Mechanism and Control of Whole-Body Electro-Hydrostatic Actuator Driven Humanoid Robot Hydra

Field robots are gaining attentions that they can perform the tasks where human cannot reach. Improvement on physical performance of robots is a fundamental issue. Backdrivability is a key mechanical feature of actuators that enables robust and stable interaction of robots with environment. We developed a humanoid robot HYDRA with backdrivable hydraulic actuators. Parallel mechanism is used extensively in multi-DOF joints to efficiently use actuator force. In this paper, mechanical structure of Hydra with backdrivability and mechanical strength is treated. Also, realtime control of hydraulic actuators that utilize backdrivability, and realtime control of robot joint systems with parallel kinematic chains are explained.