JP2013240364A - Golf club shaft fitting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a golf club shaft fitting method of a shaft with further excellent performance by taking into consideration both the kick point rate and flex of the shaft.SOLUTION: A fitting method of a shaft of a golf club includes the steps of: obtaining measurement values from a sensor attached to a grip of a golf club and capable of measuring angular velocities about three axes when a golf ball is hit by the golf club; and measuring a face angle and an approach angle of a head of the golf club immediately before impact; determining timing of top and impact of a swing from the measurement values; selecting a shaft that matches a golfer, through a usage of at least two swing characteristic amounts obtained from the measurement values, and the measured face angle and approach angle, wherein a shaft suited for a golfer is preliminarily selected based on the measured values and on a relation C created using a pre-created correlation R between a hit-ball result and face angle and approach angle immediately before impact, and then a shaft is selected with a usage of the swing characteristic amounts.

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.

  The shaft physical properties include flex, tone, torque, and weight. With conventional fittings, there are places that rely on the experience and intuition of those who do this (called "fitters"). Could not do.

  Therefore, it has been proposed to have a golfer actually swing, measure the swing using a camera, a sensor, or the like, and perform fitting from the measurement result (see, for example, Patent Document 1).

  In the fitting method described in Patent Document 1, using a plurality of golf clubs having different tone rates as shaft physical properties, face angles and hitting results (when hitting the ball) before or after the ball impact when a plurality of golfers swing. Direction and flight distance) in advance, measure the face angle when a golfer who wants to fit hits the ball, and based on the measurement result and the relationship, the tone rate suitable for the golfer is calculated. Deciding.

JP 2012-16582 A

  However, in the fitting method described in Patent Document 1, there is a problem that although the shaft tone rate can be selected, the shaft flex (total hardness) cannot be fitted.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a golf club fitting method capable of proposing to a golfer a shaft with better performance.

(1) The golf club shaft fitting method of the present invention (hereinafter also simply referred to as “fitting method”) is a golf club shaft fitting method in which a shaft matching the golfer is selected based on the golfer's swing. There,
A golf club having a sensor capable of measuring angular velocities around three axes is hit with a golf club attached to a grip to obtain a measured value from the sensor, and a face angle and an entrance angle of the head of the golf club immediately before impact are obtained. Measuring process;
Determining the top and impact timing in the swing from the measured values;
Selecting at least two of the following swing feature values (a) to (d) obtained from the measurement values, and a shaft that matches the golfer using the measured face angle and approach angle. And
Preliminarily select a shaft that fits the golfer based on the relationship C created using the correlation R between the face angle and approach angle just before impact and the hitting result, and the measured face angle and approach angle. Then, the shaft is selected using the swing feature amount.
(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 tone angle suitable for the golfer is obtained using the face angle and the approach angle obtained by the golfer actually swinging, and the shaft is preliminarily selected based on the tone rate. Similarly, a flex suitable for the golfer is obtained using a swing feature value measured from the golfer's swing. As a result, it is possible to propose to the golfer a shaft with superior performance that takes into consideration both the tone rate and the flex of the shaft.

(2) In the fitting method of (1), the correlation R is based on a hitting result with a plurality of golf clubs having different shaft tone rates,
The relation C is a predetermined relational expression between a tone ratio of the shaft prepared in advance and a face angle and an approach angle immediately before impact,
In the selection step, the shaft tone rate is calculated using the relational expression from the face angle and the approach angle immediately before the impact, and a shaft that matches the calculated tone rate is preliminarily selected from a plurality of shafts. be able to.

(3) In the fitting method of (1) or (2), (a) to (d) are shafts at four positions of 36 inches, 26 inches, 16 inches and 6 inches from the tip end of the shaft, respectively. Corresponding to the bending rigidity of
(A) to (d) obtained from the measured values based on an approximate expression that is created in advance by trial striking and represents the relationship between each of the swing feature values (a) to (d) and the bending rigidity of the shaft. From the swing feature amount, 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 is obtained.
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.

(4) In the fitting method of (3), 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. The shaft that matches the golfer can be selected based on the above.

(5) In the fitting method of (3) or (4), it is preferable that a plurality of the approximate expressions are created according to the head speed.

(6) In the fitting methods of (3) to (5), 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.

  According to the fitting method of the present invention, it is possible to propose a shaft with better performance to the golfer in consideration of both the shaft tone rate and the flex.

It is explanatory drawing of an example of the fitting apparatus which can perform the fitting method of this invention. It is explanatory drawing of the system configuration | structure of the information processing apparatus in the fitting apparatus shown by FIG. It is explanatory drawing of the other example of the fitting apparatus which can perform the fitting method of this invention. It is a front view of the fitting apparatus shown by FIG. It is explanatory drawing of an example of the golf club used with the fitting method of this invention. 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 flowchart of one embodiment of the fitting method of the present invention. It is a figure which shows the relationship between the ball flying direction (left-right deviation) and the face angle. It is a figure which shows the relationship between right-and-left deviation and a face angle for every tone rate. It is a figure which shows the relationship between a tone ratio and a face angle when a right-and-left deviation becomes small. It is a figure which shows the relationship between a face angle and a flight distance ratio for every tone rate. It is a figure which shows the other relationship between a tone ratio and a face angle when a right-and-left shift becomes small. 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 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. 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 "6 inches". It is a figure which shows the relationship between the swing feature-value (4) 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 "16 inches". It is a figure which shows the relationship between the swing feature-value (4) and bending rigidity (EI value) in the measurement point of "26 inches". It is a figure which shows the flow of EI value calculation in the measurement point of "26 inches". It is a figure which shows the relationship between the swing feature-value (4) 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.

Hereinafter, embodiments of the fitting method of the present invention will be described in detail with reference to the accompanying drawings.
[Fitting device]
First, a fitting apparatus that can be used in the fitting method of the present invention will be described.
FIG. 1 is an explanatory diagram of a fitting device 2 used in the fitting method of the present invention. The fitting device 2 is a right-handed golfer fitting device, and includes a front camera 4 and an upper camera 6 as an image photographing unit, a first sensor 8 having a light emitter 14 and a light receiver 16, a control device 10, and the like. And an information processing device 12 as a calculation unit.

  The front camera 4 is located in front of the swinging golfer, and is arranged in a position and orientation where a swing image can be taken from the front of the golfer. On the other hand, the upper camera 6 is located above the position where the ball B is placed, and is arranged at a position and orientation where a swing image can be taken from above the golfer. As the front camera 4 and the upper camera 6, for example, a CCD camera can be used. The front camera 4 and the upper camera 6 are examples, and a camera that can shoot from the front, rear, or oblique direction of the golfer can be used together with or instead of the cameras 4 and 6. Further, in the fitting device 2 shown in FIG. 1, two cameras (front camera 4 and upper camera 6) are used, but even if a fitting device having only one camera (upper camera 6) is used, The fitting method of the invention can be carried out.

  The light emitter 14 of the first sensor 8 is located in front of the swinging golfer, and the light receiver 16 is located at the foot of the swinging golfer. The light emitter 14 and the light receiver 16 are arranged at a position where a golf club swinging between them passes. The first sensor 8 detects a golf club head or shaft passing therethrough. The 1st sensor 8 should just be a position which can detect a head or a shaft, and may be arranged in the front or back of a golfer. The first sensor 8 is not limited to the one including the light emitter 14 and the light receiver 16, and may be another type such as a reflection type.

  The control device 10 is connected to the front camera 4, the upper camera 6, the first sensor 8, and the information processing device 12. The control device 10 transmits a shooting start signal and a shooting stop signal to the front camera 4 and the upper camera 6, and receives a swing image signal from the front camera 4 and the upper camera 6. The control device 10 receives a head or shaft detection signal from the first sensor 8. Then, the control device 10 outputs the received swing image signal and head or shaft detection signal to the information processing device 12.

  As shown in FIGS. 1 and 2, the information processing apparatus 12 includes a keyboard 20 and a mouse 22 as an information input unit 18, a display 24 as an output unit, an interface board 26 as a data input unit, and a memory 28. And a CPU 30 and a hard disk 32. A general-purpose computer may be used as the information processing apparatus 12 as it is.

  The display 24 that displays various types of information is controlled by the CPU 30. The output unit is not limited to the display 24 and may be a printer, for example, as long as it can display fitting information such as a fitted shaft and golf club, and swing measurement data.

  The interface board 26 receives a swing image signal, a head or shaft detection signal, and the like. Measurement data is obtained from the image signal and the detection signal. This measurement data is output to the CPU 30.

  The memory 28 is a rewritable memory. The hard disk 32 stores programs and data. For example, physical property values of a plurality of shafts are stored as a database. Specifically, for example, data and formulas representing the relationship between the index and the hit ball result are stored for each physical property value. The memory 28 constitutes a storage area, a work area, and the like for programs and measurement data read from the hard disk 32.

  The CPU 30 can read a program stored in the hard disk 32 and develop the read program in a work area of the memory 28. The CPU 30 can execute various processes according to the program.

FIG. 3 is an explanatory diagram of another example of the fitting apparatus that can execute the fitting method of the present invention, and FIG. 4 is a front view of the fitting apparatus.
1 includes a base 212, a support column 214, a floor plate 216, a tee 218, a club camera 220, a ball camera 222, a first sensor 224 (224a, 224b), and a second sensor 226 (226a, 226b). ), A strobe 228 (228a, 228b), a strobe 229 (229a, 229b), a control device 230, and an information processing device 232.

  In FIG. 3, a golf club 234 and a golf ball 236 are shown together with the fitting device 210. The golf club 234 includes a head 234a and a shaft 234b. In FIG. 3, the address posture of a right-handed golf player is indicated by a two-dot chain line. A golf ball 236 is launched to the left of the player in this address posture.

  The column 214 and the floor plate 216 are positioned and fixed to the base 212. The support column 214 extends upward from the base 212. A tee 218 is positioned and attached to the floor plate 216. The club camera 220 is positioned and attached to the upper part of the column 214. The ball camera 222 is positioned in front of the tee 218 and is positioned and attached to the side surface of the floor board 216. The club camera 220 and the ball camera 222 are arranged so as to be able to photograph the golf ball 236.

  The first sensor 224 includes a light emitter 224a and a light receiver 224b. The light emitter 224a is disposed on one side surface of the floor plate 216, and the light receiver 224b is disposed on the other side surface with the floor plate 216 in between. The light receiver 224b is disposed behind the feet of the golf player. The second sensor 226 includes a light emitter 226a and a light receiver 226b. The light emitter 226 a is disposed on one side surface of the floor plate 216, and the light receiver 224 b is disposed on the other side surface of the floor plate 216. The light receiver 226b is disposed behind the foot of the player. The first sensor 224 and the second sensor are positioned so that the head 234a or the shaft 234b of the golf club 234 to be swung down crosses between the light emitter 224a and the light receiver 224b and between the light emitter 226a and the light receiver 226b. 226 is arranged.

  The strobe 228 (228a, 228b) is attached to the center of the support column 14 in the vertical direction. The strobe 228 is disposed below the club camera 220. The control device 230 is attached to the base 212.

  A point Pb shown in FIG. 4 indicates the center point of the ball 236. A point Pc indicates the center point of the club camera 220 lens. A straight line GL indicates a ground level where the golf player stands. An alternate long and short dash line Z indicates a vertical line passing through the center point Pb. An alternate long and short dash line C indicates a straight line passing through the center point Pb and the center point Pc. The angle θc indicates the intersection angle between the perpendicular line Z and the straight line C. A double arrow Hc indicates the height from the ground level to the center point Pc. In this example, the height Hc is 1.1 m and the angle θc is 15 °.

  Although not shown, the control device 230 is connected to the club camera 220, the ball camera 222, the first sensor 224, the second sensor 226, the strobe 228, the strobe 229, and the information processing device 232. The control device 230 can transmit a shooting start signal to the club camera 220 and the ball camera 222. The control device 230 can receive image signals taken from the club camera 220 and the ball camera 222. Controller 230 may receive head 234a or shaft 234b detection signals from sensors 224 and 226. The control device 230 can transmit a light emission start signal to the strobes 228 and 229.

  Although not shown, the information processing apparatus 232 includes a monitor as an output unit, an interface board as a data input unit, a memory, a CPU, and a hard disk. The information processing apparatus 232 may include a keyboard and a mouse. A general-purpose computer may be used as the information processing apparatus 232 as it is.

  The hard disk stores a program. The memory is rewritable, and constitutes a storage area and a work area for programs called from the hard disk and various data. The CPU can read a program stored in the hard disk. The CPU can expand the program in the work area of the memory. The CPU can execute various processes according to the program.

  Club image data, ball image data, and synchronization data of the two image data can be input to the interface board. These input data are output to the CPU. The CPU performs various processes and outputs predetermined data among the club behavior value, the ball behavior value, and the calculated value calculated from these to the monitor. Further, predetermined data is stored in the hard disk.

  FIG. 5 is an example of a golf club used in the fitting device 2 shown in FIG. 1 or FIG. A golf club used in a fitting method described later is also referred to as a “test club”, but the golf club 36 is an example of such a test club. This golf club 36 has a wood type golf club head 38 having a predetermined loft angle, a shaft 40, and a grip 42. The head 38 has a hosel 46 provided with a shaft hole 44 for inserting and fixing the tip end 40a on the distal end side of the shaft 40. The butt end 40b on the rear end side of the shaft 40 is inserted into the grip hole 48 of the grip 42 and fixed. The tip end 40 a is located inside the head 38, and the butt end 40 b is located inside the grip 42. A second sensor 50 used for analyzing the behavior of the golf swing is disposed at the grip end of the grip 42.

  The second sensor 50 is wireless, and the measured data is transmitted wirelessly to a wireless reception device (not shown) built in the information processing device 12 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 second sensor 50 incorporates an angular velocity sensor (not shown) that can measure angular velocities around three axis directions (x-axis direction, y-axis direction, and z-axis direction). The second sensor 50 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 second sensor 50 may include a charging circuit for charging the battery. An example of the second sensor 50 that can be used is WAA-010 (trade name) manufactured by Wireless Technology.

  The wireless reception device that receives a signal from the second sensor 50 includes a wireless antenna, a wireless interface, a CPU, and a network interface.

  The second sensor 50 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 second sensor 50. 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 second sensor 50 is transmitted from the wireless antenna to the wireless receiving device built in the information processing device 12 via the wireless interface.

  The data transmitted from the second sensor 50 is received by the wireless interface via the wireless antenna on the wireless receiving device side. The received data is processed by the CPU 30 of the information processing apparatus 12.

  Data sent to the information processing apparatus 12 is recorded in a memory resource such as the hard disk 32. The hard disk 32 stores programs and data necessary for data processing and the like. This program causes the CPU 30 to execute necessary data processing. The CPU 30 can execute various arithmetic processes, and the calculation result is output by the display 24 or a printing device (not shown).

  When the second sensor 50 is attached to the grip end, the relationship between the measurement axis and the golf club 36 is taken into consideration. In the present embodiment, the z axis of the second sensor 50 coincides with the shaft axis of the golf club 36. The x axis of the second sensor 50 is oriented along the toe heel direction of the head 38 of the golf club 36. The y axis of the second sensor 50 is oriented along the normal direction of the face surface of the head 38. The calculation can be simplified by attaching the second sensor 50 in this way.

  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 the present embodiment, the z axis is the shaft axis of the golf club 36, and the x axis is oriented along the toe heel direction of the head 38. Further, the y-axis is oriented along the normal direction of the face surface of the head 38.

  That is, the z-axis of the local coordinate system matches the z-axis of the second sensor 50, and the y-axis of the local coordinate system matches the y-axis of the second sensor 50. Further, the x-axis of the local coordinate system coincides with the x-axis of the second sensor 50.

  The second sensor 50 can obtain a plurality of data that are continuous in time series. The number of data per unit time depends on the sampling frequency.

  6 to 9 are diagrams for explaining the swing from the address to the finish by the 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.

  6-9 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. 6, (S1) is an address, and (S2) is a takeback. (S3) in FIG. 7 is the top (top of swing). Usually, at the top, the moving speed of the head during the swing is minimum. (S4) in FIG. 7 is a downswing. Although (S5) in FIG. 8 is also a downswing, the downswing is more advanced than (S4) in FIG. (S6) in FIG. 8 is an impact, which is the moment when the head 38 of the golf club 36 and the ball B collide. In FIG. 9, (S7) is a follow-through, and (S8) is a finish. At the finish, the swing ends.

[Fitting method]
FIG. 10 is a flowchart of the fitting method according to the embodiment of the present invention. In the present invention, the shaft is selected through two main steps. Specifically, a shaft suitable for a golfer is selected through a preliminary selection process focusing on the shaft tone rate and a selection process focusing on the shaft flex.

  First, in step S1, for example, using a fitting device shown in FIG. 1, a golfer who wants to perform the fitting actually hits the ball, and the swing data at that time is input. The swing data input to the information processing device 12 includes the detection signal of the ball B and the head 38 detected by the first sensor 8, the swing image signal captured by the front camera 4 and the upper camera 6, and the second sensor. An angular velocity signal around a three-axis direction from the angular velocity sensor being used. In step S1, a plurality of swing image signals may be extracted, and each of the plurality of swing image signals may be converted into measurement data. The control device 12 may determine measurement data used for fitting from a plurality of measurement data based on information for specifying an image.

  Next, in step S2, the face angle and the approach angle are calculated using the swing data acquired in step S1, and swing feature amounts (1) to (4) described later are calculated. The swing characteristic amount is an index that represents the characteristic of the golfer's swing using the angular velocity in the three axial directions of the shaft during the swing. In this case, fitting accuracy can be improved by having a golfer swing a plurality of times and using an average value of the face angles that may average the face angles measured by the plurality of swings.

  In the present embodiment, the face angle and the approach angle immediately before impact are measured. The term “immediately before the impact” is preferably when the center line of the tee and the face surface of the head 38 are at a predetermined distance. For example, the distance between the center line of the tee and the face surface of the head 38 is It is assumed that it is 3 cm. When the tee is not used, a vertical line passing through the center of the ball B may be used instead of the center line of the tee. The face angle at the time of impact may be difficult to measure compared to the face angle just before impact. Therefore, at the time when the face angle is measured, the distance between the center of the ball and the face surface is preferably 10 cm or less, and more preferably 5 cm or less. In this embodiment, the approach angle indicates the direction of the head trajectory immediately before the impact, and can be, for example, the angle of the head trajectory when the head is viewed from above.

Next, in step S3, a recommended tone rate is calculated based on the following formula (1), for example.
Recommended tone ratio = 0.8648 × (face angle−entrance angle) + standard club tone rate−5.033 (1)
This equation (1) can be statistically obtained based on the experimental results in which a plurality of golf players hit the ball using golf clubs having a plurality of tone rates. The reference club is a club used when a golfer who desires fitting swings for measurement, and is determined in consideration of a golfer's physique, muscle strength, exercise history, preference, and the like. The reference club is preferably a club having a medium tone shaft, and more specifically, a club having a shaft having a tone ratio of about 46%.

  Expression (1) is a relational expression as an example of a relation created by using a correlation between a face angle and an approach angle immediately before impact and a hitting result (for example, a flight distance and directionality of a ball). This relational expression is not limited to a linear expression such as Expression (1), and for example, a quadratic expression or a polynomial can be used. Hereinafter, a method for obtaining the relational expression will be described by taking the linear expression as an example. The face angle indicates that the larger the value is, the more open it is. In the case of a right-handed golfer, a positive face angle means that the face of the club is facing right, and a negative face angle is This means that the club face is facing left. Also, in equation (1), assuming that the face angle is “+” in the open direction and the entry angle is “+” inside out, the ball flies straight if the face is perpendicular to the swing trajectory. Based on this assumption, “face angle−entrance angle” is used as a variable. If the inside-out is “−”, the face angle and the approach angle are variables of “face angle + approach angle”.

  As described above, the hitting result can include the direction of the ball, the flight distance, and the like. Here, a case where the direction of the ball (flying ball direction) is employed will be described. Examples of this direction include a left-right direction (horizontal direction), an up-down direction (vertical direction), and a three-dimensional direction. Examples of the left-right direction include a horizontal angle of the initial velocity vector of the ball. Examples of other left and right directions include a distance between a straight line connecting the hitting position and the target and the ball stop point, and a distance between a straight line connecting the hitting position and the target and the ball landing point.

  Hereinafter, the hitting results employed in the formula (1) will be described by exemplifying the left-right direction (hereinafter, also simply referred to as left-right deviation). Here, the left-right shift is indicated by an angle. When the ball is launched straight with respect to the target, the left / right misalignment is at an angle of 0 °. When it is deviated leftward, it is displayed as minus, and the magnitude of the deviation is indicated by an angle. On the other hand, when it is shifted to the right, it is displayed positively, and the magnitude of the shift is indicated by an angle. In the following description, for the sake of simplicity, “face angle” is used as a variable instead of “face angle−entrance angle”.

  In the information processing apparatus 12 of FIG. 1, a database is created that includes data on shaft tone ratio, right / left deviation, and face angle immediately before impact obtained by experiments.

  FIG. 11 shows the right and left misalignment of the ball when a plurality of golfers hit the ball in each of the first tone, middle tone, and original tone. In this example, the tone rate of the first tone is 48%, the tone rate of the medium tone is 46%, and the tone rate of the original tone is 44%.

  In FIG. 11, the golfer can be specified by the value of the face angle. The point of the golf club having the longest flight distance for each face angle, that is, for each golfer, is shown larger than the points of other golf clubs. Each golfer (face angle) has a tendency that the left-right misalignment tends to be smaller than that of the other shafts when the flight distance is the longest. That is, in the tone rate when the flight distance is the longest, the right / left deviation tends to approach 0 degrees.

  FIG. 12 is a graph showing the relationship between the face angle and the left / right displacement. FIG. 12 is based on the data of FIG. For each tone rate, a relational expression between the face angle and the left / right deviation is obtained. These relational expressions (straight lines) are obtained by regression analysis using the least square method. The straight line Ls1 in FIG. 12 is based on the pretone data in FIG. The straight line Ln1 in FIG. 12 is based on the data of the medium tone in FIG. The straight line Lt1 in FIG. 12 is based on the original tone data in FIG. Based on this relational expression, it is possible to obtain the tone rate at which the right / left deviation is minimized with respect to the golfer's face angle. In each of the straight line Ls1, the straight line Ln1, and the straight line Lt1, the face angle when the right / left misalignment is 0 degree is obtained. In the straight line Ls1, the face angle when the left / right misalignment is 0 degree is fs degree (see FIG. 12). In the straight line Ln1, the face angle when the left / right misalignment is 0 degree is fn degrees (see FIG. 12). In the straight line Lt1, the face angle when the left-right misalignment is 0 degrees is ft degrees (see FIG. 12).

  Here, a method of obtaining the straight line LF1 that shows the relationship between the face angle and the tone rate shown in FIG. 13 will be described. A point P1 in FIG. 13 indicates a combination of the original tone (tone rate 44%) and the face angle when the left / right misalignment angle is 0 degree. That is, the coordinates of this point P1 are (ft, 44). A point P2 indicates a combination of a medium tone (a tone rate of 46%) and a face angle when the right / left misalignment angle is 0 degree. That is, the coordinates of this point P2 are (fn, 46). A point P3 indicates a combination of the first tone (tone rate 48%) and the face angle when the left / right shift angle is 0 degree. That is, the coordinates of this point P3 are (fs, 48).

  A straight line LF1 is obtained as an approximate linear function expression passing through these points P1, P2 and P3. Here, the straight line LF1 is obtained from these three points by the least square method.

The straight line LF1 is represented by the following approximate linear expression when the tone ratio of the shaft is Y and the face angle value is X. This approximate linear expression is an example of the relational expression F1 referred to in the present invention.
Y = A1 · X + B
(Coefficient A1 and intercept B are constants)
Based on the measured face angle X, the shaft tone rate Y suitable for the subject (golfer) can be calculated by this relational expression F1.

  In the above description, the relational expression is obtained based on the relationship between one hitting result of the hitting ball directionality and the face angle, but the relational expression can also be obtained by combining two hitting ball results. Compared to the case where one hitting result is used, the accuracy of fitting can be improved by using two hitting results. Here, a case will be described in which the results regarding the ball direction and the flight distance are used as the two hit results. In this example, the right / left deviation is used as the direction of the ball, and the flight distance ratio is used as a result of the flight distance. The flight distance ratio is a relative value of the flight distance. Instead of the flight distance ratio, the absolute value of the flight distance may be used. The absolute value of the flight distance is usually displayed in yards or meters.

  First, as described above, a straight line LF1 (relational expression F1) is obtained based on the left / right shift (first hitting result). Next, the straight line LF1 is corrected based on the flight distance ratio (second hitting result). This correction is based on the correlation Rx between the flight distance ratio and the face angle.

  FIG. 14 is a graph showing this correlation Rx. In FIG. 14, the correlation Rx between the above-mentioned flight distance ratio and the face angle is obtained for each tone rate. The database used for creating FIG. 14 is the same as the database used for creating FIG. As the correlation Rx, three relational expressions are obtained. These relational expressions are obtained by regression analysis using the least square method.

  Here, based on the correlation Rx, a range in which a preferable result is obtained is selected for a shaft having a medium tone (a tone rate of 46%). As shown in FIG. 14, in this example, a shaft having a medium tone (a tone ratio of 46%) has a particularly preferable result when the face angle is between 4.7 degrees and 7.3 degrees. That is, in this range, the shaft of the medium tone (tone rate 46%) has a higher flight distance ratio than the shaft of the original tone (tone rate 44%) and the shaft of the first tone (tone rate 48%). In FIG. 14, the straight line Ln2 (medium tone) is above the straight line Ls2 (first tone) and the straight line Lt2 (original tone) when the face angle is between 4.7 degrees and 7.3 degrees. For example, an arbitrary value is selected from this preferable range (between 4.7 degrees and 7.3 degrees). Preferably, the median value of this preferred range is selected. This median is 6.0 degrees.

  In FIG. 15, a straight line LF2 is obtained from the straight line LF1. The straight line LF2 has the same inclination A1 as the straight line LF1. In this straight line LF2, the value of the intercept B is corrected so as to pass through a point P4 having a medium tone (tone rate of 46%) and a face angle of 6.0 degrees. That is, the straight line LF2 passes through the point P4 (6.0, 46) and is the same straight line as the straight line LF1. Instead of the straight line LF1, this straight line LF2 may be used as the relational expression F1. The straight line LF2 is a relational expression obtained by correcting the relational expression F1 (straight line LF1) obtained based on the first hitting result (left / right deviation) based on the second hitting result (flight distance ratio). F1. In this correction, the relational expression F1 (straight line LF1) is corrected so that the second hitting result (flying distance ratio) is preferable in the medium tone (tone rate 46%). Here, a tuning rate of 46% is adopted as the standard shaft tone Yh. In the straight line LF2, two hit results are taken into consideration. Therefore, when the formula of the straight line LF2 is adopted as the relational expression F1, the fitting accuracy can be improved.

  Next, the relational expression F1 in the present invention will be described in more detail. As described above, as the relational expression F1, in addition to the linear expression, a quadratic expression, a polynomial, or the like can be used. For simplicity, the case of the linear expression will be described.

As described above, the primary relational expression F1 can be expressed by the following expression (2).
Y = A1 · X + B (2)
Assuming that the face angle X when the golfer of the subject uses the test club (shaft tone rate D1) is Xd1, the tone rate Y1 recommended for the subject is obtained as follows based on the formula (2). .
Recommended tone ratio Y1 = A1 · Xd1 + B

  Preferably, in this formula (2), the standard shaft tone Yh (the tone of the shaft used as a reference when the preferable hitting result is recognized. In FIG. 13, “tone rate 46%” is adopted as the standard shaft tone. This reflects the preferable hitting result. The reflected relational expression F1 is also referred to as relational expression F1p below. An example of the relational expression F1p is the expression of the straight line LF2. It can be said that the relational expression F1p is the relational expression F1 optimized by the standard shaft condition Yh. Therefore, the relational expression F1p shows particularly good accuracy when the tone rate D1 of the test club, that is, the tone rate D1 of the reference club matches the standard shaft tone Yh.

This relational expression F1p may be used regardless of the tone ratio of the shaft used for fitting. However, this relational expression F1p is particularly preferable when the tone rate D1 of the test club matches the standard shaft tone Yh as described above. Therefore, it is preferable that the relational expression F1p is corrected based on the tone rate of the club used at the time of fitting.
The corrected relational expression F1 is expressed by the following expression (3).
Y = A1.X + B + (D1-Yh) (3)

  By this corrected relational expression F1, even if the shaft tone rate D1 of the test club shaft is different from the standard shaft tone Yh, the recommended tone rate can be accurately obtained.

In the relational expression F1 of the expression (3), the measured face angle X is a first input variable, and a value indicating the relation between the shaft tone D1 of the test club and the standard shaft tone Yh is a second input. It is considered a variable. In the relational expression F1 of the expression (3), the shaft condition Y suitable for the subject is the result variable. With such a relational expression F1, the accuracy of fitting can be increased regardless of the condition of the shaft used during fitting.
The equation (1) is obtained statistically based on a large number of experimental data using the equation (3) as a reference. Accordingly, the constants “0.8648” and “5.033” in the formula (1) are examples, and are not limited to these.

  In the embodiment described above, the relational expression F1 is used as the relation C in the present invention, but the relation C may not be a relational expression.

  The relationship C is a relationship between the face angle X and the shaft tone Y. In addition to the face angle X, other factors may be considered. For example, the relationship C may be a relationship between the face angle X and the approach angle and the shaft tone Y. The relational expression F1 may be a relational expression of the face angle X and the approach angle and the shaft tone Y. This approach angle indicates the direction of the head trajectory immediately before the impact. An example of this approach angle is the angle of the head trajectory when viewed from above.

  Returning to FIG. 10, it is then determined in step S3 whether the recommended tone rate calculated in step S3 is 41 or less or 53 or more. This determination is intended to exclude cases where the recommended tone rate is too small or too large, in other words, to eliminate a swing pattern in which fitting using the tone rate is not preferable. In step S4, when the recommended tone rate is larger than 41 and smaller than 53, it is “No”, so the process proceeds to step S5, and when it is 41 or less or 53 or more, “Yes”. Therefore, it progresses to step S8 and the selection of the shaft by IFC fitting mentioned later is performed.

Next, in step S5, it is determined whether or not the average angular velocities ωx, ωy, ωz from the top to the impact satisfy any of the following relationships (1) to (3). The determination in step S5 is also for eliminating a swing pattern in which fitting using the tone rate is not preferable, as in step S4.
(1) ωz> 300, or (2) ωy / ωx> 2.0, or (3) ωy / ωx> 1.5 and ωy> 800.
In step S5, if any of the relationships (1) to (3) is satisfied, the answer is “Yes”, so that the process proceeds to step S8, and a shaft is selected by IFC fitting, which will be described later. ) To (3), if none of the relationships is satisfied, the determination is “No”, and the process proceeds to step S6.

  Next, in step S6, a recommended tone rate range is determined based on the recommended tone rate calculated in step S3. In the present embodiment, the recommended tone rate range is ± 1% of the recommended tone rate. Specifically, when the recommended tone rate is 46%, the recommended tone rate range is 45 to 47%.

  In step S7, a shaft included in the recommended tone rate range determined in step S6 is selected from a shaft list including a predetermined number of shafts stored in advance in the database (preliminary selection). The database stores, for a predetermined number of shafts, physical property values of the shafts, such as the tone rate and bending rigidity at predetermined positions of the shaft described later.

  Next, in step S8, a shaft that matches the golfer is selected by IFC fitting from the shafts preliminarily selected in step S7.

[IFC fitting]
Next, the IFC fitting in step S8 described above, that is, a fitting method using an index called IFC will be described in detail. The IFC is an abbreviation for International Flex Cord, and is an index proposed by the present applicant as representing the hardness of the shaft.

  Before explaining the IFC fitting process in the present invention, the principle or theoretical background of the IFC fitting method will be explained. 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 IFC fitting method 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 during the entire swing, but is transmitted from the proximal side to the distal 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 takeback is performed from the address and the top is reached (the time indicated by (1) in FIG. 16), bending occurs near the hand of the shaft. Then, when turning back and reaching the initial stage of the downswing (at the time indicated by (2) in FIG. 16), 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. 16), the bending moves to the tip side from the center of the shaft. Then, immediately before the impact (time indicated by (4) in FIG. 16), the bending moves to the vicinity of the tip of the shaft.

  In view of the fact that the bending of the shaft during swinging is transmitted from the proximal side to the distal end side of the shaft from the top toward the impact, the present inventors have made the golfer's swing in the time zones (1) to (4). Focusing on the characteristics, we tried to select the optimal bending stiffness for each inch of the shaft.

  Specifically, as shown in FIG. 17, the shaft 40 was divided into four regions, and the bending rigidity at one point in each region was defined. In the present embodiment, a point 36 inches from the tip end 40a of the shaft 40 is the measurement point (1), a point 26 inches is the measurement point (2), a point 16 inches is the measurement point (3), and 6 The inch point is the 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, The “predetermined inches” in the present embodiment are 36 inches, 26 inches, 16 inches, and 6 inches from the tip end 40a of the shaft 40 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. There is no particular limitation, and each inch can be changed 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. 18 using, for example, an Intesco 2020 type measuring machine (maximum load 500 kgf).

  Specifically, while supporting the shaft 40 from below at the two support points 111 and 112, the deflection amount α when the load F is applied to the measurement point P from above is measured. In the present embodiment, there are four measurement points P from the tip end 40a of the shaft 40, ie, 36 inches, 26 inches, 16 inches, and 6 inches. The distance (span) between the support point 111 and the support point 112 is 200 mm. The measurement point P is an intermediate point between the support point 111 and the support point 112. The tip of the indenter 113 to which the load F is applied from above is rounded so as not to damage the shaft 40. The cross-sectional shape of the tip of the indenter 113 has a curvature radius of 10 mm in a cross section parallel to the shaft axial direction. In the cross section in the direction perpendicular to the shaft axis direction, the cross-sectional shape of the tip of the indenter 113 is a straight line, and its length is 45 mm.

  The support body 114 supports the shaft 40 from below at the support point 111. The front end of the support body 114 has a convex roundness. The cross-sectional shape of the tip end of the support body 114 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 axis direction, the cross-sectional shape of the tip of the support 114 is a straight line, and its length is 50 mm. The shape of the support body 115 is the same as that of the support body 114. The support body 115 supports the shaft 40 from below at the support point 112. The tip of the support 15 has a convex roundness. The cross-sectional shape of the tip of the support 115 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 axis direction, the cross-sectional shape of the tip of the support 115 is a straight line, and its length is 50 mm.

The indenter 113 is moved downward at a speed of 5 mm / min while the support 114 and the support 115 are fixed. Then, the movement of the indenter 113 is terminated when the load F reaches 20 kgf. 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 (4).
Flexural rigidity EI (N · m ² ) = 32.7 / α (4)

  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 the present embodiment, any one of the rank values in a plurality of stages 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.

  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, a golfer who wishes to fit a golf club actually makes a swing, and the second sensor 50 measures a swing characteristic amount specific to the golfer from the swing. As shown in FIG. 5, the second sensor 50 is attached to the grip end of the golf club 36 by double-sided tape, adhesive, screwing, or the like.

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)

  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 of the swing described above, and the angular velocity ωy is subdivided and quantified as time elapses. 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. 19 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. 19, four swing features (1) to (4) are set according to the time lapse 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 the present 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. 21 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 "." In FIG. 22, “ωy4” is the swing feature value (4) of the angular velocity in the cock direction. The same applies to FIGS. 24, 26 and 28 to be described later.

  In this 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) approximation expression and an exception (2) approximation expression are prepared together with a normal approximation expression corresponding to an average golfer.

  First, in step S11, 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 the ratio to the average value (ωy (overall) / ωx (overall)) is 0.55 or less. The EI value is calculated using this.

On the other hand, in the case of No in step S11, the process proceeds to step S12 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 S12, 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 S12, 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. 23 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 "."

First, in step S21, 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 S21, 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 S21, the process proceeds to step S22 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 S22, 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 S22, 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. 25 is a diagram showing the relationship between the swing feature (2) and the bending stiffness (EI value) at the measurement point “26 inches” created in advance as described above. 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 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 S22, 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 indicated 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 8 below.

  FIG. 27 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 S41, it is determined whether the head speed is any 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 S42 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 S42, 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 S42, the process proceeds to step S43 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 S43, 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 S44, 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 S44, the process proceeds to step S45 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 S45, 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 S45, 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 frequency of use and the like, a method of dividing into 10 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 formula (5) is calculated for all the clubs stored in the database, and the club with the smallest value is proposed to the golfer. Note that “degree of coincidence” in the present specification does not mean the degree of coincidence, but as is clear from the equation (5), the smaller the value, the closer the shaft has the bending rigidity closer 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.

  Further, 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.

<Verification 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 43, and the head speed was about 41 to 51 m / s.

  First, test the ball using a golf club with a sensor attached to the grip, measure the face angle and approach angle of the tester, and the swing feature amount. In accordance with the above-described flow (see FIG. 10), one shaft having a tone ratio and bending rigidity matching the tester was determined from the database. 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). 27. As shown in FIG. 27, the five shafts are hard and tones, hard and medium tones, medium to medium tones, soft to medium, and 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 is not bent, and one of the five easy-to-swing clubs is present, whether or not a shaft close to the shaft characteristics of the club has been selected exists. In this case, whether the selected shaft is included in the ellipse including those shafts (see the hatched portion in FIG. 29) or whether it exists in the vicinity is used as an evaluation criterion.

  For 43 testers, the case where the fitted club was included in the ellipse was defined as “correct”. The results confirmed that 38 testers out of 43 were correctly fitted. The accuracy rate was (38/43) × 100≈88%. And about 38 people who were effective (it was a correct answer), it was confirmed how much effect was there regarding a flight distance, directionality, and the ease of a swing. As an average value of 38 people, it was confirmed that the flight distance was increased by 7.4 yards, the directionality was 11.5 yards toward the center, and the ease of swinging was improved by 1.63 points. Note that the evaluation of ease of swinging is based on a nine-level evaluation ("5" is neither), as shown in FIG.

  In addition, the correct answer rate when selecting based only on the tone rate as in the past was 67%. Thereby, it turns out that the fitting method which concerns on this invention is superior to a prior art in selection accuracy.

<Other aspects of IFC fitting>
In the embodiment described above, all of the swing feature values (1) to (4) calculated in step S2 are used in the latter half of the fitting method of the present invention, that is, in step S8 in the flowchart shown in FIG. However, the present invention is not limited to this, and effective shaft selection can be performed by using at least two swing feature amounts out of the four swing feature amounts.

For example, the swing feature (1) correlated with the bending stiffness at a measurement point of 36 inches from the tip end of the shaft, and the swing feature (2) similarly correlated with the bending stiffness at a measurement point of 26 inches. The case where a shaft is selected by using will be described.
Table 10 shows ideal IFCs set by the above-described method by having testers A and B actually swing. Then, with respect to the calculation results of Mr. A and Mr. B, a plurality of shafts are given priority from the 59 shafts used in the above-mentioned verification, giving priority to the degree of coincidence of the swing feature (1) and the swing feature (2). The shaft having the smallest matching degree considering all four swing feature values was selected as the optimum shaft, and the shaft having the smallest matching degree was set as the second candidate shaft. For comparison, a shaft having a higher degree of coincidence than the second candidate out of shafts within the range of My Club weight ± 5 g was determined as an inappropriate shaft.

  The golf club having the three shafts selected in this way was swung by testers Mr. A and Mr. B, and the flight distance, the directionality of the hit ball, and the ease of swinging were measured or evaluated. The results are shown in Table 11. In Table 11 and Table 13 that will be described later, “flying distance (yard)” is the flying distance (not including the run) of the hit ball, and “direction” is the absolute value (yard) of the left / right bend of the hit ball The ease of swinging is a sensory evaluation of the tester.

  According to Table 11, for Mr. A, the shaft selected using the swing feature value (1) and the swing feature value (2) shows that the flight distance of the ball is higher than the inappropriate shaft having a high degree of coincidence. I understand. As for Mr. B, the shaft selected using the swing feature value (1) and the swing feature value (2) improves the ball flight distance and the club swingability than the inappropriate shaft having a high degree of coincidence. I understand that

  Next, as another aspect, the swing feature value (3) correlated with the bending stiffness at the measurement point of 16 inches from the tip end of the shaft, and the swing feature value correlated with the bending stiffness at the measurement point of 6 inches. The case where a shaft is selected using (4) will be described.

  Table 12 shows the ideal IFC set by the method described above by actually causing the tester C to swing. Then, with respect to the calculation result of Mr. C, a plurality of shafts are selected from the 59 shafts used in the above-mentioned verification, giving priority to the degree of coincidence of the swing feature value (3) and the swing feature value (4), Furthermore, the shaft having the smallest degree of coincidence considering all four swing feature quantities was selected as the optimum shaft, and the shaft having the smallest degree of coincidence was designated as the second candidate shaft. For comparison, a shaft having a higher degree of coincidence than the second candidate out of shafts within the range of My Club weight ± 5 g was determined as an inappropriate shaft.

  The golf club having the three shafts thus selected was swung by a tester Mr. C, and the flight distance, the directionality of the hit ball, and the ease of swinging were measured or evaluated. The results are shown in Table 13.

  From Table 13, the shaft selected using the swing feature value (3) and the swing feature value (4) has a higher flying distance and easier club swing than an inappropriate shaft having a high degree of coincidence. I understand.

  From the above, it can be seen that the shaft selected using two swing feature values out of the four swing feature values is more suitable for the golfer than the selected shaft without using the IFC fitting method. Of course, a shaft that is more suitable for a golfer can be selected by using all three swing feature values than three and three than three.

[Other variations]
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 2 Fitting apparatus 4 Front camera 6 Upper camera 8 1st sensor 10 Control apparatus 12 Information processing apparatus 14 Light emitter 16 Light receiver 18 Information input part 20 Keyboard 22 Mouse 24 Display 26 Interface board 28 Memory 30 CPU
32 Hard disk 36 Golf club 38 Head 40 Shaft 42 Grip 44 Shaft hole 46 Hosel 48 Grip hole 50 Second sensor B Ball

Claims (6)

A method for fitting a shaft of a golf club, which selects a shaft that matches the golfer based on a golfer's swing,
A golf club having a sensor capable of measuring angular velocities around three axes is hit with a golf club attached to a grip to obtain a measured value from the sensor, and a face angle and an entrance angle of the head of the golf club immediately before impact are obtained. Measuring process;
Determining the top and impact timing in the swing from the measured values;
Selecting at least two of the following swing feature values (a) to (d) obtained from the measurement values, and a shaft that matches the golfer using the measured face angle and approach angle. And
Preliminarily select a shaft that fits the golfer based on the relationship C created using the correlation R between the face angle and approach angle just before impact and the hitting result, and the measured face angle and approach angle. Then, a shaft is selected using the swing feature amount, and the method for fitting a shaft of a golf club is provided.
(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. The correlation R is based on the hitting results of a plurality of golf clubs having different shaft tone rates,
The relation C is a predetermined relational expression between a tone ratio of the shaft prepared in advance and a face angle and an approach angle immediately before impact,
In the selection step, a shaft tone rate is calculated from the measured face angle and approach angle using the relational expression, and a shaft that matches the calculated tone rate is preliminarily selected from a plurality of shafts. Item 2. A golf club shaft fitting method according to Item 1. (A) to (d) 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) obtained from the measured values based on an approximate expression that is created in advance by trial striking and represents the relationship between each of the swing feature values (a) to (d) and the bending rigidity of the shaft. From the swing feature amount, 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 is obtained.
The shaft that matches the golfer is selected based on the obtained bending stiffness of the shaft at the four positions from the plurality of shafts whose bending stiffness at the four positions is measured in advance. Golf club 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 golf club shaft fitting method according to claim 3, wherein a shaft that matches a golfer is selected based on the golf ball.   The golf club shaft fitting method according to claim 3 or 4, wherein a plurality of the approximate expressions are created according to a head speed.   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. The golf club shaft fitting method according to any one of claims 3 to 5.