JP6087132B2 - Golf club shaft fitting method - Google Patents

Description

  The present invention relates to a method for fitting a shaft of a golf club.

  It is an eternal theme for golfers to extend the distance of the ball and to fly it in the direction and angle aimed at. To that end, it is important to use a golf club that fits your swing.

  Selecting a golf club suitable for a golfer is generally referred to as fitting. In order to perform this fitting effectively, it is necessary to consider various factors such as the total weight of the golf club, the weight of the club head, and the length of the golf club. It greatly affects the quality.

For example, one of the physical properties of the shaft is flex. The flex is representative hardness of the shaft a (rigid), forward flex, as shown in Figure 36, a point 129mm from the tip end 20a of the shaft 20 and the load point W _1, the load point W _When a load Wt of 2.7 kgf is applied to the load point W ₁ with a point of 824 mm from ₁ to the butt end side of the shaft 20 as a fulcrum A and a position of 140 mm from the fulcrum A to the butt end side as an action point B Of the tip end 20a. With respect to this displacement amount F1 (this value is referred to as a forward flex), the flex is determined by a definition such that a certain value f1 to a certain value f2 is an X shaft.

  In general, flex is recommended to have a hardness suitable for the size of the head speed, and a flexible shaft is recommended for golfers with relatively slow head speeds, while it is hard for golfers with relatively fast head speeds. A shaft is recommended. However, this flex does not have a unified standard, and is defined by different standards for each manufacturer. The selection of a suitable flex value often relies on the experience and intuition of the fitting person (fitter), and the selection result is not objective but has individual differences.

In addition, the physical properties of other shafts are in tune. 37, as shown in FIG. 37, the position of 12 mm from the tip end 20a of the shaft 20 is an action point C, and the point of 140 mm from the action point C to the butt end side of the shaft 20 is a fulcrum D. as load point _{W 2} points 776mm to butt end side from D, displacement of the butt end 20b when a load Wt of 1.3kgf to the load point _{W 2} F2 a (the value of the reverse flex) Then, T is calculated from the value of this F2 and the above-mentioned F1 (forward flex) according to the following formula (1), and it is determined whether the value of T is a pretone or a hand tone. .
T = F2 / (F1 + F2) × 100 (1)

  The selection of a golf club using this tone also has to rely on the experience and intuition of the person performing the fitting, as in the case of using the flex described above, and the selection results are not objective and have individual differences.

  Therefore, it has been proposed to have a golfer actually perform a swing when fitting, and to perform the fitting from the measurement result of the swing (see, for example, Patent Documents 1 and 2).

  Patent Document 1 discloses a model generation step for generating a golf club model of a golf club used in a golf swing, and a golf club model given a predetermined boundary condition in order to reproduce a golf swing using the golf club model. A characteristic value calculating step for calculating a swing behavior of the club model and calculating a desired dynamic characteristic value of the golf club model in the golf swing, and repeating this characteristic value calculating step while changing the type of the generated golf club model By repeating the step of obtaining the dynamic characteristic value for each of the plurality of golf club models, and extracting the maximum value and the minimum value of the dynamic characteristic value among the plurality of dynamic characteristic values obtained in this repetition step, Based on the difference between the maximum and minimum values, the characteristics of the golf swing are classified. And a swing evaluation step of evaluating, the evaluation method of the golf swing is disclosed.

  Further, Patent Document 2 is a golf club swing evaluation method having a golf club head having a hosel portion on which a golf club shaft is mounted on a crown portion, and the golf club head is installed in a horizontal plane. The golf club swing speed was measured at two points at least 10 mm apart on the intersecting line that includes the axis of the golf club shaft and intersects the plane perpendicular to the horizontal plane and the crown of the golf club head. A swing evaluation method for evaluating a swing based on the speed of each point is disclosed.

JP 2006-230466 A JP 2009-18043 A

However, in the method described in Patent Document 1, the apparatus to be used is large and the installation place is limited. In addition, there is a problem that a large-scale arithmetic device is required and the cost is high.
Further, in the method described in Patent Document 2, the evaluation of the swing is performed only by the impact, and the characteristics of the entire swing from the address to the impact through the top are not reflected. Therefore, a shaft suitable for a golfer's swing may not be selected, and an improvement has been desired.

  The present invention has been made in view of such circumstances, and since the apparatus to be used can be reduced in size and weight, the selection range of the installation location is wide and more detailed reflecting the entire swing. An object of the present invention is to provide a golf club shaft fitting method capable of fitting on the basis of various shaft specifications.

(1) A golf club shaft fitting method of the present invention (hereinafter also simply referred to as “fitting method”) is a fitting method for selecting a shaft that matches a golfer based on the golfer's swing,
Hitting a golf ball with a golf club having a sensor capable of measuring angular velocities around three axes attached to the grip to obtain a measured value from the sensor;
Determining an address, top and impact in the swing from the measured values;
And a step of selecting a shaft that matches the golfer using the following swing feature values (a) to (d) obtained from the measured values.
(A) Amount of change in grip angular velocity in the cock direction near the top (b) Average value of grip angular velocity in the cock direction from the top until the grip angular velocity in the cock direction reaches the maximum during the downswing (c ) Average value of the grip angular velocity in the cock direction from the time when the grip angular velocity in the cock direction becomes maximum during the downswing to the impact. (D) Average value of the grip angular velocity in the cock direction from the top to the impact.

  In the fitting method of the present invention, the shaft can be selected based on the four swing feature values reflecting not only the limited aspect during the swing of the golfer but also the entire swing from the top to the impact. The fitting can be performed based on the specific shaft specifications. As a result, it is possible to provide a shaft with better performance (flying distance, directionality, and ease of swinging) for the golfer.

  Further, in the fitting method of the present invention, the swing characteristics can be quantified by simply attaching a sensor to the grip end of the club, and a large-scale equipment such as a conventional camera is unnecessary, so the cost of equipment for fitting is reduced. Is small. Furthermore, the data can be distributed wirelessly to the data analysis device, and the configuration of the entire facility can be simplified, so that it can be easily carried, installed and removed.

(2) In the fitting method of (1), (a) to (d) are the bending rigidity of the shaft at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft, respectively. Selected as corresponding,
(A) to (d) swing characteristics obtained from trial measurements and an approximate expression representing the relationship between each of the swing feature quantities (a) to (d) and the bending rigidity of the shaft, and the measured values. From the quantity, obtain the bending stiffness of the shaft at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft,
A shaft that matches the golfer can be selected based on the obtained bending rigidity of the shafts at the four positions from a plurality of shafts whose bending rigidity at the four positions has been measured in advance.

(3) In the fitting method of (2), for each of the bending stiffnesses at the four positions, one of a plurality of rank values is given according to the acquired bending stiffness value,
Rank values at four assigned positions from among a plurality of shafts to which any one of a plurality of rank values is assigned according to the measured bending stiffness values in advance. It is preferable to select a shaft that matches the golfer based on the above.

(4) In the fitting method of (2) or (3), when the length of the golf club of the user is different from the length of the golf club having a shaft selected from the plurality of shafts, It is preferable to change the total weight of the golf club based on the difference.

(5) In the fitting method of (1), (a) to (d) are the bending rigidity of the shaft at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft, respectively. Selected as corresponding,
(A) to (d) swing characteristics obtained from trial measurements and an approximate expression representing the relationship between each of the swing feature quantities (a) to (d) and the bending rigidity of the shaft, and the measured values. From the quantity, obtain the bending stiffness of the shaft at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft,
According to the acquired bending stiffness value, give one of the rank values of multiple stages,
The shape pattern of the change in the rank value obtained by plotting the rank value at the four positions on a plane coordinate having the vertical axis as the assigned rank value and the horizontal axis as the distance from one end of the shaft to the other. Get
A shaft corresponding to the acquired shape pattern can be selected from a plurality of shafts for which the shape pattern is obtained in advance.

(6) In the fitting method of (5), the horizontal axis of the plane coordinates can be a distance from the proximal end portion of the shaft toward the distal end portion.

(7) In the fitting method of (5) or (6), the shaft selected based on the shape pattern, wherein the bending stiffness at the four positions is measured in advance and the measured bending stiffness value is determined. Thus, a shaft that matches the golfer can be selected from the plurality of shafts to which any one of the rank values of the plurality of levels is assigned, based on the rank values at the assigned four positions.

(8) In the fitting method of (7), when selecting a shaft based on the rank value, it is preferable to select the shaft according to the following degree of coincidence.

Here, the calculated IFC is a rank value obtained by calculation, and the database IFC is a rank value calculated based on bending stiffness values measured in advance at four positions for a plurality of shafts and stored in the database. is there. Calculation 36 IFC, calculation 26 IFC, calculation 16 IFC and calculation 6 IFC are rank values obtained at 36 inches, 26 inches, 16 inches and 6 inches from the shaft tip end, respectively, obtained by calculation. The data 36 IFC, data 26 IFC, data 16 IFC, and data 6 IFC are calculated based on the bending stiffness values measured in advance for a plurality of shafts, and stored in the database, 36 inches, 26 inches, Rank values at 16 inches and 6 inches.

(9) In the fitting methods (1) to (8), it is preferable that a plurality of approximate expressions are created according to the head speed.

  According to the fitting method of the present invention, the apparatus to be used can be reduced in size and weight, so that the selection range of the installation location is wide and the fitting is performed based on a more detailed shaft specification reflecting the entire swing. Can do.

It is a figure explaining the behavior of the deflection of the shaft during swing. It is a figure explaining four positions of the shaft in which bending rigidity is measured in the fitting method of the present invention. It is a figure explaining the measuring method of the bending rigidity in this invention. It is a figure explaining the method of measuring the swing feature-value in this invention. It is a partially expanded perspective view of a golf club to which a sensor is attached. (A) is a top view of the sensor shown by FIG. 5, (b) is a side view of the sensor. It is a figure which shows the address and takeback in a swing. It is a figure which shows the top and downswing in a swing. It is a figure which shows the downswing and impact in a swing. It is a figure which shows the follow through and finish in a swing. It is a figure which shows the change according to the time passage of the angular velocity of the cock direction in a swing. It is a figure explaining the evaluation criteria of ease of swing. In the fitting method which concerns on 1st Embodiment of this invention, it is a figure which shows the relationship between the swing feature-value (4) and the bending rigidity (EI value) in the measurement point of "6 inches". It is a figure which shows the flow of EI value calculation in the measurement point of the same "6 inches". It is a figure which shows the relationship between the swing feature-value (3) and bending rigidity (EI value) in the measurement point of "16 inches". It is a figure which shows the flow of EI value calculation in the measurement point of the same "16 inches". It is a figure which shows the relationship between the swing feature-value (2) and bending rigidity (EI value) in the measurement point of said "26 inches". It is a figure which shows the flow of EI value calculation in the measurement point of the same "26 inches". It is a figure which shows the relationship between the swing feature-value (1) and bending rigidity (EI value) in the measurement point of "36 inches". It is a figure which shows the flow of EI value calculation in the measurement point of "36 inches". It is explanatory drawing of the flex and tone of five shafts used for verification of the effect of this invention. In the fitting method which concerns on 2nd Embodiment of this invention, it is a figure which shows the relationship between the swing feature-value (4) and the bending rigidity (EI value) in the measurement point of "6 inches". It is a figure which shows the flow of EI value calculation in the measurement point of the same "6 inches". It is a figure which shows the relationship between the swing feature-value (3) and bending rigidity (EI value) in the measurement point of "16 inches". It is a figure which shows the flow of EI value calculation in the measurement point of the same "16 inches". It is a figure which shows the relationship between the swing feature-value (2) and bending rigidity (EI value) in the measurement point of said "26 inches". It is a figure which shows the flow of EI value calculation in the measurement point of the same "26 inches". It is a figure which shows the relationship between the swing feature-value (1) and bending rigidity (EI value) in the measurement point of "36 inches". It is a figure which shows the flow of EI value calculation in the measurement point of "36 inches". It is a list of four factors considered as an exceptional factor when obtaining a rank value in the fitting method according to the second embodiment. It is a figure which shows the flow which determines a proposal shaft in the fitting method which concerns on 2nd Embodiment. It is a list of the change pattern of the rank value for every inch. It is a figure which shows the first half of the flow which determines the change pattern of the rank value for every inch. It is a figure which shows the second half of the flow which determines the change pattern of the rank value for every inch. It is a table | surface which shows the correspondence of the change pattern of the rank value for every inch, and the shaft type selected by this. It is a figure explaining the measuring method of a forward type flex. It is a figure explaining the measuring method of a reverse type flex.

Hereinafter, embodiments of the fitting method of the present invention will be described in detail with reference to the accompanying drawings.
[First embodiment]
[Principle of the fitting method of the present invention]
Before describing the embodiment of the fitting method of the present invention, the principle or theoretical background of the fitting method of the present invention will be described. The inventors of the present invention have focused on the fact that the bending of the shaft of the golf club is transmitted from the hand side to the tip side of the shaft as the swing proceeds from the top toward the impact. An assumption is made that there is a correlation between the swing characteristic of a certain golfer from the top to the impact (the details of the swing characteristic will be described later) and the hardness of the shaft matched to the golfer per inch. As a result of extensive research and examination, the present invention has been completed.

  In other words, the golfer's swing when hitting the ball changes from address → top → impact, but the golf club shaft has a relatively heavy head at the tip of the golf club. Bending occurs due to inertia. This bending does not occur in the same part of the shaft in the entire swing process, but is transmitted from the proximal side to the distal end side of the shaft from the top toward the impact as shown in FIG. In other words, as the swing advances from the top toward the impact, the bending position on the shaft moves from the proximal side to the distal end side of the shaft.

  Specifically, when the take-back is performed from the address and the top is reached (the time indicated by (1) in FIG. 1), bending occurs near the hand of the shaft. Next, when turning back and reaching the initial stage of the downswing (at the time indicated by (2) in FIG. 1), the bending moves slightly toward the tip side of the shaft. Further, at the time when the golfer's arm becomes horizontal (the time indicated by (3) in FIG. 1), the bending moves to the tip side from the center of the shaft. And just before the impact (at the time indicated by (4) in FIG. 1), the bending moves to the vicinity of the tip of the shaft.

  In view of the fact that the bending of the shaft at the time of swinging is transmitted from the proximal side to the distal end side of the shaft from the top toward the impact, the inventor has characterized the swing characteristics of the golfer in the time zones (1) to (4). Attempts were made to select the optimal bending stiffness for each inch of the shaft.

  Specifically, as shown in FIG. 2, the shaft 20 was divided into four regions, and the bending rigidity at one point in each region was defined. In the present embodiment and the second embodiment described later, a point 36 inches from the tip end 20a of the shaft 20 is a measurement point (1), a point 26 inches is a measurement point (2), and a point 16 inches is a measurement point. (3), and a 6-inch spot is a measurement point (4). The bending stiffness at the four measurement points of the shaft 20 is measured and digitized. In this specification, “for every inch” does not mean 1 inch, 2 inches,..., “For a plurality of locations at a distance of a predetermined inch from one end of the shaft, In this embodiment, “predetermined inches” are 36 inches, 26 inches, 16 inches, and 6 inches from the tip end 20a of the shaft 20 as described above. In this embodiment, the four measurements for measuring the bending rigidity of the shaft are 36 inches, 26 inches, 16 inches, and 6 inches from the tip end of the shaft. Without limitation, for each number of inches, it is possible to vary within a width of ± several inches. For example, the measurement point (1) can be 36 ± 2 inches from the tip end of the shaft.

The bending rigidity (EI value: N · m ² ) per inch of the shaft can be measured as shown in FIG. 3 using, for example, a 2020 type measuring machine (maximum load 500 kgf) manufactured by Intesco.

  Specifically, the deflection amount α when the load F is applied to the measurement point P from above is measured while supporting the shaft 20 from below at the two support points 11 and 12. In the present embodiment, there are four measurement points P, 36 inches, 26 inches, 16 inches, and 6 inches from the tip end 20a of the shaft 20. The distance (span) between the support point 11 and the support point 12 is 200 mm. Further, the measurement point P is an intermediate point between the support point 11 and the support point 12. The tip of the indenter 13 to which the load F is applied from above is rounded so as not to damage the shaft 20. The cross-sectional shape of the tip of the indenter 13 has a radius of curvature of 10 mm in a cross section parallel to the shaft axial direction. In the cross section perpendicular to the shaft axis direction, the cross-sectional shape of the tip of the indenter 13 is a straight line, and its length is 45 mm.

  The support 14 supports the shaft 20 from below at the support point 11. The tip of the support 14 has a convex roundness. The cross-sectional shape of the tip of the support 14 has a radius of curvature of 15 mm in a cross section parallel to the shaft axial direction. In the cross section perpendicular to the shaft axial direction, the cross-sectional shape of the tip of the support 14 is a straight line, and its length is 50 mm. The shape of the support 15 is the same as that of the support 14. The support 15 supports the shaft 20 from below at the support point 12. The tip of the support 15 has a convex roundness. The cross-sectional shape of the tip of the support 15 has a radius of curvature of 15 mm in a cross section parallel to the shaft axial direction. In the cross section perpendicular to the shaft axial direction, the cross-sectional shape of the tip of the support 15 is a straight line, and its length is 50 mm.

The indenter 13 is moved downward at a speed of 5 mm / min while the support 14 and the support 15 are fixed. Then, when the load F reaches 20 kg, the movement of the indenter 13 is terminated. The deflection amount α (mm) of the shaft 20 at the moment when the movement of the indenter 13 is finished is measured, and the bending stiffness EI (N · m ² ) is calculated according to the following equation (2).
Flexural rigidity EI (N · m ² ) = 32.7 / α (2)

  Then, fitting is performed using the measured bending rigidity of the shaft per inch as an index. The hardness (bending rigidity) of the shaft per inch has a correlation with the swing characteristic with time from the top to the impact, and if the swing characteristic of each golfer is known, the shaft of the shaft per inch suitable for the characteristic is correlated. Hardness can be determined. As described above, the bending or deformation (deflection amount) of the shaft during the swing is transmitted from the top side to the tip side of the shaft from the top to the downswing. In the present invention, focusing on the propagation of this bending, the amount of deflection of the shaft near the top is related to the fast and slow behavior of the grip near the top (angular velocity). Provide a softer shaft for slower golfers.

  In this embodiment, any one of rank values of a plurality of levels is given according to the bending rigidity of the shaft measured for each inch by the method described above. Specifically, any one of 10 levels of IFCs is assigned according to the bending rigidity. This IFC is an abbreviation for International Flex Cord, and is an index proposed by the present applicant as representing the hardness of the shaft.

  Tables 1 to 4 below are conversion tables from shaft EI values to IFC at measurement points (1) to (4), respectively. The range of shafts that Fitter has prepared to provide to users in consideration of the frequency of use and the method of dividing the shaft hardness into 10 steps for all commercially available shafts. Several methods such as a method of dividing into 10 stages are conceivable. In this embodiment, the latter method is used for fitting.

[Swing feature]
In the present invention, as shown in FIG. 4, a golfer who wants to fit a golf club actually makes a swing, and the swing feature value specific to the golfer is measured from the swing. As shown in FIGS. 5 to 6, a sensor 2 capable of measuring angular velocities around three axes is attached to the grip end of the golf club 1 via an adapter 3. The sensor 2 includes a casing 2a made of a box having a square shape in plan view. The casing 2a can be fixed to the grip end by double-sided tape, adhesive, screwing, or the like. In the example shown in FIG. 4, the golfer G is right-handed and is in an address state immediately before starting a swing for hitting the ball B set at a predetermined position.

In order to improve the fitting accuracy, if the length of the user's My Club is different from the length of the golf club based on the shaft stored in the database, the total club weight equivalent to the club length prepared in the database By changing to, a shaft that matches the user can be selected. For example, if the length of a club stored in the database is 45 inches and the user's club length A (mm) is different from 45 inches (= 1143 mm), the total weight of the club swinging for measurement is calculated. The fitting is performed by changing to the one calculated by the following formula (total weight corresponding to 45 inches).
(Total club weight used for measurement) = (A-1143) × 0.377 + (total club weight of my club)

  The sensor 2 is wireless, and the measured data is transmitted wirelessly to a wireless reception device (not shown) built in the computer 10 as a data analysis device. As the wireless communication, for example, Bluetooth (Bluetooth (Bluetooth is a registered trademark)) standard and technology can be used.

  The sensor 2 incorporates an angular velocity sensor (not shown) that can measure angular velocities about three axis directions (x-axis direction, y-axis direction, and z-axis direction). The sensor 2 further includes an A / D converter, a CPU, a wireless interface, a wireless antenna, and a power source. As the power source, for example, a button-type lithium ion battery or the like can be used. The battery may be rechargeable. The sensor 2 may include a charging circuit for charging the battery. An example of the sensor 2 that can be used is WAA-010 (trade name) manufactured by Wireless Technology.

  The wireless receiving device that receives a signal from the sensor 2 includes a wireless antenna, a wireless interface, a CPU, and a network interface.

  A computer 10 serving as a data analysis apparatus includes an input unit 6 including a keyboard 4 and a mouse 5 and a display unit 7. Although not shown, the computer 10 includes a hard disk, a memory, a CPU, and a network interface.

  The sensor 2 detects angular velocities around the x-axis, y-axis, and z-axis. These angular velocities are obtained as analog signals, and the analog signals are converted into digital signals by an A / D converter built in the sensor 2. The output from the A / D converter is transmitted to the CPU, and arithmetic processing such as primary filtering is executed. The data thus processed in the sensor 2 is transmitted from the wireless antenna to the wireless reception device built in the computer 10 via the wireless interface.

  The data transmitted from the sensor 2 is received by the wireless interface via the wireless antenna on the wireless receiving device side. The received data is processed by the CPU of the computer 10.

  Data sent to the computer 10 is recorded in a memory resource such as a hard disk. The hard disk stores programs and data necessary for data processing and the like. This program causes the CPU to execute necessary data processing. The CPU can execute various arithmetic processes, and the calculation results are output by the display unit 7 or a printing device (not shown).

  When the sensor 2 is attached to the grip end, the relationship between the measurement axis and the golf club 1 is considered. In the present embodiment, the z axis of the sensor 2 coincides with the shaft axis of the golf club 1. The x axis of the sensor 2 is oriented along the toe heel direction of the head 1 a of the golf club 1. The y-axis of the sensor 2 is oriented so as to be along the normal direction of the face surface of the head 1a. By attaching the sensor 2 in this way, the calculation can be simplified.

  In this embodiment, a local coordinate system is considered, and the x-axis, y-axis, and z-axis of this local coordinate system are a three-dimensional orthogonal coordinate system. In this embodiment, the z axis is the shaft axis of the golf club 1, and the x axis is oriented along the toe heel direction of the head 1a. Further, the y-axis is oriented along the hitting direction.

  That is, the z axis of the local coordinate system matches the z axis of the sensor 2, and the y axis of the local coordinate system matches the y axis of the sensor 2. Further, the x-axis of the local coordinate system matches the x-axis of the sensor 2.

  The sensor 2 can obtain a plurality of continuous data in time series. The number of data per unit time depends on the sampling frequency.

  7 to 10 are diagrams for explaining a swing from an address to a finish by a golfer. The swing includes a fall-through after impact. In the present invention, attention is paid to the characteristics of the swing from address to impact.

  FIGS. 7-10 is the figure which looked at the golfer from the front. The beginning of the swing is the address, and the end of the swing is called the finish. The swing proceeds in the order of (S1), (S2), (S3), (S4), (S5), (S6), (S7), and (S8). In FIG. 7, (S1) is an address, and (S2) is a takeback. (S3) in FIG. 8 is the top (top of swing). Usually, at the top, the moving speed of the head during the swing is minimum. (S4) in FIG. 8 is a downswing. Although (S5) in FIG. 9 is also a downswing, the downswing is more advanced than in (S4) in FIG. (S6) in FIG. 9 is an impact, which is the moment when the head 1a of the golf club 1 and the ball B collide. In FIG. 10, (S7) is a follow-through, and (S8) is a finish. At the finish, the swing ends.

  In the present embodiment, attention is paid to the angular velocity ωy in the cock direction during the downswing from the vicinity of the top to the impact among the various stages in the swing described above, and the angular velocity ωy is subdivided and quantified as time passes. In the present specification, “near the top” means a time period including a predetermined time immediately before the top and a predetermined time immediately after the top. Specifically, for example, 100 ms from the top −50 ms to the top +50 ms. Means the time zone.

  FIG. 11 shows the relationship between the time (s) from the address to the impact in a certain swing and the angular velocity ωy (deg / s) in the cock direction. In the present embodiment, as shown in FIG. 11, four swing features (1) to (4) are set according to the passage of time of the swing, and each swing feature is quantified.

  The swing feature quantity (1) as the swing feature quantity (a) is the inclination of the angular velocity ωy in the cock direction near the top, for example, the sum of the angular velocity ωy 50 ms before the top and the angular velocity ωy 50 ms after the top. Can be represented. This swing feature quantity (1) has a correlation with the bending stiffness at the measurement point 36 inches from the tip end of the shaft described above.

  The swing feature value (2) as the swing feature value (b) is an average value of the angular velocity ωy from the top to the time point when the angular velocity ωy becomes maximum. The maximum value of the angular velocity ωy from the top to the impact is obtained, and the average value is obtained by dividing the cumulative value of the angular velocity ωy from the top to the time when the maximum value is reached by the time from the top to the time when the maximum value is reached. The value can be determined. This swing feature amount (2) has a correlation with the bending stiffness at the measurement point 26 inches from the tip end of the shaft described above.

  The swing feature amount (3) as the swing feature amount (c) is an average value of the angular velocity ωy from the time point when the angular velocity ωy becomes maximum to the impact, and the cumulative angular velocity ωy from the time point when the angular velocity ωy reaches the impact to the impact. The average value can be obtained by dividing the value by the time from the time when the maximum value is reached until the impact. This swing feature amount (3) has a correlation with the bending stiffness at the measurement point 16 inches from the tip end of the shaft described above.

  The swing feature value (4) as the swing feature value (d) is an average value of the angular velocity ωy from the top to the impact, and the cumulative value of the angular velocity ωy from the top to the impact is divided by the time from the top to the impact. Thus, the average value can be obtained. This swing feature (4) has a correlation with the bending stiffness at the measurement point 6 inches from the tip end of the shaft.

  The above swing feature values (1) to (4) are obtained by giving a golfer who desires fitting a predetermined number of balls, for example, five balls, and calculating an average of the swing feature values calculated at each shot. It can be set as a swing feature value.

[Calculation of shaft rigidity per inch]
Next, the shaft rigidity per inch suitable for the golfer is calculated based on the calculated swing feature values (1) to (4). Prior to this calculation, an approximate expression representing the relationship between the swing feature value and the preferred shaft bending stiffness (EI value) is obtained in advance for each swing feature value. This approximate expression is created based on data collected by having a plurality of testers make trial runs. From the viewpoint of improving the reliability of the approximate expression, it is preferable that the number of testers is large. In this embodiment, the tester is an intermediate or advanced handicap of 20 or less. For each tester, several golf clubs are selected based on the weight, length, and flex (or tone) of the golf club that is usually used from a plurality of golf clubs (drivers) prepared in advance. Each of several golf clubs was given a test of several balls, for example, six balls (excluding miss shots), and a golf club that was easy to swing was selected according to the criteria described later.

  For golf clubs that are easy to swing, the three items of “flying distance”, “direction”, and “easy to swing” are scored according to the evaluation criteria shown in the following Table 5, for example, and the total score is 1.5 points or more Judge clubs as easy to swing. Several selected golf clubs were painted black on the shaft portion and were randomly provided to the testers. This made it impossible for the tester to determine which club is hitting. Trial hits were performed in two sets of 3 balls x number of clubs, and a questionnaire on ease of swinging was asked to check the score each time a 3-ball trial was made for a certain club.

  FIG. 13 is a diagram showing the relationship between the swing feature (4) and the bending stiffness (EI value) at the measurement point “6 inches” prepared in advance as described above, and FIG. It is a figure which shows the flow of EI value calculation in the measurement point of "." In FIG. 14, “ωy4” is the swing feature amount (4) of the angular velocity in the cock direction. The same applies to FIGS. 16, 18 and 20 described later.

  In the present embodiment, in order to improve the accuracy of EI value calculation, not only one approximate expression but also three approximate expressions are prepared in advance. Although it is possible to express the relationship between the swing feature (4) and the EI value at the measurement point of “6 inches” by one approximate expression, a golfer or head whose angular velocity ωx in the x-axis direction near the top is extremely small For a golfer who deviates from an average swing, such as a golfer whose speed is considerably low, there is a case where a reliable EI value cannot be calculated by one approximate expression. Therefore, in this embodiment, an exception (1) approximate expression and an exception (2) approximate expression are prepared together with a normal approximate expression corresponding to an average golfer.

  First, in step S1, exception processing (1) is executed. Specifically, the angular velocity ωx in the x-axis direction near the top is ωx <−300, and the average value of the angular velocity ωy in the y-axis direction from the top to the impact and the angular velocity ωx in the x-axis direction from the top to the impact are It is determined whether or not the ratio to the average value (ωy (overall) / ωx (overall)) is 0.55 or less. In the case of Yes, the exception (1) approximate expression indicated by the alternate long and short dash line in FIG. The EI value is calculated using this.

On the other hand, in the case of No in step S1, the process proceeds to step S2 and exception processing (2) is executed. In the exception process (2), it is determined whether at least one of the following five conditions (a) to (e) is satisfied.
(A) The cumulative value of the angular velocity ωz in the z-axis direction from the top to the impact is extremely large, and ωz> 270.
(B) The head speed is less than 41.0 m / s.
(C) The angular velocity ωx in the x-axis direction near the top satisfies ωx> 0.
(D) The ratio (ωy (overall) / ωx (overall)) of the average value of the angular velocity ωy in the y-axis direction from the top to the impact and the average value of the angular velocity ωx in the x-axis direction from the top to the impact is 2.0. That's it.
(E) The ratio (ωy (overall) / ωx (overall)) of the average value of the angular velocity ωy in the y-axis direction from the top to the impact and the average value of the angular velocity ωx in the x-axis direction from the top to the impact is 1.5. In addition, the swing feature value (4) is larger than 800.

  In the case of Yes in step S2, the EI value is calculated using the exception (2) approximate expression indicated by the broken line in FIG. On the other hand, in the case of No in step S2, the EI value is calculated using the normal approximate expression indicated by the solid line in FIG.

  The normal approximate expression, the exception (1) approximate expression, and the exception (2) approximate expression can all be a linear expression representing a regression line by the least square method. The slope and intercept of each equation are shown in Table 6 below.

  FIG. 15 is a diagram showing the relationship between the swing feature value (3) and the bending stiffness (EI value) at the measurement point of “16 inches” created in advance as described above, and FIG. It is a figure which shows the flow of EI value calculation in the measurement point of "."

First, in step S11, exception processing (3) is executed. Specifically, it is determined whether at least one of the following three conditions (f) to (h) is satisfied.
(F) The ratio (ωy (overall) / ωx (overall)) of the average value of the angular velocity ωy in the y-axis direction from the top to the impact and the average value of the angular velocity ωx in the x-axis direction from the top to the impact is 1.5. That's it.
(G) The head speed (HS) is less than 41 m / s, and the swing feature value (3) is greater than 800.
(H) The angular velocity ωx in the x-axis direction near the top is smaller than −300, and the average value of the angular velocity ωy in the y-axis direction from the top to the impact and the average value of the angular velocity ωx in the x-axis direction from the top to the impact Ratio (ωy (overall) / ωx (overall)) is 0.55 or less.

  In the case of Yes in step S11, the EI value is calculated using the exception (3) approximate expression indicated by the one-dot chain line in FIG. On the other hand, in the case of No in step S11, the process proceeds to step S12 and exception processing (4) is executed. In this exceptional process (4), it is determined whether or not the head speed is less than 41 m / s and the swing feature quantity (3) is smaller than 800.

  In the case of Yes in step S12, the EI value is calculated using the exception (4) approximate expression indicated by the broken line in FIG. On the other hand, in the case of No in step S12, the EI value is calculated using the normal approximate expression indicated by the solid line in FIG.

  The normal approximate expression, the exception (3) approximate expression, and the exception (4) approximate expression can all be a linear expression representing a regression line by the least square method. Table 7 below shows the slope and intercept of each equation.

  FIG. 17 is a diagram showing the relationship between the swing feature (2) and the bending stiffness (EI value) at the measurement point “26 inches” prepared in advance as described above, and FIG. It is a figure which shows the flow of EI value calculation in the measurement point of "." For this swing feature (2), three approximate equations are set according to the head speed of the golfer. That is, each of the case where the head speed is lower than 41 m / s (case 1), the case where the head speed is 41 m / s or more and 45 m / s or less (case 2), and the case where it is higher than 45 m / s (case 3). An approximate expression is set.

  First, in step S21, it is determined whether the head speed is any one of Case 1, Case 2, and Case 3. In case 1, the EI value is calculated using the approximate expression shown by the alternate long and short dash line in FIG. In case 2, the process proceeds to step S22 and exception processing (5) is executed. In this exception process (5), it is determined whether or not the angular velocity ωx in the x-axis direction near the top is greater than zero.

  In the case of Yes in step S22, the EI value is calculated using an approximate expression indicated by a one-dot chain line in FIG. On the other hand, in the case of No in step S22, the process proceeds to step S23 and exception processing (6) is executed. In this exceptional process (6), it is determined whether or not the weight of the club (my club) that is normally used by the golfer performing the fitting is less than 305 g.

  In the case of Yes in step S23, the EI value is calculated using an approximate expression indicated by a one-dot chain line in FIG. On the other hand, in the case of No in step S23, the EI value is calculated using the approximate expression indicated by the solid line in FIG.

  Further, in case S3 in step S21, the process proceeds to step S24 and exception processing (7) is executed. In this exceptional process (7), it is determined whether or not the angular velocity ωz in the z-axis direction is larger than 270. In the case of Yes in step S24, the EI value is calculated using the approximate expression indicated by the solid line in FIG.

  On the other hand, in the case of No in step S24, the process proceeds to step S25 and exception processing (8) is executed. In this exceptional process (8), it is determined whether or not the weight of the club (my club) that is normally used by the golfer performing the fitting is less than 318 g. In the case of Yes in step S25, the EI value is calculated using the approximate expression indicated by the solid line in FIG. On the other hand, in the case of No in step S25, the EI value is calculated using the approximate expression indicated by the broken line in FIG.

  The approximate expression of case (1), the approximate expression of case (2), and the approximate expression of case (3) can all be linear expressions representing a regression line by the least square method. The slope and intercept of each equation are shown in Table 8 below.

  FIG. 19 is a diagram showing the relationship between the swing feature (1) and the bending stiffness (EI value) at the measurement point “36 inches” created in advance as described above, and FIG. It is a figure which shows the flow of EI value calculation in the measurement point of "." For this swing feature quantity (1), three approximate equations are set according to the golfer's head speed. That is, each of the case where the head speed is lower than 41 m / s (case 1), the case where the head speed is 41 m / s or more and 45 m / s or less (case 2), and the case where it is higher than 45 m / s (case 3). An approximate expression is set.

  First, in step S31, it is determined whether the head speed is any one of Case 1, Case 2, and Case 3. In case 1, the EI value is calculated using an approximate expression indicated by a one-dot chain line in FIG. In case 2, the process proceeds to step S32 and exception processing (5) is executed. In this exception process (5), it is determined whether or not the angular velocity ωx in the x-axis direction near the top is greater than zero.

  In the case of Yes in step S32, the EI value is calculated using the approximate expression indicated by the alternate long and short dash line in FIG. On the other hand, in the case of No in step S32, the process proceeds to step S33 and exception processing (6) is executed. In this exceptional process (6), it is determined whether or not the weight of the club (my club) that is normally used by the golfer performing the fitting is less than 305 g.

  In the case of Yes in step S33, the EI value is calculated using the approximate expression indicated by the alternate long and short dash line in FIG. On the other hand, in the case of No in step S33, the EI value is calculated using the approximate expression indicated by the solid line in FIG.

  Further, in case S3 in step S31, the process proceeds to step S34 and exception processing (7) is executed. In this exceptional process (7), it is determined whether or not the angular velocity ωz in the z-axis direction is larger than 270. In the case of Yes in step S34, the EI value is calculated using the approximate expression shown by the solid line in FIG.

  On the other hand, in the case of No in step S34, the process proceeds to step S35 and exception processing (8) is executed. In this exceptional process (8), it is determined whether or not the weight of the club (my club) that is normally used by the golfer performing the fitting is less than 318 g. In the case of Yes in step S35, the EI value is calculated using the approximate expression indicated by the solid line in FIG. On the other hand, in the case of No in step S35, the EI value is calculated using the approximate expression indicated by the broken line in FIG.

  The approximate expression of case (1), the approximate expression of case (2), and the approximate expression of case (3) can all be linear expressions representing a regression line by the least square method. The slope and intercept of each equation are shown in Table 9 below.

[Calculation of IFC per inch]
For the shaft EI value calculated for each inch by the above-described method, for example, any one of 10 stages of IFC is calculated using the conversion tables shown in Tables 1 to 4 above. In the present embodiment, as described above, in consideration of the usage frequency and the like, a method of dividing the shaft into ten stages within the range of the shaft prepared by the fitter to be provided to the user is adopted.

[Selection of shaft]
As described above, the IFC for each inch is calculated for the golfer performing the fitting. As examples of the calculated IFC, 36 inches: 5, 26 inches: 4, 16 inches: 4, 6 inches: 2 can be given.

  Then, the shaft that most closely matches the calculation result is selected from the database. The database stores data such as IFC for each inch and weight measured in advance for a plurality of types of shafts. Using this database, the “coincidence” shown in the following equation (3) is calculated for all the clubs stored in the database, and the club with the smallest value is proposed to the golfer. As used herein, “degree of coincidence” does not mean the degree of coincidence, but, as is clear from Equation (3), the smaller the value, the closer the shaft has bending rigidity to the calculation result. It is an index that means that. A degree of coincidence of 0 means that the shaft has the same bending rigidity per inch as the calculation result.

  Further, when there are a plurality of shafts having the same degree of coincidence, a plurality of shafts may be proposed to the user, or may be narrowed down to one in consideration of the user's request. As a standard for narrowing down, focusing on ease of swinging, priority is given to a method of giving priority to the degree of IFC coincidence at “36 inches” or “26 inches” on the shaft side, and performance (flight distance, directionality). There is a method of giving priority to the degree of coincidence of IF at “16 inches” or “6 inches” on the shaft front end side.

  In the present embodiment, when selecting based on the above-mentioned “coincidence”, hearing of the weight of my club is performed for a golfer who performs fitting in advance. Based on the result of the hearing, fitting is performed from the shafts within the range of the golf club my club weight ± 5 g from the plurality of shafts stored in the database. If the weight of the golf club with the selected shaft changes significantly compared to the weight of the My Club that we normally use, it will be difficult to take the timing and it will be difficult to swing, so there is a possibility that the golfer's performance cannot be demonstrated is there. In order to prevent this reliably, it is preferable to perform fitting from the shaft within the range of the golf club's My Club weight of ± 5 g.

〔inspection result〕
A shaft exchange type golf club capable of freely changing the shaft was produced, and the effectiveness of the fitting method according to the present embodiment was verified using this golf club.

  Experiments were conducted on single equivalent testers using S or X shafts. The number of testers was 23, and the head speed was about 41 to 51 m / s.

  First, a golf ball having a sensor attached to a grip is used for trial hitting, a swing feature amount of the tester is measured, and a single shaft having a bending rigidity matching the tester is calculated from the swing feature amount in a database. Determined from. This database stores data of 59 shafts for which IFC for each inch has been calculated in advance.

  Next, among the 59 shafts, the tester used 5 shafts within the tester My Club ± 5 g and different shaft characteristics (flex, tone). 21. As shown in FIG. 21, the five shafts are hard and tones, hard and medium tone, medium to medium tone, soft and medium in terms of flex (hardness) and tone. And a soft and handy characteristic. A shaft having the characteristics of these five patterns was prepared according to weight.

  As a result of the test hit, if there is a large flight distance, the ball does not bend, and one of the five easy-to-swing clubs is present, whether or not a shaft close to the shaft characteristics of the club is selected, there are two or more. In this case, whether or not the selected shaft is included in the vicinity of the ellipse including those shafts (see the hatched portion in FIG. 21) was used as an evaluation criterion.

  For 23 testers, the case where the fitted club was included in the ellipse was defined as “correct”. The results confirmed that 21 out of 23 testers were correctly fitted. The accuracy rate was (21/23) × 100≈91%. And about 21 persons who had an effect (it was a correct answer), it was confirmed how much effect it had regarding flight distance, directionality, and ease of swinging. As an average value of 21 people, it was confirmed that the flight distance was increased by 5.5 yards, the directionality was 12 yards toward the center, and the ease of swinging was improved by 1.0 points. Note that the evaluation of ease of swinging is based on a nine-level evaluation ("5" is neither), as shown in FIG.

[Second Embodiment]
Next, a second embodiment of the fitting method of the present invention will be described.
In the second embodiment, the number of approximate expressions used when calculating the EI value from the swing feature value is increased so that it can be applied to a golfer with a slow head speed. In addition, the IFC value obtained from the EI value is not immediately obtained from the IFC value (see the above formula (3)), but the IFC value per inch is changed from the grip side (hand side) of the shaft to the head side (tip side). Based on the IFC value change pattern indicating how the change is directed to the IFC value change pattern, a shaft group having an IFC value change pattern close to the IFC value change pattern is selected, and then, for the selected shaft group, The shaft that fits the golfer is selected based on the degree of coincidence calculated from the values. Also in the method for calculating the coincidence, in the first embodiment, the sum of the absolute values of the differences is used as the coincidence, but in the second embodiment, in addition to the sum, the difference in the IFC value change pattern is also taken into consideration. The degree of coincidence is calculated.

  In addition, since the significance of swing feature-value (1)-(4) in 2nd Embodiment and how to obtain them are the same as that of 1st Embodiment, those description is abbreviate | omitted for simplicity.

  Also in this embodiment, one of the rank values of a plurality of stages is given according to the bending rigidity of the shaft measured for each inch by the method described with reference to FIG. Specifically, any one of 10 levels of IFCs is assigned according to the bending rigidity. This IFC is a modified IFC in which a boundary value between stages is modified with respect to the IFC used in the first embodiment.

  Tables 10 to 13 below are conversion tables from the EI value of the shaft to the IFC at the measurement points (1) to (4), respectively. The range of shafts that Fitter has prepared to provide to users in consideration of the frequency of use and the method of dividing the shaft hardness into 10 steps for all commercially available shafts. Several methods such as a method of dividing into 10 stages are conceivable. In this embodiment, the former method is used for fitting.

[Calculation of shaft rigidity per inch]
Also in the present embodiment, as in the first embodiment, the shaft rigidity per inch suitable for the golfer is calculated based on the calculated swing feature amounts (1) to (4). Prior to this calculation, an approximate expression representing the relationship between the swing feature value and the preferred shaft bending stiffness (EI value) is obtained in advance for each swing feature value. This approximate expression is created based on data collected by having a plurality of testers make trial runs. From the viewpoint of enhancing the versatility of the approximate expression, it is preferable that the number of testers is large. In the present embodiment, the tester is a golf club that is lighter than the first embodiment, and the handicap is 20 or less. For each tester, several golf clubs are selected based on the weight, length, and flex (or tone) of the golf club that is usually used from a plurality of golf clubs (drivers) prepared in advance. Each of several golf clubs was given a test of several balls, for example, six balls (excluding miss shots), and a golf club that was easy to swing was selected according to the criteria described later.

  A golf club that is easy to swing is scored according to the evaluation criteria shown in Table 5 above for the three items of “flying distance”, “direction”, and “easy to swing”, and the total score is 1.5 points or more. Judge clubs as easy to swing. Several selected golf clubs were painted black on the shaft portion and were randomly provided to the testers. This made it impossible for the tester to determine which club is hitting. Trial hits were performed in two sets of 3 balls x number of clubs, and a questionnaire on ease of swinging was asked to check the score each time a 3-ball trial was made for a certain club.

FIG. 22 is a diagram showing the relationship between the swing feature (4) and the bending stiffness (EI value) at the measurement point of “6 inches” created in advance as described above, and FIG. It is a figure which shows the flow of EI value calculation in the measurement point of "." The meanings of indices such as “ωy1” in FIG. 23 and FIGS. 25, 27, and 29 to be described later are as follows.
ωy1: Amount of angular velocity change around the y-axis near the top ωy2: Average angular velocity around the y-axis from the top to the ωy maximum value ωy2: Average angular velocity around the y-axis from the ωy maximum value to the impact timing ωy2: From the top to the impact timing Average angular velocity around the y-axis ωx1: change in angular velocity around the x-axis near the top ωz4: average angular velocity around the z-axis from the top to the impact timing ωx4 / ωy4: (average angular velocity around the z-axis from the top to the impact timing) ) / (Average angular velocity around the z-axis from top to impact timing)

  In this embodiment, in order to improve the accuracy of EI value calculation, not only one approximate expression but also three or four approximate expressions are prepared in advance. Although it is possible to express the relationship between each swing feature and the EI value at the measurement point per inch by one approximate expression, a golfer with a very low head speed, or the movement of ωx or ωz has a characteristic movement. For golfers who deviate from the average swing, such as, it may not be possible to calculate a highly reliable EI value with a single approximate expression. Therefore, in this embodiment, a plurality of approximate expressions are prepared.

  Specifically, in the present embodiment, not only the movement in the cock direction (ωy is related) but also rotation (rotation around the shaft axis) or the like for a golfer who performs a swing as shown in FIG. It is an approximate expression that takes into account the movement of the golfer's hand in the back direction.

  FIG. 30 shows four exception factors. Of these, exception factor 1 and exception factor 3 relate to the movement of the golfer's hand in the back direction, and correspond to cases where the face is extremely open and extremely closed at the top, respectively. Exception factor 2 and exception factor 4 are related to rotation, and correspond to cases where the rotation is extremely large and extremely small, respectively.

  Exception factor 1 is when the head speed is greater than 42 m / s and the face is extremely open at the top. When the face is easy to open at the top, the face once opens the grip immediately after turning over. When the shaft is in the first tone, there is a possibility that the face will open more and the face will not return immediately before impact, that is, the face may be delayed. Therefore, an approximate expression is proposed in which an EI value is calculated so that the original tone shaft is obtained. By using the proposed approximate line, the rank value considering only the head speed is changed as described in the exception factor 1 of FIG.

  Exception factor 2 is when the head speed is greater than 42 m / s and the rotation is extremely large. When the rotation is extremely large, if the shaft is in the first tone, the face returns more, and there is a possibility that the ball is likely to fly to the left, which is an inappropriate state. Therefore, in particular, an approximate expression is proposed in which the EI value is calculated such that the shaft on the middle tone rather than the first tone is obtained by lowering the hardness on the hand side. By using the proposed approximate line, the rank value considering only the head speed is changed as described in the exception factor 2 of FIG.

  Exception factor 3 is a case where the head speed is 42 m / s or less and the face is extremely closed at the top. If the face is easy to close at the top, there is a possibility that the face will be further closed if the shaft is in the first tone. Therefore, an approximate expression is proposed in which an EI value is calculated so that the original tone shaft is obtained. By using the proposed approximate line, the rank value considering only the head speed is changed as described in the exception factor 3 of FIG.

  Exception factor 4 is when the head speed is 42 m / s or less and the rotation is extremely small. If the rotation is small, you need to run the head a little. For this purpose, an approximate expression is proposed in which the EI value is calculated so that the hand side is a little hard and the shaft is a tonal system. By using the proposed approximate line, the rank value considering only the head speed is changed as described in the exception factor 4 in FIG. This is because a golfer with a slow head speed does not have a shaft that softens the tip side any more.

First, a method for calculating an EI value at a measurement point of “6 inches” will be described. The approximate expression EI (6) used for calculating the EI value at the measurement point of “6 inches” is one of the following approximate expressions (6-1) to (6-3).
Approximate expression (6-1): EI (6) = 0.012 × ωy4 + 22.5
Approximate expression (6-2): EI (6) = 0.012 × ωy4 + 16.5
Approximation formula (6-3): EI (6) = 0.012 × ωy4 + 13.5
In step S41, it is determined whether the head speed (HS) is larger than 42 m / s, ωx4 / ωy4 is 0.55 or more, and ωx1 is smaller than −300. The EI value is calculated using Equation (6-1).

  On the other hand, if No in step S41, the process proceeds to step S42. In step S42, it is determined which of the case 1, case 2, and case 3 is related to the head speed. If it is determined that the case 1 is a head speed of 45 m / s or more, an EI value is calculated using the approximate expression (6-2). If it is determined that the head speed is less than 45 m / s and greater than 42 m / s, the process proceeds to step S43. If it is determined that the head speed is case 3 of 42 m or less, the process proceeds to step S44.

In step S43, it is determined whether ωz4 is 250 or more and ωx4 / ωy4 is 1.25 or more. In the case of Yes, the EI value is calculated using the approximate expression (6-3), and in the case of No, the EI value is calculated using the approximate expression (6-2).
In step S44, it is determined whether ωx4 / ωy4 is 1.5 or more, ωx1 is 0 or more, and ωz4 is 75 or more. In the case of Yes, the EI value is calculated using the approximate expression (6-2), and in the case of No, the EI value is calculated using the approximate expression (6-3).

FIG. 24 is a diagram showing the relationship between the swing feature (3) and the bending stiffness (EI value) at the measurement point of “16 inches” created in advance as described above, and FIG. It is a figure which shows the flow of EI value calculation in the measurement point of "." The approximate expression EI (16) used for calculating the EI value at the measurement point of “16 inches” is one of the following expressions (16-1) to (16-4).
Approximation formula (16-1): EI (16) = 0.0143 × ωy3 + 30.0
Approximate expression (16-2): EI (16) = 0.140 × ωy3 + 23.2
Approximation formula (16-3): EI (16) = 0.0100 × ωy3 + 20.5
Approximation formula (16-4): EI (16) = 0.64443 × ωy3 + 19.0

  In step S51, it is determined whether or not the head speed (HS) is greater than 42 m / s, ωx4 / ωy4 is 0.55 or greater, and ωx1 is smaller than −300. The EI value is calculated using Expression (16-1).

  On the other hand, if No in step S51, the process proceeds to step S52. In step S52, it is determined which of the case 1, case 2, case 3, and case 4 is related to the head speed. If it is determined that the case 1 is a head speed of 45 m / s or more, the EI value is calculated using the approximate expression (16-2). If it is determined that the head speed is less than 45 m / s and greater than 42 m / s, the process proceeds to step S43. If it is determined that the head speed is 42 m / s or less and greater than 38 m / s, the process proceeds to step S54. If it is determined that the head speed is Case 4 of 38 m or less, the process proceeds to step S55.

In step S53, it is determined whether ωz4 is 250 or more and ωx4 / ωy4 is 1.25 or more. In the case of Yes, the EI value is calculated using the approximate expression (16-3), and in the case of No, the EI value is calculated using the approximate expression (16-2).
In step S54, it is determined whether ωx4 / ωy4 is 1.5 or more, ωx1 is 0 or more, and ωz4 is 75 or more. In the case of Yes, the EI value is calculated using the approximate expression (16-2), and in the case of No, the EI value is calculated using the approximate expression (16-3).

  In step S55, it is determined whether ωx4 / ωy4 is 1.5 or more, ωx1 is 0 or more, and ωz4 is 75 or more. In the case of Yes, the EI value is calculated using the approximate expression (16-3), and in the case of No, the EI value is calculated using the approximate expression (16-4).

FIG. 26 is a diagram showing the relationship between the swing feature value (2) and the bending rigidity (EI value) at the measurement point “26 inches” prepared in advance as described above, and FIG. It is a figure which shows the flow of EI value calculation in the measurement point of "." The approximate expression EI (26) used for calculating the EI value at the measurement point of “26 inches” is one of the following expressions (26-1) to (26-4).
Approximation formula (26-1): EI (26) = 0.0143 × ωy2 + 30.0
Approximation formula (26-2): EI (26) = 0.140 × ωy2 + 23.2
Approximation formula (26-3): EI (26) = 0.0100 × ωy2 + 20.5
Approximate expression (26-4): EI (26) = 0.64443 × ωy2 + 19.0

  In step S61, it is determined which of the case 1, case 2, case 3, and case 4 is related to the head speed. If it is determined that the case 1 is a head speed of 45 m / s or more, the process proceeds to step S62. If it is determined that the head speed is less than 45 m / s and greater than 42 m / s, the process proceeds to step S63. If it is determined that Case 3 is that the head speed is 42 m / s or less and greater than 38 m / s, the process proceeds to step S64. If it is determined that the head speed is Case 4 of 38 m or less, the EI value is calculated using the approximate expression (26-4).

In step S62, it is determined whether or not ωz4 is 250 or more. In the case of Yes, the EI value is calculated using the approximate expression (26-2), and in the case of No, the EI value is calculated using the approximate expression (26-1).
In step S63, it is determined whether ωz4 is 250 or more and ωx4 / ωy4 is 1.25 or more. In the case of Yes, the EI value is calculated using the approximate expression (26-3), and in the case of No, the EI value is calculated using the approximate expression (26-2).

  In step S64, it is determined whether ωx4 / ωy4 is 1.5 or more, ωx1 is 0 or more, and ωz4 is 75 or more. In the case of Yes, the EI value is calculated using the approximate expression (26-4), and in the case of No, the EI value is calculated using the approximate expression (26-3).

FIG. 28 is a diagram showing the relationship between the swing feature (1) and the bending stiffness (EI value) at the measurement point “36 inches” created in advance as described above, and FIG. It is a figure which shows the flow of EI value calculation in the measurement point of "." The approximate expression EI (36) used for calculating the EI value at the measurement point of “36 inches” is one of the following expressions (36-1) to (36-4).
Approximation formula (36-1): EI (36) = 0.057 × ωy1 + 71.0
Approximation formula (36-2): EI (36) = 0.035 × ωy1 + 70.3
Approximate expression (36-3): EI (36) = 0.026 × ωy1 + 68.2
Approximation formula (36-4): EI (36) = 0.0005 × ωy1 + 66.1

  In step S71, it is determined which of the case 1, case 2, case 3, and case 4 is related to the head speed. If it is determined that the head speed is case 1 of 45 m / s or more, the process proceeds to step S72. If it is determined that the head speed is less than 45 m / s and greater than 42 m / s, the process proceeds to step S73. If it is determined that Case 3 is that the head speed is 42 m / s or less and greater than 38 m / s, the process proceeds to step S74. If it is determined that the head speed is Case 4 of 38 m or less, the EI value is calculated using the approximate expression (36-4).

In step S72, it is determined whether or not ωz4 is 250 or more. In the case of Yes, the EI value is calculated using the approximate expression (36-2), and in the case of No, the EI value is calculated using the approximate expression (36-1).
In step S73, it is determined whether ωz4 is 250 or more and ωx4 / ωy4 is 1.25 or more. In the case of Yes, the EI value is calculated using the approximate expression (36-3), and in the case of No, the EI value is calculated using the approximate expression (36-2).

In step S74, it is determined whether or not ωz4 is less than 75. In the case of Yes, the EI value is calculated using the approximate expression (36-2), and in the case of No, the EI value is calculated using the approximate expression (36-3).
In step S75, it is determined whether or not ωz4 is less than 75. In the case of Yes, the EI value is calculated using the approximate expression (36-3), and in the case of No, the EI value is calculated using the approximate expression (36-4).

[Calculation of IFC per inch]
For the shaft EI value calculated for each inch by the above-described method, for example, any one of 10 stages of IFC is calculated using the conversion table shown in Tables 10-13. In this embodiment, as described above, a method of dividing all commercially available shafts into 10 stages is adopted.

[Selection of shaft]
Next, a shaft suitable for the golfer is selected using the IFC value calculated by calculation. FIG. 31 is a flow showing a method for determining a proposed shaft in the present embodiment.
First, in the present embodiment, in step S81, the first of the plurality of shafts (for example, hundreds of shafts) in which specifications such as IFC values and weights per inch are stored in the database is determined according to the weight of the shaft. Narrow down. Specifically, for example, the reference shaft (the weight of the shaft in the My Club that is usually used by golfers who desire fitting) is narrowed down to a shaft within a range of ± 5 g.

  In step S82, the IFC value per inch calculated on the plane coordinates with the horizontal axis as the distance from the proximal side to the tip side of the shaft and the vertical axis as the IFC value (rank value) is plotted. The second narrowing is performed based on the shape pattern obtained when As such a shape pattern, eleven patterns are conceivable as shown in FIG.

  The first shape pattern is a shape pattern that rises to the right as the IFC value gradually increases toward the tip end of the shaft, and the second shape pattern has an IFC value that gradually increases toward the tip end of the shaft. It is a shape pattern that decreases to the right. The third shape pattern is a shape pattern that is not as high as the first pattern but slightly increases to the right as the IFC value gradually increases toward the tip side of the shaft, and the fourth shape pattern is the same as the second pattern. Although it is not as large as the pattern, the IFC value gradually decreases to the right as it goes toward the tip of the shaft.

  In the fifth shape pattern, the IFC values at the central 16 inch and 26 inch measurement points are smaller than the IFC values at the 6 inch and 36 inch measurement points at both ends, and the same small size. This is a concave flat shape pattern. In contrast to the fifth shape pattern, in the sixth shape pattern, the IFC values at the central 16 inch and 26 inch measurement points are larger than the IFC values at the 6 inch and 36 inch measurement points at both ends. And, it is a convex flat shape pattern having the same size.

  The seventh shape pattern has an IFC value at a measurement point of 36 inches on the hand side as a reference value, which is larger than the reference value at 26 inches, and smaller than the reference value at 16 inches. In inches, the pattern is an N flat shape having a size approximately equal to the reference value. Contrary to the seventh shape pattern, the eighth shape pattern has an IFC value at a measurement point of 36 inches on the hand side as a reference value. When the size is larger than the reference value and 6 inches, it is an inverted N-flat shape pattern having a size approximately equal to the reference value.

  In addition, the ninth shape pattern shows a tendency that the IFC value gradually increases as it goes toward the tip of the shaft, but the degree is smaller than the third shape pattern and is a substantially flat upward shape pattern. Yes, the tenth shape pattern also shows a tendency that the IFC value gradually decreases as it goes to the tip end side of the shaft, but the degree is smaller than the fourth shape pattern, and is a substantially flat downward-sloping shape pattern It is.

In the eleventh shape pattern, the IFC values at the four measurement points are exactly the same or substantially equal (for example, only the IFC value at one measurement point is smaller by “1” than the IFC value at the other measurement point). Or a large shape).
The above-described shape pattern can be determined by plotting the calculated IFC values on the plane coordinates and connecting the plotted four points, but in the present embodiment, the flowchart shown in FIGS. Therefore, we are judging.

First, in step S101, the following A to E are calculated as determination indexes.
A = IFC36-IFC6
B = (IFC36 + IFC26) / 2− (IFC16 + IFC6) / 2
C = IFC36−IFC26
D = IFC16-IFC6
E = abs (IFC26-IFC16)
Here, IFC36, IFC26, IFC16, and IFC6 are IFC values calculated using Tables 10 to 13, respectively, at 36 inches, 26 inches, 16 inches, and 6 inches from the shaft tip. The value is shown.

In step S102, it is determined whether A ≦ −3. In the case of Yes, it is judged that it is the first shape pattern (upward to the right) described above, and in the case of No, the process proceeds to Step S103.
In step S103, it is determined whether A ≧ 3. In the case of Yes, it is judged that it is the above-mentioned 2nd shape pattern (lower right), and in No, it progresses to step S104.

In step S104, it is determined whether A ≦ −1 and B ≦ −1.5. In the case of Yes, it is judged that it is the above-mentioned third shape pattern (slightly upward), and in the case of No, the process proceeds to step S105.
In step S105, it is determined whether A ≧ 1 and B ≧ 2.0. In the case of Yes, it is judged that it is the above-mentioned 4th shape pattern (slightly downward), and in the case of No, it progresses to step S106.

In step S <b> 106, it is determined whether C ≧ 1 and D ≦ −1 and whether both absolute values are 2 or more. In the case of Yes, it is judged that it is the 5th shape pattern (concave flat) mentioned above, and in No, it progresses to step S107.
In step S107, it is determined whether C ≧ 1, D ≦ −1, and E ≧ 1. In the case of Yes, it is judged that it is the 5th shape pattern (concave flat) mentioned above, and in No, it progresses to step S108.

In step S108, it is determined whether C ≦ −1, D ≧ 1, and both determination indexes have an absolute value of 2 or more. In the case of Yes, it is judged that it is the 6th shape pattern (convex flat) mentioned above, and in No, it progresses to step S109.
In step S109, it is determined whether C ≦ −1, D ≧ 1, and E ≧ 1. In the case of Yes, it is judged that it is the 6th shape pattern (convex flat) mentioned above, and in No, it progresses to step S110.

In step S110, it is determined whether C ≦ −1, D ≧ −1, and both determination indices have an absolute value of 2 or more. In the case of Yes, it is judged that it is the above-mentioned 7th shape pattern (N flat), and in No, it progresses to step S111.
In step S111, it is determined whether C ≦ −1, D ≧ 1, and E ≧ 2. In the case of Yes, it is judged that it is the above-mentioned 7th shape pattern (N flat), and in No, it progresses to step S112.

In step S112, it is determined whether C ≦ 1 and D ≧ 1 and the absolute values of both determination indexes are 2 or more. In the case of Yes, it is judged that it is the above-mentioned 8th shape pattern (reverse N flat), and in No, it progresses to step S113.
In step S113, it is determined whether C ≦ 1, D ≧ 1, and E ≧ 2. In the case of Yes, it is judged that it is the above-mentioned 8th shape pattern (inverse N flat), and in No, it progresses to step S114.

In step S114, it is determined whether A ≦ −2, C = 0, and D ≦ −2. In the case of Yes, it is determined that it is the above-described ninth shape pattern (substantially flat upward), and in the case of No, the process proceeds to step S115.
In step S115, it is determined whether A ≦ −2, C ≦ −2, and D = 0. In the case of Yes, it is determined that it is the above-mentioned ninth shape pattern (substantially flat right-up), and in the case of No, the process proceeds to step S116.

In step S116, it is determined whether B = 1.5. In the case of Yes, it is determined that it is the above-described tenth shape pattern (substantially flat downward right), and in the case of No, the process proceeds to step S117.
In step S117, it is determined whether A ≧ 2, C = 0, and D ≧ 2. In the case of Yes, it is determined that it is the above-described tenth shape pattern (substantially flat downward right), and in the case of No, the process proceeds to step S118.

In step S118, it is determined whether A ≧ 2, C ≧ 2, and D = 2. In the case of Yes, it is determined that it is the above-described tenth shape pattern (substantially flat downward right), and in the case of No, it is determined that it is the above-described eleventh shape pattern (flat).
The second narrowing based on the shape pattern in step S82 is performed from among a plurality of shafts prepared in advance. For these multiple shafts, the IFC value is determined from the EI values measured at the four positions of the shaft, and the shape pattern described above is determined from the obtained IFC value. The result is associated with the shaft and stored in the database. It is remembered.

  The second narrowing down in the present embodiment is not a simple one-to-one correspondence, but is configured such that similar shape patterns are selected as shown in the correspondence table of FIG. For example, when the shape pattern obtained by the calculation is the first shape pattern, not only the shaft of the first shape pattern rising to the right but also the shaft of the third shape pattern slightly rising to the right is selected. Note that, in the fifth shape pattern (concave flat) and the sixth shape pattern (convex flat), it is possible to select either right-up or right-down depending on how the IFC values obtained by calculation are arranged. For example, when the IFC value is “4565”, the right-up is also selected (see Δ in FIG. 35). Further, for example, when the IFC value is “4543”, the lowering to the right is also selected (see the ▲ mark in FIG. 35). That is, when it is determined as the fifth or sixth shape pattern, Δ is added to ○ when the determination index A is −1 or less, and ▲ is added to ○ when A is 1 or more.

  Then, in step S83, a shaft having an IFC value closest to the calculated IFC value, in other words, a shaft that most closely matches the calculated IFC value is selected from the shafts selected in step S82. The database stores an IFC value for each inch that forms the basis of the shape pattern described above. Using this database, the “coincidence” shown below is calculated for the shafts stored in the database and selected in step S82, and the club with the smallest value is proposed to the golfer.

Here, the calculated IFC is an IFC obtained by calculation, and the database IFC is an IFC calculated based on EI values measured in advance at four positions for a plurality of shafts and stored in the database. Calculation 36 IFC, calculation 26 IFC, calculation 16 IFC and calculation 6 IFC are IFCs obtained by calculation, respectively, at 36 inches, 26 inches, 16 inches and 6 inches from the shaft tip end. The data 36 IFC, data 26 IFC, data 16 IFC, and data 6 IFC are calculated based on EI values measured in advance for a plurality of shafts and stored in the database, respectively, 36 inches, 26 inches, 16 from the shaft tip end. IFC in inches and 6 inches.

In the present embodiment, unlike the first embodiment in which the degree of coincidence is calculated based only on the sum of absolute values of differences in IFC values, the pattern of change in IFC values along the shaft axis direction, that is, the tendency of the arrangement of IFC values. Considering the above, the shaft is narrowed down, and the degree of coincidence is calculated for the narrowed down shaft.
By considering the shape pattern of the change in bending rigidity, it is possible to select a shaft that better matches the user. That is, when only the sum of absolute values of differences is calculated without considering the feature of whether the IFC values are arranged to the right (original tone) or to the right (first tone), shafts with different arrangements are used. You may choose.

  For example, in the case of the example shown in Table 14 below, the IFC value calculated by calculation is “2445”, which tends to rise to the right. If there is a shaft with an IFC value of “2356” and a shaft with an IFC value of “3444”, the flat type shaft B is selected if only the sum of absolute values of differences is calculated. On the other hand, when the user actually tried the shaft A and the shaft B, it was found that the shaft A rising to the right is more suitable for both flight distance and directionality. As in the second embodiment, by performing fitting in consideration of the arrangement of IFC values, it is possible to provide a golfer with a shaft with better performance (flying distance, directionality, and ease of swinging).

〔inspection result〕
A shaft exchange type golf club capable of freely changing the shaft was produced, and the effectiveness of the fitting method according to the present embodiment was verified using this golf club.

  An experiment was conducted on a tester having a head speed of 35.0 m / s or more, a total club weight of My Club of 290 g or more, and a handicap of up to 20. The number of testers was 63.

  First, a golf ball having a sensor attached to a grip is used for trial hitting, a swing feature amount of the tester is measured, and a single shaft having a bending rigidity matching the tester is calculated from the swing feature amount in a database. From this, it is determined through narrowing down by weight (step S81), narrowing down based on the shape pattern (step S82), and narrowing down by matching degree (step S83) in the present embodiment. This database stores data of 127 shafts for which IFC for each inch is calculated in advance.

  Next, the tester used 5 shafts with different shaft characteristics (flex, tone) within 127 ± 5 g of the tester My Club. 21. As shown in FIG. 21, the five shafts are hard and tones, hard and medium tone, medium to medium tone, soft and medium in terms of flex (hardness) and tone. And a soft and handy characteristic. A shaft having the characteristics of these five patterns was prepared according to weight.

  As a result of the test hit, if there is a large flight distance, the ball does not bend, and one of the five easy-to-swing clubs is present, whether or not a shaft close to the shaft characteristics of the club is selected, there are two or more. In this case, whether or not the selected shaft is included in the vicinity of the ellipse including those shafts (see the hatched portion in FIG. 21) was used as an evaluation criterion.

  For 63 testers, the case where the fitted club was included in the ellipse was defined as “correct”. The results confirmed that 56 out of 63 testers were fitted correctly. The accuracy rate was (56/63) × 100≈89%. On the other hand, when the same tester was tested by the fitting method according to the first embodiment, the accuracy rate was 82% (52/63). The reason why the correct answer rate is lower than the correct answer rate (91%) in the first embodiment is that the number of testers has increased and golfers with many handicaps have been included in the testers. .

  It should be noted that the embodiment disclosed this time is merely an example in all respects and is not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Golf club 2 Sensor 2a Casing 10 Computer (data analysis device)
20 Shaft 20a Tip end 20b Butt end G Golfer B Ball

Claims (9)

A golf club shaft fitting method using a computer to select a shaft that matches a golfer based on a golfer's swing,
Obtaining a measurement value from the sensor obtained by hitting a golf ball with a golf club having a sensor capable of measuring angular velocities about three axes attached to the grip by the receiving means of the computer ;
A step of determining an address, a top and an impact in a swing from the measured value by an arithmetic processing means of the computer ;
And selecting a shaft matched with a golfer by using the swing feature amount of the following (a) to (d) obtained from the measurement value by the arithmetic processing means of the computer. How to fit the club shaft.
(A) Amount of change in grip angular velocity in the cock direction near the top (b) Average value of grip angular velocity in the cock direction from the top until the grip angular velocity in the cock direction reaches the maximum during the downswing (c ) Average value of the grip angular velocity in the cock direction from the time when the grip angular velocity in the cock direction becomes maximum during the downswing to the impact. (D) Average value of the grip angular velocity in the cock direction from the top to the impact. (A) to (d) are selected to correspond to the bending rigidity of the shaft at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft, respectively.
(A) to (d) swing characteristics obtained from trial measurements and an approximate expression representing the relationship between each of the swing feature quantities (a) to (d) and the bending rigidity of the shaft, and the measured values. From the quantity, obtain the bending stiffness of the shaft at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft,
2. The golf club according to claim 1, wherein a shaft that matches the golfer is selected based on the obtained bending rigidity of the shafts at the four positions from among the plurality of shafts whose bending rigidity at the four positions is measured in advance. Shaft fitting method. For each of the bending stiffness at the four positions, one of a plurality of rank values is given according to the acquired bending stiffness value,
Rank values at four assigned positions from among a plurality of shafts to which any one of a plurality of rank values is assigned according to the measured bending stiffness values in advance. The method of fitting a shaft of a golf club according to claim 2, wherein a shaft that matches a golfer is selected based on the golf ball.   When the length of the golf club of the user is different from the length of the golf club having a shaft selected from the plurality of shafts, the total weight of the golf club is changed based on a difference between the two lengths. 4. A method for fitting a shaft of a golf club according to 2 or 3. (A) to (d) are selected to correspond to the bending rigidity of the shaft at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft, respectively.
(A) to (d) swing characteristics obtained from trial measurements and an approximate expression representing the relationship between each of the swing feature quantities (a) to (d) and the bending rigidity of the shaft, and the measured values. From the quantity, obtain the bending stiffness of the shaft at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft,
According to the acquired bending stiffness value, give one of the rank values of multiple stages,
The shape pattern of the change in the rank value obtained by plotting the rank value at the four positions on a plane coordinate having the vertical axis as the assigned rank value and the horizontal axis as the distance from one end of the shaft to the other. Get
The golf club shaft fitting method according to claim 1, wherein a shaft corresponding to the acquired shape pattern is selected from a plurality of shafts for which the shape pattern is obtained in advance.   The golf club shaft fitting method according to claim 5, wherein a horizontal axis of the plane coordinates is a distance from a proximal end portion to a distal end portion of the shaft.   For the shafts selected based on the shape pattern, the bending stiffness at the four positions is measured in advance, and a plurality of shafts having any one of rank values according to the measured bending stiffness values are provided. The method of fitting a shaft of a golf club according to claim 5 or 6, wherein a shaft that matches the golfer is selected based on rank values at four given positions. The method for fitting a shaft of a golf club according to claim 7, wherein the shaft is selected according to the following degree of coincidence when selecting the shaft based on the rank value.

Here, the calculated IFC is a rank value obtained by calculation, and the database IFC is a rank value calculated based on bending stiffness values measured in advance at four positions for a plurality of shafts and stored in the database. is there. Calculation 36 IFC, calculation 26 IFC, calculation 16 IFC and calculation 6 IFC are rank values obtained at 36 inches, 26 inches, 16 inches and 6 inches from the shaft tip end, respectively, obtained by calculation. The data 36 IFC, data 26 IFC, data 16 IFC, and data 6 IFC are calculated based on the bending stiffness values measured in advance for a plurality of shafts, and stored in the database, 36 inches, 26 inches, Rank values at 16 inches and 6 inches. The golf club shaft fitting method according to any one of claims 2 to 8, wherein a plurality of approximate expressions are created according to a head speed.

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