Biomimetic object impedance control for dual-arm cooperative 7-DOF manipulators

To mimic human behavior is an increasing trend for advanced robot control. In this paper, a novel biomimetic object impedance control strategy (BOI) is presented for dual-arm cooperative 7-DOF humanoid manipulators. A general impedance architecture comprising internal impedance control and object impedance control is adopted, which aims at conferring impedance behavior both in end-effector level and object level. Asymptotic stability and convergence of this controller are strictly derived from Lyapunov stability theory. Compared with conventional object impedance, the proposed controller can show different object impedance characteristics according to the external force applied on the object. It also can simultaneously minimize the energy cost of the adaptation process. Simulation and experimental results indicate that this controller exhibits explicit compliance behavior when the interaction with environment is weak and presents accumulation property of the stiffness and damping accordingly when the interaction is strong. This human-like characteristic enables the object/dual-arm system to deal with complex and unknown environmental disturbances.