JP5676300B2 - Measuring method of golf club head behavior - Google Patents

Description

  The present invention relates to a method for measuring the behavior of a golf club head at the time of impact on a golf ball.

  Conventionally, an apparatus and a method for analyzing the behavior of a golf club being swung by a player have been proposed. These apparatuses and methods are disclosed in, for example, Japanese Patent No. 2826697, Japanese Patent No. 2950450, Japanese Patent No. 4109076, Japanese Patent No. 4307511, Japanese Patent Application Laid-Open No. 2007-167549, and the like.

  Japanese Patent No. 2826697 discloses a club head motion measuring device. In this apparatus, marks provided at least at three locations on the face surface of the club head are imaged in multiple directions from different directions, and the marks are extracted from a plurality of captured images. This is a device for obtaining the three-dimensional coordinates of the mark from the coordinates.

  Japanese Patent No. 2950450 discloses a monitor system for measuring the flight characteristics of a moving object and an apparatus constituting the system. This system receives at least two cameras capable of capturing three or more target portions attached to a moving object to fly, receives analog signals of the captured target portions, and passes the path, speed, and flight of the moving object. Image digitizing means for determining rotation in the initial portion is included.

  Japanese Patent No. 4109096 discloses a measuring method and measuring device for the amount of rotation of a curved body and the direction of the axis of rotation. In this measurement method, a plurality of two-dimensional images are obtained by photographing a rotating curved surface with a plurality of marks a plurality of times at predetermined time intervals. On the other hand, a virtual curved surface with a plurality of marks on the surface is created in the three-dimensional coordinate space by the computer, similar to the rotating curved surface. On the computer, the posture of the virtual curved body is displaced so that the mark on the surface of the two-dimensional image matches the mark on the surface of the virtual curved body. Based on the amount of displacement, a rotation matrix related to the rotation operation when the virtual curved surface is displaced is calculated, and the amount of rotation of the curved surface and the direction of the rotation axis are obtained.

  Japanese Patent No. 4307511 discloses a behavior measuring method and a behavior measuring apparatus for a moving body. In this measurement method, a plurality of marks provided on a moving body are continuously subjected to multiple imaging at a constant time interval from at least two different directions. A three-dimensional shape model of the moving body is created. A point (corresponding point) on the three-dimensional shape model corresponding to the photographed mark is specified. Time series data of the position and orientation of the 3D shape model is calculated from the corresponding points on the 3D shape model.

  Japanese Unexamined Patent Application Publication No. 2007-167549 discloses a method for analyzing the behavior of a club head. In this analysis method, a strobe is emitted at a timing according to the swing speed of the golf club, and the club head is multiplexed with at least two cameras from different directions, and the behavior of the club head is determined from the plurality of image information. It is what you want.

Japanese Patent No. 2826697 Japanese Patent No. 2950450 Japanese Patent No. 4109096 Japanese Patent No. 4307511 JP 2007-167549 A

  In the apparatus disclosed in the above-mentioned Japanese Patent No. 2826697, the behavior of the club head before hitting the ball (impact) is measured, but the positional relationship between the club head and the ball is neither measured nor calculated. Therefore, it is not possible to estimate the hit point of the ball on the club head.

  The above-mentioned Japanese Patent No. 2950450 describes a DLT method for obtaining three-dimensional data from a plurality of two-dimensional data of a golf ball as a moving object. In the system disclosed in this publication, the track, speed, and rotation of the golf ball at the initial stage can be obtained, but the positional relationship between the club head and the ball cannot be obtained. Therefore, it is not possible to estimate the hit point of the ball on the club head.

  In the method and apparatus disclosed in Japanese Patent No. 4109096 and Japanese Patent No. 4307511, the behavior of a target club head is obtained using CAD data of the club head created on a computer. Since the CAD data does not completely match the actual shape of the club head, a measurement error may occur. Further, since the CAD data of the club head is required, measurement is not easy. In this method and apparatus, the positional relationship between the club head and the ball is neither measured nor calculated. Therefore, it is not possible to estimate the hit point of the ball on the club head.

  Although the above Japanese Unexamined Patent Application Publication No. 2007-167549 describes “face angle, blow angle, lie angle, hitting point position (toe-heel direction, vertical direction) at impact”, the method is specifically disclosed. It has not been. Of course, the hitting points cannot be obtained quantitatively.

  The present invention has been made in view of the above-described present situation, and an object of the present invention is to provide a method for measuring the behavior of a golf club immediately before or at the time of impact.

The method for measuring the behavior of the head of the golf club according to the present invention includes:
Marking at least three marks on the face of the club head;
Obtaining a plurality of two-dimensional data of the mark at at least two points of the moving club head by a plurality of cameras;
Identifying a position on a three-dimensional coordinate of the mark from the plurality of two-dimensional data;
Identifying a face surface from position data on three-dimensional coordinates of three or more marks;
And updating the positional relationship between the face surface and the golf ball in time series to specify the point of contact between the face surface and the golf ball.

  Preferably, it is assumed that the positions of the at least three marks are in constant velocity linear motion, and are normal vectors of a plane constituted by these three positions, and normal vectors passing through the center of the golf ball Is used to determine when this surface is in contact with the golf ball.

  Preferably, the positional relationship between the face surface and the golf ball is specified by setting the origin of the three-dimensional coordinates as the center position of the golf ball. Although the origin can be set freely, in order to shorten the calculation time by simplifying the calculation formula, it is preferable to set the origin to the center position of the golf ball.

  Preferably, the two-dimensional coordinates of the face surface are set from the position data of the three or more marks on the face surface on the three-dimensional coordinates.

  Preferably, obtaining the data on the three-dimensional coordinates of the contact point at the time of contact between the face surface and the golf ball, and converting the data on the three-dimensional coordinates of the contact point into the two-dimensional coordinates of the face surface; In addition.

  Preferably, the dynamic loft angle of the club head is calculated using a position vector of the mark on the three-dimensional coordinates and a reference axis vector obtained from the position vector.

  Preferably, the face angle of the club head is calculated using a position vector of the mark on the three-dimensional coordinates.

  Preferably, the blow angle of the club head is calculated using the position vector on the three-dimensional coordinates of the mark at the above-mentioned at least two time points.

  Preferably, the approach angle of the club head is calculated using the position vector on the three-dimensional coordinates of the mark at the above-mentioned at least two time points.

Preferably, a step of attaching a band-shaped mark to the top portion of the crown portion of the club head;
Calculating a rotation angle of the band mark between the two time points from each position data of the band mark at the two time points, and obtaining a rotation matrix;
From the position data of three or more marks at one time point among the two time points and the position data of a smaller number of marks at the one time point at the other time point, And a step of estimating position data of unacquired marks at the point of time.

Or attaching at least two marks spaced apart from each other to the top of the crown of the club head;
Calculating a rotation angle of the virtual straight line between the two time points from each position data of the virtual straight line connecting the two marks of the top portion at the two time points, and obtaining a rotation matrix;
From the position data of three or more marks at one of the two time points and the position data of a smaller number of marks at the one time point at the other time point, Preferably, the method further includes estimating position data of unacquired marks at the time.

A system for measuring the behavior of a head of a golf club according to the present invention includes:
Comprising at least three marks attached to the face of the golf club head, a right camera and a left camera for continuously photographing the behavior of the club head, and an information processing device;
The right camera is installed on the right front side in the flying direction, the left camera is installed on the left front side in the flying direction,
The above cameras are synchronized so that continuous shooting is possible,
The information processing device identifies the position of the mark on the three-dimensional coordinates from the continuously captured club image data, identifies the face surface from the position data, and determines the positional relationship between the face surface and the golf ball in time series. By updating to, the time point of contact between the face surface and the golf ball is specified.

Preferably, each optical axis of the right camera and the left camera has an angle of 30 ° or more and 60 ° or less with respect to a horizontal line in an XZ plane of an XYZ three-dimensional orthogonal coordinate system in which the Z axis is vertical.
The optical axis of the left camera forms an angle of 0 ° to 35 ° with respect to the X axis on the XY plane,
The optical axis of the right camera forms an angle of minus 35 ° or more and 0 ° or less with respect to the X axis on the XY plane,
The optical axes of the left and right cameras form an angle of 20 ° or more and 90 ° or less on the XY plane.

Preferably, an upper camera for continuously photographing the behavior of the head of the golf club is provided, and the upper camera is installed above the golf ball to be hit,
The optical axis of the upper camera forms an angle of 80 ° to 100 ° with respect to a vertical line passing through the center of the golf ball.

Preferably, the first mark of the marks on the face surface is disposed on the toe side of a vertical virtual straight line extending vertically on the face surface through the midpoint of the face surface, and the second mark is It is arranged on the heel side from the vertical virtual straight line,
With one of the first and second marks as a reference mark, a third mark is arranged above or below the reference mark,
A virtual straight line connecting the reference mark and the third mark and a virtual straight line connecting the first mark and the second mark form an angle of 85 ° to 95 °.

  According to the club head behavior measuring method of the present invention, it is possible to estimate the contact point between the face surface and the golf ball at the time of impact.

FIG. 1 is a schematic front view showing an embodiment of a measuring system for carrying out a club head behavior measuring method according to the present invention. FIG. 2 is a plan view of FIG. FIG. 3A is a plan view showing an example of a wood-type club head, and FIG. 3B is a front view thereof. FIG. 4A is a plan view showing an example of an iron-based club head, and FIG. 4B is a front view thereof. FIG. 5 is a flowchart showing an embodiment of a club head behavior measuring method according to the present invention. FIG. 6 is a perspective view schematically showing the behavior of the club head at the time of impact. FIG. 7 is a flowchart showing a procedure for calculating the three-dimensional coordinate position of the contact point between the face surface and the golf ball. FIG. 8 is a diagram showing the hitting point of the golf ball on the face surface of the iron-based club head in two-dimensional coordinates. FIG. 9 is a diagram showing the hitting point of the golf ball on the face surface of the wood club head in two-dimensional coordinates. FIG. 10 is a diagram for explaining the calculation of the dynamic loft angle of the club head. FIG. 11 is a diagram for explaining the calculation of the face angle of the club head. FIG. 12 is an explanatory diagram for estimating a position on a three-dimensional coordinate of a mark on the toe side that has not been photographed. FIG. 13 is an explanatory diagram for estimating a position on a three-dimensional coordinate of a mark on the heel side that has not been photographed.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 and FIG. 2 are diagrams schematically showing an embodiment of a measuring system for carrying out the club head behavior measuring method according to the present invention. The measurement system 1 measures the behavior of the golf club swung by the golfer P. In this measurement, the three-dimensional orthogonal coordinates of the golf club during the swing are measured in time series. Three or more points on the golf club head 2 are measured on three-dimensional coordinates.

  For the measurement of the three-dimensional coordinates, a method called a DLT (Direct Linear Transformation) method is preferably used. This DLT method is described in, for example, Japanese Patent No. 2950450 and Japanese Patent Application Laid-Open No. 2004-344418. The DLT method is generally used also in the field of biomechanics.

  The DLT method is a method for obtaining three-dimensional coordinates using a plurality of images viewed from different directions. That is, this is a method of obtaining position data of one three-dimensional coordinate from a brute force combination of position data of a plurality of two-dimensional coordinates from different directions of the object. Of course, the position data of the plurality of two-dimensional coordinates need to be obtained at the same time (photographed at the same time). This DLT method has few restrictions regarding the arrangement of cameras and is highly versatile. In addition, the DLT method has an advantage that information regarding camera constants such as the position of the camera in the real space, the direction of the optical axis, and the focal length of the lens may be unnecessary. In the DLT method, three-dimensional coordinates are reconstructed based on an image of a known point in three-dimensional coordinates, that is, a point (control point) whose coordinate value in real space is known. The control point is usually set using a reference frame (calibration frame) in which six or more marks whose positional relationships are quantitatively determined are formed.

  In measuring the behavior, a mark is attached to a predetermined location of the club head 2. The attachment site of the mark will be described later. The behavior of this mark is measured. In the behavior analysis of the club head 2, the analysis is performed based on the measurement result of the behavior of the mark. The three-dimensional coordinates of this mark are obtained by the aforementioned DLT method.

  The embodiment shown in FIGS. 1 and 2 illustrates a three-dimensional behavior measurement system 1 using the DLT method. The measurement system 1 includes a plurality of cameras 3, an information processing device 4, a golf club 5, and a plurality of marks M attached to the golf club 5. The camera 3 is a high-speed camera capable of continuous shooting at high speed. In this measurement system 1, a golf ball striking direction (ball flight direction) in which the front-rear direction of the golf player P is the Y-axis direction, the vertical direction is perpendicular to the Y-axis direction, and the vertical direction is the Z-axis direction. ) In the X-axis direction. The origin of the three-dimensional orthogonal coordinates is set at the center of a golf ball (hereinafter simply referred to as a ball) 6 placed at a fixed position. In the X axis, the direction in which the ball 6 flies is positive. The Y axis is positive on the side where the golfer P stands. The Z axis is positive at the top. In this three-dimensional coordinate, the position and posture of the club head 2 are specified.

  The plurality of cameras 3 are connected to the information processing device 4. The information processing apparatus 4 has a control unit (not shown). The control unit controls the plurality of cameras 3 to be able to shoot in synchronization. The information processing apparatus 4 includes a storage unit in which an analysis program based on the DLT method is stored, and a calculation unit. A typical storage unit is a hard disk. A typical arithmetic unit is a CPU.

  The plurality of cameras 3 are installed at different positions. In the present embodiment, three cameras 3 are used. The shutters of the three cameras 3 are synchronized. One camera (referred to as the first camera) 3A is installed almost directly above the ball mounting position so that the behavior of the club head immediately before impact and the top part of the club head 2 can be photographed. . The other two cameras (referred to as a second camera and a third camera) 3B and 3C are installed in the ball flying direction so that the face surface can be photographed. Specifically, it is as follows. The number of cameras 3 is not limited to three. Four or more cameras 3 may be used.

  The first camera 3A is installed at a position slightly rearward from the origin on the X axis (the center of the ball 6). In this embodiment, it is located 80 mm behind the origin and 4000 mm above the floor (X = −80 mm, Y = 0, Z = 4000 mm). The first camera 3A can be called the upper camera 3A. The second camera 3B is installed 4000 mm forward from the origin on the X axis and 14000 mm above the Y axis plus direction and 4000 mm above (X = 4000 mm, Y = 1250 mm, Z = 4000 mm). The second camera 3B can be called the left camera 3B. The third camera 3 </ b> C is installed 4000 mm forward from the origin on the X axis and 4000 mm above each position of 1250 mm in the Y axis minus direction (X = 4000 mm, Y = −1250 mm, Z = 4000 mm). . The third camera 3C can be called the right camera 3C. Each of the second and third cameras 3B and 3C is movable in the range of 1000 mm in the X-axis direction. That is, the positions of the two cameras 3B and 3C can be adjusted within a range of 3000 to 4000 mm from the origin. Each said dimension is an illustration and is not limited to them.

  When the second and third cameras 3B and 3C are arranged so that their optical axes are orthogonal to each other, the accuracy of the solution obtained by the numerical solution of the DLT method is increased. However, as the crossing angle between the optical axes increases, the angle formed by the face surface of the club head to be imaged and the optical axis decreases. As a result, the images of the plurality of marks are close to each other and are not easily identified. Conversely, as the crossing angle between the optical axes decreases, the accuracy of the solution obtained by the numerical solution of the DLT method decreases.

  From the viewpoint of the accuracy of the numerical analysis described above, the installation position of the camera 3 is preferably determined as follows. In the first camera 3A, the optical axis LA forms an angle of 80 ° to 100 ° with respect to the vertical line VL passing through the center of the ball 6. The second and third cameras 3B and 3C are installed such that the directions of the optical axes LB and LC are at an angle of 30 ° to 60 ° with respect to the ground (floor surface) from the mounting position of the ball 6, respectively. Is done. The second camera 3B is installed such that the direction of the optical axis LB forms an angle of 0 ° to 35 ° (plus direction of the Y axis) with respect to the X axis in plan view. The third camera 3C is installed such that the direction of the optical axis LC forms an angle of minus 35 ° (minus direction of the Y axis) or more and less than 0 ° with respect to the X axis in plan view. However, the angle formed by the optical axis LB of the second camera 3B and the optical axis LC of the third camera 3C in plan view is set to 20 ° or more and 90 ° or less.

  A first strobe 7A is attached to each of the front and rear sides of the first camera 3A in the X-axis direction. The first strobe 7A is attached to each of the positions of X = −30 mm and −130 mm when Y = 0 and Z = 4000 mm. Further, two second strobes 7B are attached at positions of X = 2000 mm, Y = 0, and Z = 4000 mm. The first strobe 7A irradiates substantially downward in the vertical direction. The second strobe 7B irradiates the vicinity of the ball 6. These strobes 7 irradiate in synchronization with the operation of the camera 3. The second strobe 7B is installed at an angle of 40 ° or more and 80 ° or less with respect to the ground (floor surface) from the placement position of the ball 6 from the viewpoint of effective illumination.

  Behind the ball 6 is installed a trigger device for determining the operation timing of the three cameras 3A, 3B, 3C and the strobes 7A, 7B. This trigger device is composed of two optical sensors 8A and 8B. The optical sensors 8A and 8B have detection light irradiators 9A and 9B arranged opposite to each other across the X axis that is the movement path of the club head 2, and light receivers 10A and 10B that can receive the detection light. . The first optical sensor 8A is at a position where X = −130 mm, and the second optical sensor 8B is at a position where X = −30 mm. When the head 2 of the golf club 5 swung blocks the detection light, the light receivers 10A and 10B detect this. Due to the shielding detection by the respective light receivers 10A and 10B, each detection time becomes the reference time. The strobe 7 and the camera 3 are operated based on this reference time.

  3 and 4 show the formation position of the mark M in the club head 2. FIG. 3 shows a wood club head 2W. 3A is a plan view of the club head 2W, and FIG. 3B is a front view of the club head 2W. Four marks MA, MB, MC, MD are formed on the face surface 12W. As these marks, all prism type reflection marks are employed. A face center Fo that is the midpoint of the face surface is set on the face surface 12W. A vertical virtual straight line extending in the vertical direction on the face surface 12W through the face center Fo is defined as a Yw axis. A horizontal imaginary straight line extending in the toe-heel direction on the face surface 12W through the face center Fo perpendicularly to the Yw axis is taken as an Xw axis. The four marks MA, MB, MC, MD are located at the four vertices A, B, C, D of the rectangle on the face surface 12W. The two sides AC and BD are parallel to the Yw axis, and the other two sides AB and CD are parallel to the Xw axis. The intersection of the virtual straight line AD and the virtual straight line BC is the face center Fo.

  The face center Fo can be set at an arbitrary position that seems to be appropriate for the acquisition of position data to be described later. For example: First, the face center can be specified from the width and height of the face surface. Second, the area center of gravity of the face surface can be set as the face center. Third, the face center can be specified from the positional relationship between the center of gravity of the entire club head and the face surface. As an example, a method for setting the face center from the width and height of the face surface will be described below. First, the club head is set on a horizontal plane so as to have a predetermined real loft angle (face angle is 0) and a lie angle. That is, the golf club is fixed in the above posture. In this posture, the most toe side point (face most toe side point) of the face surface of the club head is identified, and the most heel side point (face most heel side point) is identified. The horizontal distance between the face most toe side point and the face most heel side point is specified as the face width. A plane that passes through the center point of the face width, is perpendicular to the horizontal plane, and is perpendicular to the face surface at the center position (vertical plane) is specified. A line of intersection between the vertical surface and the face surface on the face surface is specified (vertical line). The uppermost point (face uppermost point) of this vertical line on the face surface is specified. Next, the lowest point of the vertical line on the face surface (face lowest point) is specified. The center point of the virtual straight line connecting the face uppermost point and the face lowermost point is set as the face center. This face center setting method is an example.

  In the wood-based club head 2W, a band-shaped mark ME is formed on the top portion (top portion) 13W of the crown portion. As shown in FIG. 3A, the top portion 13W is a portion close to the face surface 12W on the upper surface of the crown portion. The strip-shaped mark ME extends in the toe-heel direction on the top portion 13W. As will be described later, when only two of the marks on the face surface 12W are photographed, the band mark ME is used to estimate the position of the mark that has not been photographed. This strip mark ME can be easily photographed by the first camera 3A described above.

  FIG. 4 shows an iron club head 2A called a sand wedge having a large loft angle. 4A is a plan view of the head 2A, and FIG. 4B is a front view of the head 2A. Three marks MA, MB, and MC are formed on the face surface 12A. For these marks, a glass bead type reflective tape is adopted as a reflective mark. In the case of a club having a small loft angle, it is preferable to use a prism type reflection mark because light reflected by the reflection mark is difficult to be photographed. On the other hand, in the case of a club having a large loft angle, the light reflected by the reflection mark is easily photographed, so that it is not particularly necessary to use a prism type reflection mark. Therefore, in the case of a club having a large loft angle, it is preferable to use a lower-cost glass bead type reflective tape or the like. Specifically, a prism type reflection mark is preferable for a club having a loft angle of 25 ° or less. It is more preferable for a club having a loft angle of 20 ° or less. It is particularly preferable for a club having a loft angle of 15 ° or less. On the other hand, from the viewpoint of cost reduction, a glass bead type reflective tape or the like is preferable for a club having a loft angle of 16 ° or more. It is more preferable for a club having a loft angle of 21 ° or more. It is particularly preferable for a club having a loft angle of 26 ° or more. All of the marks MA, MB, and MC are formed on the blasted central portion of the face surface 12A. This is because the face surface A itself is likely to be reflected at both ends in the toe-heel direction, which may make it difficult to identify the mark.

  A face center Fo is set on the face surface 12A. The Xa axis that is a horizontal virtual straight line and the Ya axis that is a vertical virtual straight line are set in the same manner as in the wood club head 2W. The three marks MA, MB, and MC are located at three vertices A, B, and C of the right triangle on the face surface 12A. The base AB coincides with the Xa axis. The face center Fo is the midpoint of the base AB. The side AC is parallel to the Ya axis. The face center Fo of the head 2A of the iron club can also be set by the various setting methods described above. It can also be set by the following method. First, the posture of the target club is fixed so that the lie angle predetermined for each club is obtained. The center point in the width direction of the face material of the face surface (for example, a range surrounded by a straight line (AC line) passing through A and C in FIG. 4B and a line passing through B and parallel to the AC line). The vertical line (center vertical line) passing through the center point is specified. The uppermost point (face uppermost point) of the center vertical line on the face material is specified. Next, the lowermost point (face lowermost point) of the central vertical line on the face material is specified. The center point of the virtual straight line connecting the face uppermost point and the face lowermost point is set as the face center. This face center setting method is an example.

  The iron-based club head 2A has two marks MF and MG formed on the top portion 13A of the crown portion. As shown in FIG. 4A, the top portion 13A is a portion close to the face surface 12A on the upper surface of the crown portion. The two marks MF and MG are formed on the top portion 13A so as to be separated from each other in the toe-heel direction. As will be described later, when only two of the marks on the face surface 12A are photographed, these two marks MF and MG are used to estimate the positions of the marks that have not been photographed. For this purpose, a virtual straight line connecting the two marks MF and MG is used. These two marks MF and MG can be easily photographed by the first camera 3A.

  In the present embodiment, four marks are formed on the face surface 12 of the wood club head 2W, but the number is not limited to four. Three may be sufficient and five or more may be sufficient. Three marks are formed on the face surface 12 of the iron club head 2A, but the number is not limited to three. There may be four or more. The marks on the face surface are required at least at three positions that can constitute the surface. That is, at least three marks that are not arranged in a straight line are required. This is because it is necessary to specify the face surface of the club head 2.

  The positions of the marks MA, MB, MC, MD are not limited to those in the above embodiment. Any one of the marks on the face surface 12 (first mark) is arranged on the toe side from the Ya axis and the Yw axis (hereinafter represented by the Ya axis), and any one of the other marks The mark (second mark) is arranged on the heel side from the Ya axis, and any one of the other marks (third mark) is one of the first and second marks (reference) The virtual straight line connecting the reference mark and the third mark and the virtual straight line connecting the first mark and the second mark are 85 ° or more and 95 ° or less. An angle is preferred. The most preferred angle is 90 °. In the present embodiment, the reference mark corresponds to the mark MA in FIGS. 3B and 4B. It is more preferable that such first, second and third marks satisfy at least one of the following requirements (a) to (e).

(A) It is preferable that the reference mark is arranged on the toe side from the Ya axis. This is because the face surface is generally wider on the toe side than on the heel side, so that a plurality of marks can be widely distributed. As a result, a situation in which adjacent marks are hidden behind the ball can be avoided.

(A) It is preferable that the first mark and the second mark are arranged so that a virtual straight line connecting them is divided into two equal parts by the Ya axis. This is because the face center Fo can be easily calculated. Furthermore, it is possible to avoid a situation where the mark is hidden behind the ball when the ball collides near the center of the face surface.

(C) It is preferable that the first mark and the second mark are arranged so that a virtual straight line connecting them is perpendicular to the Ya axis. This is because, when the three-dimensional coordinate is converted into the two-dimensional coordinate, the “spot” can be defined by the distance in the vertical and horizontal directions from the face center Fo. As a result, it is easy to imagine which part of the face surface the ball collides with.

(D) The distance between the first mark and the second mark (the actual length of the imaginary straight line connecting both marks; the same applies hereinafter) is preferably 40 mm or more, and more preferably 45 mm or more. This is because it is possible to avoid a situation in which adjacent marks are hidden behind the ball. This separation distance is set within the range of the size of the face surface, but can usually be set to 80 mm or less, and further to 70 mm or less. In the present embodiment, the separation distance is set to 60 mm for both the wood club head 2W and the iron club head 2A.

(E) The distance between the reference mark and the third mark is preferably 22 mm or more, and more preferably 24 mm or more. This is because it is possible to avoid a situation in which adjacent marks are hidden behind the ball. This separation distance is set within the range of the size of the face surface, but can usually be set to 50 mm or less, and further to 40 mm or less. In the present embodiment, the separation distance is 30 mm for the wood club head 2W and 25 mm for the iron club head 2A.

  The measurement system 1 described above uses the DLT method to obtain three-dimensional data such as the position and posture of the club head 2 in time series. Based on the obtained three-dimensional data, the positional relationship between the face surface 12 and the ball 6 on the three-dimensional coordinates is updated in time series, and the contact point (at the time of impact) between the face surface and the ball is specified. Finally, the behavior of the club head 2 at the time of impact is estimated. Examples of the behavior include a dynamic loft angle, a face angle (opening angle), a blow angle, an approach angle, and a hitting point of the ball 6 on the face surface 12 of the club head 2.

  An example of estimating the behavior of the club head 2 at the time of impact will be described with reference to FIGS. 5 and 6 to 13. In FIG. 5, the club head immediately before the impact is photographed simultaneously by the first to third cameras 3A, 3B, 3C described above (STEP 1). This photographing is performed at each of two time points, for example. Next, the positions of a plurality of marks on the face surface 12 are extracted from the captured image by image processing (STEP 2). The plurality of marks means four marks for a wood club head and three marks for an iron club head. However, three marks may be employed for the wood club head.

  When the position of each mark is extracted in any captured image of the three cameras (STEP 3), each position is three-dimensionally coordinated by a three-unit measurement correction formula (approximate formula defined in the DLT method). (STEP 4). When the position of each mark is extracted only in the image captured by two of the three cameras (STEP 5), each position is determined by a correction equation for measuring two devices (approximate equation defined in the DLT method). Conversion into three-dimensional coordinates (STEP 6). Or, for example, even when only the second and third cameras are used (STEP 5), each position is converted into a three-dimensional coordinate by a correction equation (specified in the DLT method) for measuring two devices. (STEP 6).

  The correction formula defined in the DLT method is stored in the information processing apparatus 4. The correction formula for measuring three units is obtained in advance based on the images of the control points photographed by the first camera 3A, the second camera 3B, and the third camera 3C. The correction equations for measuring the two cameras of the first camera 3A and the second camera 3B are obtained in advance based on the images of the control points photographed by the first camera 3A and the second camera 3B. The correction formulas for measuring the two cameras of the first camera 3A and the third camera 3C are obtained in advance based on the images of the control points photographed by the first camera 3A and the third camera 3C. The correction formulas for measuring the two cameras of the second camera 3B and the third camera 3C are obtained in advance based on the images of the control points photographed by the second camera 3B and the third camera 3C. Since the conversion from the two-dimensional coordinates of (STEP 1) to (STEP 6) is performed by a known DLT method, a detailed description is omitted.

  It is determined whether or not the three-dimensional position information of three or more marks on the face surface at each of the two time points has been acquired (STEP 7). When the three or more three-dimensional position information can be acquired, as will be described later, the position of the face surface 12 at the time of impact is estimated from the position of the face surface at two points in time, and the face surface 12 and the ball 6 The position of the contact point on the three-dimensional coordinate is calculated (STEP 8). In (STEP 8), the positional relationship between the face surface 12 and the ball 6 on the three-dimensional coordinates is updated in time series, whereby the contact point between the face surface 12 and the ball 6 is specified, and the contact point is calculated. The

  When the three-dimensional position information of three or more marks can be acquired at any one of the two time points, but on the other hand, only a smaller number of position information is obtained than the mark position information acquired at the above one (STEP 9), the three-dimensional coordinate position of the mark not acquired on the other side is estimated (STEP 10). Specifically, for the four marks M formed on the face surface 12W of the wood-based club head 2W, the three-dimensional position information of the four marks M can be acquired at the first time, but at the later time, This is a case where three marks are not photographed behind the ball 6 and the three-dimensional position information cannot be acquired (STEP 9). In this case, based on the rotation angle between the two time points of the strip mark ME of the top portion 13W, the three-dimensional position information of the two marks that could not be acquired at the later time point is estimated (STEP 10). This estimation method will be described later. The position of the face surface 12 at the time of impact is estimated from the position of the face surface 12 at two points in time, and the position on the three-dimensional coordinate of the contact point between the face surface 12 and the ball 6 is calculated (STEP 8).

  The calculated three-dimensional coordinates of the contact point between the face surface 12 and the ball 6 are converted into the two-dimensional face surface coordinates, and the behavior of the club head including the hit point at the time of impact is estimated (STEP 11).

[Estimation of contact point between face and ball]
The calculation of the position on the three-dimensional coordinate of the contact point between the face surface 12 and the ball 6 in (STEP 8) will be described below with reference to FIGS. As shown in FIG. 6, marks are respectively formed at three locations A, B, and C on the face surface of the illustrated club head. The basic concept of the calculation of the three-dimensional coordinate position of the contact point is assumed to be that the three points A, B, and C are in constant linear motion, and is composed of the three points A, B, and C. And obtaining the coordinates of the position A, B, C and the contact point Q at that time.

Of the two time points, the first time point is t = 0, and the later time point is t = 1. As shown in the figure, the coordinate positions of the points A, B, and C at time t are A (t), B (t), and C (t). The coordinate positions of points A, B, and C at time t = 0 are A (0), B (0), and C (0). The coordinate positions of points A, B, and C at time t = 1 are A (1), B (1), and C (1). The origin (0, 0, 0) of the three-dimensional coordinates is the center point of the ball 6 shown in FIG. The time interval between t = 0 and t = 1 is T. This time T is a measured value of the light shielding time interval. The light blocking time interval is a time interval from when the club head 2 blocks the detection light of the first optical sensor 8A shown in FIG. 2 until the detection light of the second optical sensor 8B is blocked. From the above, the coordinate positions A (t), B (t), and C (t) are expressed by the following formula (1).

A (t) = A (1) + (A (1) −A (0)) / T × δt
B (t) = B (1) + (B (1) −B (0)) / T × δt (1)
C (t) = C (1) + (C (1) −C (0)) / T × δt

  In the above equation (1), δt is a calculation time interval. The initial value of δt is set to, for example, 100 μs (microseconds), the end value is set to, for example, 300 μs, and the increase step is set to, for example, 1 μs. For example, the radius of the ball is set to r.

  In the flowchart of FIG. 7, the coordinate positions A (t), B (t), and C (t) are calculated by the above equation (1) (STEP 21). The AB vector and the AC vector at time t are calculated. Then, the outer product N (Nx, Ny, Nz) of both vectors is calculated (STEP 22). The outer product N of these vectors is a normal vector. This normal vector is a unit vector. This normal vector is a vector perpendicular to the face surface (face surface vector).

Using the above A (t), B (t), C (t) and the normal vector N, the shortest distance between the ball center (0, 0, 0) and the face surface according to the following equation (2): The distance rr is calculated (STEP 23).

rr = -Nx * A (t) x-Ny * A (t) y-Nz * A (t) z (2)

It is determined whether or not the shortest distance rr is equal to or smaller than the radius r of the ball (STEP 24). When the radius r is equal to or less than the radius r, it is determined that δt at that time is δt at the time of impact, and the coordinate positions A (t), B (t), and C (t) at the time of impact are determined (STEP 25). Next, hit points (Qx, Qy, Qz) on the three-dimensional coordinates at the time of impact are determined by the following equation (3) (STEP 26).

Qx = −Nx × r
Qy = −Ny × r (3)
Qz = −Nz × r

  In (STEP 24), while the shortest distance rr is not less than or equal to the radius r of the ball and the accumulation of δt is not 300 μs, δt is replaced with δt + 1 μs (STEP 28), and from (STEP 21) to (STEP 24) ) Is repeated. The hit points (Qx, Qy, Qz) obtained by the above calculation are positions on three-dimensional coordinates. Therefore, this hit point needs to be converted into the two-dimensional coordinates of the face surface in accordance with (STEP 11) in FIG. The conversion of the hit points on the three-dimensional coordinates into the two-dimensional coordinates will be described below with reference to FIGS. 8 and 9 for the iron club head 2A and the wood club head 2W. Is done.

[Two-dimensional conversion of hit points of iron club head 2A]
The positions A, B, and C of the three marks at the time of impact are respectively (Xa, Ya, Za), (Xb, Yb, Zb), (Xc, Yc, Zc), and the hit points are (Xq, Yq, Zq). ). The hit points (Xq, Yq, Zq) are at the same positions as the hit points (Qx, Qy, Qz) described above. As described above, the mark position on the iron-based face surface 12A is determined such that the midpoint between AB is the face center Fo (FIGS. 4 and 8). FIG. 8 shows two-dimensional orthogonal coordinates on the face surface 12A composed of the FX axis and the FY axis. The three-dimensional coordinate positions of the face center Fo and point B are known, and the three-dimensional coordinate position of the hit point Q is also known. As a result, the magnitudes | FoQ vector |, | FoB vector | of the FoQ vector and the FoB vector, and the angle α (FIG. 8) between the FoQ vector and the FoB vector are expressed by the following equations (4) and (5). ) And Equation (6). Note that sqrt represents the square root in (). Further, the vector shown in the mathematical expression is marked with an arrow → at the top to indicate that it is a vector.

  The position of the hit point Q on the FX axis (Y axis on the face surface) is determined by | FoQ vector | · cos α. Since the angle β formed by the FY axis (Y axis on the face surface) and the FoQ vector is 90 ° −α, the position of the hit point Q on the FY axis is obtained by | FoQ vector | · cos β. Thus, conversion of the hit point Q into the two-dimensional coordinates in (STEP 11) in FIG. 5 is easy.

[Two-dimensional conversion of hit points of wood club head 2W]
FIG. 9 shows two-dimensional orthogonal coordinates on the face surface 12W composed of the FX axis and the FY axis. The positions A, B, C, and D of the four marks at the time of impact are (Xa, Ya, Za), (Xb, Yb, Zb), (Xc, Yc, Zc), (Xd, Yd, Zd), respectively. The hit point is set as (Xq, Yq, Zq). The hit points (Xq, Yq, Zq) are at the same positions as the hit points (Qx, Qy, Qz) described above. As described above, the mark position of the wood-based face surface 12W is determined so that the midpoint of the rectangle ABCD is the face center Fo (FIGS. 3 and 9). Since each point of A, B, C, and D is known, the coordinate position (Fox, Foy, Foz) of the face center Fo is obtained by the following equation (7).

Fox = ((Xa + Xb) / 2 + (Xc + Xd) / 2) / 2
Foy = ((Ya + Yb) / 2 + (Yc + Yd) / 2) / 2 (7)
Foz = ((Za + Zb) / 2 + (Zc + Zd) / 2) / 2

With the above values, the magnitudes | FoQ vector |, | FoB vector | of the FoQ vector and the FoB vector, and the angle α (FIG. 9) formed by the FoQ vector and the FoB vector are expressed by the following equations (8) and (8): (9) It is calculated | required by Formula (10).

  The position of the hit point Q on the FX axis is obtained by | FoQ vector | · cos α. Since the angle β formed by the FY axis and the FoQ vector in FIG. 9 is 90 ° −α, the position of the striking point Q on the FY axis is obtained by | FoQ vector | · cos β. Thus, conversion of the hit point Q into the two-dimensional coordinates in (STEP 11) in FIG. 5 is easy.

Ｘｃ＜Ｘａの場合、動ロフト角θはプラスとなる。 [Estimation of dynamic loft angle]
The estimation of the dynamic loft angle θ immediately before and at the impact will be described below with reference to FIG. FIG. 10 shows two-dimensional coordinates and three-dimensional coordinates set on the face surface. The dynamic loft angle is a loft angle that changes according to the movement of the club head due to a swing or the like. Here, as shown in FIG. 10, the dynamic loft angle θ is an angle θ formed by the outer product AJ of the X axis and the AB vector and the AC vector. Therefore, the AJ vector becomes the reference axis of the dynamic loft angle θ. Here, AB vector = (Xb−Xa, Yb−Ya, Zb−Za), AC vector = (Xc−Xa, Yc−Ya, Zc−Za), and X axis vector = (1, 0, 0). The AJ vector is calculated by obtaining the outer product of the AB vector and the X-axis vector. And dynamic loft angle (theta) is calculated | required by following formula (11).

When Xc <Xa, the dynamic loft angle θ is positive.

Ｘａ＜Ｘｂの場合、フェース角γはプラスであり、いわゆるオープンである。それ以外であればフェース角γはマイナスであり、いわゆるクローズである。上記フェース角の推定方法と同様な手法により、動的ライ角を推定することも可能である。動的ライ角を推定する際には、ＢＡベクトルが投影されるのはＹＺ平面ではなくＸＹ平面であり、ＢＡベクトルのＸＹ平面に投影されたベクトルと、ＢＡベクトルとのなす角度と、クラブの所定のライ角とにより、動的ライ角が求められる。 [Estimation of face angle]
The estimation of the face angle (opening angle) γ immediately before and during the impact will be described below with reference to FIG. FIG. 11 shows the two-dimensional coordinates set on the face surface and the three-dimensional coordinates together. Here, the face angle γ is an angle γ formed by the vector BG projected on the YZ plane of the BA vector and the BA vector. Here, BA vector = (Xa−Xb, Ya−Yb, Za−Zb). The vector BG = (0.0, Ya−Yb, Za−Zb) projected onto the YZ plane of the BA vector. The face angle γ is obtained by the following equation (12).

When Xa <Xb, the face angle γ is positive and so-called open. Otherwise, the face angle γ is negative, so-called close. It is also possible to estimate the dynamic lie angle by the same method as the face angle estimation method. When estimating the dynamic lie angle, the BA vector is projected on the XY plane, not the YZ plane. The angle formed between the BA vector projected onto the XY plane, the BA vector, and the club The dynamic lie angle is obtained from the predetermined lie angle.

（Ｚa1＋Ｚb1）／２ ＞ （Ｚa0＋Ｚb0）／２の場合、ブロー角はプラスであり、いわゆるアッパーブローである。それ以外ではブロー角はマイナスであり、いわゆるアンダーブローである。 [Blow angle estimation]
Next, the estimation of the blow angle η immediately before and at the impact will be described below. Here, the blow angle η is formed by the vector Fot0′-Fot1 ′ projected onto the XY plane of the face center vector Fot0-Fot1 at t = 0 and t = 1, and the face center vector Fot0-Fot1. The angle η. First, the movement distance of the face center at t = 0 and t = 1 is obtained. The coordinates of the face center Fo are ((Xa + Xb) / 2, (Ya + Yb) / 2, (Za + Zb) / 2). The movement distance of the face center is obtained from the coordinates of Fo at t = 0 and the coordinates of Fo at t = 1. The face center vector Fot0-Fot1 is expressed by the following equation (13). The vector Fot0′-Fot1 ′ projected onto the XY plane of the face center vector is expressed by the following equation (14). Therefore, the blow angle η is obtained by the following equation (15).

In the case of (Za1 + Zb1) / 2> (Za0 + Zb0) / 2, the blow angle is positive, so-called upper blow. Otherwise, the blow angle is negative, so-called underblow.

[Estimation of approach angle]
Next, the estimation of the approach angle ξ immediately before and at the time of impact will be described below. Here, the approach angle ξ is an angle ξ formed by coordinates projected on the XY plane of coordinates of a line segment connecting the face centers at t = 0 and t = 1, and the X axis. At t = 0, the face center Foxy0 projected onto the XY plane is expressed by the following equation (16). At t = 1, the face center Foxy1 projected onto the XY plane is expressed by the following equation (17). Therefore, the approach angle ξ is obtained by the following equation (18).

Foxy0 = ((Xa0 + Xb0) / 2, (Ya0 + Yb0) / 2, 0) (16)

Foxy1 = ((Xa1 + Xb1) / 2, (Ya1 + Yb1) / 2, 0) (17)

tanξ = ((Ya1 + Yb1) / 2− (Ya0 + Yb0) / 2) /
((Xa1 + Xb1) / 2-(Xa0 + Xb0) / 2) (18)

In the case of (Ya1 + Yb1) / 2> (Ya0 + Yb0) / 2, the approach angle is negative, so-called inside-out. Otherwise, the approach angle is positive, so-called outside-in.

  As described above, the club head behavior measurement method using the measurement system 1 measures the behavior of the club head immediately before and at the time of impact, and identifies and estimates it on the coordinates. That is, the positional relationship of the club head is quantified.

[Estimation of unacquired position]
Next, estimation of the position of the mark that was not acquired at one of the two time points in STEP 9 and STEP 10 in FIG. 5 will be described below.

  FIG. 12 shows the face 12W of the wood club head at two time points t = 0 and t = 1. At t = 0, all four mark positions A, B, C, and D were extracted. At t = 1, the two marks on the toe side were hidden behind the ball and were not photographed, and the two positions A ′ and C ′ were not extracted. Two positions B 'and D' on the heel side were extracted. In FIG. 12, the unextracted positions A ′ and C ′ are shown in white. The strip-shaped mark ME formed on the top portion 13W can be almost certainly photographed by the first camera 3A (see FIGS. 1 and 2). End positions in the longitudinal direction of the band-shaped mark ME are point E and point F, respectively.

  The basic idea of the estimation of the two positions A ′ and C ′ is that D ′ at t = 1 using DC vectors (DCx0, DCy0, DCz0) and BA vectors (BAx0, BAy0, BAz0) at t = 0. C ′ vector (DCx1, DCy1, DCz1) and B′A ′ vector (BAx1, BAy1, BAz1) are obtained. At this time, the rotation angle of the FE vector at the end position of the strip mark ME from t = 0 to t = 1 is used.

である。 First, the FE vector at t = 0 (FEx0, FEy0, FEz0) and the F′E ′ vector at t = 1 (FEx1, FEy1, FEz1) are obtained. here,

It is.

Second, an outer product vector V (Vx, Vy, Vz) of the FE vector at t = 0 and the F′E ′ vector at t = 1 is obtained. Here, Vx, Vy, and Vz are obtained by the following equations (19), (20), and (21), respectively.

Third, an angle φ formed by the FE vector at t = 0 and the F′E ′ vector at t = 1 is obtained by the following equation (22). Acos means arc cosine.

Fourth, the rotation matrix (rotation matrix of the line segment FE) Mt of the band-shaped mark ME from t = 0 to t = 1 is obtained by the following equation (23).

である。 Fifth, DC vectors (DCx0, DCy0, DCz0) and BA vectors (BAx0, BAy0, BAz0) at t = 0 are obtained. here,

It is.

Each of the DC vector and BA vector is multiplied by the rotation matrix Mt. As a result, the estimated D′ C ′ vector and B′A ′ vector at t = 1 are obtained. It is as the following formula (24) and formula (25).

  The position A ′ (the position of the mark MA at t = 1) that has not been acquired is estimated by adding the B′A ′ vector to the position B ′ that has been acquired. Further, by adding the D′ C ′ vector to the position D ′ that can be acquired, the position C ′ that has not been acquired (the position of the mark MC at t = 1) is estimated. By using the estimated value obtained in this manner, the operations after STEP 8 in FIG. 5 are executed. As a result, the behavior of the club head can be estimated immediately before and during the impact, as in the case where three or more positions can be extracted at both the time points t = 0 and t = 1.

  In the wood-type club head shown in FIG. 13, all the positions A, B, C, and D of the four marks are extracted at t = 0. At t = 1, unlike FIG. 12, since the two marks on the heel side were hidden behind the ball, they were not photographed, and the two positions B ′ and D ′ were not extracted. Even in this case, the same method as that described with reference to FIG. 12 is used to estimate the unacquired positions B ′ and D ′. Therefore, detailed description is omitted. For the example shown in FIG. 13, the direction of the vector is opposite to that in FIG. That is, using the CD vector (CDx0, CDy0, CDz0) and the AB vector (ABx0, ABy0, ABz0) at t = 0, the C′D ′ vector (CDx1, CDy1, CDz1) and A′B ′ at t = 1. A vector (ABx1, ABy1, ABz1) is obtained. At this time, the rotation angle of the vector EF at the end position of the band mark ME from t = 0 to t = 1 is used.

  In the “estimation of unacquired position” described above, position data on the three-dimensional coordinates of each mark is used, but the present invention is not limited to this method. Position data on the two-dimensional coordinates of each mark may be used. Specifically, for example, a second-order rotation matrix obtained from data captured by the first camera 3A located directly above the club head may be used. Two-dimensional position data is preferably used when reduction of calculation time is important, and three-dimensional position data is preferably used when accuracy is important.

  The club head behavior measuring method according to the present invention is useful for swing diagnosis, golf club development, and the like.

DESCRIPTION OF SYMBOLS 1 ... Measuring system 2A ... (Iron type) club head 2W ... (Wood type) club head 3A, 3B, 3C ... Camera 4 ... Information processing device 5 ... Golf club 6 ... Ball 7A, 7B ... Strobe 8A, 8B ... Optical sensor 12A ... Face surface (of iron-based club head) 12W ... Face surface (of wood-based club head) 13A ... Top part of iron club head 13W ... Top part of wood club head MA, MB, MC, MD,
ME, MF, MG ... mark LA, LB, LC ... (camera) optical axis

Claims (13)

A method for measuring the behavior of a golf club head,
Marking at least three marks on the face of the club head;
Marking the top of the crown of the club head;
Obtaining a plurality of two-dimensional data of three or more marks on the face surface by at least two time points of the moving club head by a plurality of cameras;
Identifying a position on a three-dimensional coordinate of the mark from the plurality of two-dimensional data;
Identifying a face surface from the position data of the three-dimensional coordinates of the three or more marks on the face surface,
Identifying the point of contact between the face surface and the golf ball by updating the positional relationship between the face surface and the golf ball in time series ; and
Calculating the rotation angle of the mark of the top part between the two time points from the position data of the mark of the top part at the two time points to obtain a rotation matrix;
From the position data of the three or more marks on the face surface at one time point among the two time points, and the position data of the fewer number of marks on the face surface at the one time point at the other time point Using the rotation matrix to estimate position data of unacquired marks at the other time point,
The mark on the top portion is one of a band-shaped mark and at least two marks spaced apart from each other;
When the top mark is at least two marks separated from each other, the position data of the top mark is the position data of a virtual straight line connecting the two marks, and the club head behavior is measured. Method.   Assuming that the positions of the at least three marks are in constant-velocity linear motion, a normal vector of a surface constituted by these three positions, and using a normal vector passing through the center of the golf ball, 2. The method for measuring the behavior of a club head according to claim 1, wherein a time point at which this surface comes into contact with the golf ball is obtained.   The club head behavior measuring method according to claim 1 or 2, wherein the positional relationship between the face surface and the golf ball is specified by setting the origin of the three-dimensional coordinates as the center position of the golf ball.   4. The club head behavior measuring method according to claim 1, wherein two-dimensional coordinates of the face surface are set from position data on three-dimensional coordinates of the three or more marks on the face surface.   Obtaining the data on the three-dimensional coordinates of the contact point at the time of contact between the face surface and the golf ball, and converting the data on the three-dimensional coordinates of the contact point into the two-dimensional coordinates of the face surface. Item 5. The club head behavior measuring method according to Item 4.   2. The club head behavior measuring method according to claim 1, wherein a club head dynamic loft angle is calculated using a position vector of the mark in three-dimensional coordinates and a reference axis vector obtained from the position vector.   The club head behavior measuring method according to claim 1 or 6, wherein a face angle of the club head is calculated using a position vector of the mark on three-dimensional coordinates.   8. The club head behavior measuring method according to claim 1, wherein the club head blow angle is calculated using a position vector on the three-dimensional coordinates of the mark at at least two time points.   9. The club head behavior measurement according to claim 1, wherein an angle of approach of the club head is calculated using a position vector on the three-dimensional coordinates of the mark at at least two time points. Method. A system for measuring the behavior of a golf club head,
At least three marks attached to the face surface of the golf club head, a mark attached to the top of the crown of the club head, a right camera and a left camera that continuously shoot the behavior of the club head, and information A processing device,
The mark on the top portion is one of a band-shaped mark and at least two marks spaced apart from each other;
The right camera is arranged on the front right side in the flying direction, the left camera is arranged on the left side in the flying direction,
The above cameras are synchronized so that continuous shooting is possible,
The information processing apparatus is
From the image data of the mark on the face surface of the club head taken continuously, the position on the three-dimensional coordinates of three or more marks on the face surface is specified, the face surface is specified from this position data, and the face By updating the positional relationship between the surface and the golf ball in chronological order, the point of contact between the face surface and the golf ball is specified ,
From the position data of the mark on the top portion at two time points of the moving club head, the rotation angle of the mark on the top portion between the two time points is calculated to obtain a rotation matrix,
From the position data of the three or more marks on the face surface at one time point among the two time points, and the position data of the fewer number of marks on the face surface at the one time point at the other time point , And configured to estimate position data of unacquired marks at the other time point using the rotation matrix,
When the top mark is at least two marks apart from each other, the club head behavior measurement is such that the position data of the top mark is the position data of a virtual straight line connecting the two marks. system. Each optical axis of the right camera and the left camera has an angle of 30 ° or more and 60 ° or less with respect to a horizontal line in the XZ plane of the three-dimensional orthogonal coordinate system of XYZ.
The optical axis of the left camera forms an angle of 0 ° to 35 ° with respect to the X axis on the XY plane,
The optical axis of the right camera forms an angle of minus 35 ° or more and 0 ° or less with respect to the X axis on the XY plane,
The club head behavior measurement system according to claim 10 , wherein the optical axes of the left and right cameras form an angle of 20 ° to 90 ° in the XY plane. An upper camera for continuously photographing the behavior of the head of the golf club, and the upper camera is disposed above the hit golf ball;
The club head behavior measurement system according to claim 10 or 11 , wherein an optical axis of the upper camera forms an angle of 80 ° to 100 ° with respect to a vertical line passing through a center of the golf ball. Of the marks on the face surface, the first mark is arranged on the toe side of the vertical virtual line on the face surface, the second mark is arranged on the heel side of the vertical virtual line, and the vertical virtual line is the face A straight line extending up and down through the midpoint of the face surface,
With one of the first and second marks as a reference mark, a third mark is arranged above or below the reference mark,
A virtual straight line connecting the said reference mark and the third mark, the first mark and the imaginary straight line connecting the second mark, according to claim 10 to 12, forms an angle of less than 95 ° 85 ° or more The club head behavior measurement system according to any one of the above.

Images