GOLF BALL TRAJECTORY PREDICTION METHOD, GOLF BALL TRAJECTORY PREDICTION APPARATUS, AND GOLF CLUB SELECTION METHOD

Abstract

A golf ball trajectory prediction method that can predict the trajectory of a golf ball with high accuracy is provided. The golf ball trajectory prediction method includes: a swing measurement step of measuring a golfer's swing using a test golf club; a head behavior prediction step of predicting a behavior of a head of a target golf club when using the target golf club, with a measurement value of the swing measured in the swing measurement step as input; a ball initial behavior calculation step of calculating an initial behavior of a golf ball after colliding with the head of the golf club, based on the behavior of the head predicted in the head behavior prediction step; and a ball trajectory prediction step of predicting a trajectory of the golf ball, from the initial behavior of the golf ball calculated in the ball initial behavior calculation step.

Description

TECHNICAL FIELD

The disclosure relates to a golf ball trajectory prediction method, a golf ball trajectory prediction apparatus, and a golf club selection method.

BACKGROUND

Techniques of predicting, through calculation, the golf swing, the state of collision between a golf club and a golf ball, the trajectory of a golf ball, etc. are in high demand. These prediction techniques are particularly important upon golf club fitting (selection, adjustment, custom-making).

In golf club fitting, typically, a golfer's swing using a club for measurement is measured to predict, based on the measured swing data, the state of golf swing when using each of various clubs, and the predicted golf swing state is used as an index of fitting.

For example, Patent Literature (PTL) 1 discloses a technique of analyzing the golf swing based on information including the speed of the grip end of a golf club in the impact state immediately before hitting a golf ball, and selecting an optimal golf club for the golf swing.

Ideal golf club fitting is based on the trajectory (carry distance and direction) of a golf ball after colliding with a golf club. Thus, a suitable golf club can be selected according to the ball's carry distance and direction desired by the golfer.

CITATION LIST

Patent Literature

PTL 1: JP 4184363 B2

SUMMARY

It could therefore be helpful to provide a golf ball trajectory prediction method and golf ball trajectory prediction apparatus that can predict the trajectory of a golf ball with high accuracy, and a golf club selection method that can select a suitable golf club.

We thus provide the following:

A golf ball trajectory prediction method according to the disclosure includes: a swing measurement step of measuring a golfer's swing using a test golf club; a head behavior prediction step of predicting a behavior of a head of a target golf club when using the target golf club, with a measurement value of the swing measured in the swing measurement step as input; a ball initial behavior calculation step of calculating an initial behavior of a golf ball after colliding with the head of the golf club, based on the behavior of the head predicted in the head behavior prediction step; and a ball trajectory prediction step of predicting a trajectory of the golf ball, from the initial behavior of the golf ball calculated in the ball initial behavior calculation step.

With such a method, the trajectory of the golf ball can be predicted with high accuracy.

Preferably, in the ball initial behavior calculation step, the initial behavior of the golf ball after colliding with the head of the golf club is calculated using a regression equation derived beforehand from collision analysis between the head of the golf club and the golf ball, with a prediction value of the behavior of the head predicted in the head behavior prediction step as input. In this way, the trajectory of the golf ball can be predicted accurately in a shorter time.

Preferably, in the ball initial behavior calculation step, the initial behavior of the golf ball after colliding with the head of the golf club is calculated by collision analysis based on a finite element method, with a prediction value of the behavior of the head predicted in the head behavior prediction step as input. In this way, the trajectory of the golf ball can be predicted more accurately.

Preferably, in the swing measurement step, a meeting rate of the golf ball in the swing is further measured, and in the head behavior prediction step, only a swing with a meeting rate not less than a predetermined threshold is used as input, from among the swing measured in the swing measurement step. More preferably, the meeting rate is an initial speed of the launched golf ball with respect to a speed of the head of the golf club upon impact. In this way, the trajectory of the golf ball can be predicted more accurately.

Preferably, in the swing measurement step, the initial behavior of the golf ball in the swing is further measured, and the initial behavior of the golf ball measured in the swing measurement step and the initial behavior of the golf ball calculated in the ball initial behavior calculation step are compared with each other, to correct a result of the calculation that is based on the prediction value of the behavior of the head. In this way, the trajectory of the golf ball can be predicted more accurately.

Preferably, in the swing measurement step, the initial behavior of the golf ball in the swing is further measured, and the initial behavior of the golf ball measured in the swing measurement step and the initial behavior of the golf ball calculated in the ball initial behavior calculation step are compared with each other, to correct a result calculated from the regression equation. In this way, the trajectory of the golf ball can be predicted more accurately.

Preferably, the initial behavior of the golf ball includes an initial speed, a launch angle, and a spin rate of the golf ball after colliding with the head of the golf club. In this way, the trajectory of the golf ball can be predicted more accurately.

Preferably, the regression equation is derived from motion analysis based on a finite element method. In this way, the trajectory of the golf ball can be predicted more accurately.

A golf ball trajectory prediction apparatus according to the disclosure: measures a golfer's swing using a test golf club; predicts a behavior of a head of a target golf club when using the target golf club, with the measured swing as input; calculates an initial behavior of a golf ball after colliding with the head of the golf club, based on a prediction value of the behavior of the head; and predicts a trajectory of the golf ball, from the calculated initial behavior of the golf ball.

With such a structure, the trajectory of the golf ball can be predicted with high accuracy.

Preferably, the initial behavior of the golf ball after colliding with the head of the golf club is calculated using a regression equation derived beforehand from collision analysis between the head of the golf club and the golf ball, with the prediction value of the behavior of the head as input. In this way, the trajectory of the golf ball can be predicted accurately in a shorter time.

A golf club selection method according to the disclosure selects a golf club based on a trajectory of a golf ball predicted by the golf ball trajectory prediction method according to the disclosure.

With such a method, a suitable golf club can be selected.

It is possible to provide a golf ball trajectory prediction method and golf ball trajectory prediction apparatus that can predict the trajectory of a golf ball with high accuracy, and a golf club selection method that can select a suitable golf club.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a flowchart illustrating one of the embodiments of a golf ball trajectory prediction method according to the disclosure; and

FIG. 2 is a flowchart illustrating another one of the embodiments of the golf ball trajectory prediction method according to the disclosure.

DETAILED DESCRIPTION

Our methods and apparatuses are described in detail below, by way of embodiments. FIG. 1 and FIG. 2 each illustrate a different one of the embodiments of a golf ball trajectory prediction method according to the disclosure.

(Golf Ball Trajectory Prediction Method)

One of the embodiments of a golf ball trajectory prediction method according to the disclosure is described below.

As illustrated in FIG. 1 and FIG. 2, the disclosed golf ball trajectory prediction method includes: a swing measurement step of measuring a golfer's swing using a test golf club (FIG. 1(a) and FIG. 2(a)); a head behavior prediction step of predicting a behavior of a head of a target golf club when using the target golf club, with a measurement value of the swing measured in the swing measurement step as input (FIG. 1(b) and FIG. 2(b)); a ball initial behavior calculation step of calculating an initial behavior of a golf ball after colliding with the head of the golf club, based on the behavior of the head predicted in the head behavior prediction step (FIG. 1(c) and FIG. 2(c)); and a ball trajectory prediction step of predicting a trajectory of the golf ball, from the initial behavior of the golf ball calculated in the ball initial behavior calculation step (FIG. 1(d) and FIG. 2(d)).

With such a method, the trajectory of the golf ball can be predicted with high accuracy.

The most important information when a golfer selects a golf club is the ball trajectory, i.e. the flight path that the ball follows when launched with the club. The ball trajectory can be theoretically calculated from the initial behavior of the golf ball immediately after the launch. It is therefore important to recognize the initial behavior of the golf ball, in order to obtain the trajectory information.

The initial behavior of the ball is typically recognized by actually trial-hitting the ball with a target golf club and measuring the initial behavior of the ball immediately after the launch by a measuring instrument. However, given that the number of clubs a golfer can actually trial-hit is physically and temporally limited and also a person's swing varies, it is difficult to compare many clubs under the same conditions.

Hence, the following technique is employed: The use of each of a plurality of target clubs is calculated on a computer by a computer simulation, and an optimal club is selected from many target clubs by using the calculation results as fitting indices. The computer simulation includes two steps: a swing simulation step (head behavior prediction step) of calculating the behavior of the head with the person's swing feature as input; and a collision simulation step (ball initial behavior calculation step) of predicting the initial behavior of the ball from the behavior of the head upon impact (approach condition).

In view of the above, the disclosed technique calculates the initial behavior of the golf ball after colliding with the head based on, for example, the finite element method or a regression equation obtained from the finite element method. This enables accurate prediction of the initial behavior of the golf ball, and as a result enables accurate prediction of the trajectory of the golf ball.

Swing Measurement Step

The disclosed golf ball trajectory prediction method includes a swing measurement step of measuring a golfer's swing using a test golf club, as illustrated in FIG. 1(a) and FIG. 2(a).

The swing measurement step is a step of measuring, by a given measuring instrument, input data for performing a swing simulation.

The test golf club is used for the golfer's swing, as mentioned above. Even in the case where the conditions of the golf club or golf ball are changed, the prediction can be made by calculation. This reduces the time and labor required to change the golf club, the number of swings, and the like.

The test golf club is not particularly limited as long as its physical characteristics are known. A golf club prepared by the golfer may be used as the test golf club. In such a case, it is desirable to perform a swing simulation that reflects the physical characteristics of the golf club prepared by the golfer.

The measurement value of the swing obtained in the swing measurement step is not particularly limited as long as a measurement method for measuring the golfer's swing feature is used.

For example, the measurement value of the swing is preferably the acceleration data or three-dimensional coordinate data of the grip portion acquired using an accelerometer, motion capture, or the like.

The measurement conditions of the accelerometer or motion capture are not particularly limited, and may be adjusted as appropriate to acquire desired swing data.

In the swing measurement step, preferably, the initial behavior of the golf ball launched in the swing is further measured (FIG. 1(e) and FIG. 2(e)). The measured initial behavior of the golf ball can be used to correct the calculation result obtained based on the below-mentioned regression equation. The measurement of the initial behavior of the golf ball in the swing measurement step is performed for each golfer, to acquire data for correction as described later. Accordingly, the initial behavior of the golf ball need not be measured again after the correction.

Measurement of Meeting Rate and Comparison with Threshold

The disclosed golf ball trajectory prediction method further measures the meeting rate in the swing measurement and determines whether or not the meeting rate is not less than a predetermined threshold, as illustrated in FIG. 1(h). Only each swing with a meeting rate not less than the threshold is preferably used as input in the below-mentioned head behavior prediction step.

In the case where the head of the golf club and the ball collide in an ideal form, the meeting rate is high. The meeting rate can thus be used as an index of such ideal collision. By using only each swing measurement with a meeting rate not less than the threshold as input, any swing measurements corresponding to mishits are excluded, so that the initial behavior of the golf ball can be calculated more accurately. For example, in the case of measuring a driver swing using TrackMan manufactured by TrackMan A/S, the threshold of the meeting rate may be 1.4 or more and, if the golfer is capable of considerably accurate collision, 1.45 or more. A meeting rate not less than 1.4 may not be able to be obtained depending on the measuring instrument or the club used. In such a case, the threshold is desirably readjusted as appropriate.

The meeting rate mentioned here is the initial speed of the launched ball with respect to the speed of the head upon impact ((initial ball speed)/(head speed)). The method of acquiring the meeting rate is not particularly limited, and the meeting rate may be acquired by measuring each of the initial speed of the launched ball and the head speed upon impact by a commercially available measuring instrument or the like.

Head Behavior Prediction Step

The disclosed golf ball trajectory prediction method includes, after the above-mentioned swing measurement step, a step (head behavior prediction step) of predicting the behavior of the head when using a target golf club with the measured swing as input, as illustrated in FIG. 1(b) and FIG. 2(b).

The head behavior prediction step is a step of predicting, through calculation from the measured swing, the behavior of the head which serves as an input value (explanatory variable) in the calculation using the regression equation or the like in the below-mentioned ball initial behavior calculation step (FIG. 1(c) and FIG. 2(c)).

The behavior of the head mentioned here is the approach condition of the head immediately before impacting the golf ball. For example, the behavior of the head includes the attitude angle (θ) and the magnitude of the speed vector (v) of the head of the golf club. Any other necessary parameter(s) may be predicted as appropriate, as an input value to the below-mentioned regression equation.

The behavior of the head is predicted in a state where information about the shaft and head of the target golf club is incorporated in the measured swing of the test golf club, to enable prediction of the behavior of the head when using the target golf club. The information about the shaft and head of the target golf club includes the bending rigidity (EI), torsional rigidity, weight, length, etc. of the shaft of the golf club, and the center of gravity, loft angle, lie angle, etc. of the head of the golf club. A golf club model reflecting these information is used for the calculation.

The target golf club mentioned here is a golf club that is subject to golf ball trajectory prediction.

The behavior of the head can be predicted by calculation using a computer, with the measured swing as an input value. For example, a method of simulating the behavior of the head with the measured swing as an input value to calculate the attitude angle (θ) and speed vector (v) of the head is available.

Ball Initial Behavior Calculation Step

The disclosed golf ball trajectory prediction method includes, after the above-mentioned head behavior prediction step, a step (ball initial behavior calculation step) of calculating the initial behavior of the golf ball after colliding with the head of the golf club based on the behavior of the head predicted in the head behavior prediction step, as illustrated in FIG. 1(c) and FIG. 2(c).

The ball initial behavior calculation step is a step of calculating the initial behavior of the golf ball after colliding with the head by motion analysis based on the finite element method or calculation of the regression equation prepared beforehand, etc., and can determine the accurate initial behavior of the golf ball.

The initial behavior of the golf ball is the state of the golf ball after colliding with the head of the golf club, and the trajectory of the golf ball is predicted based on the initial behavior of the golf ball. The initial behavior of the golf ball is not particularly limited, and may be any of various parameters. The initial behavior of the golf ball preferably includes the initial speed, launch angle, and spin rate of the golf ball after colliding with the head of the golf club. These parameters are factors that significantly affect the trajectory of the golf ball. By using these parameters as the initial behavior, the trajectory of the golf ball can be predicted with high accuracy.

The calculation of the initial behavior of the golf ball based on the prediction value of the behavior of the head of the golf club is preferably performed as follows: The initial behavior of the golf ball after colliding with the head of the golf club is calculated using a regression equation derived beforehand from collision analysis between the head of the golf club and the golf ball, with the prediction value of the behavior of the head predicted in the head behavior prediction step as input, as illustrated in FIG. 2(c).

In the case of calculating the initial behavior of the golf ball after the launch by a collision simulation based on the finite element method or the like, the simulation using existing computer resources takes long time. In view of this, the behavior of the ball after the collision is calculated beforehand by the finite element method or the like with various head behaviors as input to derive the regression equation for the behavior of the head and the initial behavior of the ball, and the initial behavior of the golf ball is calculated using the regression equation. This significantly reduces the calculation time, as compared with the case of performing the simulation based on the finite element method or the like. Approximating such complex calculation by the regression equation typically leads to lower prediction accuracy. By setting the threshold of the meeting rate, however, the calculation can be limited within the range where the regression equation applies efficiently.

The regression equation is preferably an equation generated based on the result of collision analysis by the finite element method or the like for the behavior of the head of the golf club with various approach conditions prepared beforehand. The collision analysis technique is not particularly limited, and may be any known technique as appropriate.

The regression equation is not particularly limited as long as the intended initial behavior of the golf ball can be calculated with the prediction value of the behavior of the head as input. To predict the initial behavior of the golf ball with higher accuracy, the regression equation is preferably derived from motion analysis based on the finite element method.

The collision analysis mentioned here is the analysis of motion before and after the collision between the head of the golf club and the ball.

The regression equation differs depending on the head and the ball. In the case where the characteristics (e.g. loft angle, center of gravity of each head are different, the regression equation needs to be derived for each head.

The regression equation is, for example, the following equation (1):

Y=αX+β  (1)

where Y is the launch angle (the angle between the ball's target line and the horizon), α is a proportionality constant (e.g. about 0.9±0.1), X is the angle between the face of the head and the horizon (dynamic loft), and β is a proportionality constant (e.g. about −0.3).

While the initial behavior of the golf ball is preferably calculated using the above-mentioned regression equation derived beforehand from the collision analysis between the head of the golf club and the golf ball, collision analysis based on the finite element method with the prediction value of the behavior of the head as input may also be used. This enables accurate calculation of the initial behavior of the golf ball, although the calculation time is longer. The collision analysis mentioned here is the analysis of motion before and after the collision between the head of the golf club and the ball.

The finite element method (FEM) is one of the numerical analysis methods, and can numerically find an approximate solution to a hardly-analyzable differential equation by dividing the area in which the equation is defined into smaller areas (elements) and approximating the equation in each smaller area by a common interpolation function.

When using the finite element method to predict the initial behavior of the golf ball, for example, a method of numerically finding the initial behavior (e.g. the initial speed, spin rate, etc. after the collision) of the golf ball by dividing the head of the golf club which collides with the golf ball into smaller areas and analyzing the areas is available.

The result of calculation using the motion analysis based on the finite element method or the regression equation is preferably corrected according to the result of comparing the calculated initial behavior of the golf ball and the measured initial behavior of the golf ball. This enhances the correctness of calculation, and enables more accurate prediction of the trajectory of the golf ball.

As illustrated in FIG. 1 and FIG. 2, the initial behavior of the launched golf ball is also measured (FIG. 1(e) and FIG. 2(e)) in the swing measurement step (FIG. 1(a) and FIG. 2(a)), and then the measured initial behavior of the golf ball and the calculated initial behavior of the golf ball are compared with each other (FIG. 1(f) and FIG. 2(f)) to perform the correction based on the comparison result (FIG. 1(g) and FIG. 2(g)).

The method of correcting the calculation result and the regression equation is not particularly limited as long as it can enhance the correctness of calculation. To easily and reliably enhance the correctness of calculation, offset correction that directly adds the difference from the measured initial behavior of the golf ball to the calculated initial behavior of the golf ball is more preferable.

The offset correction is described in detail below.

The calculated initial behavior of the ball contains a certain amount of error (hereafter “error X”). As various factors cause the error X, it is hard to precisely specify the cause of the error X. Examples include a measurement error during swing measurement and a deviation from the sweet spot at impact.

When a golfer selects a club, the relative difference between clubs, that is, how the trajectory changes in the case of switching from a reference club to a target club, is important. In the disclosed technique, the test club is used as the reference club. Hence, the difference between the initial condition of the ball obtained through simulation and calculation (including the regression equation) with a club model corresponding to the test club and the actual initial behavior of the ball measured using the test club is determined. This difference corresponds to the error X.

The difference is added to (or subtracted from) the initial behavior of the ball obtained through simulation and calculation for each of the various target clubs. By such correction, the relative difference, that is, how the trajectory changes with respect to the actual trajectory when using the target club, is obtained. The easy-to-understand result can thus be presented to the golfer.

Ball Trajectory Prediction Step

The disclosed golf ball trajectory prediction method includes, after the above-mentioned ball initial behavior calculation step, a step (golf ball trajectory prediction step) of predicting the trajectory of the golf ball from the initial behavior of the golf ball calculated in the ball initial behavior calculation step, as illustrated in FIG. 1(d) and FIG. 2(d).

The golf ball trajectory prediction step is a step of predicting, through calculation, which trajectory the ball launched from the target golf club follows, based on the calculated initial behavior of the golf ball. The trajectory may be visual data representing the trajectory, or numerical data of the carry distance, horizontal deviation, launch angle, landing angle, trajectory height, etc.

The method of predicting the trajectory of the golf ball is not particularly limited, and may be any known prediction method.

For example, a method of deriving, from the calculated initial behavior of the golf ball, the motion component of the golf ball by computer operation and simulating the trajectory is available.

(Golf Ball Trajectory Prediction Apparatus)

One of the embodiments of a golf ball trajectory prediction apparatus according to the disclosure is described below.

The disclosed golf ball trajectory prediction apparatus: measures a golfer's swing using a test golf club; predicts a behavior of a head of a target golf club when using the target golf club, with the measured swing as input; calculates an initial behavior of a golf ball after colliding with the head of the golf club, based on the prediction value of the behavior of the head; and predicts a trajectory of the golf ball, from the calculated initial behavior of the golf ball.

With such a structure, the trajectory of the golf ball can be predicted with high accuracy.

Preferably, the golf ball trajectory prediction apparatus further measures the meeting rate in the swing measurement and uses, from among the measured swings, only each swing with a meeting rate not less than a predetermined threshold as input in the head behavior prediction.

The reasons for using only each swing with a meeting rate not less than the threshold, the suitable threshold, etc. are as described above.

The golfer's swing measurement is not particularly limited, and may be performed using the above-mentioned accelerometer or motion capture as an example.

The meeting rate measurement is not particularly limited. For example, the meeting rate may be calculated by measuring each of the head speed upon impact and the initial speed of the launched ball using a measuring instrument such as a high-speed camera, or measured using a commercial available meeting rate measuring instrument.

The head behavior prediction is not particularly limited, and may be performed using a computer installed with commercially available simulation software.

The golf ball initial behavior calculation may be performed using a computer installed with motion analysis software based on the finite element method or a specific regression equation.

The golf ball trajectory prediction is not particularly limited, and may be performed using a computer installed with commercially available simulation software.

In the golf ball trajectory prediction apparatus, preferably, the initial behavior of the golf ball after colliding with the head of the golf club is calculated using a regression equation derived beforehand from collision analysis between the head of the golf club and the golf ball, with the prediction value of the behavior of the head as input.

As mentioned earlier, the behavior of the golf ball after the collision is calculated based on the finite element method or the like with various head behaviors as input to generate the regression equation for the behavior of the head and the initial behavior of the golf ball beforehand, and the initial behavior of the golf ball is calculated using the regression equation. In this way, the calculation time can be significantly reduced as compared with the case of performing the simulation based on the finite element method or the like.

The details of the other components in the disclosed golf ball trajectory prediction apparatus are the same as those described with regard to the disclosed golf ball trajectory prediction method.

(Golf Club Selection Method)

One of the embodiments of a golf club selection method according to the disclosure is described below.

The disclosed golf club selection method selects a golf club based on a trajectory of a golf ball predicted by the golf ball trajectory prediction method described above.

With such a method, a suitable golf club can be selected based on the accurately predicted trajectory of the golf ball.

For example, the golfer can select his or her favorite club based on an image representing the predicted trajectory or prediction data of the carry distance, launch angle, landing angle, trajectory height, etc. Moreover, the store(s) or manufacturer(s) can select and recommend an optimal golf club to the golfer based on the predicted trajectory.

INDUSTRIAL APPLICABILITY

It is possible to provide a golf ball trajectory prediction method and golf ball trajectory prediction apparatus that can predict the trajectory of a golf ball with high accuracy, and a golf club selection method that can select a suitable golf club.

Claims

1. A golf ball trajectory prediction method comprising:

a swing measurement step of measuring a golfer's swing using a test golf club;

a head behavior prediction step of predicting a behavior of a head of a target golf club when using the target golf club, with a measurement value of the swing measured in the swing measurement step as input;

a ball initial behavior calculation step of calculating an initial behavior of a golf ball after colliding with the head of the golf club, based on the behavior of the head predicted in the head behavior prediction step; and

a ball trajectory prediction step of predicting a trajectory of the golf ball, from the initial behavior of the golf ball calculated in the ball initial behavior calculation step.

2. The golf ball trajectory prediction method according to claim 1,

wherein in the ball initial behavior calculation step, the initial behavior of the golf ball after colliding with the head of the golf club is calculated using a regression equation derived beforehand from collision analysis between the head of the golf club and the golf ball, with a prediction value of the behavior of the head predicted in the head behavior prediction step as input.

3. The golf ball trajectory prediction method according to claim 1,

wherein in the ball initial behavior calculation step, the initial behavior of the golf ball after colliding with the head of the golf club is calculated by collision analysis based on a finite element method, with a prediction value of the behavior of the head predicted in the head behavior prediction step as input.

4. The golf ball trajectory prediction method according to claim 1,

wherein in the swing measurement step, a meeting rate of the golf ball in the swing is further measured, and

in the head behavior prediction step, only a swing with a meeting rate not less than a predetermined threshold is used as input, from among the swing measured in the swing measurement step.

5. The golf ball trajectory prediction method according to claim 4,

wherein the meeting rate is an initial speed of the launched golf ball with respect to a speed of the head of the golf club upon impact.

6. The golf ball trajectory prediction method according to claim 1,

wherein in the swing measurement step, the initial behavior of the golf ball in the swing is further measured, and

the initial behavior of the golf ball measured in the swing measurement step and the initial behavior of the golf ball calculated in the ball initial behavior calculation step are compared with each other, to correct a result of the calculation that is based on a prediction value of the behavior of the head.

7. The golf ball trajectory prediction method according to claim 2,

wherein in the swing measurement step, the initial behavior of the golf ball in the swing is further measured, and

the initial behavior of the golf ball measured in the swing measurement step and the initial behavior of the golf ball calculated in the ball initial behavior calculation step are compared with each other, to correct a result calculated from the regression equation.

8. The golf ball trajectory prediction method according to claim 1,

wherein the initial behavior of the golf ball includes an initial speed, a launch angle, and a spin rate of the golf ball after colliding with the head of the golf club.

9. The golf ball trajectory prediction method according to claim 2,

wherein the regression equation is derived from motion analysis based on a finite element method.

10. A golf ball trajectory prediction apparatus that:

measures a golfer's swing using a test golf club;

predicts a behavior of a head of a target golf club when using the target golf club, with the measured swing as input;

calculates an initial behavior of a golf ball after colliding with the head of the golf club, based on a prediction value of the behavior of the head; and

predicts a trajectory of the golf ball, from the calculated initial behavior of the golf ball.

11. The golf ball trajectory prediction apparatus according to claim 10,

wherein the initial behavior of the golf ball after colliding with the head of the golf club is calculated using a regression equation derived beforehand from collision analysis between the head of the golf club and the golf ball, with the prediction value of the behavior of the head as input.

12. A golf club selection method of selecting a golf club based on a trajectory of a golf ball predicted by the golf ball trajectory prediction method according to claim 1.