Design of a joint actuation module for external force detection

A joint actuation module has been developed by the author. It is able to detect joint external force or moment by unplanned collision between the robot manipulator and the environment. For this purpose it has joint torque sensor equipped on between the link and the flexspline of the harmonic drive. The limited stiffness of the harmonic drive and the joint torque sensor makes the joint actuator is deformed when the actuator generates joint torque or the external moment is applied to it. In this reason, the actuation module has double encoder system. One is equipped on the rotor shaft of the BLDC motor and the other is equipped behind of the first encoder to detect the joint rotation including rotor rotation and the rotational deformation of the harmonic drive and the joint torque sensor. The research results will be introduced.