A composite algorithm for flow rate and ground reaction force reduction in a hydraulic actuated quadruped robot with kinematic redundancy

A hydraulic actuator has merits of high torque and small size. So it is very useful for a standalone type walking robot. But this hydraulic actuator needs a hydraulic power pack which supplies pressure and flow rate to generate the torque. The weight of the hydraulic power pack is in proportion to the supply pressure and the supply flow. Therefore to generate high torque and large flow, a big and heavy power pack is needed. Especially this hydraulic power pack is a burden to the standalone type walking robot. So a lightweight hydraulic power pack is required for the standalone type walking robot. Also ground reaction force is a major reason to make balancing of the robot unstable in walking robot. In this paper, we propose a redundantly actuated quadruped robot which is actuated by hydraulic actuator. Using the kinematic redundancy of each leg mechanism, flow rate and ground reaction force reduction algorithm is proposed simultaneously. We demonstrate the reduction of the flow rate and ground reaction force of the robot through simulation and experiment.