Digital control of a flexible manipulator

Investigates a digital control technique applicable to motion and vibration control of a flexible manipulator in both horizontal and vertical planes under the influence of gravity. Discrete-time system identification has been performed to obtain an appropriate model for control without the need of much a priori knowledge about the manipulator system. The model identified is of minimum order for a flexible manipulator. Based on the identified model, a discrete-time pole-placement controller can be easily designed to give desired dynamic response in closed loop. The desired closed-loop poles have been chosen by considering sensitivity function characteristics to improve robustness of the resulting system. It is important to note that the influence of gravity in vertical motion can be compensated by adding an explicit control loop to supply the torque required to support the weight of the manipulator. Despite being of low order, the proposed digital pole-placement controller has been shown experimentally to be very effective.