Compliant humanoid robot control by the torque transformer

Abstract

This paper presents a new control architecture for compliant motion control and safe physical interaction between humanoid robot and human. One of the key technologies in this framework is the torque transformer, which enables the implementation of joint torque control on the traditional joint position controlled robots. In this framework, the torque control is accomplished by converting desired joint torque command into instantaneous increments of joint velocity command. Through the transformer, the Operational Space Formulation was applied to account for the dynamics of the system on the current joint position controlled robots. This approach was experimentally implemented on the physical humanoid robot, HONDA ASIMO's upper body control. The ZMP based stable balance controller of ASIMO was integrated to control the lower body of the robot. In this framework, dynamics control by the torque transformer and stable position based balance controller were connected and coordinated together on the current position controlled humanoid robot. The paper presents modeling process of the torque transformer, whole body controller and the results of the implementation which demonstrate the effectiveness of this approach.