US20180243627A1

US20180243627A1 - Measuring system and measuring method

Info

Publication number: US20180243627A1
Application number: US15/877,696
Authority: US
Inventors: Tomotaka ISHIHARA
Original assignee: Bridgestone Sports Co Ltd
Current assignee: Bridgestone Sports Co Ltd
Priority date: 2017-02-28
Filing date: 2018-01-23
Publication date: 2018-08-30
Also published as: JP6876466B2; JP2018140082A

Abstract

A measuring system includes a first measuring unit configured to be attached to a golfer, a second measuring unit configured to measure a floor reaction force of each of left and right leg portions of the golfer, and a specifying unit configured to specify a swing start timing of the golfer based on measurement results of the first measuring unit and the second measuring unit.

Description

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a measuring technique of a golf swing.

Description of the Related Art

There have been proposed techniques of analyzing a swing to improve a swing of a golfer or improve equipment (Japanese Patent Laid-Open Nos. 2016-209180, 2015-178026, 2012-254205, 2002-034609, and 2014-224769).
In swing analysis, data that needs to be analyzed is extracted from measurement data measured during a swing and analyzed. For the swing analysis, data after a swing start timing are often important. In many cases, data before the swing start timing are not important, and if these data are included in the analysis range, the analysis accuracy is influenced. As a method of specifying the swing start timing, Japanese Patent Laid-Open Nos. 2016-209180, 2015-178026, and 2012-254205 disclose methods each based on the angular velocity of a club or an arm. There is room for improvement from the viewpoint of specifying accuracy.

SUMMARY OF THE INVENTION

It is an object of the present invention to improve the specifying accuracy of a swing start timing.
According to an aspect of the present invention, there is provided a measuring system comprising: a first measuring unit configured to be attached to a golfer; a second measuring unit configured to measure a floor reaction force of each of left and right leg portions of the golfer; and a specifying unit configured to specify a swing start timing of the golfer based on measurement results of the first measuring unit and the second measuring unit.
According to another aspect of the present invention, there is provided a measuring method comprising: acquiring a measurement result of each of a first measuring unit configured to be attached to a golfer and a second measuring unit configured to measure a floor reaction force of each of left and right leg portions of the golfer; and specifying a swing start timing of the golfer based on the measurement results of the first measuring unit and the second measuring unit.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a measuring system according to an embodiment of the present invention;

FIG. 2A is an explanatory view of a force plate;

FIG. 2B is an explanatory view of a center of foot pressure;

FIG. 2C is an explanatory view of an angular velocity about a horizontal axis;

FIG. 3 is a flowchart showing an example of processing executed by a processing device;

FIGS. 4A to 4C are explanatory views of examples of measurement results; and

FIG. 4D is an explanatory view of an example of specifying of a start timing.

DESCRIPTION OF THE EMBODIMENTS

<Arrangement of System>
FIG. 1 is a schematic view of a measuring system A according to an embodiment of the present invention. The measuring system A includes a pair of force plates 1R and 1L, measuring units 2 to 5, a processing device 6, a display device 7, and an input device 8. Arrows X, Y, and Z represent the three-dimensional coordinate system of a test shot box in the measuring system A. The force plates 1R and 1L and the measuring units 2 to 4 are placed in correspondence with the coordinate system. The arrows X and Y represent horizontal directions orthogonal to each other, and the arrow Z represents the vertical direction. The arrow X is set to the target line direction of a golf ball.
The force plates 1R and 1L constitute a measuring unit that measures the floor reaction forces of the left and right leg portions of a golfer. The force plates 1R and 1L are arranged in the X direction. The force plate 1R is expected to measure the floor reaction force of the right leg of the golfer, and the force plate 1L is expected to measure the floor reaction force of the left leg of the golfer. A golfer 100 to be measured places the right leg on the force plate 1R and the left leg on the force plate 1L. In the following explanation, the force plates 1R and 1L will be referred to as a force plate 1 if they are not distinguished.
Note that in this embodiment, the pair of force plates 1R and 1L are used in correspondence with the left and right leg portions of the golfer. However, a single force plate capable of measuring the floor reaction force of each of the left and right leg portions can also be employed.
The force plate 1 can measure, for example, translational forces in the three, X, Y, and Z axial directions and a moment about the Z-axis as floor reaction forces. FIG. 2A is a schematic view showing an example of the force plate 1. The force plate 1 is formed by arranging a plurality of load sensors 13 between a main body 11 and a footboard 12. Translational forces Fx, Fy, and Fz in the three axial directions and a moment Mz about the Z-axis are derived from the detection results of the plurality of load sensors 13.
The force plate 1 can also derive the position and size of the center of foot pressure from the detection results of the plurality of load sensors 13. As shown in FIG. 2B, let RCOP be the center of foot pressure of the right leg detected by the force plate 1R, and LCOP be the center of foot pressure of the left leg detected by the force plate 1L. A center COP of foot pressure for both legs as a whole can be calculated from the positions and sizes of the centers RCOP and LCOP of foot pressure. The center COP of foot pressure is located on a line connecting the centers RCOP and LCOP of foot pressure at a position according to the ratio of the sizes of the centers RCOP and LCOP of foot pressure. If the centers RCOP and LCOP of foot pressure have the same size, the center COP of foot pressure is located at the middle point. If the center RCOP of foot pressure is larger, the center COP of foot pressure is located close to the side of the center RCOP of foot pressure;
A change in the center COP of foot pressure over time can be considered as the moving velocity of the center COP of foot pressure. In the following description, the moving velocity of the center COP of foot pressure in the X direction will be referred to as the velocity V, the velocity to the rear side of the target line will be defined as negative, and the velocity to the front side of the target line will be defined as positive.
Referring back to FIG. 1, the measuring unit 2 includes at least an angular velocity sensor. As the measuring unit 2, for example, TSND121 available from ATR-Promotions can be used. The measuring unit 2 is attached to the golfer 100. For example, the measuring unit 2 is attached to the trunk of the body. In the example shown in FIG. 1, the measuring unit 2 is attached at the position of the waist. The measuring unit 2 is attached on the back side in the example shown in FIG. 1 but may be attached on the breast side. As shown in FIG. 2C, the measuring unit 2 measures an angular velocity ω of the golfer 100 during a swing. The angular velocity ω almost corresponds to the angular velocity about the spine of the golfer 100.
Referring to FIG. 1, the measuring unit 3 detects an impact. In this embodiment, an impact timing is detected based on a striking sound. For this purpose, the measuring unit 3 is a microphone, and is arranged near an impact area.
The measuring unit 4 includes an inertial sensor (at least one of an acceleration sensor and an angular velocity sensor), and is attached to the grip or shaft of a golf club 101. As the measuring unit 4, for example, TSND121 available from ATR-Promotions can be used. The measurement result of the measuring unit 4 can be used in the swing analysis of the golfer. Additionally, an impact may be detected based on the detection result of not the measuring unit 3 but the measuring unit 4. At the time of impact, the acceleration or angular velocity of the golf club 101 abruptly changes. Hence, the timing of the peak of the change in the detection result of the measuring unit 4 can be detected as the timing of the impact.
The measuring unit 5 measures the head speed of the golf club 101 or the ball flight of a shot. In the example shown in FIG. 1, the measuring unit 5 is a ball flight measuring instrument arranged on the rear side of the target line with respect to the golf ball to be struck. As such a measuring instrument, for example, TRACKMAN available from TRACKMAN can be used. The measurement result of the measuring unit 5 can be used in the swing analysis of the golfer. For the purpose of measuring the head speed, as the measuring unit 5, a measuring instrument that is arranged on the front side near the golf ball to be struck and measures the passage and the passage time of the golf club head may be used in place of the ball flight measuring instrument, as shown as, for example, a measuring unit 5′.
The processing device 6 can be formed from a general personal computer. The processing device 6 includes a processing unit 61, a storage unit 62, and an I/F unit (interface unit) 63 which are electrically connected to each other. The processing unit 61 is a processor such as a CPU. The storage unit 62 includes one or a plurality of storage devices. The storage devices are, for example, a RAM, a ROM, a hard disk, and the like. The storage unit 62 stores a program to be executed by the processing unit 61 and various kinds of data. The program to be executed by the processing unit 61 can be formed from a plurality of instructions readable by the processing unit 61.
The I/F unit 63 performs input/output of data between an external device and the processing unit 61. The I/F unit 63 can include an I/O interface and a communication interface. The measuring units 2 to 5 are communicably connected to the processing device 6 by wired communication or wireless communication, and the detection results of the measuring units are acquired by the processing device 6.
The display device 7 and the input device 8 are connected to the processing device 6. The display device 7 is, for example, an electronic image display device such as a liquid crystal display device and displays the processing result of the processing device 6. The input device 8 is a mouse or a keyboard and is used by a measurer to do data input or operation instruction for the processing device 6.
<Example of Measurement Processing>
An example of a measurement processing program executed by the processing unit 61 will be described with reference to FIG. 3. FIG. 3 is a flowchart of the measurement processing program. In this embodiment, the golfer 100 is caused to make a test shot of a golf ball using the golf club 101. Then, the measuring units 2 to 5 analyze the swing of the golfer.
In step S1, initial setting is done. Here, various kinds of settings necessary for analysis are done. When the initial setting ends, the golfer 100 is made to prepare for striking. At the same time as the start of measurement in step S2, the golfer is made to stand on the force plate 1 and strike the golf ball. When the measurement starts, the measurement results (measurement data) of the measuring units 2 to 5 for each minute time are acquired and stored together with the information of time. As the storage destination, the storage unit 62 can be used. However, the data may be stored in a data logger provided outside the processing device 6. The measurement is performed only for a sufficient time from the start to end of the swing of the golfer 100. The end of measurement may be defined by a time, or may be defined by an operation of the measurer.
In step S3, the start timing of the swing is specified from the measurement data acquired in step S2. Details will be described later. In step S4, of the measurement data acquired in step S2, the range of data to be used in swing analysis is set. All measurement data acquired in step S2 may be used to calculate energy, but it may be inefficient. In this embodiment, the start timing of the swing is specified in step S3, thereby excluding data before the start of the swing from the range of data to be used in swing analysis. Accordingly, it is possible to exclude, for example, the preparing motion of the golfer before the swing from the measurement data and accurately analyze the energy exhibited by the golfer during the swing.
In step S5, swing analysis is performed using the measurement data within the range set in step S4. The contents of the swing analysis can include, for example, various kinds of analysis of the relationship between the energy exhibited by the golfer during the swing and energy used for the striking, the track of the golf club, and the like. The analysis result can be displayed on the display device 7. Processing of one unit thus ends.
<Example of Specifying of Swing Start Timing>
An example of specifying of the swing start timing in step S3 will be described with reference to FIGS. 4A to 4D. In this embodiment, the swing start timing is specified based on the measurement results of the force plate 1 and the measuring unit 2. The specifying accuracy of the swing start timing can be improved by using two types of measurement results. In particular, when the measurement result of the measuring unit 1 is used, the swing start timing can be specified while reducing the influence of a waggle and the like.
FIG. 4A shows the range of measurement data (target data) to be used to specify the swing start timing. The measurement data acquired in step S2 includes measurement data in a state in which the golfer is not substantially making a swing. When specifying the swing start timing, if all the measurement data of the measuring units 1 and 2 acquired in step S2 are used, the calculation or accuracy may be influenced. To prevent this, in this embodiment, measurement data within a predetermined period back from the impact timing is used.
In FIG. 4A, time t0 represents the start timing of measurement, and time ti represents an impact timing. As for the impact timing, a timing specified from the measurement data of the measuring unit 3, at which the sound pressure abruptly rises, can be specified as the impact timing. The target data is measurement data up to time t1 back a time T from the time ti. In other words, measurement data of the force plate 1 and the measuring unit 2 from the time t1 to the time ti are used to specify the swing start timing. The time T is, for example, several sec (for example, 2 sec).
When starting a swing, in general, a golfer almost comes to rest at least for a moment. In this embodiment, the timing when the golfer has come to rest is specified from the angular velocity ω and the moving velocity V, and used as the swing start timing. First, the angular velocity ω will be described.
FIG. 4B shows a change in the angular velocity ω from the time t1 to the time ti. In a section in which the angular velocity ω falls within the range of threshold 1, the behavior of the golfer about the Z-axis is regarded as rest. Threshold 1 is, for example, ±0.1 rad/sec. In the example shown in FIG. 4B, the angular velocity ω falls within the range of threshold 1 in sections R11 and R12.
The moving velocity V will be described next. FIG. 4C shows a change in the moving velocity V from the time t1 to the time ti. In a section in which the moving velocity V falls within the range of threshold 2, the behavior of the golfer in the X direction is regarded as rest. Threshold 2 is, for example, ±100 mm/sec. In the example shown in FIG. 4C, the moving velocity V falls within the range of threshold 2 in sections R21 to R26.
Next, a section in which the angular velocity ω falls within the range of threshold 1, and the moving velocity V falls within the range of threshold 2 is extracted. FIG. 4D shows an extraction result, and sections R31 and R32 are extracted sections. Of the sections R31 and R32, the latest time is specified as the swing start timing. When the angular velocity ω and the moving velocity V are used, the swing start timing can accurately be specified. For example, if the swing start timing should be specified using only the angular velocity ω, depending on the golfer, the angular velocity may exceed the threshold only in the preparing motion before a swing, and it may be impossible to accurately specify the swing start timing.
When the swing start timing is specified in the above-described manner, the specifying accuracy of the swing start timing can be improved. In the above embodiment, the swing start timing is specified using the angular velocity ω and the moving velocity V. Although the moving distance or moving angle of the center COP of foot pressure may be used in place of the moving velocity V, the moving velocity V is preferably used.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefits of Japanese Patent Application No. 2017-037472, filed Feb. 28, 2017, which is hereby incorporated by reference herein in its entirety.

Claims

What is claimed is:

1. A measuring system comprising:

a first measuring unit configured to be attached to a golfer;

a second measuring unit configured to measure a floor reaction force of each of left and right leg portions of the golfer; and

a specifying unit configured to specify a swing start timing of the golfer based on measurement results of the first measuring unit and the second measuring unit.

2. The system according to claim 1, wherein the specifying unit specifies, as the swing start timing, a timing at which a first value of a behavior of the golfer based on the measurement result of the first measuring unit falls within a first threshold range, and a second value of the behavior of the golfer based on the measurement result of the second measuring unit falls within a second threshold range.

3. The system according to claim 1, wherein an angular velocity of the golfer is measured by the first measuring unit.

4. The system according to claim 1, wherein a moving velocity of a center of foot pressure of the golfer is measured by the second measuring unit.

5. The system according to claim 1, further comprising a third measuring unit configured to detect an impact,

wherein the specifying unit specifies the swing start timing based on, of the measurement results of the first measuring unit and the second measuring unit during a swing, a measurement result within a predetermined period back from a timing of the impact measured by the third measuring unit.

6. A measuring method comprising:

acquiring a measurement result of each of a first measuring unit configured to be attached to a golfer and a second measuring unit configured to measure a floor reaction force of each of left and right leg portions of the golfer; and

specifying a swing start timing of the golfer based on the measurement results of the first measuring unit and the second measuring unit.