JPS6232950B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a swing measuring method for measuring the inclination and height of the swinging surface of a baseball bat, and the speed of the baseball bat.

Conventionally, there was no measuring device of this kind that could be used outdoors, so in order to train Nogi players, it was necessary to set up a controlled area within the rainy day practice field and practice under sufficient safety management, increasing the efficiency of training. It wasn't easy.

This invention was made in consideration of the above points, and includes a laser oscillator that generates a highly directional light beam inside the sensor section at a position corresponding to the home base, and also receives the reflected light from the baseball bat. A light-receiving element and optical system are installed for
This device is capable of measuring the elevation angle and height of the swinging surface of a baseball bat and the speed of the baseball bat without contacting either the baseball player or the baseball bat outdoors, and will be described in detail below with reference to the drawings.

FIG. 1 is a diagram for explaining the principle of this invention. In the figure, 1 is the sensor section, 2 is the sensor section 1
a first transmitting/receiving port for emitting a first ray perpendicular to , and receiving the reflected light from the baseball bat; 3 emits a second ray that is inclined toward the catcher with respect to the first ray; and a second transmission/reception port for receiving reflected light from the baseball bat.
4 is a third transmitting/receiving port for emitting a third light beam having an inclination a in the direction of the pitcher within a plane formed by the first light beam and the second light beam, and for receiving the reflected light from the baseball bat; 5 is the first ray, 6 is the second ray
, 7 is the third ray, 8 is the swinging surface of the baseball bat, and the above-mentioned first to third rays 5,
This is the intersection line of the planes determined by 6.7.

Now, suppose that the first light ray 5 and the line of intersection 8 intersect at a distance h' above the sensor section 1, and that the line of intersection 8 is inclined at an angle θ with respect to the sensor section, then the three light rays 6, Intersection points P ₁ , P ₂ , P ₃ of 5, 7 and intersection line 8 and line segments
_{1 2} , _{2 3} , and _{1 3} are determined as follows.

Intersection P ₁ (-h'/tanθ-a, -a・h'/t
anθ−a) Intersection P ₂ (o, h′) Intersection P ₃ (−h′/tanθ+a, ah′/tan
θ+a) Line segment _{1 2} = 1/tanθ−a√1+ ²・h′
...(1) Line segment _{2 3} = 1/tanθ+a√1+ ²・h'
...(2) Line segment _{1 3} = 2ah'/tan ² θ−a ² √1+
² ...(3) Therefore, the ratio r between line segment _{1 2} and line segment _{2 3} is expressed as follows.

r≡P ₁ P ₂ /P ₂ P ₃ = tanθ+a/tanθ−
a...(4) By transforming this equation, the angle θ becomes θ=tan ^-1 (r+1/r-1a)...(5). From this, the difference between the time when the baseball bat, which is proportional to the line _{segment 12} , crosses the second ray 6 and the time when it crosses the first ray _{5, and the baseball bat, which is proportional to the line segment 23 , is} the difference between the first ray 5 and the first ray 5. By measuring the difference in time when the second and third light rays 7 cross, the ratio r between the two can be obtained. The swing angle θ of the bat is determined.

Also, since the velocity v is the amount obtained by dividing the line segment _{1 2} by the difference △t between the times when the baseball bat crosses the second ray 6 and the third ray 7, the height h' of the swinging surface of the baseball bat is If it is known, it is determined as shown in equation (6) using θ and Δt obtained earlier.

v=P ₁ P ₂ /△t = h'/2a・r-1/r √(-1) ² + (+1) ²・² ...(6) ≒h'/2 (r-1) (r+1 )/r (7) Note that equation (7) is an approximate equation when r is approximately close to 1, that is, the slope θ is close to zero.

We will explain how to measure the height h' of the swinging surface of a baseball bat, which has not been mentioned in the previous explanation.

Now, if a reflective sheet made of a large number of small ball lenses made of a transparent material with a high refractive index arranged in a flat plate is glued to a baseball bat using heat-activated adhesive, and a laser beam is irradiated onto it, the reflected light will be It has a retroreflection characteristic as shown in FIG. An example of such a reflective sheet is Scotchilite High Intensity, sold by 3M.
Grade reflective sheet 2870. Therefore, as shown in FIG. 3, by using a photoreceiver 9 with two concentric light-receiving areas and performing arithmetic processing as shown in the following equation for the signals S ₁ and S ₂ of each photoreceptor area, the photoreceiver and reflection pattern can be calculated. By knowing the size of , that is, the distance between the light receiver and the reflective sheet, we can determine the height of the swinging surface of the baseball bat.

H=(S ₁ −S ₂ )/(S ₁ +S ₂ ) (8) FIG. 4 shows the dependence of the calculation result H on S ₁ and S ₂ . In the light receiver 9 shown in FIG. 3, the radius of the inner light-receiving area 10 is selected to be half the outer radius of the outer light-receiving area 11.

The above is the operating principle of the swing measuring device according to the present invention. Next, a specific configuration of an apparatus for realizing the above-mentioned operating principle will be explained.

FIG. 5 is a top view showing the arrangement of optical components, electrical components, and a laser oscillator inside the sensor section 1. As shown in FIG. In the figure, 12 is a laser oscillation product, 13 is a total reflection mirror, and 14 is an output light of the laser oscillation product 12. Further, FIG. 6 shows the arrangement of components inside the sensor section 1 as a bird's-eye view. In the figure, reference numeral 15 indicates a part of the incident laser beam 14 to the sensor unit 1.
A first beam splitting cube 16 reflects the light vertically upward from the baseball bat to which a reflective sheet is attached and transmits the reflected light from the baseball bat to reach the concentric light receiver 9; The transmitting filter 17 is a first lens that collects the reflected light from the baseball bat. Note that the concentric light receiver 9 is located closer to the first beam splitting cube 1 than the rear focus of the first lens 17.
It is installed on the side of 5. 18 is a second beam splitting cube that reflects a part of the incident laser beam obliquely upward to generate the second beam 6 and transmits the reflected light from the reflection sheet; 19 generates the third beam. It is a mirror for

Because the parts are arranged in this way, when the baseball bat crosses the three light beams 6, 5, and 7, the reflected light enters the concentric light receiver 9 according to the passing time, as shown in Figure 7. A received signal is generated. In the figure, the horizontal axis is time, the vertical axis is a received signal proportional to the received light intensity, 21 is a received signal of the light receiving area 10 inside the concentric optical receiver 9, and 22 is the received signal of the light receiving area 11 outside. This is the received signal. The extreme value of the received signal at time _t2 indicates that the baseball bat to which the retroreflective sheet is attached has crossed the second beam 6, and the extreme value of the received signal at time _t1 indicates that the baseball bat has crossed the second beam 6. The extreme value of the first beam 5 at time _t3 indicates that the baseball bat crossed the third beam 7 at that time. Time t ₂ -t ₁ is proportional to the length of line segment _{1 2} in FIG. 1, and time t ₃ -t ₁ is proportional to line segment _{2 3} . From the received signal 21 of the inner light-receiving area 10 of the concentric light receiver 9 and the received signal 22 of the outer light-receiving area 11, the emission point O of the laser beam on the sensor unit 1 and the above-mentioned intersection point are determined according to equation (8). The distances to P ₁ , P ₂ , and P ₃ can be found.
As already mentioned in the explanation of the principle, the quantities required to find the height, slope, and swing speed of the swinging surface of a baseball bat are the length h′ of line segment ₂ , and the lengths of line segments ₁ and ₃ are Although this information is redundant, it is appropriate to use it as verification data for the length h' of line segment ₁ , which has relatively low measurement accuracy.

As is clear from the coordinates of the intersection P ₁ , P ₂ , and P ₃ already described, the lengths of the line segments ₁ and ₃ are expressed by the following two equations.

₁ =h'/a-tanθ√1+ ² ...(9) ₃ =h'/a+tanθ√1+ ² ...(10) Therefore, from equations (9) and (10), the line segment OP ₂ length
When h' is determined, equations (11) and (12) are obtained, and it can be seen that the method using equation (13) is effective as a method for determining h'.

h'= ₁・(a-tanθ)/√1+ ² ...(11) h'= ₃・(a+tanθ)/√1+ ² ...(12) h'={ ₁・(a-tanθ)/√1+ ² + ₂ + ₃ (a+tanθ)/√1+ ² }/3
...(13) Although the above explanation does not describe the specific method of signal processing, equations (5) to (8) and
It is appropriate to use a digital computer to calculate equations (11) to (13).

[Brief explanation of the drawing]

Figures 1 and 2 are diagrams explaining the principle of the present invention. In particular, Figure 2 shows the reflection pattern of the laser beam from the reflective sheet, which is necessary when determining the height of the swing surface, and Figure 3 shows the concentric light reception. An explanatory diagram of a light-receiving element having a region, FIG. 4 is a calculation result when determining the swing height, FIG. 5 is a diagram of the component arrangement inside the sensor of the swing measuring instrument according to the present invention, and FIG. 6 is a diagram of the component arrangement. The bird's-eye view of FIG. 7 shows the received signals from the concentric light-receiving elements 9. In the figure, 1 is a sensor section, 2 to 4 are transmitting and receiving ports that emit and receive the first to third light beams, 5 to 7 are first to third light beams, and 8
9 is a concentric light receiving element, 10 is an inner light receiving area, 11 is an outer light receiving area, 12 is a laser oscillator, 13 is a total reflection mirror, 14
is a laser beam, 15 is a first beam splitting cube, 16 is a filter, 17 is a first lens,
18 is a second beam splitting prism, 19 is a mirror, 21 is a received signal, and 22 is a received signal. Note that the same or corresponding parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1. A sensor section is disposed at a position corresponding to the home base, a laser oscillator is provided inside the sensor section, the output beam from the laser oscillator is divided into three, and the first beam divided into three is transmitted to the A second beam is emitted upward perpendicular to the sensor part, and the second beam is divided into three parts. A beam is emitted within the vertical plane formed by the two beams, on the opposite side of the second beam, at an angle a with the first beam, and a baseball bat crosses the three beams. The height of the baseball bat is measured from the reflection pattern that occurs when the baseball bat crosses the three beams, and the inclination of the swinging surface of the baseball bat and the swing speed are measured from the difference in time when the baseball bat crosses the three beams. How to measure swing. 2. The swing measuring method according to claim 1, wherein the reflection pattern generated when a baseball bat crosses the three beams is measured by a single concentric light receiver.