JP2004033463A - Device for evaluating impact resilience characteristic of golf club head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a golf club head impact resilience characteristic evaluating device which obtains the restitution coefficient of a golf head without disassembling the golf club, and also easily obtains the restitution resilience characteristic in a short period of time by visiting a desired place. <P>SOLUTION: The golf club impact resilience characteristic evaluating device 10 includes: an analog input/output card 20 for fetching a response signal from a shot surface F which is generated by oscillating the shot surface F of the golf club head H with an impact; a frequency analyzing unit 22a for obtaining a first resonance frequency f on the shot surface F from the response signal; a restitution coefficient calculating unit 22b for obtaining the restitution coefficient e when a golf ball is shot against the shot surface F from the first resonance frequency f; and a display 22d for displaying the evaluation result of the golf club which is evaluated through the use of the calculated restitution coefficient e. The respective units are comprised in a mobile computer 22. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rebound characteristic evaluation apparatus for a golf club head that evaluates a rebound characteristic of a striking surface of a golf club head when a golf ball is hit with a golf club head such as a hollow golf club head made of metal or the like.
[0002]
[Prior art]
Today, golf club manufacturers have proposed various golf clubs with golf club heads with good resilience so that even less powerful golfers can fly golf balls far away through improvements and developments in the structure and materials of golf club heads. ing.
[0003]
On the other hand, the US Golf Association (USGA) and R & A (Royal and Associate Golf Club of St. Andrews) have ruled that the golf clubs that fly too much are ruled out because the resilience characteristics are so good. It stipulates that golf clubs that meet the criteria e will be used in golf competitions.
For example, in USGA, in order to investigate the coefficient of restitution e between a golf ball and a golf club head, as shown in FIG. 7, the face surface of the golf club head H is placed with the golf club head H placed on a mounting table. by colliding a golf ball perpendicular to F, repelled from the relational expression between the mass m of the mass M and the golf ball at that time the golf ball of the incoming velocity V _in the reflection rate V _out and the golf club head (formula) A method for obtaining the coefficient e is proposed.
V _out / V _in = (e · M −m) / (M + m)
[0004]
[Problems to be solved by the invention]
However, when the coefficient of restitution e is obtained by the above method, the face surface F of the golf club head H is set perpendicular to the incident direction of the golf ball, and a predetermined position on the face surface F of the golf ball is set as the hit position. Therefore, it is necessary to accurately align the golf club head H. Further, since it is necessary to remove the golf club head from the shaft and perform measurement with the golf club head alone, a complicated operation of disassembling the golf club and reassembling it after measurement is also required.
[0005]
Furthermore, the above-described method results in a large-scale apparatus configuration, and it is not possible to go to a desired place and easily obtain the coefficient of restitution e to evaluate the rebound characteristics of the golf club head.
Thus, by calculating the coefficient of restitution e by the above method, it is not only possible to inspect each golf club of professional golfers participating in the competition within a limited time before the start of the competition. Cannot be evaluated easily in a short time.
In addition, when the disassembled golf club is reassembled, the feeling of the golf club that has been favorable until now often changes.
[0006]
Therefore, in order to solve the above-mentioned problems, the present invention estimates the restitution coefficient of the golf club head without removing the golf club head from the shaft and disassembling the golf club, and goes to a desired place to repel the rebound. It is an object of the present invention to provide a golf club head rebound characteristic evaluation apparatus capable of obtaining a coefficient extremely easily and in a short time.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a golf club head rebound characteristic evaluation apparatus for evaluating a rebound characteristic of a golf club head,
An input device that captures a response signal of the striking surface generated by impact vibration of the striking surface of the golf club head;
An analysis unit for obtaining a resonance frequency of the striking surface from the response signal;
A calculation unit for obtaining a coefficient of restitution when the golf ball is hit with the hitting surface from the resonance frequency;
There is provided a golf club head rebound characteristic evaluation apparatus, comprising: a display for displaying an evaluation result of a golf club head evaluated using a calculated restitution coefficient.
[0008]
Here, the calculation unit uses either a reference table that represents a relationship between the coefficient of restitution when the golf ball is hit with the hitting surface and the resonance frequency, or a relational expression that represents the relationship as a function. The restitution coefficient of the striking surface is preferably obtained.
In addition, the evaluation unit includes an evaluation unit that determines the pass / fail of the rebound characteristics of the golf club head by comparing the restitution coefficient calculated by the calculation unit with a predetermined value. The evaluation result is preferably displayed on the display.
[0009]
The response signal is, for example, one of an acceleration signal of vibration of the striking surface and a sound pressure signal of the striking surface.
The resonance frequency is preferably a primary resonance frequency.
Moreover, it is preferable that the input device, the analysis unit, and the calculation unit in the repulsion characteristic evaluation apparatus for the golf club head are incorporated in a mobile computer.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the golf club head rebound characteristic evaluation apparatus of the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
FIGS. 1A and 1B are diagrams showing an outline of a golf club head rebound characteristic evaluation apparatus 10 according to an embodiment of the present invention.
The rebound characteristics evaluation device 10 is an apparatus for evaluating the rebound characteristics of a golf club head, and is generated by this vibration when the striking surface F is vibrated by giving an impact to the striking surface F of the golf club head H. And an analog input / output card 20 that captures the response signal of the striking surface F, and a mobile computer 22 that evaluates the resilience characteristics using the response signal supplied from the analog input / output card 20. The analog input / output card 20 is inserted into a predetermined position of the computer 22 and integrated with the computer 22.
[0011]
In the computer 22, the frequency analysis unit 22a for obtaining the resonance frequency of the striking surface F from the response signal during vibration of the striking surface F, and the coefficient of restitution e when hitting the golf ball with the striking surface F are given to the frequency analyzing unit 22a. By comparing the restitution coefficient calculation unit 22b calculated from the resonance frequency obtained in this way and the restitution coefficient e calculated by the restitution coefficient calculation unit 22b with a predetermined value, the pass / fail characteristics of the golf club head H are determined. And a display 22d for displaying an evaluation result of the rebound characteristics of the golf club head evaluated using the calculated restitution coefficient e.
The frequency analysis unit 22a, the restitution coefficient calculation unit 22b, and the evaluation unit 22c are units that exhibit functions by executing a predetermined program, that is, units that perform functions by software processing.
[0012]
Here, the rebound characteristics of the golf club head H are evaluated using the microphone 12, the amplifier 14, and the hammer 24 in addition to the rebound characteristics evaluation device 10.
That is, the striking surface F of the golf club head H vibrates (by impact excitation) when the striking force by the hammer 24 is applied, but the striking sound generated by this vibration is converted into a sound pressure signal by the microphone 12. Then, it is amplified by the amplifier 14 and further taken into the computer 22 through the analog input / output board 20.
The tip of the hammer 24 is made of a metal material having a hardness that does not scratch the striking surface F, and the impact of the hammer 24 is a light striking that does not scratch the striking surface F.
The golf club head H that receives the hit forms, for example, a free end with the hosel portion suspended from the ceiling. Alternatively, the shaft S of the golf club 12 is lightly fixed and supported. In any case, any fixing method may be used as long as it does not affect the resonance frequency when the striking surface F of the golf club head H vibrates like a film.
[0013]
The microphone 12 is a small microphone that converts sound into an electric signal, for example, a condenser microphone.
The amplifier 14 is a device provided with a connection terminal 14a so as to amplify a sound pressure signal taken from the microphone 12, and connected to the microphone 12 by, for example, a 3.5 mm pin jack connector. In addition to the connection terminal of the microphone 12, the connection terminal 14a of the amplifier 14 is, as will be described later, a pickup 32a (see FIG. 4) that measures the acceleration signal obtained by the acceleration pickup 30 (see FIG. 4) and impact impact force. ) To amplify the striking signal.
The amplifier 14 is connected to the analog input / output card 20 via the connection connector 18. For example, a D-sub 37-pin connector is used as the connection connector 18.
The analog input / output card 20 is a device that is installed in a predetermined slot of the computer 22 and converts a sound pressure signal that is an analog signal amplified by the amplifier 14 into a digital signal, and corresponds to the input device in the present invention. . As the analog input / output card 20, for example, AD-12-8 (PM) manufactured by CONTEC is used.
[0014]
The frequency analysis unit 22a is a unit that obtains a primary resonance frequency f of the striking surface F of the golf club head H by performing frequency analysis of the sound pressure signal input from the amplifier 14 using FFT (Fast Fourier Transform).
In the frequency analysis, for example, a sound pressure spectrum waveform as shown in FIG. 2 is obtained. Here, the sound pressure waveform has five peaks in the band of 4000 Hz to 7000 Hz. However, the primary resonance is preliminarily classified according to the brand of the golf club 12, the product, or the type of the golf club number, driver, spoon, or the like. The generation band of the frequency f is determined in advance, for example, 5200 to 6200 Hz, and the frequency at the position B can be obtained as the primary resonance frequency f from the frequency waveform of the sound pressure signal.
The obtained primary resonance frequency f is sent to the restitution coefficient calculation unit 22b.
[0015]
The restitution coefficient calculating unit 22b is either a reference table that represents the relationship between the restitution coefficient e and the primary resonance frequency f from the primary resonance frequency f that has been sent, or a relational expression that represents this correspondence as a function. This is a unit for estimating and calculating the coefficient of restitution e when hitting a golf ball obtained by the method proposed by USGA shown in FIG. The reference table or the relational expression represents, for example, the relationship between (primary resonance frequency f) ² and the restitution coefficient e.
In this way, the repulsion coefficient e of the golf ball can be estimated and calculated because the (primary resonance frequency f) ² of the golf ball obtained by the method shown in FIG. 7 regardless of the golf club manufacturer, brand, or type. This is because the present inventors have found that there is a very strong correlation with the restitution coefficient e.
[0016]
FIG. 3 shows an example of the relationship between (primary resonance frequency f) ² and the restitution coefficient e of the golf ball.
3 indicates the square value of the primary resonance frequency f on the striking surface F of the golf club head H of various golf clubs of different golf club manufacturers, brands and types, and the coefficient of restitution e determined by the method shown in FIG. Shows the relationship.
According to this, in various golf club heads of different golf club manufacturers, brands and types, the primary resonance frequency f is located at about 4400 Hz to 6200 Hz, and the restitution coefficient e of the golf ball is a correlation coefficient R of 0.9507. ² has a linear correspondence with the square value of the primary resonance frequency f. The rebound coefficient e of the golf ball is estimated using such a linear regression equation L, and, as will be described later, the rebound coefficient e satisfies the regulations set by USGA and R & A, that is, the rebound coefficient e satisfies the condition of 0.830 or less. Can be evaluated.
[0017]
In FIG. 3, the square value of the primary resonance frequency f is used for the estimation evaluation of the restitution coefficient e. This is because the restitution coefficient e is considered to change according to the vibration energy of the striking surface F. . The present invention is not limited to the case where the restitution coefficient e is estimated and evaluated using the square value of the primary resonance frequency f. For example, the restitution coefficient e may be estimated and calculated from the primary resonance frequency f.
In addition, the present invention is not necessarily limited to the primary resonance frequency, and may be a resonance frequency such as a secondary, tertiary,... It is preferable to use a primary resonance frequency which is a fundamental resonance frequency of F.
The restitution coefficient e thus calculated is sent to the evaluation unit 22c.
[0018]
The evaluation unit 22c compares a predetermined allowable range of the restitution coefficient, for example, an allowable range such as a restitution coefficient of 0.83 or less, with the restitution coefficient e calculated by the restitution coefficient calculation unit 22b, and calculates the restitution coefficient When e is within the allowable range, the rebound coefficient e of the golf club head H is determined to be an acceptable product that has cleared the regulations. When the calculated restitution coefficient e is outside the allowable range, the rebound characteristics of the golf club head H are not regulated. It is a unit that is judged as a rejected product that is not cleared.
The determination result is sent to the display 22d together with the calculated restitution coefficient e.
On the display 22d, the calculated coefficient of restitution e and information on pass / fail judgment results are displayed.
[0019]
In the evaluation of the rebound characteristics, first, impact is applied to the striking surface F by the hammer 24 and impact excitation is performed, and the sound pressure signal that is a response signal of the striking surface F generated at this time is an analog input / output signal. The data is taken into the computer 22 via the card 20.
In the computer 22, first, frequency analysis is performed in the frequency analysis unit 22a to obtain the primary resonance frequency f.
Further, in the restitution coefficient calculation unit 22b, it is obtained by a method proposed by the USGA using either a reference table representing the relationship between the restitution coefficient e and the primary resonance frequency and a relational expression representing the relationship as a function. The restitution coefficient e when a golf ball is hit is accurately estimated and calculated.
Thereafter, the calculated coefficient of restitution e is compared with a predetermined allowable range, for example, an allowable range of 0.83 or less, to determine whether the allowable range is satisfied, and the determination result is displayed on the display 22d. Is done. Of course, the allowable range can be freely changed by setting.
Since the mobile computer 22 is driven using a battery or a storage battery, the rebound characteristics of the golf club head H can be easily evaluated at a desired location.
[0020]
As described above, the amplifier 14 is provided with the connection terminal 14a for capturing a striking signal from the acceleration pick-up and the pick-up for measuring the impact force of the hammer, and is attached to the striking surface F as shown in FIG. It is also possible to configure the amplifier 14 to take in the acceleration signal of the striking surface F from the accelerometer 30 and the striking signal from the pick-up 32a attached to the tip of the hammer 32 and measuring the striking force.
As the acceleration pickup 30, for example, a small and lightweight one such as Model 122 manufactured by Endevco is used.
[0021]
In this case, the acceleration signal and the hit signal amplified by the amplifier 14 are taken into the computer 22 via the analog input / output card 20, and the transfer function representing the ratio of the acceleration signal to the hit signal is obtained by the frequency analysis unit 22. The primary resonance frequency f is obtained from the spectrum waveform of this transfer function.
That is, in the method of obtaining the primary resonance frequency f using the acceleration signal, since the primary resonance frequency f of the striking surface F of the golf club head H exists in a band of, for example, 4000 Hz to 7000 Hz, not only the sound pressure but also the striking surface. The fact that the information of the primary resonance peak is also included in the vibration of F is utilized.
In this case, as shown in FIG. 4, the acceleration pickup 30 is attached to the striking surface F of the golf club head H, and the striking surface F is impacted and vibrated using the hammer 32. The acceleration signal obtained from the acceleration pickup 30 via the amplifier 14 and the striking signal obtained via the amplifier 14 from the pickup 32a for measuring the striking force are taken into the computer 22, and the acceleration signal corresponding to the striking force is obtained by the frequency analysis unit 22a. Find the transfer function as a ratio. At that time, the striking positions of the hammers 32 are dispersed on the striking surface F of the golf club head H, and excitation is performed at a plurality of points, and a transfer function is obtained for each striking position. In the plurality of transfer functions thus determined, steep peaks having the same phase due to the mode of the vibration mode of the primary resonance frequency of the striking surface F appear regardless of the striking position. The frequency at this peak position is taken out as the primary resonance frequency f.
[0022]
For example, FIG. 5 shows waveforms of the imaginary part of the transfer function when impacts are given at five different hitting positions on the hitting surface F, respectively. According to this, at the position A having a frequency of 5820 Hz, the imaginary part forms a steep peak and forms a resonance peak in any of the five transfer functions. From this, the frequency 5820 Hz is taken out as the primary resonance frequency f.
Alternatively, the peak frequency of the steep peak formed with the transfer function having the same phase regardless of the striking position may be obtained as the primary resonance frequency. The primary resonance frequency can be obtained by finding a steep peak of the same phase in this way. The vibration mode of the primary resonance frequency is one in which the striking surface F is perpendicular to the striking surface F like a film. This is because it deforms in a form that protrudes or dents.
[0023]
In this way, when there are a plurality of peaks in the spectrum waveform of the sound pressure signal and the primary resonance frequency cannot be obtained from this spectrum waveform, a transfer function is obtained using the acceleration signal and the impact signal, and this transfer is performed. The primary resonance frequency f can be obtained by specifying a peak having a phase matching the form of the vibration mode at the primary resonance frequency from the function.
[0024]
In the example shown in FIG. 4, the transfer function is obtained for each striking position of the hammer 32 to obtain the primary resonance frequency f. The transfer function obtained for each striking position is averaged and expressed as one transfer function. The primary resonance frequency f may be specified and obtained with the maximum peak obtained in the averaged transfer function as the peak due to the primary resonance.
Further, instead of the transfer function, the primary resonance frequency f may be obtained by specifying the primary resonance peak from the coherent value of the transfer function. This is because the coherent value of the transfer function has a characteristic that the response signal becomes large at the resonance peak and the coherent value becomes approximately 1, and thus the primary resonance peak can be specified using this characteristic.
Further, the primary resonance frequency f may be obtained using the spectrum waveform of the acceleration signal. FIG. 6 shows an example of the spectrum waveform of the acceleration signal. The maximum peak formed at the position C is the primary resonance peak. Accordingly, the frequency at the position C is obtained as the primary resonance frequency.
In the above examples, frequency analysis is performed in the band of 4000 to 7000 Hz to identify the primary resonance frequency f. However, the present invention is not limited to this band. For example, the frequency analysis may be performed in the band of 3000 to 7000 Hz, and the resonance frequency may be obtained in the band of 3000 Hz to 7000 Hz.
The primary resonance frequency thus obtained is used for calculating the restitution coefficient e by the restitution coefficient calculation unit 22b.
[0025]
In the repulsive characteristic evaluation device 10, the spectrum waveform of the sound pressure signal is obtained by capturing the striking sound of the striking surface F from the microphone 12, thereby obtaining the primary resonance frequency and the vibration of the striking surface F from the acceleration pickup 30. In addition to the capture, the impact force can be captured from the pickup 32a, the transfer function can be obtained, and the primary resonance frequency can be obtained from the transfer function. In the repulsive characteristic evaluation apparatus 10, these two methods can be switched freely. It is possible to select either one of the methods.
As a result, when the primary resonance frequency f cannot be obtained from the sound pressure signal, the transfer function is obtained and the primary resonance frequency f can be quickly and reliably determined.
[0026]
As mentioned above, although the restitution coefficient evaluation apparatus of the golf club head of the present invention has been described in detail, the present invention is not limited to the above-described embodiments, and various improvements and modifications are made without departing from the gist of the present invention. Of course it is also good.
For example, the frequency analysis unit 22a is not limited to executing a program and exhibiting a function by software processing, but may be configured by a dedicated circuit, and the analog input / output board 20 may be converted from analog to digital. It may be configured by a dedicated circuit for performing the above. Further, the coefficient of restitution evaluation device 10 may be a dedicated device configured by a circuit in addition to the computer 22.
[0027]
【The invention's effect】
As described above in detail, in the present invention, the restitution coefficient of the golf club head is estimated and obtained without removing the golf club head from the shaft and disassembling the golf club. Can be obtained very easily and in a short time.
[Brief description of the drawings]
FIGS. 1A and 1B are configuration diagrams showing a schematic configuration of an aspect of a golf club head restitution coefficient evaluation apparatus according to the present invention.
FIG. 2 is a diagram showing an example of a spectrum waveform obtained by the golf club head restitution coefficient evaluation apparatus of the present invention.
FIG. 3 is a diagram showing an example of a relationship between a primary natural frequency of a striking surface of a golf club head and a restitution coefficient e.
FIG. 4 is a configuration diagram showing a schematic configuration of another aspect of the golf club head restitution coefficient evaluation apparatus of the present invention.
5 is a diagram showing an example of an imaginary part of a transfer function obtained by the restitution coefficient evaluation apparatus shown in FIG.
6 is a diagram showing an example of a spectrum waveform obtained by the restitution coefficient evaluation apparatus shown in FIG.
FIG. 7 is a diagram for explaining a conventional restitution coefficient calculation method.
[Explanation of symbols]
10 Repulsion Characteristic Evaluation Device 12 Microphone 14 Amplifier 20 Analog I / O Card 22 Computer 22a Frequency Analysis Unit 22b Restitution Coefficient Calculation Unit 22c Evaluation Unit 22d Display 24, 32 Hammer

Claims (6)

A golf club head rebound characteristic evaluation apparatus for evaluating a rebound characteristic of a golf club head,
An input device that captures a response signal of the striking surface generated by impact vibration of the striking surface of the golf club head;
An analysis unit for obtaining a resonance frequency of the striking surface from the response signal;
A calculation unit for obtaining a coefficient of restitution when the golf ball is hit with the hitting surface from the resonance frequency;
A golf club head rebound characteristic evaluation apparatus, comprising: a display that displays an evaluation result of a golf club head evaluated using the calculated restitution coefficient. The calculation unit uses either one of a reference table representing a relationship between a coefficient of restitution when the golf ball is struck on the striking surface and the resonance frequency, and a relational expression representing the relationship as a function. 2. The golf club head rebound characteristic evaluation apparatus according to claim 1, wherein a rebound coefficient of the surface is obtained. An evaluation unit that determines the pass / fail of the rebound characteristics of the golf club head by comparing the restitution coefficient calculated by the calculation unit with a predetermined value;
3. The golf club head rebound characteristic evaluation apparatus according to claim 1, wherein a determination result of the evaluation unit is displayed on the display as the evaluation result. 4. The repulsion of the golf club head according to any one of claims 1 to 3, wherein the response signal is one of an acceleration signal of vibration of the striking surface and a sound pressure signal of the striking surface. Characteristic evaluation device. The repulsion characteristic evaluation apparatus for a golf club head according to any one of claims 1 to 4, wherein the resonance frequency is a primary resonance frequency. 6. The golf club head rebound characteristic evaluation apparatus according to claim 1, wherein the input device, the analysis unit, and the calculation unit are incorporated in a mobile computer.

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