A simple active damping control for compliant base manipulators

When a robotic manipulator is mounted to a crane, boom or mobile platform, it loses its accuracy and speed due to the compliance of the base. This paper presents a simple robust control strategy that will reduce mechanical vibrations and enable better tip positioning. The control algorithm uses the sensory feedback of the base oscillation to modulate the manipulator actuator input to induce the inertial damping forces. The authors' previous work (1999) demonstrated the feasibility of the proposed concept using linear analysis. This work extends the concept to a more general case of a nonlinear multiple link manipulator using acceleration feedback and one sample delayed torque. A simulation and an experimental study show very promising results for a test bed consisting of a two-link manipulator and a compliant base.