Position control of a manipulator with one flexible link

Flexible link manipulators are characterized by a low tip positioning precision due to vibration. To overcome this problem, in this work we implement control schemes that combine feedback control with feedforward control. The use of feedback control of the tip position to reduce the tip vibration typically suffers from non-minimum phase related problems. Therefore, we use feedback control just for joint angle control while the vibration of the end-effector is reduced with feedforward control. Two feedback controllers have been implemented and compared: feedback linearization and sliding mode control. For the feedforward control we use filtering techniques and the input shaping technique. The controllers were tested experimentally on a two joint planar manipulator with a flexible link.