Development of a 7DOF soft manipulator arm for the compliant humanoid robot COMAN

This paper presents the design and implementation of an intrinsically soft arm system for the COMpliant huMANoid COMAN robot. The two arms (left and right) use state-of-the-art technologies on actuator design that combine both active and passive compliance principles. Robustness of the arms is ensured by integrating intrinsic Series Elastic Actuation (SEA) into the joints to protect the arm at the initial time of the impacts while impedance control based on joint torque sensing and feedback permits the regulation of arm stiffness and damping properties and provides enhanced physical interaction performance. The tuning of the intrinsic stiffness level of the compliant joints is performed by a systematic method to obtain desired performance. A rich sensing system is developed to allow implementation of advanced control algorithms. The functionality of the arms was validated in several tasks requiring high payload, rich sensing ability, and compliant interaction.