JP2014059175A - Moving body having marker fixed thereto and method of fixing marker to moving body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving body having a marker that reflects light fixed thereto and a method of fixing the marker to the moving body.SOLUTION: A moving body is used in a moving body detection method, the method including the steps of capturing an image of a moving body 2b having a marker 30 with a reflection surface that reflects light fixed thereto by means of a camera, and detecting a posture of the moving body 2b based on the marker 30 whose image has been captured. In the marker 30 a reflection surface 30A is a plane.

Description

  The present invention relates to a moving body to which a marker that reflects light is fixed, and a method for fixing the marker to the moving body.

  2. Description of the Related Art In recent years, detection of a moving body including a step of imaging with a camera a moving body to which a marker having a reflective surface that reflects light is fixed, and a step of calculating the posture of the moving body based on the captured marker A method has been proposed.

  As the moving body, for example, sports equipment such as a golf club that is moved by a player's operation is employed. For example, a reflective tape is employed as the marker, and the marker is attached to a plurality of locations (for example, 3 locations or more) of the golf club head. The specific position (for example, centroid) of the attached reflective tape is stored in the computer as known coordinate information.

  A computer is used to calculate the posture of the moving body. The computer calculates the posture of the moving body based on the position of the marker imaged by the camera and the known information. For this calculation, for example, a DLT (Direct Linear Transformation) method is preferably used. Calculating the posture of the golf club head during a swing is useful for club development or for teaching a swing. Related technologies include the following.

JP 2004-24488 A JP 2007-167549 A JP 2004-61483 A

  When the posture of the moving body is calculated, the outline of each marker is extracted from the captured image, and a specific position of each marker, for example, the centroid is calculated. The centroid of the marker must be accurately identified because it is the basis for subsequent calculations.

  However, for example, as shown in FIG. 12A, when the marker a pasted along the spherical convex curved surface portion is imaged obliquely, the centroid b1 of the actual marker and the image processing are calculated. It may deviate greatly from the centroid b2 of the marker.

  Moreover, when the marker a stuck on the curved surface portion is imaged from an oblique direction, a part of the marker a may be hidden. Even in such a case, the centroid b1 of the actual marker and the centroid b2 of the marker calculated by the image processing may greatly deviate.

  As described above, the posture of the moving body calculated based on the centroid information of the wrong marker also includes an error.

  In particular, in recent years, a marker may be imaged with one camera. In such a case, since the direction in which the marker is imaged is limited, the above problem tends to occur.

  The present invention has been devised in view of the above problems, and is based on the fact that the reflecting surface of the marker is a plane, and a movable body and a movable body that can accurately detect the posture of the movable body It aims at providing the method of adhering a marker to.

  According to the first aspect of the present invention, the step of imaging with a camera a moving body to which a marker having a reflective surface that reflects light is fixed, and the posture of the moving body is detected based on the captured marker. The marker is characterized in that the reflecting surface of the marker is a flat surface.

  The invention according to claim 2 is the moving body according to claim 1, wherein the marker is fixed to a curved surface portion of the moving body.

  According to a third aspect of the present invention, a support is disposed between the marker and the movable body, and the support includes a marker support surface that faces the marker and is a flat surface. The moving body according to 1 or 2.

  The invention according to claim 4 is the movement according to claim 3, wherein the support has a fixing surface facing the moving body, and an adhesive is filled between the fixing surface and the moving body. Is the body.

  According to a fifth aspect of the present invention, the support has a fixing surface facing the moving body, and the fixing surface has an inverted shape of the outer surface of the moving body facing the fixing surface. Or it is a moving body of 4.

  The invention according to claim 6 is the moving body according to any one of claims 1 to 5, wherein the moving body is a sports equipment that moves by an operation of a player.

  According to a seventh aspect of the present invention, there is provided a step of imaging with a camera a moving body to which a marker having a reflecting surface that reflects light is fixed, and a step of detecting the posture of the moving body based on the imaged marker. A method for fixing the marker to the moving body used in a method for detecting a moving body, including the step of fixing the marker to an outer surface of the moving body so that the reflecting surface is a flat surface. It is characterized by that.

  According to an eighth aspect of the present invention, the step of fixing the marker includes the step of providing a marker support surface including a flat surface on the curved surface portion of the outer surface of the movable body. Is the method.

  According to a ninth aspect of the present invention, in the movement according to the eighth aspect, the marker supporting surface is provided by fixing a supporting body made of a different member different from the marker and the moving body to a curved surface portion of the moving body. It is a method of fixing a marker to the body.

  According to a tenth aspect of the present invention, the marker is formed in advance on the marker support surface, or is fixed to the marker support surface after the support is fixed to a moving body. This is a method of fixing a marker to the moving body.

  The invention according to claim 11 is the method of fixing the marker to the movable body according to claim 8, wherein the marker support surface is provided by cutting or plastically deforming the curved surface portion of the movable body.

  According to the first aspect of the present invention, a step of imaging with a camera a moving body to which a marker having a reflecting surface that reflects light is fixed, and a step of detecting the posture of the moving body based on the imaged marker. The marker is characterized in that the reflective surface of the marker is a flat surface.

  In the invention described in claim 8, a step of imaging with a camera a moving body to which a marker having a reflective surface that reflects light is fixed, and a posture of the moving body is detected based on the captured marker. The marker is fixed to the moving body used in the moving body detection method including the step of fixing the marker to the outer surface of the moving body so that the reflecting surface is a flat surface. Including the step of:

  By setting the reflecting surface of the marker to be a flat surface, even when the marker is imaged obliquely, the actual centroid of the marker and the centroid of the marker calculated by image processing substantially coincide. In addition, a part of the marker is hardly hidden and imaged. Therefore, by using the moving body or method of the present invention, the posture of the moving body can be detected with high accuracy.

It is a whole block diagram of the measuring device which performs the detection method of a moving body. It is a front view of FIG. It is a front view of a wood type golf club head. It is a top view of a wood type golf club head. It is a diagram which shows the relationship between the coordinate in real space, and the coordinate on the film surface of a camera. (A) thru | or (c) are all the embodiment of this invention, and are sectional drawings of the part to which the marker of the crown part of the club head was fixed. FIG. 3 is a cross-sectional view of a portion to which a marker of a crown portion of the club head is fixed according to the embodiment of the present invention. Other embodiment of this invention is shown, (a) is a perspective view of a shaft, (b) It is the AA sectional drawing. FIG. 4 shows another embodiment of the present invention, in which (a) is a perspective view of a head of an iron type golf club, and (b) is a BB sectional view thereof. The other embodiment of this invention is shown, (a) is a front view of a tennis racket, (b) is the CC sectional drawing. It is a top view of the wood type golf club head used in the Example. (A) is a top view of the image which image | photographed the conventional marker, (b) is a top view of the image which image | photographed the marker of this embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In the present invention, a step of capturing with a camera a moving body to which a marker having a reflecting surface that reflects light is fixed (imaging step), and a step of detecting the posture of the moving body based on the captured marker (calculation) And a moving body used in a method for detecting a moving body. First, the imaging process and the calculation process will be briefly described.

  FIG. 1 shows an example of an overall configuration diagram of a measuring apparatus 10 used in the imaging process, and FIG. 2 shows a front view thereof. This measuring apparatus 10 images a club head (hereinafter, simply referred to as “head”) 2 of the golf club 1 as a moving body. The head 2 of the golf club 1 does not move by itself, but can become a moving body by the swing of the golfer M. The moving body is not limited to the head 2, and any object can be used as long as it can move.

  In the embodiment of FIG. 1, a right-handed golfer M is shown. With the swing of the golfer M, the golf ball 3 is launched to the left of the golfer M in the address posture of FIG. However, the golfer M may be substituted with a swing robot or the like.

  The measuring device 10 includes, for example, a base 12, a first camera 14 for photographing the head 2 of the golf club 1, a second camera 16 for photographing the golf ball 3, and a control device that controls the cameras 14 and 16. 18 and a computer 20 that records information captured by the cameras 14 and 16.

  The base 12 has a plate shape, and is placed, for example, on the floor surface of the measurement room. On the base 12 of this embodiment, a floor board 21 on which the golfer M stands and addresses is placed. A tee 23 for placing the golf ball 3 is provided on the floor plate 21.

  The base 12 is provided with a support column 24 extending upward. A strobe 25 that emits light toward the head 2 of the golf club 1 is provided at the top of the support 24.

  For convenience of explanation, as shown in FIGS. 1 and 2, orthogonal coordinates having an X axis, a Y axis, and a Z axis are defined in the measurement apparatus 10. The X axis is parallel to the ground and parallel to a straight line connecting the ball 3 before hitting the ball and the target direction. The Z axis is the vertical direction. The Y axis is both perpendicular to the X axis and Z.

  A trigger sensor 26 is provided on the base 12. The trigger sensor 26 is a combination of a projector 26a provided on the front (abdominal side) of the swinging golfer M and a light receiver 26b provided on the rear (back side) of the golfer M and receiving the light of the projector 26a. . The trigger sensor 26 is aligned so that the light emitted from the light projector 26a in the Y-axis direction is blocked by the passage of the golf club 1 during the downswing.

  The base 12 is further provided with a first sensor 27. The first sensor 27 includes a projector 27a provided in front of the swinging golfer M, and a light receiver 27b provided in the rear of the golfer M and receiving the light of the projector 27a. The first sensor 27 is provided in front of the swing (the flying direction of the hit golf ball 3) in the X-axis direction than the trigger sensor 26. Accordingly, during the downswing, the first sensor 27 detects the golf club 1 that is swinging slightly behind the trigger sensor 26.

  A second sensor 28 is further provided on the base 12. The second sensor 28 also includes a light projector 28a provided in front of the swinging golfer M and a light receiver 28b provided in the rear of the golfer M and receiving the light from the light projector 28a. The second sensor 28 is provided in front of the swing in the X-axis direction with respect to the first sensor 27. Therefore, the second sensor 28 detects the golf club 1 during the swing slightly later than the first sensor 27 during the downswing.

  The first camera 14 is provided above the golfer M so that a crown portion that is the upper surface portion of the head 2 of the golf club 1 can be photographed.

  The second camera 16 is provided in front of the golfer M from the tee 23 and in front of the swing in the X-axis direction so that the shot golf ball 3 can be photographed from the side. A strobe 29 is provided around the second camera 16.

  FIG. 3 is a front view of the club head 2, and FIG. 4 is a plan view thereof. The head 2 includes a face 2a which is a surface for hitting a ball, and a crown portion 2b which is connected to the face 2a and forms a head upper surface portion.

  The club head 2 is provided with a marker 30. For the marker 30, for example, a reflective tape that reflects light is used. It is desirable that the head 2 is provided with a plurality of markers 30, preferably three or more markers 30 in one photographing frame. The marker 30 is desirably provided at a position other than the face 3a. In this embodiment, four markers 30 a to 30 d are provided on the crown portion 2 b of the head 2.

  Each of the markers 30a to 30d has a diagonal line drawn on a white rectangular reflective tape. The intersections of the diagonal lines of the markers 30a to 30d are defined as specific positions (representative points) of the markers 30, for example. This specific position coincides with the center of gravity of each marker 30. The size and the like of the marker 30 can be arbitrarily determined.

  A first camera 14, a second camera 16, a trigger sensor 26, a first sensor 27, a second sensor 28, a strobe 25, a strobe 29, and an information processing device 20 are connected to the control device 18.

  The operation of the control device 18 is as follows. When the golf swing is started by the golfer M, the control device 18 receives a detection signal indicating that the trigger sensor 26 has detected the golf club 1 during the downswing. Based on this detection signal, the control device 18 outputs a shooting start signal that causes the first camera 14 and the second camera 16 to start shooting.

  Based on this imaging start signal, the shutter of the first camera 14 is opened for a predetermined time (for example, 1/30 second). While the shutter is open, a detection signal indicating that the first sensor 27 and the second sensor 28 have detected the head 2 or the shaft of the golf club 1 is sequentially input to the control device 18. The control device 18 outputs a signal for causing the strobe 25 to emit light based on the detection signal from the first sensor 27. Thereafter, the control device 18 outputs a signal for causing the strobe 29 to emit light based on the detection signal from the second sensor 28.

  Therefore, the strobe 25 and the strobe 29 emit light sequentially while the shutter is open. As a result, the first camera 14 can capture one piece of image data including the club head 2 detected by the first sensor 27 and the club head 2 detected by the first sensor 28. . Therefore, in this embodiment, the club head 2 as a moving body is photographed by one camera. Further, the second camera 29 photographs the hit ball 3.

  Image data photographed by the first camera 14 and the second camera 16 is output to the computer 20.

  The computer 20 stores a program. This program processes the image obtained in the imaging step and causes the computer 20 to execute a calculation step for calculating the position and orientation of the head 2.

The calculation process includes, for example, the following steps a to d.
(A) Identify each marker 30 from the obtained image of the head 2 (b) Calculate the three-dimensional position of each marker 30 (c) Calculate the position, posture, etc. of the head 2 based on the three-dimensional position (d) Output of calculation results

[Step a]
Step a is performed manually or automatically. When step a is performed manually, the user discriminates the marker 30 from the image with the naked eye, and inputs the position information of the marker 30 to the computer 20. When step a is automatically performed, generally, the computer 20 performs a known edge extraction process or the like on each pixel of the image using luminance information or the like. Thereby, the marker 30 is extracted from the image.

[Step b]
In step b, the three-dimensional coordinates of each marker 30 are calculated. As an example of this calculation method, the DLT method described above is known. The DLT method is a method for obtaining three-dimensional spatial coordinates of a specific position using a plurality of images viewed from different directions. In the DLT method, three-dimensional coordinates are reconstructed based on an image of a point (control point) whose three-dimensional coordinates are known.

  FIG. 5 shows coordinates (X, Y, Z) in the real space and coordinates (U) on the film plane of the camera (U) when a point P in the real space (Object space) is photographed by the camera. , V). Point O is the center point of the lens of the camera. The coordinate system X′Y′Z ′ is a coordinate system in which the point O is the origin and the on-film coordinate system UV is parallel to the X ′ axis and the Y ′ axis. The distance L is a distance on the Z ′ axis from the point O to the point P. The distance F is a distance on the Z ′ axis from the point O to the point Q (mapping point P). Point (U, V) is an intersection of a straight line including the Z ′ axis and the film surface. In this case, the following explanation and formula (F1) are established.

  In order to obtain the eleven camera constants of the above formula (F1), first, six or more points with known real space coordinates (X, Y, Z) and film surface coordinates (U, V) are photographed by the camera. The Next, (X, Y, Z) and (U, V) of each point are substituted into the formula (F1), and a total of 12 or more equations are set. Then, eleven camera constants are obtained by solving these equations by the method of least squares (calibration). If eleven camera constants are obtained, the coordinates (U, V) on the film plane can be obtained for points whose real space coordinates (X, Y, Z) are known.

  On the other hand, in order to obtain the real space coordinates (X, Y, Z) from the coordinates (U, V) on the film plane, the same point is obtained by using two or more cameras with known camera constants. By substituting (U1, V1), (U2, V2)... Into the above equation, four or more equations are set, and (X, Y, Z) is obtained by the least square method.

  In the above method, two cameras are required to obtain the coordinates of one independent point in space. However, with respect to the coordinates of a plurality of points fixed to an object having a size, if the positional relationship between the points (that is, the coordinates of each point in the object coordinate system) is known, the relational expression is the spatial coordinate (X , Y, Z) is added to the equation for obtaining the coordinates, so that the coordinates of a plurality of points can be obtained.

[Step c]
The coordinates of each marker 30 in the object coordinate system (the coordinate system of the club head 2) can be obtained, for example, by measuring a three-dimensional shape of the object. Hereinafter, a case where the spatial coordinates (X, Y, Z) of the representative point of the object and the posture (α, β, γ) of the object are solved as unknowns will be described.

  In the above formula (F3), Ri (x) represents the x component of Ri, Ri (y) represents the y component of Ri, and Ri (z) represents the z component of Ri.

  The simultaneous equations (F3) having six unknowns and 2n equations can be solved by the Newton-Raphson method (solution of nonlinear simultaneous equations). Thereby, six unknowns, that is, the position of the object representative point and the posture of the object can be obtained. Note that α, β, and γ indicate coordinate conversion angles from the space coordinate system to the object coordinate system. In the present embodiment, the coordinate system Cs1 is obtained by rotating the spatial coordinate system XYZ about the Z axis by α °, and the coordinate system Cs2 is obtained by rotating the coordinate system Cs1 by β ° about the Y axis. When the coordinate system Cs3 is rotated by γ ° around the X axis to obtain the coordinate system Cs3, the coordinate system Cs3 coincides with the object coordinate system.

  The 2n simultaneous equations described above are defined as an equation (F3). A method for solving the equation (F3) by the Newton-Raphson method is as follows.

  The above method is an example of a so-called gradient method. This gradient method is simpler in calculation than, for example, the genetic algorithm used in Patent Document 3 above. In this way, based on the relative relationship between points whose coordinates in the object coordinate system are known, from one head image, the spatial coordinates of the representative point of the head and the three-dimensional posture (for example, face angle, lie angle, etc.) ) Can be calculated. Then, the calculation result is output.

  In the detection method as described above, the representative point of the marker 30 (in this embodiment, the centroid of the marker) serves as a reference for calculation, and must be accurately specified. Therefore, the present embodiment is characterized in that a marker 30 whose reflecting surface is a flat surface is fixed to the head 2 of the golf club 1 as a moving body.

  Since the reflecting surface of the marker 30 is a flat surface, as shown in FIG. 12B, even when the marker 30 is imaged obliquely, the centroid b1 of the actual marker 30 is calculated by image processing. It almost coincides with the centroid b2 of the marker. In addition, a part of the marker is hardly hidden and imaged. Therefore, the posture of the moving body can be detected with high accuracy by using the moving body of the present embodiment.

  On the other hand, the crown portion 2b of the head 2 provided with the marker 30 is configured as a smooth curved surface portion that protrudes outward from the head. There are various modes for fixing the marker 30 having a flat reflecting surface to the crown portion 2b having such a curved surface portion. In the following, several representative embodiments are described.

[First Embodiment]
In the first embodiment, as shown in FIG. 6A, the marker 30 is fixed to the crown portion 2 b of the head 2 via the support body 32.

  The outer surface of the crown portion 2b is configured as a curved surface portion that protrudes outward from the head.

  The support body 32 is composed of another member different from the marker 30 and the moving body. The support body 32 is a plate having a small thickness, and has a marker support surface 34 facing the marker 30 side and a fixing surface 36 facing the crown portion 2b side of the head 2 as a moving body.

  The marker support surface 34 of the present embodiment is substantially formed entirely on a flat surface. A marker 30 made of a reflective tape is affixed to the marker support surface 34. The marker 30 may be formed in advance on the marker support surface 34, or may be fixed to the marker support surface 34 after the support 32 is fixed to the head 2.

  In the present embodiment, since the marker 30 is made of a reflective tape having flexibility, at least the marker support surface 34 of the support 32 needs to have a rigidity that does not easily deform the plane state during the swing. From this point of view, the support 32 is preferably made of rubber, resin, or metal material.

  In the present embodiment, the fixing surface 36 of the support body 32 is also substantially entirely flat. An adhesive 38 is filled between the fixing surface 36 and the outer surface of the crown portion 2b. As shown in FIG. 6A, the adhesive 38 fills a gap between the fixing surface 36 and the outer surface of the crown portion 2b. That is, the thickness of the adhesive 38 is gradually increased from the central portion toward the end portion, whereby the flat fixing surface 36 is firmly bonded to the crown portion 2b of the curved portion.

  In such an embodiment, the marker 30 whose reflecting surface 30A forms a flat surface can be fixed to the curved surface portion of the moving body (head 2) with a simple configuration.

[Second Embodiment]
Also in the second embodiment, as shown in FIG. 6B, the marker 30 is fixed to the crown portion 2 b of the head 2 via the support body 32. In the second embodiment, the fixing surface 36 of the support 32 is different from the first embodiment in that the fixing surface 36 has an inverted shape of the outer surface of the crown portion 2b that the fixing surface 36 faces. That is, the adhering surface 36 is configured by a concave curved surface portion that is an inverted shape of the convex curved surface portion of the crown portion 2b. When the fixing surface 36 is placed on the crown portion 2b, the position thereof is stable, and the thickness of the adhesive 36 disposed between the fixing surface 36 and the crown portion 2b can be made uniform. . For this reason, the adhesive strength between the fixing surface 36 and the crown portion 2b is increased.

  The above “reversed shape” means that it is sufficient that the position of both of them is stabilized when the fixing surface 36 of the support 32 is fitted to the outer surface of the moving body (head 2). It should not be construed that the outer surface of the support and the fixing surface 36 of the support 32 must be in complete contact.

  The second embodiment is the same as the first embodiment except for the above differences. In the embodiment of FIG. 6B, the outer surface of the head 2 is a convex curved surface portion, and the corresponding fixing surface 36 of the support 32 is a concave curved surface portion. However, the combination is limited to such a combination. Is not to be done. That is, the outer surface of the head 2 may be a concave curved surface portion, and the fixing surface 36 of the support 32 may be a convex curved surface portion. Furthermore, each surface may be a curved surface in which a convex surface and a concave surface are mixed.

[Third Embodiment]
In the third embodiment as well, as shown in FIG. 6C, the marker 30 is fixed to the crown portion 2 b of the head 2 via the support body 32. The third embodiment is also common to the second embodiment in that the fixing surface 36 of the support 32 has an inverted shape of the outer surface of the crown portion 2b that the fixing surface 36 faces. However, in the third embodiment, the fixing surface 36 of the support body 32 is different from the second embodiment in that the fixing surface 36 is fitted into a recess 40 provided in the crown portion 2b of the head 2.

  According to this embodiment, the position of the moving body and the support body 32 is more stable, and a stronger fixing state can be obtained. Whether or not the adhesive 36 is used together is arbitrarily determined according to the fitting force. About another point, it is the same as 2nd Embodiment.

[Fourth Embodiment]
In the fourth embodiment, as shown in FIG. 7A, the outer surface of the crown portion 2b of the head 2 forming the curved surface portion is cut or plastically deformed. Thereby, the marker support surface 42 which consists of a plane is formed in the outer surface of the crown part 2b. Then, as shown in FIG. 7B, the marker 30 is fixed to the flat marker support surface 42 with an adhesive or an adhesive, so that the reflective surface 30A is a flat marker. It can be fixed to. Needless to say, the cutting process includes a polishing process. The plastic deformation process may include pressing, forging, and the like.

  According to 4th Embodiment, since the support body 32 which consists of another member can be made unnecessary, a number of parts can be reduced.

[Modification of moving body]
In the embodiment, the head 2 of the wood-type golf club 1 is shown as the moving body, but various objects can be adopted as the moving body. In particular, the following sports equipment is preferably used as the moving body.

  FIG. 8A shows a perspective view of a shaft 44 of a golf club as a moving body to which the marker 30 is fixed, and FIG. 8B is a cross-sectional view taken along the line AA. The marker 30 is fixed to the shaft 44 via the support 32. The support body 32 has a marker support surface 34 formed of a flat surface and a fixing surface 36 formed of a concave curved surface having an inverted shape along the cylindrical outer surface of the shaft 44. In such an embodiment, the movement of the shaft can be detected.

  FIG. 9A shows a perspective view of a head 48 of an iron-type golf club as a moving body to which the marker 30 is fixed, and FIG. Has been. The marker 30 is fixed to the top blade 48 a of the head 48 via the support 32. The support 32 has a marker support surface 34 that is a flat surface, and a fixing surface 36 that is a concave curved surface having an inverted shape so as to follow the convex curved surface of the top blade 48a. In such an embodiment, the movement of the head 48 of the iron type golf club can be detected.

  10A shows a front view of a tennis racket 50 as a moving body to which the marker 30 is fixed, and FIG. 10B shows a CC cross-sectional view thereof. A marker 30 is fixed to the top of the frame 52 of the tennis racket 50 via a support 32. As shown in FIG. 10B, the support body 32 has a flat marker support surface 34 and a fixed surface 36 formed of a curved surface having an inverted shape along the curved surface of the frame 52. . In such an embodiment, the movement of the tennis racket being played can be detected.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments and can be implemented with various modifications. For example, as a moving body, various things are used without being limited to sports equipment.

  In order to confirm the effect of the present invention, a marker was fixed to the crown portion of the head of the wood type golf club, and the shaft angle, face angle and lie angle of the club head were measured.

[Example]
The head of the example was fixed with a marker made of white reflective tape using the support shown in the first embodiment. The reflective surface of each marker was a flat surface. The marker was fixed to the crown as shown in FIG.

[Comparative example]
On the other hand, in the comparative example, a marker made of white reflective tape was directly fixed to the head. Each of the reflective surfaces of the markers was a convex curved surface along the outer surface of the crown portion. The fixing position of the marker is the same as in the example.

[Fixing jig for fixing the posture of the head]
A fixing jig was used to fix each head of the example and the comparative example in a desired posture. The fixed jig is a jig in which the head can be placed in any posture (α, β, γ) with respect to a coordinate system unique to the fixed jig (hereinafter referred to as “fixed jig coordinate system”). Note that α, β, and γ in the description of the embodiment for carrying out the present invention, the real space coordinate system is a fixed jig coordinate system, and the object coordinate system is a head-specific coordinate system (hereinafter referred to as “head coordinate system” It is an angle when it says.

[Calibration method]
The calibration for obtaining the camera constant was performed using a fixing jig. Six points with known coordinates in the fixed jig coordinate system were photographed with a camera and calibrated. That is, in this embodiment, the fixed jig coordinate system corresponds to the real space coordinate system described in the embodiment for carrying out the invention, and the head unique coordinate system is the object described in the embodiment for carrying out the invention. Corresponds to the coordinate system.

[Head attitude detection method]
The head posture is detected by shooting a head fixed in a known posture with a fixing jig from above, specifying each marker from the photographed image using a computer, and the positional relationship between the marker representative points ( Based on the coordinates of each marker representative point in the head coordinate system), the shaft angle, face angle, and lie angle of the head were calculated according to the Newton-Raphson method.

In the head coordinate system in this embodiment, as shown in FIG. 3, the end point on the heel side of the face line FL located at the lowermost side among the plurality of face lines is set as the origin O, passes through the origin O, and passes through the face line. The axis passing through the toe side end point of the FL is the X axis, the axis passing through the origin O and extending in the face back direction perpendicular to the X axis and the shaft axis is the Z axis, passing through the origin and the X axis and the Z axis The axis extending to the top of the vertical head is the Y axis. Accordingly, the shaft angle indicates γ of the above posture (α, β, γ), the face angle indicates β, and the lie angle indicates α.
The test results are shown in Tables 1 and 2.

  In Tables 1 and 2, the set values indicate the shaft angle, face angle, and lie angle of the head when held by the fixing jig. The measurement error is the absolute value of the difference between the set value and the calculated value (the values of the head shaft angle, face angle, and lie angle obtained from the captured image of the head by the DLT method). In addition, the “spot” in the left column of Tables 1 and 2 indicates that a hit point on either the toe side or the heel side of the face is assumed. That is, when the hit point is described as “toe”, it is assumed that the ball is hit on the toe side of the face, and the head is placed so that the head is located in the lower part of the photographed image. On the contrary, when the hit point is described as “heel”, it is assumed that the ball is hit on the heel side of the face, and the head is placed so that the head is positioned in the upper part of the captured image.

  As is clear from the test results, both the example and the comparative example include measurement errors. However, the measurement error of the example is 55% for the shaft angle, 26% for the face angle, and 66% for the lie angle compared to the comparative example. Therefore, it was confirmed that the present invention greatly improves the detection accuracy of the moving body.

1 golf club 2 head (moving body)
2B Crown 30 Marker 32 Support 34 Marker Support Surface 36 Adhering Surface 38 Adhesive

Claims (11)

Use in a method for detecting a moving body, which includes a step of imaging a moving body to which a marker having a reflective surface for reflecting light is fixed with a camera, and a step of detecting a posture of the moving body based on the imaged marker. A movable body,
The marker is a moving body characterized in that the reflecting surface is a flat surface.   The moving body according to claim 1, wherein the marker is fixed to a curved surface portion of the moving body. A support is disposed between the marker and the moving body,
The said support body is a moving body of Claim 1 or 2 including the marker support surface which faces the said marker side and consists of a plane.   The moving body according to claim 3, wherein the support has a fixing surface facing the moving body, and an adhesive is filled between the fixing surface and the moving body.   The moving body according to claim 3, wherein the support has a fixing surface facing the moving body, and the fixing surface has an inverted shape of an outer surface of the moving body facing the fixing surface.   The moving body according to any one of claims 1 to 5, wherein the moving body is a sporting tool that moves by an operation of a player. Use in a method for detecting a moving body, which includes a step of imaging a moving body to which a marker having a reflective surface for reflecting light is fixed with a camera, and a step of detecting a posture of the moving body based on the imaged marker. A method for adhering the marker to the moving body, comprising:
A method for adhering a marker to a moving body, comprising the step of adhering the marker to an outer surface of the moving body so that the reflecting surface is a flat surface.   The method of adhering a marker to a moving body according to claim 7, wherein the step of adhering the marker includes a step of providing a marker support surface including a flat surface on a curved surface portion of an outer surface of the moving body.   9. The method for fixing a marker to a moving body according to claim 8, wherein the marker supporting surface is provided by fixing a supporting body made of a different member different from the marker and the moving body to a curved surface portion of the moving body.   The method of adhering a marker to a moving body according to claim 9, wherein the marker is formed in advance on the marker supporting surface, or is fixed to the marker supporting surface after the supporting body is fixed to the moving body. .   The method of adhering a marker to a moving body according to claim 8, wherein the marker support surface is provided by cutting or plastically deforming the curved surface portion of the moving body.

Images