address of the time t _a at the posture matrix N (t _a) is calculated. Specifically, φ and θ at the time of address are calculated according to the following equations. Note that the following expression uses that the golf club 4 is stationary at the time of addressing and only the gravity in the vertical direction is detected by the acceleration sensor 11. The grip accelerations a _x , a _y , and a _z in the following expressions are values at the time of addressing.

Subsequently, ψ at the time of addressing is calculated according to the following equation.
However, the values of m _xi and my _{y in} the above formula are calculated according to the following formula. Further, the following grip geomagnetic m _x in the formula, m _y, m _z is the value at the address.

From the above, during the address phi, theta, [psi is grip acceleration a _x in the xyz local coordinate system, a _y, a _z and grip geomagnetism m _x, m _y, is calculated on the basis of the m _z. And these phi, theta, by substituting the value Expression 2 of [psi, address when the posture matrix N (t _a) is calculated.

Subsequently, the posture matrix N (t) from the address to the impact is calculated by updating the posture matrix N (t _a ) at the time of time at intervals of the sampling period Δt. More specifically, first, the attitude matrix N (t) is expressed by the following expression using four quaternion variables q ₁ , q ₂ , q ₃ , q ₄ (q ₄ is a scalar part).

Therefore, from Equations 1 and 7, the four quaternion variables q ₁ , q ₂ , q ₃ , and q ₄ can be calculated according to the following equations.

Now, the value of a~i that defines the address at the time of the attitude matrix N (t _a) is known. Therefore, according to the above formula, first, quaternion four variables q ₁ , q ₂ , q ₃ , and q ₄ at the time of address are calculated.

The quaternion q ′ after a lapse of a minute time from the time t is expressed by the following equation using the quaternion q at the time t.

The first-order differential equation representing the temporal change of the four quaternion variables q ₁ , q ₂ , q ₃ , and q ₄ is expressed by the following equation.

By using the equations (9) and (10), the quaternion at time t can be sequentially updated to the quaternion at the next time t + Δt. Here, the quaternion from the address to the impact is calculated. Then, by sequentially substituting the four quaternion variables q ₁ , q ₂ , q ₃ , and q ₄ from the address to the impact into the formula 7, the attitude matrix N (t) from the address to the impact is calculated. The

Next, in step S4, the index calculation unit 24B determines that the grip accelerations a _x , a _y , a _{z in} the xyz local coordinate system from the address to the impact are based on the posture matrix N (t) from the address to the impact. The time series data of the grip angular velocities ω _x , ω _y , ω _z is converted into time series data in the XYZ global coordinate system. The converted grip accelerations a _X , a _Y , a _Z and grip angular velocities ω _X , ω _Y , ω _Z are calculated according to the following equations.

In the subsequent step S5, the index calculation unit 24B integrates the time series data of the grip accelerations a _X , a _Y , and a _Z , thereby obtaining the grip speeds v _X , v _Y , in the entire XYZ coordinate system from the address to the impact. Derived v _Z. At this time, it is preferable to perform offset so that the grip speeds v _X , v _Y , and v _Z from the address to the impact are 0 m / s at the top. For example, the offset at an arbitrary time t is calculated from (grip speeds v _X , v _Y , v _{Z at} the top time t _t ) × t / (t _{t from} the grip speeds v _X , v _Y , v _Z at the time _t. is performed by subtracting the -t _a).

<2-3. Second conversion step>
Hereinafter, the second conversion step for converting the behavior of the grip 42 in the XYZ global coordinate system calculated in the first conversion step into the behavior of the grip 42 in the swing plane P will be described. In the present embodiment, the swing plane P is defined as a plane that includes the origin of the XYZ global coordinate system and is parallel to the Y axis and the shaft 40 of the golf club 4 at the time of impact (see FIG. 8). In the second conversion step, the index calculation unit 24B projects the grip speeds v _X , v _Y , v _Z and the grip angular velocities ω _X , ω _Y , ω _Z in the XYZ global coordinate system into the swing plane P. _pX , v _pY , v _pZ
And grip angular velocities ω _pX , ω _pY , and ω _pZ are calculated.

Specifically, based on the z-axis vector (g, h, i) included in the posture matrix N (t) representing the extending direction of the shaft 40, the golf player 7 is viewed from the front. E) Time series data of the inclination of the shaft 40 is calculated. Then, based on this time series data, the time when the shaft 40 is parallel to the Z axis when viewed from the positive direction of the X axis is specified, and this is set as the impact time t _i . Here, the impact time t _i does not always coincide with the impact time t _i already described. Subsequently, the inclination of the shaft 40 viewed from the negative Y-axis direction is calculated based on the z-axis vector (g, h, i) included in the posture matrix N (t _i ) at the time t _i of the impact. That is, an angle α ′ formed between the shaft 40 and the X axis viewed from the negative direction of the Y axis at the time of impact is calculated, and this is set as the swing plane angle.

When the swing plane angle α ′ is obtained, a projection transformation matrix A for projecting an arbitrary point in the XYZ global coordinate system onto the swing plane P can be calculated as follows. However, α = 90 ° −α ′.

Here, based on the above projective transformation matrix A, the grip speeds v _pX , v _pY , v _pZ and the grip angular velocities ω _pX , ω _pY , ω _pZ after the projective transformation from the address to the impact according to the following formula: Series data is calculated.

Note that the grip speed (v _pY , v _pZ ) obtained by the above calculation represents the grip speed (vector) in the swing plane P, and the grip angular speed ω _pX is an axis perpendicular to the swing plane P. It represents the angular velocity around. Here, the grip speed (scalar) in the swing plane P from the address to the impact is calculated according to the following equation.

Further, here, the inclination of the shaft 40 at the top in the swing plane P, which is necessary for the later calculation, is also calculated. Specifically, first, the z-axis vector (g, h, i) included in the top posture matrix N (t _t ) is projected into the swing plane P using the projective transformation matrix A according to the following equation. To do. Here, the projected vector is (g ′, h ′, i ′).

The vector (h ′, i ′) specified by the above expression is a vector representing the inclination of the shaft 40 at the top in the swing plane P. Therefore, the inclination β of the shaft 40 at the top in the swing plane P is calculated by substituting the above calculation results into the following equation.

<2-4. Shoulder behavior derivation process>
Hereinafter, a shoulder behavior derivation that derives a pseudo shoulder behavior in the swing plane P based on the grip behavior (grip speed V _GE and grip angular velocity ω _pX ) in the swing plane P while calculating FIG. The process will be described. In the present embodiment, the behavior of the golf club 4 is a double pendulum model in which the shoulder of the golfer 7 and the grip 42 (or the wrist of the golfer who holds the golf club 7) are nodes, and the arm of the golfer 7 and the golf club 4 are linked. Based on the analysis. However, the shoulder behavior is not directly measured, but is derived as a pseudo shoulder behavior based on the actually measured grip behavior. In the following, unless otherwise specified, the term “shoulder” simply means such a pseudo shoulder. The same applies to the pseudo “arm” defined as extending linearly between the pseudo shoulder and the grip 42 (wrist).

In specifying the shoulder behavior from the grip behavior, the double pendulum model according to the present embodiment is based on the following (1) to (5). FIG. 10 is a diagram conceptually illustrating the following preconditions.
(1) On the swing plane P, the grip 42 (wrist) moves circularly around the shoulder. (2) On the swing plane P, the distance (radius) R between the shoulder and the grip 42 is constant.
(3) The shoulder does not move (but rotates) during the swing motion.
(4) On the swing plane P, the angle between the top arm and the golf club 4 is 90 °.
(5) The arm at the time of impact faces the lower side of the Z axis when viewed from the positive direction of the X axis.

Under the above assumption, the index calculation unit 24B calculates the movement distance D of the grip 42 from the top to the impact in the swing plane P (step S21). The moving distance D is derived by integrating the grip speed V _GE from the top to the impact.

  Subsequently, the index calculation unit 24B calculates the arm rotation angle γ from the top to the impact in the swing plane P (step S22). The rotation angle γ is calculated based on the inclination β of the shaft 40 at the top calculated in the second conversion step. Next, the index calculation unit 24B calculates a radius R = D / γ (step S23).

Then, the index calculation unit 24B calculates an angular velocity (an angular velocity of the arm) ω ₁ around the shoulder from the top to the impact in the swing plane P as the behavior of the shoulder according to the following equation. That is, the arm angular velocity ω ₁ is a value reflecting the measured grip velocity V _GE .
ω ₁ = V _GE / R

<2-5. Index calculation process>
Hereinafter, the index calculation process for calculating the swing index based on the behavior of the grip 42 and the behavior of the shoulder will be described with reference to FIG. In the present embodiment, the head speed V _h is calculated as the swing index.

Specifically, first, in step S31, the index calculation unit 24B integrates the angular velocity ω ₁ of the arm from the top to the impact, and calculates the rotational angle θ ₁ of the arm from the top to the impact. At this time, it is preferable to use trapezoidal integration. The rotation angle θ ₁ is defined as shown in FIG. 12, and the plane of FIG. 12 is equal to the swing plane P. In the following, the analysis proceeds based on the new XY coordinate system in the swing plane P shown in FIG. The X and Y axes of the new XY coordinate system in the swing plane P are different from the X and Y axes of the XYZ overall coordinate system described above.

The index calculation unit 24B differentiates the angular velocity ω ₁ of the arm from the top to the impact, and calculates the angular acceleration ω ₁ ′ from the top to the impact. Next, the index calculation unit 24B calculates the position (X ₁ , Y ₁ ), the speed (V _X1 , V _Y1 ), and the acceleration (A _X1 , A _Y1 ) of the center of gravity of the arm from the top to the impact. These values are calculated by substituting the calculation results described above into the following equations.

  Where r is the distance from the shoulder to the center of gravity of the arm. In the present embodiment, it is assumed that the center of gravity of the arm is at the center of the arm. Therefore, R = 2r.

Next, in step S <b> 32, the index calculation unit 24 </ b> B performs the same calculation as that in step S <b> 31 for the periphery of the grip 42. That is, the grip angular velocity ω _pX from the top to the impact = the angular velocity ω ₂ of the golf club 4 around the grip 42 is integrated, and the rotation angle θ ₂ of the golf club 4 (shaft 40) around the grip 42 from the top to the impact is calculated. To do. Also at this time, it is preferable to use trapezoidal integration, and the rotation angle θ ₂ is defined as shown in FIG.

Subsequently, the index calculation unit 24B differentiates the angular velocity ω ₂ of the golf club 4 from the top to the impact, and calculates the angular acceleration ω ₂ ′ from the top to the impact. Next, the index calculation unit 24B calculates the position (X ₂ , Y ₂ ), speed (V _X2 , V _Y2 ), and acceleration (A _X2 , A _Y2 ) of the golf club 4 from the top to the impact. These values are calculated by substituting the calculation results described above into the following equations.

  However, L is the distance from the grip 42 to the center of gravity of the golf club 4. The value of L is a specification of the golf club 4 and is set in advance.

Next, in step S33, the index calculation unit 24B substitutes the calculation result described above into the following formula to thereby obtain the restraining force R ₂ = (R _X2 , R _Y2 ) generated in the grip 42 from the top to the impact. calculate. The following formula is based on the balance of forces in the translational direction. Where m ₂ is the mass of the golf club and g is the acceleration of gravity. Further, m ₂ is the specification of the golf club 4 and is determined in advance.

In step S34, the index calculation unit 24B, by substituting the following equation calculation results described above, calculates the torque T ₁ and the torque T ₂ of the around the grip 42 of the shoulder around from the top to the impact.

However, I ₁ is the moment of inertia around the center of gravity of the arm, and I ₂ is the moment of inertia around the center of gravity of the golf club 4. In this embodiment, the moment of inertia I ₁ of the arm of the center of gravity around the center of gravity of the arm under the assumption that the center of the arm is calculated as ^{_{I 1 = m 1 r 2/}} 3. m ₁ is the mass of the arm. In the present embodiment, the mass m ₁ of the arm is appropriately determined in advance. For example, before starting the analysis, the weight of the golfer 7 is input, and the weight of the arm is automatically calculated by multiplying the input weight by a predetermined coefficient. I ₂ is the specification of the golf club 4 and is predetermined.

In subsequent step S35, the index calculation unit 24B calculates the power (power) E ′ of the entire system of the double pendulum from the top to the impact based on the calculation result described above. Work rate in the entire system E 'is arms work rate of E _1' is calculated as the sum of the work rate E ₂ of the golf club 4 '. Specifically, E ′ is represented by the following equation, where v _s is the velocity vector of the shoulder and v _g is the velocity vector of the grip 42. Here, R ₁ is a binding force generated on the shoulder. Further, v _s and v _g can be calculated by first-order differentiation of the shoulder position vector d _s and the grip 42 position vector d _g = d _s + (2X ₁ , 2Y ₁ ), respectively.

In this embodiment, since the shoulder does not move, v _s = (0, 0), and the power E ′ of the entire system is calculated according to the following equation. The index calculation unit 24B calculates the power E ′ of the entire system from the top to the impact by substituting the above calculation result into the following formula.

In subsequent step S36, the index calculation unit 24D identifies the time t _c which arms work rate in the subsequent top E ₁ 'turns from positive to negative, the workload of the arm from time t _t of the top to the time t _c ( energy) to calculate the E _1. The work E ₁ of the arm is calculated by integrating the work E ₁ ′ of the arm in the interval from time t t to _{t c} (see FIG. 13). The work amount E ₁ can be considered as an index representing the work amount (energy) exerted by the arm between the times t t and _{t c} , and in this sense, the work amount E ₁ can be referred to as the arm energy exertion amount. it can. The index calculation unit 24D calculates E _{1_AVE} = E ₁ / (t _c −t _t ) based on the energy _application amount E ₁ . E _{1_AVE} is the average work rate of the arm between times t t and _{t c} , or the average amount of energy per unit time (average energy exerted amount) exhibited by the arms between times t _{t and t c.} means.

In addition, the index calculation unit 24B specifies a time t _d at which the work rate E ′ in the entire system changes from positive to negative after the top, and the work in the entire system from the top time t _t to the time t _d ( Energy) E is calculated. The work amount E in the entire system is calculated by integrating the work rate E ′ in the entire system in the interval from time t t to _{t d} . The work amount E can be considered as an index representing the work amount (energy) exerted in the entire system between times t t and _{t d} , and in this sense, is called the energy exerted amount in the entire system. be able to. In addition, the index calculation unit 24B calculates E _AVE = E / (t _d −t _t ) based on the energy application amount E. E _AVE, the average work rate of the whole system between times t _t ~t _d, or energy per average unit time exerted by the entire system between times t _t ~t _d (average energy exerted Amount).

In subsequent step S37, the index calculation unit 24B calculates the cock release timing t _r during the swing. The present inventors, through experimentation, head speed V _h at impact as the swing indicator, cook release timing t _r, the energy exerted amounts E ₁ and the average workload rate during the swing (average energy exhibited weight) E We found that there is a correlation with each of _{1_AVE} . Therefore, here, in order to calculate the head speed V _h at impact, cock release timing t _r is calculated. In the present embodiment, the cock release timing, the time t _t ~t work rate in the interval E ₁ to _d 'is a time to be a maximum is identified as a cook release timing t _r (see FIG. 13).

In subsequent step S38, the index calculation unit 24B based on the cock release timing t _r and the average work rate E _{1_AVE,} calculates the head speed V _h at impact. Specifically, the head speed V _h at the time of impact is calculated according to the following formula. Note that k ₁ , k ₂ , and k ₃ are constants obtained by multiple regression analysis from the results of many experiments performed in advance, and are values that are stored in the storage unit 23 in advance. Thus, the index calculation process ends.
_{V h = k 1 · E 1_AVE} + k 2 · t r + k 3

When the index calculation step is finished above, the head speed V _h derived from the extremely light one golf club 4, and the head velocity V _h derived from the prohibitive two golf clubs 4 is calculated. In the following, the head speed V _h derived from one extremely light golf club 4 is represented as V _h1, and the head speed V _h derived from the lighter of two extremely heavy golf clubs 4 is represented as V _h2 . The head speed V _h derived from the heavier of the two extremely heavy golf clubs 4 is represented as V _h3 .

<2-6. Optimal index identification process>
Hereinafter, the optimum index specifying step for specifying the optimum weight m _OP of the golf club 4 suitable for the golfer 7 will be described based on the head speeds V _{h1 to} V _h3 which are swing indices calculated in the index calculating step. Specifically, in this embodiment, the optimum weight is based on a graph obtained by plotting the values of the head speeds V _{h1 to} V _{h3 in} the m ₂ (golf club weight) -V _h (head speed) plane. m _OP is specified.

Note that the algorithm of the optimum index specifying step described below is based on the relationship between the head speed V _h and the golf club weight m ₂ as shown in FIG. FIG. 14 to FIG. 17 are examples of graphs in which measurement data when four golfers are made to hit golf clubs of various weights are plotted in the m ₂ -V _h plane. From these graphs, the head velocity V _h is divided by a point P _c as a boundary, a proportional region is proportional to the golf club weight m _2, to a generally constant region is constant irrespective of the golf club weight m ₂ I understand that. That is, when the golf club becomes heavy, the golf club cannot be shaken off by the golfer's force, and the head speed V _h becomes small. However, even if it is lighter than a certain level, it cannot be shaken with a force greater than a full swing, so the head speed V _h reaches its peak. That is, it can be seen that there is a point where the head speed V _h does not increase even if the golfer reaches the limit and is lighter than that. If the head speed V _h is the same, the larger the golf club weight m ₂ , the greater the kinetic energy, and the faster the initial velocity of the golf ball. Therefore, from the viewpoint of extending the flight distance, it can be said that the golf club weight corresponding to the changing point P _c is optimal.

Based on the above knowledge, first, the optimum index specifying unit 24C plots a point P ₁ corresponding to the head speed V _h1 in the m ₂ -V _h plane, passes through the point P ₁ , and has a zero slope. l ₁ (first regression line) is specified (see FIG. 18A).

Subsequently, the optimum index specifying unit 24C plots points P ₂ and P ₃ corresponding to the head velocities V _h2 and V _h3 in the m ₂ -V _h plane, and a straight line l ₂ passing through the points P ₂ and P _3. (Second regression line) is specified (see FIG. 18B).

Subsequently, the optimum index specifying unit 24C specifies the intersection point P _c of the straight lines l ₁ and l ₂ , specifies the golf club weight m ₂ corresponding to the intersection point P _c, and sets the optimum weight m _op (FIG. 18 (C )reference). In this embodiment, in order to check the reliability of the measurement data, it is determined whether V _h2 > V _h3 and whether the point P _c is between the points P ₁ and P _2. The If this condition is not satisfied, it is determined that the measurement is not performed correctly, and therefore a message for requesting the measurement re-execution is output on the display unit 21. However, when the point P _c is on the left side of the point P ₁ , the correlation coefficient of the three regression lines P _c , P ₁ , and P ₂ is equal to or greater than a predetermined value (for example, 0.8 or greater). In this case, instead of performing error processing, the golf club weight m ₂ corresponding to P ₁ can be set as the golf club weight m _op .

Then, the optimum index specifying unit 24C specifies a region having a predetermined width centered on the optimum weight m _op and sets it as the optimum weight band of the golf club 4 (see FIG. 18D). This is to absorb the influence of errors. Specifically, for example, the optimum weight band can be an area of ± 5 g centered on the optimum weight m _op . In this case, when the above-described σ is equal to or smaller than a predetermined value, it is determined that accurate measurement has been performed, and thus the optimum weight width may be reduced. For example, the optimum weight band can be an area of ± 3 g centered on the optimum weight m _op .

When the above processing is completed, the display control unit 24D displays the optimum weight m _op and the optimum weight band on the display unit 21. As a result, the golfer 7 can grasp the weight m _op of the golf club 4 optimum for the golf club 7 and the optimum weight zone in the vicinity thereof, and can select the golf club 4 based on the weight m _op . Further, in order to improve the persuasiveness of the above output values, the display control unit 24D can also display the graph shown in FIG. Further, as a reference, the display control unit 24D can also display the calculated energy _application amounts E and E ₁ and the average _powers E _AVE and E _{1_AVE} on the display unit 21 in addition to the head speed V _h .

<2-7. Optimal club identification process>
Hereinafter, among the plurality of golf clubs (hereinafter referred to as candidate clubs) belonging to the optimal weight range identified in the optimum index identifying step, it is particularly preferable to identify a golf club (hereinafter referred to as optimal club) capable of increasing the head speed. Explain the club identification process. The optimum club is specified based on the values of the grip end inertia moment I _G and the swing inertia moment I _S when the golfer 7 performing the fitting uses each candidate club.

The grip end inertia moment I _G is the moment of inertia around the grip end and is calculated as I _G = I ₂ + m ₂ L ² . On the other hand, the swing inertia moment _IS is the inertia moment around the shoulder during the swing, and can be calculated according to the following equation.
I _S = I ₂ + m ₂ (2r + L) ² + I ₁ + m ₁ r ²

However, for each golfer 7, the weight of the arm is the same even if the golf club changes. Therefore, for the sake of simplicity, the swing inertia moment I _S in this embodiment is defined according to the following equation, omitting the moment of inertia of the arm rotation.
I _S = I ₂ + m ₂ (2r + L) ²

The algorithm of the optimum club specifying process described below is based on the relationship between the head speed V _h , the grip end inertia moment I _G, and the swing inertia moment I _S as shown in FIGS. 19 to 21 show the results of simulations performed by the present inventors. Thirteen points (circles) in the I _G -I _S plane in FIG. 19 are points indicating (I _G , I _S ) when the subject swings 13 golf clubs having different specifications. However, this data is not the data obtained by actually making a test shot of 13 golf clubs, but the data obtained by making a trial hit of one golf club (hereinafter referred to as a reference club) and simulating from this data. It is.

The specifications of the reference club (golf club weight m ₂ [g], center of gravity L [mm], moment of inertia I ₂ [kg · cm ² ]) were (272, 936, 453). Further, the sensor unit 1 as used in the measurement process was attached to the reference club. Then, the subject was given a test by hitting the reference club, and inverse dynamics analysis was performed according to the same algorithm as described above, and the torque T ₁ around the shoulder, the torque T ₂ around the grip 42, and the arm length R were calculated. Subsequently, assuming that these parameters T ₁ , T ₂ , and R are constant, the values of the specifications of the 13 golf clubs (golf club weight m ₂ , center of gravity distance L, inertia moment I _2, etc.) are used. A forward kinematics analysis was performed. In the simulation of FIG. 19, golf club weight m ₂ = 272 g (constant) is used, and the specifications (L, I ₂ ) of the remaining 12 golf clubs excluding the reference club are (941, 192). ) (941, 138) (938.5, 324) (936, 507) (941, 83) (938.5, 270) (933.5, 633) (931, 809) (936, 399) (933. 5,578) (931, 755) (931, 700). Through the above forward kinematic analysis, the head speed V _h , the grip end inertia moment I _G, and the swing inertia moment I _S for each golf club were calculated. The 10 diagonal lines drawn in FIG. 19 are contour lines of the head speed V _h derived based on the values of the 13 head speeds V _h .

The result of the same simulation performed on 13 different golf clubs is shown in FIGS. Specifically, in the simulation of FIG. 20, golf clubs having a center of gravity L = 936 cm (constant) are used, and the specifications (m ₂ , I ₂ ) of the remaining 12 golf clubs excluding the reference club are (284). , 349) (284, 294) (278, 400) (272, 507) (284, 240) (278, 346) (266, 560) (260, 666) (272, 399) (266, 506) (260 612) (260, 557). In the simulation of FIG. 21, golf clubs having a moment of inertia I ₂ = 453 kg · cm ² (constant) are used, and the specifications (L, m ₂ ) of the remaining 12 golf clubs excluding the reference club are (932). ., 293) (930.9, 297) (934.3, 282) (937.8, 267.6) (929.2, 302) (932.5, 287) (933.5, 258) ( 943.5, 244) (934.2, 276.4) (937.8, 262) (941.5, 248) (939.7, 252).

The above contour maps in FIGS. 19 to 21 are drawn in increments of 0.1 m / s. The numerical values attached to these contour lines are relative head speed V _h values when the head speed V _h in the reference club is 0.0 m / s. From these contour maps, it can be seen that in the I _G -I _S plane, the head speed V _h increases as it goes to the lower right and decreases as it goes to the upper left. In other words, it can be seen that the head speed V _h increases as the value of the swing inertia moment I _S decreases and the grip end inertia moment I _G increases. This tendency does not depend on conditions such as whether the golf club weight m ₂ is constant, the center of gravity L is constant, or the moment of inertia I ₂ is constant.

By the way, in general, and the grip end moment of inertia I _G and swing moment of inertia I _S is increased, become golf club is less likely to swing for the position of the center of gravity is closer to the head side, the head speed V _h is believed to decrease. However, from the simulation results of FIGS. 19 to 21, the inventors of the present invention, even if the grip end inertia moment I _G is increased, if the increment of the swing inertia moment I _{S with} respect to the increment is set to a certain value or less, I have noticed that it is possible to improve the head speed V _h. The inventors have further studied and found that this can be explained from the result of another simulation shown in FIG.

FIG. 22 is a contour diagram of the cock angle derived based on the values of 13 cock angles when the subject swings 13 golf clubs in the simulation of FIG. Here, the cock angle refers, it is the angle formed between the arm and the golf club in the cock release timing t _r (angle indicated by the constant chain line in FIG. 12).

The contour lines in FIG. 22 are drawn in 0.5 ° increments. The numerical values attached to these contour lines are relative angles when the cock angle at the reference club is 0.0 °. From these contour maps, it can be seen that in the I _G -I _S plane, the cock angle decreases toward the right and increases toward the left. In other words, as the grip end moment of inertia I _G increases, it can be seen that cock angle decreases. On the other hand, since the contour lines extending generally vertically, cock angle is not affected by the swing moment of inertia I _S. For simplification, only the simulation result corresponding to FIG. 19 is shown, but the same tendency with respect to the cock angle was also confirmed in the simulations corresponding to FIGS.

The small cock angle means that the wrist cock is accumulated and the golf club passes near the golfer's body during the swing. Therefore, when the cock angle is small, the effective swing inertia moment I _S is small, and an increase in the head speed V _h is expected.

As described above, even if the grip end inertia moment I _G increases, if the increment of the swing inertia moment I _S is set to a certain value or less, the advantage of having a smaller cock angle than the disadvantage of making it difficult to swing the golf club. It is clear that the head speed V _h is improved. That is, if the grip end inertia moment I _G can be increased and the swing inertia moment I _S can be reduced, the head speed V _h can be improved.

Based on the above knowledge, the optimum club specifying step is executed. First, the optimum club specifying unit 24E narrows down candidate clubs from a plurality of golf clubs (hereinafter referred to as target clubs) to be fitted. Specifically, information indicating the specifications of each target club (hereinafter, specification information) is stored in the storage unit 23 in advance. In the present embodiment, as specifications here, for each target club, the golf club weight m ₂ , the moment of inertia I ₂ around the center of gravity of the golf club 4, and the distance from the grip 42 to the center of gravity of the golf club 4 (center of gravity distance). A value such as L is stored. Accordingly, the optimum club specifying unit 24E specifies all the golf clubs belonging to the optimum weight belt as candidate clubs by referring to the specification information in the storage unit 23. When there is only one candidate club, the following processing is omitted and the one candidate club is specified as the optimum club.

On the other hand, when there are a plurality of candidate clubs, an optimum club that is a golf club capable of particularly increasing the head speed is identified from these candidate clubs. Specifically, the optimum club identification unit 24E, as defined formulas described above, when a golfer 7 doing the fitting swings each candidate club, derives the grip end moment of inertia I _G and the swing moment of inertia I _S . At this time, using the parameter R already calculated in the steps from the measurement step to the optimum index specifying step and the specifications of the candidate club specifications (golf club weight m ₂ , center of gravity distance L, inertia moment I _2, etc.) A forward kinematic analysis is performed. In this case, it is not necessary for the golfer 7 to swing the candidate club again.

When the inertia moments I _G and I _S corresponding to each candidate club are found, the optimum club specifying unit 24E has a smaller swing inertia moment I _{S and a} higher grip end inertia moment I _G than the plurality of candidate clubs. A large golf club is identified and is designated as the optimum club. Specifically, the optimum club specifying unit 24E plots the points of (I _G , I _S ) corresponding to each candidate club in the I _G -I _S plane, and the candidate club corresponding to the point at the lower rightmost position. Is determined to be the best club. For example, when there are three candidate clubs A, B, and C as shown in FIG. 23A, the candidate club C is determined as the optimum club. On the other hand, when there are three candidate clubs A, B, and C as shown in FIG. 23B, it is not possible to determine which of the candidate clubs B and C exists at the lower right. . In this case, both B and C are determined as the optimum clubs.

Incidentally, B of FIG. 23 (B), also a plurality of candidate club corresponding and C, if it is possible to draw contour lines as shown in FIGS. 19 to 21 in I _G -I _S plane, determines superiority or inferiority be able to. Therefore, in another embodiment, the optimum club specifying unit 24E may determine the parameters T ₁ , T ₂ , R that have already been calculated, and various predetermined golf club specifications (golf club weight m ₂ , center of gravity distance L, moment of inertia). The contour of the head velocity V _h in the I _G -I _S plane may be derived by forward dynamic analysis using the value of I ₂ etc. This contour line depends on the golfer 7. Then, from the slope of the contour line, the head speed V _h corresponding to a plurality of candidate clubs such as B and C is determined (see FIG. 23C), and the highest one is determined as the optimum club. Can do.

  When the above processing is completed, the display control unit 24D causes the display unit 21 to display information for specifying the optimum club. Thereby, the golfer 7 can grasp | ascertain the optimal golf club for himself. In addition, in order to improve the persuasiveness of the output values described above, the display control unit 24D can also display the graphs shown in FIGS. 23A to 23C on the display unit 21 together.

<3. Modification>
As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the meaning. For example, the following changes can be made. Moreover, the gist of the following modifications can be combined as appropriate.

<3-1>
In the above-described embodiment, the sensor unit 1 including the acceleration sensor, the angular velocity sensor, and the geomagnetic sensor is used as the measurement device that measures the swing motion of the golfer 7, but the measurement device may have other configurations. . For example, the geomagnetic sensor can be omitted. In this case, the measurement data can be converted from the xyz local coordinate system to the XYZ global coordinate system by a statistical method. In addition, since such a method is a well-known technique (refer to Unexamined-Japanese-Patent No. 2013-56074 if needed), detailed description is abbreviate | omitted here. Alternatively, a three-dimensional measurement camera can be used as a measurement device. Since a method of measuring the behavior of a golfer, a golf club, or a golf ball with a three-dimensional measurement camera is also known, detailed description thereof is omitted here. If a 3D measurement camera is used, the process of converting the measurement data from the xyz local coordinate system to the XYZ global coordinate system can be omitted, and the grip behavior in the XYZ global coordinate system can be measured directly. can do.

<3-2>
In the above embodiment, the head velocity V _h is calculated based on the cock release timing t _r and the average work rate E _{1_AVE} the multiple regression equation as explanatory variables, it is possible to calculate in other ways. For example, cook release timing t _r during the swing, may be calculated based on the regression equation, including as at least one of the explanatory variables of energy exerted amounts E ₁ and the average work rate E _{1_AVE.} Of course, all these three parameters may be explanatory variables. Or it can also calculate geometrically according to the following formula | equation. However, L _club is the length of the golf club which is the spec of the golf club. Further, the head speed V _h can be directly measured using a measuring device such as a camera.
Position vector (d _hX , d _hY ) of the head at the tip of the shaft 40
d _hX = 2X ₁ + L _club cos θ ₂
d _hY = 2Y ₁ + L _club sin θ ₂
Speed vector (V _hX , V _hY ) of the head at the tip of the shaft 40
V _hX = 2V _X1 -L _club ω ₂ sin θ ₂
V _hY = 2V _Y1 + L _club ω ₂ cos θ ₂
V _h = sqrt (V _hX ² + V _hY ² )

<3-3>
In the above embodiment, the optimal weight m _op of the golf club 4 is calculated based on the head speed V _h, the swing indicator other than the head velocity V _h, the swing easiness index other than the weight m ₂ of the golf club 4 1 also holds the relationship as shown in FIG. Specifically, for example, the above-described energy application amounts E and E ₁ and average work rates E _AVE and E _{1_AVE} can be used as swing indexes for calculating an optimal _swingability index. Further, the torque display amount T _ti and the average torque T _AVE described below can also be used as the swing index. It should be _noted that the energy exerted amounts E and E ₁ and the average work rates E _AVE and E _{1_AVE} can be applied to the model of FIG. 1A, and the torque exerted amount T _ti and the average torque T _AVE are represented in FIG. ).

Further, the grip end inertia moment I _G and the swing inertia moment I _S can be used as a swing ease index. It should be noted that the swing index described in this specification and the ease of swinging index can be arbitrarily combined.

Also, when the grip end moment of inertia I _G and swing easiness index, golf club 4 used in the test hitting at the measurement step includes a golf club large extreme grip end moment of inertia I _G, extremely grip end inertia it is preferable that the small golf club of the moment I _G. In this case, an extremely large grip end inertia moment I _G (minimum if there are plural) and an extremely small grip end inertia moment I _G (maximum if there are plural). The difference is preferably 250 kg · cm ² or more, and more preferably 400 kg · cm ² or more. The difference between I _G between two golf clubs 4 belonging to the proportional region is preferably at 100 kg · cm ² or more, and more preferably 125 kg · cm ₂ or more. Further, the difference between the head velocities V _h by the two golf clubs 4 belonging to the proportional region is preferably 0.8 m / s or more, and more preferably 1.0 m / s or more.

(Torque capacity T _ti and average torque T _AVE )
The torque exertion amount T _ti is a value obtained by integrating the torque T ₁ around the shoulder in the swing period, and is calculated by, for example, integrating in the section from the top to the impact. T _ti means the torque exerted by the entire double pendulum system during the swing. In calculating the torque exerting amount T _ti , only the positive torque T ₁ may be integrated, or the average value of the torque T ₁ may be integrated.
The average torque T _AVE is an average torque per unit time exhibited in the entire system, and can be calculated as, for example, T _AVE = T _ti / (t _i −t _t ).

<3-4>
The number of golf clubs 4 to be tried in the measurement process is three in the above embodiment, but is not limited thereto. By obtaining measurement data from more golf clubs 4 and plotting more points based on this data in the swing index-easiness of swing index plane, more accurate swing index regression lines l ₁ and l ₂ can be obtained. It can also be calculated. Such regression lines l ₁ and l ₂ can be calculated by a method such as a least square method.

In addition, the number of golf clubs 4 to be hit in the measurement process can be two. That is, the first regression line l ₁ can be calculated based on the measurement data obtained by one golf club 4, and the second regression line l ₂ can be calculated based on the measurement data obtained by one golf club 4.

Specifically, in the analysis based on the relationship of at least the head speed V _h -golf club weight m ₂ , the inventors have determined that the slope of the second regression line l ₂ is the cock release timing _tr and the head speed V. It was confirmed that there was a correlation with each of _h . Therefore, the slope of the second regression line l ₂ can be expressed by a regression equation using the cock release timing _tr and / or the head speed V _h as explanatory variables. That is, the inclination u of the regression line l ₂ in the proportional region can be calculated by the following equation (t _r, if the explanatory variables both V _h).
u = w ₁ · _tr + w ₂ · V _h + w ₃

The coefficients w ₁ , w ₂ , and w ₃ can be calculated from multiple experimental data by multiple regression analysis. In calculating the coefficients w ₁ , w ₂ , and w ₃ based on multiple regression analysis, the testers can be stratified based on the head speed V _{h and the} like, and can be calculated for each layer.

When the slope of the second regression line l ₂ is obtained as described above, the second regression line l ₂ is calculated as a straight line having the slope and passing through the point corresponding to the swing index based on the measurement data. can do.

<3-5>
In the above embodiment, the first regression line l ₁ is a straight line parallel to the axis of the ease index, but it may be a straight line having an inclination. This is because, as shown in the experimental data of FIG. 17, the swing index may change gradually (generally constant) with respect to the swing ease index. In this case, even against the calculation of the first regression line l _1, equal to measure the measurement data of a plurality of golf clubs 4, it is to identify the first regression line l ₁ in the same manner as the second regression line l ₂ it can.

1 Sensor unit (measuring device)
2 Fitting device 3 Fitting program 4 Golf club 7 Golfer 24A Acquisition unit 24B Index calculation unit 24C Optimal index specification unit 41 Head 42 Grip

Claims (12)

A golf club fitting device,
An acquisition unit for acquiring measurement values obtained by measuring swing motions of a plurality of golf clubs;
Based on the measured value, for each of the golf clubs, an index calculation unit that calculates a swing index that is an index characterizing the swing motion;
Based on the swing index calculated by the index calculation unit, a first regression line of the swing index in a constant region where the swing index is substantially constant with respect to the swing ease index representing the ease of swinging of the golf club; , Specifying an intersection with the second regression line of the swing index in a proportional region in which the swing index is substantially proportional to the swing ease index, and an optimal index or an optimum that is the swing ease index at or near the intersection An optimal index specifying unit for specifying an index band,
Fitting device. The acquisition unit measures a first measurement value obtained by measuring the swing motion of a golf club having an extremely small swing ease index, and a second value obtained by measuring the swing motion of a golf club having an extremely large swing ease index. Get the measured value,
The optimum index specifying unit specifies the first regression line based on the swing index based on the first measurement value, and determines the second regression line based on the swing index based on the second measurement value. Specifying or specifying the first regression line based on the swing index based on the second measurement value and specifying the second regression line based on the swing index based on the first measurement value ,
The fitting device according to claim 1. The optimal index specifying unit specifies the first regression line as a straight line having a slope of zero through a point corresponding to the swing index based on the measurement value of one golf club.
The fitting apparatus according to claim 1 or 2. The optimum index specifying unit specifies the second regression line based on a regression equation of an inclination of the second regression line having at least one of a cock release timing during the swing operation and a head speed during impact as an explanatory variable. To
The fitting apparatus in any one of Claim 1 to 3. The optimum index specifying unit passes the point corresponding to the swing index based on the measurement value by one golf club, and uses the second regression line as a straight line having the slope calculated based on the regression equation. Identify,
The fitting device according to claim 4. The swing ease indicator includes at least one of a weight of the golf club, a grip end moment of inertia, and a moment of inertia around a golfer's shoulder.
The fitting apparatus in any one of Claim 1 to 5. The swing index includes at least one of head speed, torque display amount, average torque, average power, and energy display amount.
The fitting apparatus in any one of Claim 1 to 6. 8. An optimum club specifying unit that specifies a golf club having a small swing inertia moment and a large grip end inertia moment from a plurality of golf clubs that match the optimum indicator or the optimum indicator band. The fitting apparatus in any one of. A golf club fitting method,
Measuring a swing motion of a plurality of golf clubs using a measuring device;
Calculating a swing index, which is an index characterizing the swing motion, for each golf club based on the measured value of the swing motion;
Identifying a first regression line of the swing index in a constant region where the swing index is substantially constant with respect to the swing ease index representing the ease of swinging of the golf club based on the calculated swing index;
Identifying a second regression line of the swing index in a proportional region where the swing index is generally proportional to the ease of swing based on the calculated swing index;
Identifying an intersection between the first regression line and the second regression line, and identifying an optimal index or an optimal index band that is the index of ease of swinging at or near the intersection. The method according to claim 9, further comprising: identifying a golf club having a small swing inertia moment and a large grip end inertia moment from among a plurality of golf clubs that match the optimum indicator or the optimum indicator band. A golf club fitting program,
Obtaining a measurement value obtained by measuring the swing motion;
Calculating a swing index, which is an index characterizing the swing action, for each golf club based on the measured value;
Identifying a first regression line of the swing index in a constant region where the swing index is substantially constant with respect to the swing ease index representing the ease of swinging of the golf club based on the calculated swing index;
Identifying a second regression line of the swing index in a proportional region where the swing index is generally proportional to the ease of swing based on the calculated swing index;
Identifying an intersection of the first regression line and the second regression line, and causing the computer to execute an step of identifying an optimal index or an optimal index band that is the ease of swinging index at or near the intersection.
program. 12. The computer according to claim 11, further comprising a step of identifying a golf club having a small swing inertia moment and a large grip end inertia moment from a plurality of golf clubs that match the optimum indicator or the optimum indicator band. Program.