Improvement in force control with force projection for 2-DOF tendon-driven spherical joint mechanisms

Recently, more and more master-slave robots have been developed. Those robots can make contacts with remote environment with appropriate force when force sensation is transmitted to operators with bilateral control. The transmitted force sensation depends on the performance of force control. In addition, human cannot feel clear force sensation when the robot has large inertia because manipulating them smoothly is hard. Therefore, tendon-driven spherical joint mechanisms are suited for the system. However, precise force control for the mechanisms has not been proposed. In this research, force control for the mechanisms is proposed. The method utilizes projection of force acting on the sphere. In addition, the compensation of disturbance force is also realized by projecting the force to the plane. The results of experiments show realization of precise force control and compensation of disturbance force.