Masaki Hokari

Kinematical analysis and measurement of sports form

This study describes a method for the measurement of sports form. The data obtained can be used for quantitative sports-skill evaluation. Here, we focus on the golf-driver-swing form, which is difficult to measure and also difficult to improve. The measurement method presented was derived by kinematical human-body model analysis. The system was developed using three-dimensional (3-D) rate gyro sensors set at positions on the body that express the 3-D rotations and translations during the golf swing. The system accurately measures the golf-driver-swing form of golfers. Data obtained by this system can be related quantitatively to skill criteria as expressed in respected golf lesson textbooks. Quantitative data for criteria geared toward a novice golfer and a midlevel player are equally useful

Measurement of 3-D Loci and Attitudes of the Golf Driver Head While Swinging

This paper describes a novel method to measure the loci and attitudes of a high-speed moving object in a three-dimensional space. Here, the method to the golf driver head is applied. The employed sensor is a line-charge-coupled device (CCD) camera with a high-speed scanning. Because the camera captures only one-dimensional (line) information in a two-dimensional image, the scanning speed is very high. During a measurement, the line-CCD camera captures the positions of markers located on the driver head. Simple signal processing yields the position at every scan interval and estimates the loci and attitudes of the golf club head. Here, the method to the golf head motion measurement is applied: However, it can be applied to a variety of high-speed moving objects other than a driver head

Estimation of Golf Club Head and Ball Motions by Neural Network

In sports that are one of the life science fields, the performance of tools such as wear, shoes, clubs and so on advances remarkably, and the record has improved spectacularly. However, it tends to the restriction of “tools that expand distance of a jump” in golf that is one of ball sports toward the target in the distance. The improvement of the sports skill will need not only improvement of tools performance but also improvement of humans sports skill in the future. In the previous paper, we related the golfers cock-roll motions in the golf driver swing and eight club head and/or ball motions (head velocity, ball velocity, upper angle, side angle, back spin, side spin, carry and traverse) by experiment and multiple regression analysis method. In this paper, the club performance is newly added to the explaining variable. Moreover, by using measured variables and/or factors, the estimated system at head and ball velocity based on the neural network is proposed. When the estimated value by the suggesting method is compared with the measurement value, the maximum error margin and the average error margin are smaller. When the presumption value is compared with the measurement value, the maximum and the average error of the suggesting method are smaller than that of the previous method. Using the sensitivity analysis, we found that the most important factors in improving the head velocity and ball velocity

Measurement and Analysis of Arm Motion in Golf Club Swing

To measure and analyze the golf swing form, there is a method that uses a high-speed camera or video camera. However, it is difficult to measure the motion of a thin part like the wrist or ankle by using this method. In golf, the cock motion is one of the wrist motions that is done at the near point of contact between the body and the club. It is regarded as the position that transmits the energy stored in the rotation of the body to the club. In this paper, we proposed a new measurement method that uses a gyro sensor in order to measure cock motion. To measure this motion, the sensor was attached to the left wrist and the forearm. Finally, the features of the cock motions that middle and novice class players exhibit were measured by the experiment. Although this method was developed for cock motion measurement in golf swing, it can be applied to baseball, tennis and so on.