Analysis of torque capacities in hybrid actuation for human-friendly robot design

A formidable challenge in the development of human-friendly robots is to simultaneously achieve desired levels of performance and safety. To address this issue, a hybrid actuation concept has been proposed, combining large, low impedance actuators and small, high-frequency actuators. However, the determination of design parameters remains a challenge, as stiffness and electrical motor torque capacity simultaneously affect both the control performance and the safety of the manipulator. Using analytical models of the hybrid actuation system, we propose a methodology to achieve a combination of low impedance and high control bandwidth. The optimized parameters are verified and compared with previous ones through simulation and experimentation.