Immediate feedback of generating mechanism of articulate movement using IMUs

Abstract

The purpose of this study was to examine the possibility of a system which can act immediate feedback of generating mechanism of ball throwing motions in different sports (baseball and handball) using inertial measurement units (IMUs). The IMUs were attached on the upper trunk, upper arm, fore arm and hand segments. The posture of each segment was estimated from the angular velocity outputs of the IMUs. Dynamics contribution analyses were carried out with respect to the estimated motion. The contributions of the individual terms such as, joint torque term, gravitational force term, and motion-dependent term (MDT) to the generation of ball speed were quantified using the equation of the target system with estimated segmental postures. Furthermore, the generating factor of the MDT was considered using a recurrent formula derived from the equation of motion for the target system. The results of this study show that almost good agreements between estimated motions with IMU outputs and measured motions obtained by a motion-capture system in terms of generating mechanism of ball speed. Moreover, dynamic contribution analysis obtained from estimated motion data could show the difference in terms of generating mechanism of ball speed in throwing motion by balls of different sports. Constructing immediate feedback system with respect to the speed generating mechanism using IMUs would be expected to evaluate generating mechanism at sports fields.