JP2003210638A - Movement measuring instrument of golf club head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow a measuring instrument to have a portable size and to precisely measure the movement that is the speed and acceleration of a golf club head in the case of swinging it. <P>SOLUTION: By combining an ultrasonic sensor, a DSP, a display, a battery, and a few electronic circuits, the instrument itself comes to have a portable size. The movement measuring instrument provided with the ultrasonic sensor consisting of a transmitter and receiver of an independent reflection system is installed at 5 in front of or at 6 in rear of swinging on a target line 4. The ultrasonic wave of a basic frequency is transmitted from the transmitter and collides with a club face. The ultrasonic wave of a frequency converted by the doppler effect is received by the receiver, and the received wave is converted to a digital signal by an A/D converter. In addition, the signal is sampled at high speed, fetched into the DSP and time - frequency-analyzed by wavelet conversion to precisely measure the speed and acceleration of the club head. <P>COPYRIGHT: (C)2003,JPO

Description

Description: BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to measuring the speed and acceleration of a club head during a swing of a golf club, and more particularly to measuring the club head using ultrasonic Doppler technology. Method and system for determining velocity and acceleration. 2. Description of the Related Art Golf lovers, whether professional or amateur, desire to fly a golf ball as far as possible. As is well known, the flight distance of a golf ball is related to the law of conservation of momentum at the time of collision between a club head and a golf ball, and the momentum is represented by the product of the mass and speed of an object, and is proportional to the speed of the club head. Will do. For this reason, many people want to be able to swing the club faster. Therefore, many devices for measuring the head speed during a swing have been devised. For example,
Speaking of the prior art, there is an apparatus characterized by incorporating a base in which a rectangular mat is fitted, and a box-shaped main body having a built-in measuring component on the side of the base. [0004] The mat is installed so that its longitudinal direction is parallel to the flying ball line. At least three light-emitting elements are installed on the main body on the side of the mat at a predetermined distance along the swing trajectory, and a light-receiving element for receiving the light beam emitted by these light-emitting elements forms a sensor. , These sensors detect the passage of the club head. In other words, when the measurement is performed using this device, each light receiving element detects the transit time when the club head crosses the light beam emitted from each light emitting element, and the time difference of the detection signal between each sensor is measured. Then, the speed and acceleration of the club head are calculated from the measured values, and the calculation results are displayed on the display unit. In another invention, a magnetic sensor is incorporated in place of the above light emitting element and light receiving element. [0007] In the conventional invention as described above, the size of the device itself such as a rectangular mat becomes unportable, and such a large device is used in a driving range or the like. If you bring in, you must get the permission of the training area manager, which is inconvenient. Therefore, the product of the present invention is intended to be easily portable and easily installed. Another object of the present invention is to accurately measure the speed and acceleration of a club head using Doppler technology based on ultrasonic waves, unlike the conventional measuring method. [0008] In order to achieve the above-mentioned object, the product of the present invention is provided on an end face of a portable size device.
Kind Code: A1 An object of the present invention is to provide a motion measuring device in which an ultrasonic sensor including an independent reflection type transmitter and a receiver is arranged so as to oppose the movement of a detection object, that is, a club head. That is, the ultrasonic waves emitted from the transmitter are:
A method is provided in which a reflected wave reflected by a club head is received by a receiver, and the speed of the club head is calculated by comparing the frequency of a transmitted wave with the frequency of a received wave by the Doppler effect. [0010] Further, regarding the acceleration of the club head,
The wave reflected by the club head can be obtained by performing a time-frequency analysis as a time-varying signal by a wavelet transform and analyzing a change in frequency with respect to time. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A club head motion measuring device according to the present invention is installed in front of or behind a swing of a club head on a flight line. It is the DSP or digital signal processor that controls and computes the entire measurement system. DSP generates a digital signal as the base of a sine wave to generate a sinusoidal waveform of the fundamental frequency f ₀ through the D / A converter circuit drives the ultrasonic transmitter. [0013] Ultrasonic fundamental frequency f ₀ which is emitted in the air, hit the club face, the reflected wave is returned to the device. The reflected wave shifted to the frequency f by the Doppler effect is received by the ultrasonic receiver. The signal received by the receiver is sampled by the DSP as a digital signal by the A / D conversion circuit. The DSP analyzes the frequency of the sampled digital signal by Fourier transform, and obtains the frequency main component of the received wave, that is, the frequency f at which the power spectrum is maximized. Assuming that the velocity of the club face is ν and the velocity of sound in the air is c, the frequency f calculated from the Doppler formula is expressed by the following equation, so that the velocity of the club face can be easily obtained. . ## EQU1 ## However, the frequency components contained in the received signal, reflecting off the dynamically moving club face, are by no means stationary and change with time t. The sound pressure level of the received signal is sampled at high speed, and the analysis signal x
(T), which is subjected to a wavelet transform to obtain a time-frequency characteristic. Further, a frequency principal component is obtained in a time series, and a speed change of the club face is obtained from this. The maximum value of the speed and the maximum value of the acceleration are obtained from the characteristic of the speed change of the club face, and these values are displayed on a display. The wavelet transform is an integral transform using a function Ψ ((t−b) / a) obtained by applying a scale transform a (> 0) and a shift transform b to a mother wavelet function Ψ (t). Where x (t) is the input signal and is represented by the following equation. ## EQU2 ## Here, the superscript bar represents a complex conjugate, and Ψ (t) is a function satisfying the following condition. [0019] -The wavelet function Ψ (t) is expressed by Gab
An or function can be adopted. [Equation 3] Here, σ is an index indicating the width of the Gaussian window. When the wavelet transform is performed on the input signal shown in FIG. 3, the result shown in FIG. 4 is obtained. In FIG. 4, the a-axis indicates the frequency axis, and the b-axis indicates the time axis. a-
On the b-plane, the line g has the characteristic of the temporal change of the frequency main component. The characteristic of the line g that changes with time is f (t)
Then, the characteristic ν (t) of the speed change of the club face can be obtained according to the following equation derived from Equation 1. [Equation 4] From the characteristic of the speed change, the maximum value of the speed ν
_{The maximum} change α (t) of the acceleration is determined by the following equation, and the maximum value α _{max of the} acceleration is determined, and each value is displayed on the display. [Equation 5] FIG. 1 shows an embodiment for measuring the movement of a club head by using the product of the present invention. The swing trajectory 3 of the person 1, the club head, the flying ball 4 and the position of the measuring device 5 are shown. Show the relationship. The measuring device 5 is usually installed in front of the swing on the flying ball. If you only practice swing without using a golf ball, you can set up in front of the swing, but if you practice using a golf ball, there is a risk that the hit ball will hit the measuring device and destroy the device, It is set at 6 behind the swing on the trajectory. FIG. 2 shows a system configuration of the apparatus main body.
Is a DSP which is the central part of the measurement system. The DSP generates a digital signal that is the basis of the sine waveform,
/ Via the A conversion circuit to generate a sine wave of the fundamental frequency f _0, and drives the ultrasonic transmitter 9. The reflected waves emitted in the air, hit the club face, and shifted to the frequency f by the Doppler effect are received by 10 ultrasonic receivers. The received signal is converted into a digital signal by 11 A / D conversion circuits.
Sampled at high speed by SP. The DSP performs a time-frequency analysis on the sampled digital signal by wavelet transform according to Equation 2 to calculate a characteristic f (t) of the change of the main frequency component.
From this, the characteristic of the speed change of the club face is obtained according to Equation 4, and from the characteristic of this speed change, the maximum value ν of the speed is obtained.
_{The maximum} change of the acceleration with time is obtained from Expression 5, and the maximum value α _{max of the} acceleration is determined based on the expression 5, and the value is displayed on the display unit 12. By combining an ultrasonic sensor, a DSP, a display, a battery, and a few electronic circuits, the measuring device itself can be suppressed to a compact and portable size. Using the Doppler effect due to ultrasonic waves, the signal captured by the ultrasonic sensor is time-
By performing the frequency analysis, the movement of the club head, that is, the velocity and the acceleration can be accurately measured.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an embodiment of a golf club head motion measurement. FIG. 2 is a system diagram of a motion measuring device. FIG. 3 is a reception waveform of an ultrasonic sensor. FIG. 4 is an example of time-frequency analysis by wavelet transform. [Description of Signs] 1 person 2 golf club 3 swing trajectory 4 trajectory line 5 motion measuring device 6 motion measuring device 7 when installed behind swing 7 DSP 8 D / A converter 9 ultrasonic transmitter 10 ultrasonic receiver 11 A / D converter 12 Display

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[Procedure for Amendment] [Date of Submission] March 19, 2002 (2002.3.1)
9) [Procedure amendment 1] [Document name to be amended] Description [Item name to be amended] Number 1 [Correction method] Change [Content of amendment] [Procedure amendment 2] [Document name to be amended] Specification [Item name to be amended] Equation 4 [Correction method] Change [Content of amendment] [Equation 4]

Claims (1)

Claims: 1. An ultrasonic sensor installed to face a golf club face, and A / D conversion of a sound pressure detected by the ultrasonic sensor.
By combining a DSP for frequency analysis of the digital signal and a display for numerically displaying the analysis result,
We measure the speed and acceleration of the club head by making the device itself a portable size, using Doppler technology with ultrasonic waves, and performing time-frequency analysis on the signals captured by the ultrasonic sensor by wavelet transform. Characteristic exercise measurement device.