JPH0968539A - Rotating speed measuring device for flying sphere - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the rotating speed of a flying sphere (a golf ball, for instance) hit in the air. SOLUTION: A mark M different in light reflectance from the skin surface of a flying sphere B is added to a part of the surface of the flying sphere B, and the reflected light quantity is detected to measure the rotating speed of the flying sphere B. A flying sphere rotating speed measuring device is provided with a light projecting part 10 for making light irradiation toward a measuring object area A in space including a predicted path of the flying sphere B after being hit from a sphere hitting position, a light receiving part 20 for receiving reflected light from the flying sphere B flying in the measuring object area A and outputting signals corresponding to the fluctuation of the reflected light quantity, and a rotating speed detecting means 30 for detecting the rotating speed of the flying sphere B on the basis of an output signal from the light receiving part 20. The spin quantity of the flying sphere B near the highest point of a flying locus, for instance, is measured.

Description

Detailed Description of the Invention

[0001]

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

[0002]

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

The principle is the same for golf balls. For example, in Japanese Examined Patent Publication No. 60-21349, reflection marks are provided at two points on the surface of the golf ball so that a predetermined angle .theta. While sticking, arrange the light emitting portion and the light receiving portion with respect to the golf ball passing surface when this golf ball is hit and flies,
The light emitted from the light projecting portion hits the reflective mark and is reflected by the light receiving portion, and the spin amount of the golf ball is calculated from the time interval t between the two electric signals obtained from the two reflective marks. S to S = 60 × θ / t × 360r.
p. It is determined from the formula of m (conventional example 1).

Other methods similar to the conventional example 1 include Japanese Patent Publication No. 60-22302 (conventional example 2) and Japanese Examined Patent Publication No. 60.
No. 22303 (conventional example 3) and the like. Although the principle is the same, it is also known to measure the number of revolutions of a flying sphere by taking a picture or using 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 by calculation from the moving amount of a mark attached to a specific position on the flying sphere (conventional). Example 4).

[0005]

However, in the case of the 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 made of a bundle of optical fibers, and the irradiation area and the irradiation light amount are different. Since there is a limit, the effective detection range of a flying sphere (eg, golf ball) is at most 500 vertical.
mm, width 15 mm, height only about 10 cm.

Therefore, it is possible to measure a ball which is relatively low in shake immediately after the shot and is still in a low position, but to measure the rotation speed of a ball which is hit high after that and the ball streak is not constant. I can't.

On the other hand, even if a still image is taken with a photo camera or a video camera as in the conventional example 4, if the ball rotates at a high speed or its moving speed is high, the time for capturing an image is long. Then, since the image is crushed, a separate light emitting device such as a high-speed shutter and a microflash which has a short light emitting time is required, and there is a drawback that the device becomes complicated as a whole.

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

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

Further, regarding the amount of spin of a tennis ball in tennis, it is more difficult to measure the spin because the trajectory of the ball is more constant than that of golf.

The present invention has been made in view of such a conventional situation, and an object thereof is to measure a rotation speed of a flying sphere, which is a highly launched flight sphere, by setting a space of a predetermined range on a field as a measurement target area. An object of the present invention is to provide a rotation speed measuring device for a flying sphere having a relatively simple structure.

[0012]

In order to achieve the above object, the present invention provides a part of the surface of a flying sphere with a mark having a light reflectance different from that of the ground surface, and detecting the amount of reflected light. A flying sphere rotation number measuring device for measuring the number of revolutions of the flying sphere, irradiating light toward a measurement target region of a space including an expected flight path of the flying sphere after being launched from a hitting position. And a light receiving unit that receives the reflected light from the flying sphere flying in the measurement target region, and outputs a signal according to the variation of the reflected light amount, and from the light receiving unit. It is characterized by further comprising: a rotation speed detecting means for detecting the rotation speed of the flying sphere based on the output signal.

In this case, a photodiode, a phototransistor, a photoelectric tube, or the like is used as an optical sensor in the light receiving section, but when the measurement area is darkened or nighttime measurement is performed, it is extremely sensitive and has low noise. It is preferable to use a photomultiplier tube. Further, it is preferable that the light projecting unit is a DC light which does not change its light amount.

Further, it is preferable that the area to be measured is at least a range in which the flying sphere moves by rotating at least two times, and the illuminance thereof is 100 lux or more.

In the case of measuring the number of revolutions of the golf ball, a cylindrical region having a diameter of about 3.6 m centered on the optical axis of the light projecting section and located in front of the light projecting section 5 It is preferable that the illuminance within a region of 5 m within 50 m is 100 lux or more.

That is, a golf ball usually has a velocity of 40.
It is said that the aircraft flies at ˜60 m / s and a spin rate of 2000 to 9000 rpm, and the spin rate at the maximum speed of 60 m / s is about 2000 rpm even if it is small. on the other hand,
When the number of rotations is measured by attaching a light reflecting tape to a golf ball, at least one cycle is required for the measurement of the variation in the amount of reflected light. Then, in order to obtain a variation in the amount of reflected light for one cycle from the golf ball, the golf ball may make one revolution regardless of the form of the light reflecting tape. From these facts, the condition that requires the widest measurement area, that is, the maximum speed (60 m / s) and the minimum spin amount (2000
The distance traveled by the golf ball flying at 1 rpm during one revolution is calculated 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 portion is at least 1.8 m.
It has only to have the length.

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

For example, the light projecting portion is arranged below a flight area where a flying sphere (eg, a golf ball) is expected to fly, and light is emitted from the light projecting portion toward the space above it, that is, the sky. In this case, the brightness of the background (sky when outdoors) does not change suddenly in seconds or minutes and is relatively stable, so if the golf ball does not fly,
The detection signal output from the light receiving unit is stable at a level that can be regarded as substantially constant, apart from the level of the level.

In this state, when a golf ball with the above mark comes in, the amount of light received by the light receiving portion (light receiving level) changes according to the number of rotations of the golf ball. The rate of change at that time is so high that it cannot be compared with the background change,
And because it is large, by extracting the amount of change,
The number of revolutions of the golf ball is calculated.

In short, even if the background is bright and dark, if the cycle of the light quantity change does not match the cycle of the light quantity change when the golf ball flies, it is possible to measure the rotation speed of the golf ball. Become. Therefore, it is preferable to use a DC light that does not include fluctuations in light quantity as the light projector.

[0021]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic view of a state in which the rotational speed (spin amount) of the golf ball B in 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 ½ surface of the golf ball B, that is, the hemispherical surface A mark M made of, for example, black coating is attached so as to cover it.

The measuring device of this measuring apparatus 10 irradiates light to the measurement target area A, which is a space including the expected flight path of the golf ball B after being hit from the hit position, for example, from directly below. In order to receive the scattered light reflected from the golf ball B flying in the measurement target area A, for example, the light receiving section 20 with its optical axis oriented in the vertical direction.
A rotation speed detecting means 30 for detecting the rotation speed of the golf ball B based on an output signal output from the light receiving portion 20 according to the amount of received light, and a DC for supplying electric power to the light projecting portion 10.
A high voltage power supply circuit 40 for supplying electric 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 quantity change is used for the light projecting portion 10 so that the light quantity change of itself does not hinder the measurement of the light quantity change due to the rotation of the golf ball B. ing. Specifically, 16 85W automotive halogen lamps 11 and DC 0-12V variable DC for supplying the electric power required for them.
It is composed of a constant voltage power supply 12. The halogen lamps 11 are arranged such that their optical axes are oriented so that the illuminance in the measurement target area A is substantially uniform.

On the other hand, the light receiving section 20 is composed of, 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 photomultiplier tube is used here because a photodiode or a photomultiplier tube is used for nighttime measurement in order to obtain a large fluctuation amount of the reflected light amount from the golf ball B with respect to the light amount existing in the background. Higher S / N than signal amplification by amplifier using phototransistor, phototube, etc.
This is because the ratio can be obtained.

The rotation speed detecting means 30 converts the output current output from the photomultiplier tube of the light receiving section 20 according to the change in light quantity into a voltage signal, and a current-voltage conversion circuit 31 that converts the analog voltage signal into a digital signal. A / D conversion circuit 32 for converting into
c) is calculated, and 60 (sec) is calculated from the data of this cycle T.
A digital calculation circuit 33 for obtaining the spin amount S of the golf ball B by the calculation of / T (sec) and a display unit 34 for displaying the spin amount S are provided. The period T of voltage fluctuation is obtained by a calculation for recognizing the maximum of the voltage fluctuation and a calculation for calculating the time between the 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 the CRT for observation. I am able to do it. Further, in this embodiment, the period T is calculated from the time between the maximums of the fluctuation signals on the assumption that the fluctuation of the light amount existing in the background is small, but the light amount itself existing in the background largely fluctuates. If so, unnecessary fluctuation components may be removed by providing a filter circuit. Further, by appropriately designing the light projecting unit 10 so as to obtain a desired waveform of the fluctuation of the light quantity, and subjecting the signal to fast Fourier transform (FFT),
It is also possible to obtain the fluctuation cycle of the reflected light amount of the golf ball B from the frequency component.

Further, in the above-mentioned embodiment, a mark M made of black coating is attached to the hemispherical surface of the golf ball B in order to change the light reflectance thereof. 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 provided on the two opposing division surfaces, and the color is not limited to black.

The point is that the amount of reflected light changes as the golf ball B rotates, 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 paint is divided into 4 equal parts, 2
Compared to the case of equal division, the cycle of light quantity change with respect to the number of revolutions of the ball becomes 1/2, so especially when there is a light quantity change in the background or the projection itself, the cycle of light quantity change and the reflected light due to ball rotation. Separation may be facilitated by making the light intensity change cycle different from the above.

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

Next, a state in which the golf ball B is rotating in the air is artificially created, and the spin amount (rotation number) is measured by this rotation number measuring device.
It will be described based on. It should be noted that FIG. 7A is a schematic side view of the test scene, and FIG. 8B is a schematic plan view thereof.

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

In this test, as described above, the light receiving section 20
When the light projecting portion 10 is arranged in the vicinity of the light receiving portion 20 because the light receiving optical axis of the golf ball is horizontal, only the golf ball B is projected because the light reflected from the ground may appear as noise. As described above, a dry battery type penlight was used as the light source, and the golf ball B was projected from an obliquely lower position.

This test was conducted at night in order to obtain a large variation in the light quantity from the golf ball B with respect to the light quantity existing in the background, and the illuminance near the golf ball B was measured by the illuminometer 51. Assuming an actual case where the golf ball B rotates while flying in 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. 2B. The measurement was performed at the (middle) position and at each of the (right) position and the (left) position that were moved 2.5 m in the left-right direction from the light receiving optical axis. Further, the rotation speed of the golf ball B by the motor 10 is 2000 rpm and 6000 respectively at each position.
rpm and 9000 rpm.

<Test 1> The golf ball B receives the light receiving portion 20.
The motor 50 was rotated at 9000 rpm, with the illuminance around the (middle) position on the light receiving optical axis of No. 2 as 70 lux. Then, the amount of reflected light was detected by the light receiving unit 20, the output signal thereof was taken into the rotation speed detecting means 30, and the fluctuation period was tried to be observed by observing the waveform, but the waveform could not be measured.

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

<Test 3> Illuminance around the golf ball B is set to 100 lux, and the motor 50 drives the motor to 6000 rpm.
When the measurement was performed under the same conditions as in Test 1 except for the above, a waveform with a cycle of 0.010 sec was observed, and 6000 rpm, which is the same as the actual rotation speed, was measured.

<Test 4> Illuminance around the golf ball B is 100 lux, and the motor 50 is 2000 rpm.
When the measurement was performed under the same conditions as in Test 1 except for the above, the waveform with a period of 0.030 sec was observed. As a result, 2000 rpm, which is the same as the actual rotation speed, was measured.

<Test 5> The golf ball B is used as the light receiving portion 20.
The position moved to the right by 2.5 m from the light receiving optical axis (right), and the illuminance around it is 100 lux, and the motor 50
It was rotated at 00 rpm. Then, the light receiving section 20 detects the amount of reflected light, and outputs the output signal as the rotation speed detecting means 30.
Waveform was observed and the period was 0.0067se.
The waveform of c was observed. Therefore, the measured value in this case was 8960 rpm, which was slightly lower than the actual rotational speed.

<Test 6> The golf ball B is driven by the motor 50.
When rotated at 6000 rpm and measured otherwise under the same conditions as in Test 5, a waveform with a cycle of 0.010 sec was observed.
The rpm was measured.

<Test 7> The golf ball B is driven by the motor 50.
At 2000 rpm, the measurement was performed under the same conditions as in Test 5, except that a waveform with a period of 0.030 sec was observed.
0 rpm was measured.

<Test 8> The golf ball B receives the light-receiving portion 20.
The position moved to the left by 2.5 m from the light receiving optical axis (left), and the illuminance around it is 100 lux, and the motor 50
It was rotated at 00 rpm. Then, the light receiving section 20 detects the amount of reflected light, and outputs the output signal as the rotation speed detecting means 30.
Waveform observation, the period was 0.030 sec
Waveform is observed, which means that it is the same as the actual rotation speed.
00 rpm was measured.

<Test 9> The golf ball B is driven by the motor 50.
When rotated at 6000 rpm and measured under the same conditions as in Test 8 except for that, a waveform with a cycle of 0.010 sec was observed.
The rpm was measured.

<Test 10> The golf ball B is moved to the motor 5
Rotate at 9000 rpm at 0, otherwise test 8
When measured under the same conditions as above, the cycle is 0.0067 sec
The waveform of was observed. Therefore, the measured value in this case was 8960 rpm, which was slightly lower than the actual rotational speed.

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

[0046]

[Table 1]

Next, the test 11 in which the golf ball B is actually hit in the air and the spin amount in the vicinity of the highest point of the flight trajectory is measured will be described. <Test 11> The golf ball was black-coated on two divided surfaces of the sphere divided into four equal parts so that the opposed two divided surfaces had different light reflectances from the bare surface.
Therefore, when this golf ball makes one rotation, the light amount fluctuation of the reflected light can be obtained for two cycles. Then, this golf ball was shot into the air by a driver of a golf club attached to a swing robot at an initial speed of about 60 m / s, a launch angle of about 11 degrees, and an initial spin amount of about 3300 rpm.

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

FIG. 3 shows fluctuations in the amount of reflected 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 revolutions 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

If the speed at which the golf ball passes the measurement target region is 60 m / s, the distance traveled by the golf ball during three revolutions can be calculated approximately from the following equation as approximately 3.6 m. 0.05762 × 60 = about 3.6 m That is, in other words, the length of the measurement target region is 3.6 m.
If the light projecting unit 10 is appropriately set so as to be the above,
It can be seen that the amount of light fluctuation can be obtained when the golf ball makes three revolutions, and thus the spin amount of the golf ball can be measured with high accuracy.

Such a measuring device was able to measure even if only a total of 8 lights were lit every other column out of the 16 lights forming the light projecting section 10. In short, this measuring device can measure the spin amount of the golf ball even if any number of the 16 lights is used and the golf ball passes while intersecting the optical axis. . For reference, FIG. 4 shows the results of an investigation of the illuminance distribution of one 85 W automobile 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 irradiates 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 hit from a hitting position, and flying in the measurement target area. Receiving the reflected light from the flying sphere, and detecting the rotation speed of the flying sphere based on the output signal from the light receiving unit that outputs a signal according to the fluctuation of the reflected light amount. According to the invention of claim 1, which is provided with the rotation speed detecting means, it is possible to measure the rotation speed of a ball actually flying in the air, for example, near the highest point of its flight trajectory.

Further, according to the invention of claim 2 in which the photomultiplier tube is used for the light receiving portion, a high S / N ratio can be obtained, which is particularly convenient for nighttime measurement.

Further, according to the invention of claim 3 in which the light projecting section is a DC light, there is no light fluctuation from the light projecting section, and noise can be reduced accordingly.

According to the invention as set forth in claim 4, the measurement target region is set to be a range in which the flying sphere moves by rotating at least two times. Required to.

On the other hand, according to the invention of claim 5 in which the illuminance of the measurement target region is 100 lux or more, even if the ball is off from the light receiving optical axis of the light receiving portion, the ball can stably respond to the rotational speed of the ball. An output signal is obtained.

In relation to each of the above inventions, it is a cylindrical region having a diameter of about 3.6 m centered on the optical axis of the light projecting part and within 5 to 50 m in front of the light projecting part. According to the invention of claim 6, the illuminance is 100 lux or more in the area of 5 m, and it is possible to reliably observe the light intensity fluctuation waveform over two cycles or more, and therefore, the rotational speed of the flying sphere can be measured with higher accuracy. can do.

[Brief description of drawings]

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

2A and 2B are 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 number of rotations thereof is measured by a rotation number measuring device according to the present invention.

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

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

[Explanation of symbols]

 10 Light Emitting Section 12 DC Constant Voltage Circuit 20 Light Receiving Section 31 Current-Voltage Conversion Circuit 32 A / D Conversion Circuit 33 Digital Conversion Circuit 34 Display Section (CRT) 40 High Voltage Power Supply Circuit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiaki Miyamoto 1-3270, Migatadai, Nishi-ku, Kobe-shi, Hyogo Prefecture 2703 (72) Inventor Tetsuo Yamaguchi 3-4 Ishizai-cho, Nishinomiya-shi, Hyogo

Claims (6)

[Claims] 1. A flight sphere rotation number measurement method, wherein a mark having a light reflectance different from that of the ground surface is attached to a part of the surface of the flight sphere, and the rotation number of the flight sphere is measured by detecting the amount of reflected light. A device, which emits light toward a measurement target area of a space including an expected flight path of the flying sphere after being launched from a hitting position, and flying in the measurement target area. A light receiving unit that receives the reflected light from the flying sphere and outputs a signal according to the fluctuation of the reflected light amount, and a rotation that detects the number of revolutions of the flying sphere based on the output signal from the light receiving unit. An apparatus for measuring the number of revolutions of a flying sphere, comprising: a number detecting means. 2. The rotational speed measuring device for a flying sphere according to claim 1, wherein a photomultiplier tube is used for the light receiving section. 3. The device for measuring the number of revolutions of a flying sphere according to claim 1, wherein the light projecting unit is a DC light. 4. The rotational speed measuring device for a flying sphere according to claim 1, wherein the measurement target area is set to be equal to or more than a range in which the flying sphere moves by rotating at least two times. 5. The rotational speed measuring device for a flying sphere according to claim 1, wherein the illuminance of the measurement target region is 100 lux or more. 6. A cylindrical region having a diameter of about 3.6 m centered on the optical axis of the light projecting portion, and 5 in front of the light projecting portion.
The rotation speed measuring device for a flying sphere according to claim 1, 3, 4 or 5, wherein an illuminance of 100 lux or more is set in an arbitrary area of 5 m within 50 m.