Performance prediction of the badminton racket

(Modelling and boundary condition on the prediction)

Abstract

The purpose of this study was to derive a dynamic equation which quantifies dynamical roles of joint torque inputs considering mechanical elements of racket such as strings, frame, shaft and grip handle during badminton smash motion. The racket shaft was divided into a set of rigid segments connecting to its adjacent segments via virtual joints with rotational springs. The deformation of racket shaft was approximated by using a 2nd order polynomial function from measured data during swing motion. The string is modelled as an elastic cord intersecting with each other. Displacements of the cross points of the cord with forced displacement input was calculated by using an equation which simulates the deformation of the cord. Grip firmness is modelled by setting spring and damper between racket-grip handle and hand. Combining all equation regarding racket deformation and human dynamics, a recurrent formula of expanded generalized velocity vector consisting of generalized velocity vector of system, grip displacement and shaft deformation was derived.