Hybrid position/force control of a spatial compliant mechanism

This paper provides a hybrid position/force control design for a flexible L-shape mechanism in a three dimensional (3D) environment. The analytical mechanism model was developed with a highly accurate dynamic system based on equivalent rigid link system theory and finite element discretisation without the need for any dedicated force/torque sensors. The gravity force and dynamic model nonlinear parameters were taken into account. This paper also presents and describes a real-time approach based on a comparison between joint acceleration and the time evolution of a simplified rigid mechanism model for estimating external forces applied on the tip of the mechanism. The most significant simulation results are presented and discussed; in particular, position controller has a high accuracy in terms of trajectory tracking with max error of 2.6 degree.