In playing the golf, using suitable golf club is important to put out high score and to hit the correct shot. So various manufacturers develop the system which suggest for golfers to suitable golf club. For golf club suggestion, it is necessary to analyze golf swing. Especially, it is important to analyze that the changes of the golf swing due to golf club characteristics. If we elucidate the change of golf swing, we could suggest the golf club that is more suitable for golfers. In this study, we thought that we could confirm　the changes of golf swing by analyzing torque data golfers exert. So, we analyzed the change of torque data due to mass difference of golf club shafts using “Short Time Fourier Transform” (hereinafter called “STFT”). First, we measured the golf swing of multiple golfers using two shafts different mass by a motion capture system (VICON). We created a 3D rigid body model consisting of arm and club link from measured data. We calculated torque data golfer exerted during the golf swing by inverse dynamics calculation. Then, we examined the length of the window function and the number of overlaps as preparing of STFT and determined them. We confirmed how fluctuate spectrum data during the golf swing, after applied STFT. Finally, we investigated spectrum fluctuation data due to mass difference of golf club shafts. As a result, we found common points between golfers and were able to divide golfers into groups based on them.

Short Time Fourier Transform,golf swing,inverse dynamics calculation,torque analysis