JP3227384B2 - Flight sphere rotation speed measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the number of revolutions of a flying sphere such as a golf ball and a tennis ball, and more specifically, the number of revolutions (spin amount) when a launched flying sphere is flying in space. The present invention relates to an apparatus for measuring the number of revolutions of a flying sphere, which can measure the rotation speed.

[0002]

2. Description of the Related Art In order to measure the number of rotations of a rotating body in a non-contact manner, a specific light reflecting mark is generally attached to the rotating body, and the moving amount of the light reflecting mark within a predetermined time is optically measured. I try to read.

The same applies in principle to a golf ball. For example, in Japanese Patent Publication No. Sho 60-21349, a reflection mark is provided at two places on the surface of a golf ball so as to have a predetermined angle θ ° with respect to the center of the ball. Along with sticking, the light emitting portion and the light receiving portion are arranged with respect to the golf ball passing surface when the golf ball is hit and fly,
The light emitted from the light projecting portion hits the reflection mark and is reflected by the light receiving portion, and the spin amount of the golf ball is obtained from the time interval t between the two electric signals obtained from the two reflection marks. S is S = 60 × θ / t × 360r.
p. It is determined from the equation for m (conventional example 1).

Other methods similar to the conventional example 1 include Japanese Patent Publication No. 60-22302 (Conventional Example 2) and Japanese Patent Publication No.
No. -22303 (conventional example 3). Although the principle is the same, it is also known to measure the number of revolutions of a flying sphere using a photograph or a video camera. That is, a plurality of images of a flying sphere in flight are taken at predetermined time intervals, and the number of rotations is calculated from the movement amount of a mark attached to a specific position on the flying sphere (conventionally. Example 4).

[0005]

However, in the case of Conventional Examples 1 to 3, both the light projecting surface of the light projecting portion and the light receiving surface of the light receiving portion are formed of a bundle of optical fibers, and the irradiation area and the irradiation light amount are reduced. Due to limitations, the effective detection range of a flying sphere (eg, golf ball) is at most 500
mm, width 15 mm, height several tens cm.

[0006] Therefore, it is possible to measure a ball which is relatively blurred immediately after a shot and is still at a low position, but it is necessary to measure the number of revolutions of a ball which is hit later and has a non-uniform ball line. Can not.

On the other hand, even when a still image is obtained by photographing or a video camera as in the conventional example 4, if the ball rotates at a high speed or the moving speed is high, the time to capture the image is long. In such a case, since the image is crushed, a light emitting device such as a high-speed shutter or a micro flash having a short light emitting time is required separately, and there is a disadvantage that the device becomes complicated as a whole.

Further, a method of taking a still image into a computer by an image input device, reading a moving amount by positioning a cursor on the monitor, and binarizing the image for the purpose of automating the measurement, and providing the computer with a sphere Although a method of recognizing the mark at the above specific position is also known, in any case, there is a problem that the program becomes complicated and data processing takes time.

Further, in order to improve the accuracy of measuring the amount of movement,
It is necessary to capture the ball largely in the image, but in this case, the measurement target area is reduced, and the conventional example 1
As in the case of Conventional Example 3, it is difficult to measure the number of revolutions of a ball that is hit high and flutters in the air, for example, near the highest point.

[0010] In addition, the spin amount of a tennis ball in tennis is more difficult to measure because the trajectory of the ball is not as constant as in golf.

The present invention has been made in view of such conventional circumstances, and has as its object to measure the rotation speed of a flying sphere that has been launched high, for example, by setting a predetermined range of space on the field as a measurement target area. It is an object of the present invention to provide a flying sphere rotational speed measuring device having a relatively simple configuration.

[0012]

In order to achieve the above object, according to the present invention, a mark is provided on a part of the surface of a flying sphere having a light reflectance different from that of the ground surface, and the amount of reflected light is detected. In the flight sphere rotation speed measuring device for measuring the rotation speed of the flight sphere, the flight sphere moves by rotating at least two times in a space including an expected flight path of the flight sphere after being launched from a hitting position. A light projecting unit composed of a DC light that irradiates light toward the measurement target area, and a reflected light from the flying sphere flying in the measurement target area is set. And, a light receiving unit composed of a photomultiplier tube that outputs a signal according to the change in the amount of reflected light, and rotation speed detection means for detecting the rotation speed of the flying sphere based on an output signal from the light receiving unit with a In front 5~50m of the light projecting portion
It is characterized in that the illuminance in an arbitrary 5 m area is 100 lux or more .

[0013] A DC lamp having a very small change in the amount of light
The light intensity changes due to the rotation of the flying sphere
Can be measured with high accuracy.

Further, a photomultiplier tube is used for the light receiving section.
Photodiodes, phototransistors,
Compared to tubes, etc., the amount of light existing in the background
To increase the variation in the amount of reflected light from the flying sphere
it can.

Further , regarding the illuminance, 5 to 5 in front of the light emitting portion
Illuminance of 100 lux or more in any 5 m area within 0 m
The golf ball flying high in the air
The rotation speed of the tool can be measured with high accuracy.

That is, a golf ball usually has a speed of 40
It is said that it flies at ６０60 m / s and a spin amount of 2000 to 9000 rpm, and the spin amount at a maximum speed of 60 m / s is about 2000 rpm even if it is small. on the other hand,
When a light reflecting tape is attached to a golf ball to measure the number of rotations, the fluctuation in the amount of reflected light requires at least one cycle in measurement. Then, in order to obtain a change in the amount of reflected light in one cycle from the golf ball, the golf ball only needs to make one rotation regardless of the form of the light reflecting tape. From these facts, the conditions that require the widest measurement area, that is, the maximum speed (60 m / s) and the minimum spin amount (2000)
The flight distance of the golf ball flying at one revolution per minute (rpm) is obtained as 1.8 m from the following equation. 60 m / s × (1 × 60/2000) s = 1.8 m Therefore, the irradiation range of the light projecting unit is at least 1.8 m.
What is necessary is just to have length.

When one peak of the light change is obtained near the center of the measurement area, for example, the other peak is preferably measured as the measurement area becomes wider. That is,
If the measurement area is about twice the moving distance per rotation of the ball, at least two periods of fluctuation in the amount of reflected light can be obtained. The quantity can be measured with high accuracy. Therefore, when the irradiation range of the light projecting unit is set to about 1.8 m in radius and about 3.6 m in diameter based on the following formula, the spin amount of a ball hit by any ordinary club can be measured reliably. 60m / s × (2 × 60/2000) s = 3.6m

For example, the light projecting unit is disposed below a flight area where a flying sphere (eg, a golf ball) is expected to fly, and the light projecting unit emits light toward the space above, that is, toward the sky. In this case, the brightness of the background (the sky in the case of outdoors) is relatively stable without sudden changes in at least seconds and minutes, so if the golf ball does not fly,
The detection signal output from the light receiving section is stable at a level that can be regarded as substantially constant except for the level of the level.

In this state, when a golf ball marked with the mark comes in, the amount of light received by the light receiving section (light receiving level) changes according to the number of revolutions. The speed of change at that time is so fast that it can not be compared with the change of the background,
And because it is large, by extracting the amount of change,
The number of revolutions of the golf ball is determined.

In short, even if the background is light and dark, if the period of the change in the amount of light does not coincide with the period of the change in the amount of light when the golf ball lands, the rotation number of the golf ball can be measured. Become. Therefore, it is preferable to use a DC light that does not include a fluctuation in light amount as the light projector.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a state in which the rotational speed (spin amount) of the golf ball B during flight is measured by this measuring device. In this case, a mark M having a light reflectance different from that of the ground surface is attached to a part of the surface of the golf ball B. In this embodiment, the half surface of the golf ball B, that is, the hemisphere is A mark M made of, for example, black paint is provided so as to cover.

This measuring device emits light toward a measurement target area A which is a space including an expected flight path of a golf ball B after being hit from a hitting position, for example, from below the light emitting section 10. And a light receiving unit 20 having, for example, an optical axis directed vertically to receive scattered light reflected from the golf ball B flying in the measurement target area A.
A rotation number detecting means 30 for detecting the rotation number of the golf ball B based on an output signal output from the light receiving section 20 in accordance with the amount of light received, and a DC for supplying power to the light projecting section 10
A high voltage power supply circuit 40 for supplying power to the constant voltage power supply 12 and the light receiving unit 20 is provided.

In this embodiment, a DC light having no light amount change is used for the light projecting unit 10 so that the light amount change of the golf ball B does not interfere with the measurement of the light amount change due to the rotation of the golf ball B. ing. Specifically, sixteen 85W automotive halogen lamps 11 and a variable DC0 to 12V DC for supplying electric power required therefor are provided.
And a constant voltage power supply 12. The directions of the optical axes of the halogen lamps 11 are set and arranged so that the illuminance in the measurement target area A is substantially uniform.

On the other hand, the light receiving section 20 comprises, for example, a condenser lens having a diameter of 100 mm and a focal length of 75 mm, and a photomultiplier tube. As this photomultiplier tube, for example, R2228 (trade name) manufactured by Hamamatsu Photonics KK
and so on.

The reason why the photomultiplier tube is used here is to measure the amount of light reflected from the golf ball B with respect to the amount of light existing in the background at the time of nighttime measurement in order to obtain a large variation in the amount of reflected light. S / N higher than signal amplification by amplifier using phototransistor, phototube, etc.
This is because a ratio can be obtained.

The rotation number detecting means 30 includes a current-voltage conversion circuit 31 for converting an output current output from the photomultiplier tube of the light receiving section 20 in accordance with a change in light quantity into a voltage signal, and converting the analog voltage signal into a digital signal. And an A / D conversion circuit 32 for converting the digital signal and a period of voltage fluctuation T (se
c) is calculated, and 60 (sec) is calculated from the data of the cycle T.
The digital arithmetic circuit 33 calculates the spin amount S of the golf ball B by the calculation of / T (sec), and the display unit 34 displays the spin amount S. The period T of the voltage fluctuation is obtained by an operation for recognizing the local maximum of the voltage fluctuation and an operation for calculating the time between the local maximums.

In this embodiment, the A / D conversion circuit 32, the digital operation circuit 33, and the display unit 34 are realized by using a personal computer, and the waveform of the voltage fluctuation is displayed on a CRT and observed. I can do it. In this embodiment, the period T is determined from the time between the maximum values of the fluctuation signal, assuming that the fluctuation of the light amount existing in the background is small. In such a case, an unnecessary fluctuation component may be removed by providing a filter circuit. Furthermore, the light projecting unit 10 is appropriately designed so that a desired light quantity fluctuation waveform can be obtained for a sufficiently long time, and the signal is subjected to a fast Fourier transform (FFT).
It is also possible to obtain the fluctuation cycle of the amount of reflected light of the golf ball B from the frequency component.

Further, in the above embodiment, the mark M made of black paint is attached to the hemisphere to change the light reflectivity of the golf ball B, but how to change the partial reflectivity is different from this embodiment. It is not limited. For example, the coating is divided into four equal parts, that is, the surface of the golf ball B is divided into four equal parts,
The light reflection mark M may be attached to the two opposing divided surfaces, and the color is not limited to black.

The point is that the amount of reflected light only needs to change according to the rotation of the golf ball B, and there is no particular limitation as long as the number of rotations of the ball can be obtained from the change in the amount of reflected light. For example, if the color separation is divided into four equal parts, 2
Since the period of the change in the amount of light with respect to the number of rotations of the ball is halved compared to the case where the ball is equally divided, especially when there is a change in the amount of light in the background or the projection itself, the period of the change in the amount of light and the reflected light due to the rotation of the ball In some cases, the separation is made easier by making the period of the light amount change different.

In the above embodiment, the light projecting unit 10 and the light receiving unit 20 are arranged immediately below the measurement target area A in order to measure the backspin of the golf ball B.
The direction of each optical axis of 0 and the light receiving unit 20 is not limited to this, and can be appropriately set in consideration of the direction of the rotation axis of the spin to be measured, the reflected light from the background of the measurement place, and the like.

Next, a state was created in which the golf ball B was rotating in the air in a pseudo manner, and the spin amount (number of rotations) was measured by this rotation number measuring device.
It will be described based on. FIG. 1A is a schematic side view of the test scene, and FIG. 1B is a schematic plan view.

First, the golf ball B having a black surface as described above is attached to the rotation shaft of the motor 50 whose rotation speed is variable, and the golf ball B is set at a position of 850 mm from the ground, and the light receiving unit 20 is set. Was set at a position 30 m away from the golf ball B so that its light receiving optical axis passed the center of rotation of the golf ball B and was horizontal.

In this test, the light receiving section 20 was
Since the light-receiving optical axis of the light-emitting device is set in the horizontal direction, if the light-projecting unit 10 is arranged near the light-receiving unit 20, the light reflected from the ground may appear as noise, so that only the golf ball B is projected. As a result, a dry cell type penlight was used as the light source, and the golf ball B was projected from a diagonally lower position.

This test is performed at night to obtain a large variation in the amount of light from the golf ball B with respect to the amount of light existing in the background, and the illuminance meter 51 measures the illuminance near the golf ball B. Assuming a real case in which the golf ball B rotates while flying over the measurement area, the position of the golf ball B is on the light receiving optical axis of the light receiving unit 20 as shown in FIG. The measurement was performed at the (middle) position and at the (right) position and the (left) position moved by 2.5 m in the left and right directions from the same light receiving optical axis. The rotation speed of the golf ball B by the motor 10 is 2000 rpm and 6000 at each position.
rpm and 9000 rpm.

<Test 1> The golf ball B was placed on the light receiving section 20.
The luminous intensity around the (middle) position on the light receiving optical axis and the surrounding area was set to 70 lux, and the motor 50 was rotated at 9000 rpm. Then, the amount of reflected light was detected by the light receiving section 20, the output signal was taken into the rotation number detecting means 30, and the waveform was observed to read the fluctuation cycle.

<Test 2> When the illuminance around golf ball B was increased to 100 lux and the other conditions were the same as in test 1, a waveform having a period of 0.0067 sec was observed. Therefore, the measured value in this case was 8960 rpm, which is slightly lower than the actual rotation speed.

<Test 3> The illuminance around the golf ball B was set to 100 lux, and the
Then, when the measurement was performed under the same conditions as in Test 1, a waveform having a period of 0.010 sec was observed. As a result, 6000 rpm, which is the same as the actual rotation speed, was measured.

<Test 4> The illuminance around the golf ball B was set to 100 lux and the motor 50 was used at 2000 rpm.
When the measurement was performed under the same conditions as in Test 1, a waveform having a period of 0.030 sec was observed. Thereby, the same 2000 rpm as the actual rotation speed was measured.

<Test 5> The golf ball B was placed on the light receiving section 20.
Assuming that the illuminance around the position (right) moved 2.5 m to the right (right) from the light receiving optical axis of
Rotated at 00 rpm. Then, the amount of reflected light is detected by the light receiving section 20 and the output signal is detected by the rotation number detecting means 30.
The observation of the waveform
The waveform of c was observed. Therefore, the measured value in this case was 8960 rpm, which is slightly lower than the actual rotation speed.

<Test 6> The golf ball B was
The rotation was performed at 6000 rpm, and the other conditions were measured under the same conditions as in Test 5. As a result, a waveform having a period of 0.010 sec was observed.
rpm was measured.

<Test 7> The golf ball B was
The rotation was performed at 2,000 rpm, and the other conditions were measured under the same conditions as in Test 5. As a result, a waveform having a period of 0.030 sec was observed.
0 rpm was measured.

<Test 8> The golf ball B was placed on the light receiving section 20
Assuming that the illuminance around the position (left) moved to the left by 2.5 m from the light receiving optical axis (left) and the surroundings was 100 lux, the motor 50
Rotated at 00 rpm. Then, the amount of reflected light is detected by the light receiving section 20 and the output signal is detected by the rotation number detecting means 30.
When the waveform was captured, the cycle was 0.030 sec.
Is observed, which results in 20 times the same as the actual rotation speed.
00 rpm was measured.

<Test 9> The golf ball B was
At 6000 rpm, and the other conditions were measured under the same conditions as in Test 8, whereupon a waveform having a period of 0.010 sec was observed.
rpm was measured.

<Test 10> The golf ball B was
Rotate at 9000 rpm at 0, otherwise test 8
When measured under the same conditions as above, the cycle was 0.0067 sec.
Waveform was observed. Therefore, the measured value in this case was 8960 rpm, which is slightly lower than the actual rotation speed.

As a result of these tests, if the illuminance in the vicinity of the ball (flying sphere) is at least 100 lux, even if the ball is displaced from the light receiving axis of the light receiving portion, the ball is stably transmitted from the light receiving portion (rotation speed). ) Was obtained. For reference, above Tests 1-10
The results of the measurement are shown in the following table.

[0046]

[Table 1]

Next, a test 11 in which the golf ball B is actually launched into the air and the spin amount near the highest point of the flight trajectory is measured will be described. <Test 11> A black coating was applied to the two divided surfaces of the golf ball so that the light reflectance of the two opposing divided surfaces was different from the light reflectance of the ground surface among the four equally-divided spherical surfaces.
Therefore, when the golf ball makes one rotation, the fluctuation of the amount of reflected light is obtained in two cycles. Then, the golf ball was launched into the air at an initial velocity of about 60 m / s, a launch angle of about 11 degrees, and an initial spin amount of about 3300 rpm by a driver of a golf club attached to a swing robot.

On the other hand, the light projecting unit 10 is installed so that the spin amount of the golf ball at a position 140 m ahead of the launch position can be measured. The flight height of the golf ball at this position was about 30 m. This light emitting section 1
Assuming 0, 85W automotive halogen lamp 300m
Eight rows at m intervals were provided in two rows at 300 mm intervals in parallel (a total of 16 rows), the optical axis of each lamp was adjusted vertically, and 12 V was applied to each lamp by a DC constant voltage power supply.

FIG. 3 shows the variation in the amount of light reflected by the golf ball. According to this figure, it can be seen that the time required for the golf ball to make three rotations is 0.05762 seconds. Therefore, the spin amount of the golf ball at this time can be approximately calculated as about 3120 rpm from the following equation. 60 / (0.05762 / 3) = about 3120 rpm

Assuming that the speed at which the golf ball passes through the measurement target area is 60 m / s, the distance that the golf ball moves during three rotations can be approximately calculated to be about 3.6 m from the following equation. 0.05762 × 60 = about 3.6 m In other words, the length of the measurement target area is 3.6 m
As described above, if the light emitting unit 10 is appropriately set,
It can be seen that a variation in the amount of light when the golf ball rotates three times is obtained, whereby the spin amount of the golf ball can be measured with high accuracy.

Such a measuring device can measure even when only a total of eight lights are turned on every other column out of the sixteen lights constituting the light projecting section 10. In short, this measuring device can measure the spin amount of a golf ball even if any number of the 16 lights are used and the golf ball passes so as to intersect the optical axis. . For reference, FIG. 4 shows the results of a survey on the illuminance distribution of one 85W automotive halogen lamp 30 m away.

[0052]

As described above, according to the present invention,
The following effects are obtained. That is, a light projecting unit that emits light toward a measurement target area in a space including an expected flight path of a flying sphere (for example, a golf ball) after being launched from a hitting position, and a flight in the measurement target area A light receiving unit that receives reflected light from the flying sphere and outputs a signal corresponding to a change in the amount of reflected light, and detects a rotation speed of the flying sphere based on an output signal from the light receiving unit According to the first aspect of the present invention including the rotation speed detecting means, it is possible to measure the rotation speed of the ball actually flying in the air, for example, near the highest point of the flight trajectory.

In this case, by setting the measurement target area to be equal to or larger than the range in which the flying sphere moves by at least two rotations, the fluctuation frequency of the flying sphere due to the light reflection mark can be obtained with higher accuracy.

Also, the light quantity change in the light projecting portion is extremely small.
By using the DC light, the rotation of the flying sphere
The change in light amount can be measured with high accuracy.

Also, a photomultiplier tube is used for the light receiving section.
Photodiodes, phototransistors,
Compared to tubes, etc., the amount of light existing in the background
To increase the variation in the amount of reflected light from the flying sphere
it can.

Further, an arbitrary point within 5 to 50 m in front of the light emitting section
By setting the illuminance of 100 lux or more in the area of 5 m
Especially for golf balls flying high in the air.
It can measure with high accuracy.

[0057]

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining one embodiment of a rotation speed measuring device according to the present invention.

FIG. 2 is a side view and a plan view schematically showing a state at the time of a test in which a golf ball is rotated by a motor and the rotation speed is measured by a rotation speed measuring device according to the present invention.

FIG. 3 is a graph showing a change in the amount of reflected light reflected by a golf ball in Test 11;

FIG. 4 is a graph showing the results of an investigation on the illuminance distribution of one 85W automotive halogen lamp.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Projection part 12 DC constant voltage circuit 20 Light receiving part 31 Current-voltage conversion circuit 32 A / D conversion circuit 33 Digital conversion circuit 34 Display part (CRT) 40 High voltage power supply circuit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yuichi Takeuchi 7-40 Shimobayashi-cho, Toyota-shi, Aichi Prefecture Sumitomo Rubbersho Mountain Dormitory (72) Inventor Yoshiaki Miyamoto 1-3-2 Migattadai, Nishi-ku, Kobe-shi, Hyogo 2703 (72) Inventor Tetsuo Yamaguchi 3-4 Ishizai-cho, Nishinomiya-shi, Hyogo (56) References JP-A-62-254057 (JP, A) JP-B-60-21349 (JP, B2)

Claims (1)

(57) [Claims] 1. A flying sphere rotation speed measuring device for measuring the rotation speed of the flying sphere by marking a part of the surface of the flying sphere with a light reflectance different from that of the ground surface and detecting the reflected light amount. In the device, in the space including the expected flight path of the flying sphere after being launched from the hitting position, to set a measurement target area or more than the range in which the flying sphere moves by at least two rotations,
From a DC light that irradiates light to the measurement target area
And a light receiving unit including a photomultiplier tube that receives reflected light from the flying sphere flying in the measurement target area, and outputs a signal corresponding to a change in the amount of reflected light. , and a rotation speed detecting means for detecting a rotational speed of the flying sphere based on an output signal from the light receiving portion, the light projecting
100 liters in any 5 m area within 5 to 50 m in front of the part
An apparatus for measuring the number of revolutions of a flying sphere, the illuminance of which is equal to or greater than a lux .