JPS6247557A - Swing speed measuring instrument - Google Patents

Abstract

PURPOSE:To measure a correct swing speed even for a swing body whose track is not fixed by arranging a pair of centrifugal sensors at the prescribed distance in the axial direction of the swing body so as to measure the centrifugal force acting on the swing body. CONSTITUTION:A pair of centrifugal sensors 4a, 4b, an arithmetic circuit 8 to operate the swing speed of a swing body 1 base on the output value of the sensors 4a, 4b and a display part 9 to display the arithmetic output of the circuit 8 are arranged at the prescribed distance in the axial 2 direction of the swing body 1 of a bat, racket, etc. The measurement of the speed is thus made possible without the position swinging the swing body 1 being regulated by instruments by directly fitting a set of the instruments to the swing body 1. Consequently the swing speed can correctly be measured even in case of the moving track of the swing body 1 being not fixed like the case of striking a flying ball, etc. No error is caused as well even if the swing body 1 itself is rotated around the axis is order to measure the swing speed by detecting the centrifugal force acting on the axial direction of the swing body 1.

Description

[Detailed Description of the Invention] [Technical Field 1] The present invention relates to a swing speed measuring device, and more particularly, a swing speed measurement device for measuring the swing speed when swinging a swinging body such as a Domington racket with a baseball bat or tennis racket. This invention relates to a speed measuring device.

[Background Art] Devices that measure the speed of swinging objects such as baseball bats, tennis and badminton rackets, and golf clubs have conventionally measured the head speed of golf clubs as shown in Figure 9. There is something to offer. In this system, a pair of sensors 20a and 20b that detect the passage of a club head using magnetism or light are arranged at a predetermined distance apart before and after a position 21 where a ball is set. , 20b, the head speed of the club can be calculated and displayed on the display section 22. That is, as shown in FIG. 10, the outputs of both sensors 20a+20b are input to an arithmetic circuit 23 consisting of a microfum computer, and the swing speed S is calculated from the distance r between the rain sensors 20a and 2Ob and the head passage time It. This is determined as S=J/l and displayed on the display unit 22.

This measuring device (in this case, the sensors 20a and 20b are placed apart from the club, and the club needs to pass within the detection area of both sensors 20a and 20b, so the position at which the club is swung is The mounting position of the sensors 20a and 20b is restricted, and when the movement trajectory of the swinging body is not constant, such as when hitting a flying ball with a bat, it is difficult to swing the swinging body in the detection area of the sensors 20a and 20b. It becomes virtually impossible to measure swing speed in such cases.

On the other hand, devices have been considered that calculate swing speed from the acceleration of swing objects such as bats and rackets. This is because when swinging the swing body, the swing body accelerates from a stopped state, decelerates and stops again, as shown in Fig. 11. By integrating the acceleration a at , the swing speed S at the time after the start of the swing is determined as S=J, adt. However, in order to obtain the maximum value Smax of the swing speed, integration is performed from time tn when the sign of the acceleration a changes from positive to negative.

However, when swinging a bat, racket, etc., a person's waist, arms, wrists, etc. are involved in a complex combination of Q linear motion and circular motion, so the swinging body rotates around its own axis during the swing. will also undergo rotational motion. Here, the pongee of the swing body refers to the pongee 2 running in the longitudinal direction of the swing body 1, as shown in FIG. @13 As shown in the figure, when the swing body 1 is swung in the direction a, the acceleration sensor 24 attached to the swing body 1 and which detects the acceleration of the swing body 1 rotates in the direction b, so that the acceleration detected by the acceleration sensor 24 is Since the direction is not constant, the swing speed cannot be accurately measured using one acceleration sensor 24.

[Objective of the Invention 1 The present invention has been made in view of the above-mentioned points, and its main purpose is to swing objects such as bats, rackets, etc., which have inconsistent trajectories. An object of the present invention is to provide a swing speed measuring device that can accurately measure swing speed.

[Disclosure of the Invention 1 (Principle) The present invention basically consists of a swing body having a predetermined distance M in the axial direction;
This device attempts to detect swing speed based on the output of a pair of centrifugal force sensors that are arranged apart from each other and measure the centrifugal force acting on the swing body, and the principle thereof will be explained below based on Fig. 7. do.

When swinging the swing body 1, it is considered to be a complex combination of linear motion and circular motion caused by the movements of the person's hips, arms, wrists, etc., but the movement of the swing body 1 during the swing is basically a circular motion. It can be approximated by Considering it as a circular motion, if the centrifugal force of the swing body 1 in the direction along l[lI2 is measured, the velocity in the circumferential direction around the rotation center 3 can be obtained.

V=F go down...■ Here, α is the acceleration of the swing body 1 in the axial direction, and since the mass of the swing body 1 is a constant value, the centrifugal force and the acceleration are in a proportional relationship. Further, r is the radius from the rotation center 3 to the measurement point. Swing speed using centrifugal force sensor■
When calculating, the radius r is the distance between the center of rotation 3 and the centrifugal force sensor, so if the gripping position of the swing body 1 or the mounting position of the centrifugal force sensor changes, the radius r also changes. It is difficult to accurately calculate the swing speed V in response to such changes in the radius r.

However, two centrifugal force sensors 4a and 4b are arranged at a predetermined distance l apart from each other on the swing body 1, and the two centrifugal force sensors 4a and 4b are arranged at a predetermined distance l apart.
Consider calculating the swing speed V from the output value of 4b. At this time, the accelerations αa and αb acting on each centrifugal force sensor 4a and 4b are expressed by the following equation ffi.

aa=ω2 also ra...■αb=ω2・r
b...■ In Uni, ra and rb are the distances from the rotation center 3 to each centrifugal force sensor 4a, 4b, respectively,
ω is the angular velocity.

Determining ω2 from both equations, we get
b aa-ffboa” °°゛■ Here, the distance between both centrifugal force sensors 4a and 4b is open!=
Since =ra rb is a constant value, by substituting the formula ■ into the formula 0 and organizing it, the swing speed Va can be calculated as shown in the following formula, and the output value αa of both centrifugal force sensors 4a and 4b, αa,
If αb and the distance r between both centrifugal force sensors 4a, 4b are obtained, the swing speed Va at which one of the centrifugal force sensors 4a, 4b moves can be determined. Here, if you want to find the maximum speed Vmax, you can calculate the formula 0 every moment and find the maximum value. Note that the maximum speed V max is obtained at the time t when the maximum acceleration is reached, as shown in FIG.
Matches n. In the figure, Fa and Fb are each centrifugal force sensor 4a,
It shows the centrifugal force acting on 4b, and the acceleration αa,
It is in a proportional relationship with αb.

(Example) In this example, a baseball bat is illustrated as the swing body 1. @1 As shown in Figure 1, a device main body 6 including a belt 5 wrapped around the circumferential surface of the bat 1 is detachably attached. As shown in FIG. 4, the belt 5 consists of a pair of belt strips 5ai? with one end fixed to each side edge of the device main body 6. The free ends of both belt strips 5a are overlapped with each other, and are removably connected to each other by planar 7 aseners 10 provided at the ends. Therefore, the main body 6 of the device is arranged to be detachably attached to the bat 1. The device main body 6 includes a pair of centrifugal spindles f4a, 4b,
A power source 7 consisting of a battery, an arithmetic circuit 8 consisting of a microcomputer, and a display section 9 consisting of a liquid crystal display are provided.

The device main body 6 is a molded body of synthetic resin, and as shown in FIG. 5, centrifugal force sensors 4a and 4b are integrally incorporated therein.

The centrifugal force sensors 4a and 4b are a type of acceleration sensor, and as shown in FIG.
A piezoelectric bimorph 11 configured by stacking a and llb and having one end fixed to the device main body 6, and a piezoelectric bimorph 1
1 and a weight 12 fixed to the free end of the weight 12. However, by attaching the piezoelectric bimorph 11 so that the direction connecting the free end and the fixed end is substantially perpendicular to the axial direction When a force of

The signals received from both centrifugal sensors 4a and 4b are @
As shown in FIG. 2, the signal is input to the arithmetic circuit 8. The arithmetic circuit 8 converts the voltages taken out from both centrifugal sensors 4a and 4b into digital signals, as shown in FIG.
The swing speed Va of the sensor 4a of each centrifugal force sensor 4a, 4b is determined by the above equation (2), and the output value of the centrifugal force sensor 4a, 4b is sampled at a predetermined time interval sufficiently shorter than the swing time. The swing speed Va is calculated at each sampling period, and the swing speed Va is calculated at each sampling period. s, maximum speed V am
A comparison is made with ax, and if it is greater than the maximum speed Vamax, the speed Va is stored as the maximum speed Vamax. Also, the speed Va
When V is smaller than the maximum speed V aiax , the maximum speed V amax is displayed on the display section 9 and the displayed value is held.

In the above example, a bat was used as the swing body 1, but the swing body 1 can also be attached to a tennis or badminton racket, a golf club, etc. in addition to the bat.

[Effects of the Invention 1] As described above, the present invention detects the swing speed of the swing body based on the output values of both centrifugal force detection means, which are arranged at a predetermined distance in the axial direction of a swing body such as a bat or a racket. Since the device is equipped with a calculation means for calculating , and a display means for displaying the output result of the calculation means, since the device is directly attached to the swing body, the position of swinging the swing body is regulated by the VC position. It has the advantage that the swing speed can be measured accurately even when the trajectory of the swing body is not constant, such as when hitting a flying ball. In addition, since the swing speed is measured by detecting the centrifugal force acting in the axial direction of the swing body, there is no error even if the swing body rotates around its own pongee, and the swing speed can be measured. This has the advantage of being accurate.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an embodiment of the present invention, FIG. 2 is a block diagram of the same as above, FIG. 3 is an explanatory diagram of the operation of an arithmetic circuit used in the above, and FIG. 4 is a line A-A in FIG. Cross-sectional view, Figure 5 is the first
B-B in the diagram! 6 is a sectional view showing the centrifugal force sensor used in the above, FIG. 7 is a diagram explaining the principle of the same, and FIG. 8 is an operation explanation showing the relationship between the output of the centrifugal force sensor and swing speed in the same as the above. 9 is a plan view showing the conventional example, FIG. 1510 is a block diagram of the same as above, FIG. 11 is an operation explanatory diagram showing the relationship between acceleration and velocity in the moving direction of the swing body, and FIG. 12 is a diagram of the swing body. FIG. 13 is an explanatory diagram showing the axis and is an explanatory diagram of the operation of another conventional example. 1 is a swing body, 2 is a shaft, 4a and 4b are centrifugal force sensors,
5 is a belt, 6 is a device main body, 8 is an arithmetic circuit, and 9 is a display section. Agent Patent Attorney Stone 1) Ai 7b Fig. 3 Fig. 4 Fig. 5 Cause 4a, 4b Fig. 7 Fig. 8 Fig. 10 Fig. 11・I To Tn Te
M] Shun No. 12 No. 13

Claims (2)

[Claims] (1) A pair of centrifugal force detection means arranged a predetermined distance apart in the axial direction of a swing body such as a bat or a racket to detect centrifugal force in the axial direction, and a swing based on the output values of both centrifugal force detection means. A swing speed measuring device comprising a calculation means for calculating the swing speed of the body and a display means for displaying the output result of the calculation means. (2) The swing speed measuring device according to claim 1, wherein the centrifugal force detection means is attached to a belt detachably wrapped around the swing body.