Special Issue: 81st Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM)
When robots should work in interaction with humans, the robots have to comply. Not only the human is acting in the environment of the robot, the environment itself is vaguely defined.
A modular articulated redundant robot with 7 joints is considered. The joints are actuated by brushless DC motors combined with Harmonic Drive gears.
The development of the differential equations of the robot is done with the projection equation in subsystem description. The resulting dynamic behavior is used for feedback control design. To obtain the robust numerical inverse kinematics, singular value avoidance and additional conditions have to be added like joint damping and the limits of working space.
Three different impedance controllers for human robot interaction are considered. The first active one uses a 6 axes force/torque sensor to regulate the compliance in joint space. The second one performs the same task in Cartesian space with respect to the end-effector.
The passive approach does not require additional sensors at all and also includes the null-space of the redundant structure in addition to Cartesian end-effector movements. This scheme is based solely on the feedback of joint positions and their time derivatives. Measurements and simulation results are presented.