Measurement of Up/Down Motion in Sports

Abstract

It is interesting and significant if sport players can detect their playing form by themselves and feed back it in their training. This paper describes a new up/down sports motion sensor which is compact, not heavy, economical, free in setting to humans.
The sensor detects the up/down speed by differentiating the atmospheric pressure decreasing in proportional to the height. The change in atmospheric pressure is detected by using condenser microphones as the fine pressure detectors. The fine pressure detectors by the microphones involve the problems of characteristic in the low frequency range. Further because of its high sensitivity, the condenser microphones detect not only the change in atmospheric pressure due to up/down motion but also the pressure disturbances of air in the microphone chamber especially due to the acceleration and the kinetic energy component accompanied with the sport motion.
Here we investigated how the various pressures acted to the pressure detection surface of the microphone when moving, influence to the measurement of the up/down motion in sports and presented a new up/down speed sensor that catches only the atmospheric pressure change. Validity of the method was examined by detecting the up/down speed of head of a golf player when swinging.