JPH03210282A - Instrument for measuring speed of sphere immediately after hitting - Google Patents

Abstract

PURPOSE:To accurately recognize the motion of a sphere immediately after hitting by accurately measuring the linear velocity in the prescribed direction of the center of the sphere and angular velocity around a prescribed axis passing the center of the sphere. CONSTITUTION:Two linear markers 1a, 1b are attached on the sphere 1 so as to cross with each other at confronting two points on an outer peripheral plane. Also, two image pickup means 4A, 4B perform the image pickup of the sphere 1 immediately after hitting at least for two times in a right above direction at a time interval corresponding to travel speed and in a direction perpendicular to the right above direction and a hitting direction, respectively. Furthermore, a first arithmetic part 5 finds the amount of travel of the center position of the sphere 1 from the video signal of each image pickup means, and computes the linear velocity of the sphere in a prescribed direction from the amount of travel and the above-mentioned time interval. A second arithmetic part 5 finds the travel angles of the prescribed parts of the markers 1a, 1b around prescribed diameters from the video signal of each image pickup means, and computes the angular velocity around the prescribed diameter from the angle and the above-mentioned time interval.

Description

[Detailed description of the invention] [Industrial application field]

This invention is a golf training exercise that measures the linear velocity in a predetermined direction at the center of a golf ball and the angular velocity around a predetermined diameter passing through the center in order to know the positive behavior of a spherical object, especially a golf ball, immediately after hitting. The present invention relates to a speed measuring device for a ball immediately after being hit, which is optimal for use.

[Conventional technology]

In order to improve the effectiveness of golf practice or baseball batting practice, the behavior of a stationary ball immediately after being hit is investigated and used as reference. Note that the behavior of the ball in this case is expressed by the linear velocity and rotational angular velocity of the ball immediately after being hit. The following will be explained using the example of golf as a representative example. Conventionally, the following methods have been used to measure the spin (rotational angular velocity) of a ball. The first method is to mark the ball and take photographs at each moment immediately after the ball is hit by firing a strobe light source at regular time intervals. The angular velocity around the diameter of the ball is determined from the amount of change in the position of the mark and the time interval between firings. The second method is to attach reflective tape to the ball and capture images at each moment immediately after the ball is hit using a photoelectric camera by firing a strobe light source at regular intervals. The angular velocity around a certain diameter of the ball is determined from the change in the intensity of the reflected light and the time interval between firings. The third method is based on Japanese Patent Application Laid-Open No. 62-254057, in which a line mark is drawn with black ink or the like along a large circle on the outer circumferential surface of the ball, and the ball is moved in the line direction of the line image sensor/camera. A line image sensor/camera is used to capture the optical image of the ball at each moment immediately after the ball is hit so as to rotate around the axis perpendicular to the line direction and the camera optical axis, that is, the vertical axis of the ball. Images are captured by firing a strobe light source at regular time intervals. Then, by image processing, a decrease in the signal level related to the line mark is detected, the rotation angle of the ball around the vertical axis is determined, and the angular velocity is obtained from this and the firing interval of the strobe light source.

[Question B that the invention attempts to solve]

The conventional techniques described above each have the following problems. In the first method, it takes time to develop the photograph, the procedure for determining the angular velocity from the marks on the photograph is complicated and time-consuming, and the obtained angular velocity is not very accurate. In the second method, errors are likely to occur due to the influence of reflected light from the ball's dimples and the club, and because reflective tape is attached to the outer circumferential surface of the ball, the dimples are partially shielded and the outer circumferential surface of the ball is In addition to changing the unevenness, it also slightly increases the weight of the ball. The fact that the outer circumferential surface condition and weight of these balls differ from the actual case means that the obtained angular velocity is slightly different from the actual case, which reduces its reliability. In the third method, the axis of the measured angular velocity is limited to the axis perpendicular to the line direction of the line image sensor/camera and the camera optical axis, that is, the vertical axis of the ball. However, since it is completely unknown which direction the rotational diameter of the ball will take immediately after the actual impact, in order to know the exact behavior of the ball immediately after the impact, three fixed axes that are orthogonal to each other are set, and each fixed axis is It is reasonable to calculate it by decomposing it into angular velocities around the axis. In addition, linear velocity as well as angular velocity are important factors for knowing the exact behavior of the ball, and measuring only angular velocity using this method is insufficient. An object of this invention is to solve the problems of the conventional technology and to determine the linear velocity of the sphere in a predetermined direction at its center and a predetermined axis passing through the center, in order to know the accurate behavior of the sphere immediately after impact. An object of the present invention is to provide a speed measuring device for a sphere immediately after being hit, which measures the angular velocity around the ball.

[Means to solve the problem]

In order to solve this problem, a velocity measuring device for a sphere immediately after impact according to a first aspect of the invention measures the linear velocity in a predetermined direction at the center and the angular velocity around a predetermined diameter of the sphere immediately after impact. In a device that measures the linear velocity in a predetermined direction at the center and the angular velocity around a predetermined diameter of a sphere immediately after impact, two linear A spherical object with a mark attached; Imaging the spherical object immediately after the impact at least twice at a time interval corresponding to its moving speed from directly above the object and from directly above the object and from a direction perpendicular to the direction of the impact. a first calculation unit that calculates the amount of movement of the center position of the sphere from the video signals of each of the image pickup means, and calculates the linear velocity of the sphere in a predetermined direction from this amount of movement and the time interval; and; a second calculation unit that calculates a movement angle around a predetermined diameter at a predetermined location of the sign from the video signals of each of the imaging means, and calculates an angular velocity around the predetermined diameter from this angle and the time interval; Be prepared. The second aspect of the present invention provides a velocity measuring device for a spherical body immediately after impact, which measures the linear velocity in a predetermined direction at the center and the angular velocity around a predetermined diameter of the spherical object immediately after impact, comprising: a sphere with two linear marks attached so as to intersect with each other at two points; a sphere that images the sphere immediately after being hit at least twice from directly above at time intervals corresponding to its moving speed; an imaging means; a first calculation unit that calculates the amount of movement of the center position of the sphere from the video signal of the imaging means and calculates the linear velocity of the sphere in a predetermined direction from this amount of movement and the time interval; a second calculation unit that calculates a movement angle around a predetermined diameter at a predetermined location of the sign from the video signal of the imaging means, and calculates an angular velocity around the predetermined diameter from this angle and the time interval;

[Effect]

In the speed measuring device for a sphere immediately after impact according to the first aspect of the invention, the two imaging means detect the sphere directly above the sphere,
Images are taken from directly above the ball and from a direction perpendicular to the direction of the impact, and based on the data regarding the center position of the ball and the position and shape of the marker from the video signals of each imaging means, the calculation unit calculates the shape of the ball. The linear velocity and angular velocity related to are calculated respectively. In the speed measuring device for a sphere immediately after impact according to the second invention, the image capturing means images the sphere from directly above the sphere, and the center position of the sphere and the position and shape of the marker are determined from the video signal. Based on the data, the calculation unit calculates the linear velocity and angular velocity of the sphere. Embodiment An embodiment (hereinafter referred to as the first embodiment) of the speed measuring device for a ball immediately after impact according to the first invention will be described below with reference to the drawings. FIG. 1 is a block diagram of the first embodiment. In Figure 1,
1 is a golf ball (hereinafter simply referred to as a ball), and marks as described in detail later are drawn on the outer peripheral surface. 2 is a golf club (hereinafter simply referred to as a club) as a hitting member. Both 3A and 3B are optical sensors, and each optical sensor 3A
, 3B, the time required for the club 2 to pass between them immediately before the impact is calculated, and the speed of the club 2 immediately before the impact is calculated from this passing time. In addition, each optical sensor 3A, 3B is
Although this is a light transmission method consisting of a light emitting part and a light receiving part, a light reflection method based on reflection from the club 2 may also be used. Both 4A and 4B are photoelectric cameras (hereinafter simply referred to as cameras), and camera 4A sees ball 1 from directly above it, and camera 4B sees ball 1 from right side facing the golfer.
Still images taken at each predetermined point in time are captured in a multiplexed manner. To capture this still image, the strobe firing described below functions. 6 is a strobe power supply; 7 is a strobe light source; ignition of the strobe light source 7 is performed by activation of the strobe power supply 6 in response to a command from the control/calculation section 5; The control/calculation unit 5 determines the first issuance time of the activation command, the subsequent time interval (firing interval), and the number of firings from the signals from each optical sensor 3A, 3B, that is, the club 2. It is determined based on a predetermined time immediately before the impact and the speed at that time. In other words, if the speed of the club 2 immediately before impact is high, the firing interval is narrowed and the positional relationship of each still image is determined to be suitable for calculating the speed and angular velocity of the ball l. 8 is a frame memory, during a predetermined period immediately after the impact,
Still image data captured by each firing at least twice is stored. Regarding the data of this still image,
This will be described in detail later. The control/calculation unit 5 also takes in data from the frame memory 8 and calculates the velocity and angular velocity of the ball 1 based on this data. The details of this calculation will be described in detail later. A display 9 numerically displays the calculation results from the control/calculation section 5, that is, the velocity and angular velocity of the ball l. The operation of the first embodiment will be explained with reference to the following illustrative diagrams of still images. FIG. 3 is an illustrative diagram of a still multiple image taken in the first embodiment by the camera 4A in FIG. 1 from directly above the ball l, and FIG. FIG. 3 is an exemplary diagram of multiple images. In FIG. 3, the horizontal axis represents the hitting direction (X), the vertical axis represents the horizontal direction (Y) facing the golfer, and the vertical axis from the origin (O) represents the direction directly above the ball l (Z). The ball 1 passes through each of the opposing fixed points Kl, 2 on its outer circumferential surface, and marks each linear mark la, l along two mutually perpendicular great circles.
b is drawn, and before striking, place the center C on the horizontal plane with the origin 0 of the coordinate axes, each fixed point Kl, 2 with the Z axis, and each mark la, lb with each of the X and Y coordinate axes. It will be destroyed. Now, to simplify the explanation, it is assumed that the first firing is performed at the moment of impact, and the second firing is performed after a minute time T, and that firing occurs only two times. In FIG. 3, an image of the ball l at the moment of impact at the origin 0 and an image of the ball l whose center C is located at coordinates X and Y after time T are illustrated as still images. Ball 1 after time T is on each coordinate axis X. It is assumed that the rotation is made by angles α, β, and γ (not shown) around Y and Z. Also, in the image of ball 1 after time T, each mark la, l
b is expressed as one side of the long sleeve of the ellipse, and the points at which each semi-ellipse is inscribed with the circle of the outline of the ball 1 are designated as points PI and P2, and points Ql and Q2, respectively. Note that an ellipse on the other side of each mark la and 1b with respect to the long axis does not appear in the image, but is shown by a broken line in the figure. Let A be the distance between a straight line passing through the center C of the ball l and parallel to the X and Y axes and the fixed point 1. B. If the radius of ball l is R, then A=Rsin a, B=Rsinβ Also, the angle that the straight line connecting each point Pi and P2 makes with the X axis is
It is the rotation angle T around the Z axis. Therefore, the values obtained by dividing the obtained angles α, β, and T by the time T are the coordinate axes X and Y of the ball l. It becomes the angular velocity around Z. Note that the angular velocity around the coordinate axis Z is called side spin, and the angular velocity around the coordinate axis Y is called topspin or backspin depending on its direction, and the angular velocity around the coordinate axis X is generally so small that it is not a problem. The linear velocity of the ball 1 in each of the coordinate axes X and Y directions is the value obtained by dividing the coordinates X and Y of the center C of the ball 1 by the time T in FIG. The linear velocity in the direction of the coordinate axis Z is shown in Fig. 4 instead of Fig. 3, and is the value obtained by dividing the coordinate 2 of the center C of the ball l by the time T. Image processing or calculations related to each angular velocity are performed by the control/calculation unit 5 in FIG. 1 based on the images shown in FIGS. 3 and 4.
It is carried out by And then, the ball immediately after hitting
The behavior of is completely expressed by the linear velocity in each of the coordinate axes x, y, and z, as well as the angular velocity around it, which determines the subsequent trajectory of the ball l. In the above description, for convenience, the strobe light source was ignited twice: at the moment of impact and after time T. However, the ignition is not limited to this, and generally it is sufficient that the ignition occurs two or more times immediately after the hit, that is, immediately after the fly ball. If the number of firings is three or more, there are also the same number of still images of the ball, so between each still image there are multiple coordinate axes
, Y, and Z directions, as well as the angular velocities around them, and average them to obtain a more accurate value. The timing of the first firing is determined after a predetermined time based on the detection by the optical sensor 3B on the side closer to the ball l in FIG. Also, the firing time interval is club 2
The reason why it is determined based on the speed immediately before the ball is hit is to capture a predetermined number of still images of the ball l within the field of view of each camera 4A, 4B, and in a manner in which they are properly arranged. Of course, the initial point in time and time interval of ignition;
The predetermined number of still images is related. In addition, the direction of the ball 1 before hitting is as shown in Fig. 3.
The fixed point Kl coincides with the origin O, and each mark 1a, 1b corresponds to each X.
, and the Y axis, but this is for ease of explanation and is not generally limited to this. An embodiment (hereinafter referred to as a second embodiment) of a speed measuring device for a ball immediately after impact according to the second invention will be described below with reference to the drawings. FIG. 3 is an illustrative diagram of a still multiplexed image taken from directly above the ball in the second embodiment, and is the same diagram as in the first embodiment. The second embodiment corresponds to the behavior when the ball flies in a substantially horizontal direction immediately after being hit. In the second embodiment, since the behavior of the ball immediately after impact is completely expressed by the linear velocity in the X and Y coordinate axes and the angular velocity around the coordinate axes x, y, and z, There is no need to measure speed. Therefore, as shown in FIG. 2, the configuration diagram of the second embodiment does not include the camera 4B in FIG. 1, because there is no need to image the ball 1 from the side facing the golfer. Other components are the same as those in FIG. 1 showing the first embodiment. Furthermore, since the operation of the second embodiment is similar to that of the first embodiment except that there is no need to measure the linear velocity in the Z-axis direction, detailed explanation will be omitted. By the way, the ball in the second embodiment flies almost horizontally immediately after being hit, but after that, the trajectory of the ball in the vertical direction is mainly influenced by rotation around the Y axis, that is, backspin or topspin. It is determined.

【Effect of the invention】

Therefore, according to the first aspect of the present invention, each linear velocity in a predetermined direction of the center with respect to the sphere, for example, in the direction of impact 9 directly above the sphere, in the transverse direction perpendicular to these, and in each of the linear velocities around the diameter of the sphere in each of these directions. By accurately measuring the angular velocity, 1. The behavior of the ball immediately after being hit can be accurately and completely known, and the effectiveness of batting practice for golf and baseball can be improved. Furthermore, the measurement results of the linear velocity and angular velocity of the ball immediately after impact can be obtained automatically and quickly, making it very convenient to use. Furthermore, according to the second invention, since the measurement conditions are simplified and only one photoelectric camera is required, it is possible to obtain substantially the same effects as in the first invention, while further reducing the cost of the apparatus. .

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of an embodiment according to the first invention, and FIG. 2 is a configuration diagram of an embodiment according to the first invention.
The configuration diagram of the embodiment according to the invention, FIG. A common illustrative diagram of a still multiple image taken from directly above the ball in the embodiments according to the second invention; FIG. FIG. 3 is an exemplary diagram of an image. Code explanation Kl, 2: Fixed point l: Ball, la, lb: Mark, 2: Club, 3A,
38: Optical sensor, 4A, 4B: Camera, 5: Control/
Arithmetic unit, 6: Strobe power supply, 7: Strobe light source, 8: Frame memory, 2nd diagram

Claims (1)

[Scope of Claims] 1) A device for measuring linear velocity in a predetermined direction at the center and angular velocity around a predetermined diameter of a sphere immediately after impact, comprising: A sphere with a book linear marker attached; Immediately after being hit, this sphere is viewed from directly above at time intervals according to its moving speed, and at least from directly above and in a direction perpendicular to the direction of the impact. two imaging means that take images twice; the amount of movement of the center position of the sphere is determined from the video signal of each of the imaging means, and the linear velocity of the sphere in a predetermined direction is calculated from this amount of movement and the time interval; a first calculation unit that calculates a movement angle around a predetermined diameter of a predetermined location of the sign from the video signals of each of the imaging means, and a second calculation unit that calculates an angular velocity around the predetermined diameter from this angle and the time interval; 1. A speed measuring device for a ball immediately after being hit, comprising: a calculating section; and; 2) In a device that measures the linear velocity in a predetermined direction at the center and the angular velocity around a predetermined diameter of a sphere immediately after impact, two linear markers are placed so as to intersect each other at two opposing points on the outer peripheral surface. a sphere marked with; an imaging means for photographing the sphere immediately after being hit at least twice from directly above at time intervals corresponding to its moving speed; and a center of the sphere from the video signal of the imaging means; a first calculation unit that calculates the amount of movement of the position and calculates the linear velocity of the sphere in a predetermined direction from the amount of movement and the time interval; A second calculation unit that calculates a movement angle of the ball and calculates an angular velocity around a predetermined diameter from this angle and the time interval.