Force-controllable Quadruped Robot System with Capacitive-type Joint Torque Sensor

This paper introduces a force-controllable quadruped robot system consists of twelve Actuator Modules embedded a novel Capacitive-type Joint Torque Sensor (CJTS) which is accurate (0.05 Nm), robust to impact, and easy to manufacture at low cost. The Actuator Module with CJTS shows accurate joint torque controllability in range of ±70 Nm (90 % settling time 0.04 s). The leg made by the three Actuator Modules is capable of generating forces in the z-axis up to 350 N and shows force control performances with zero-force control and lifting weights in three-dimensional space. To reduce the reflected limb inertia, all the Actuator Modules are located on the body frame and light-weight limbs made of the carbon pipe (3.6 % of total body weight). The introduced robot performed the motion on various terrains with walking/trot gaits.