Constrained motion control of robots with task constraints identification by US sensing

The use of ultrasonic range sensing in constrained motion control of robots is investigated. An ultrasonic sensing system is integrated into a force/position control scheme and allows online identification of the motion constraints during contact with a partially unknown environment. Measurement of the relative distance of the end effector from the surface is used to obtain a fast but safe approach motion. A planar three-dimensional task space is considered in a case study; thus two translational/force components and one rotation/torque component are of interest. Experimental results on a PUMA-560 manipulator show the effectiveness of the scheme