Stable contact force control of a link manipulator with collision phenomena

A methodology using the Lyapunov direct method is proposed to analyze the stability of a one-link manipulator system which is positioned on a flexible wall with collision phenomenon. Experimental results of collision control are included. As collision is a phenomenon with energy loss, it is considered to have a stabilizing effect to a system which includes collision. However, from the point of view of robotics, a controlled system shows poor controllability, if collision occurs. The authors have adopted a Herz-type model with energy loss parameter to express the impact force between the manipulator and the wall. Using this model, they prove the stabilizing effect of collision using the Lyapunov method. An experiment was also carried out to show the possibility of stable control including collision using sensor-based force control. As a result, the stable contact control of the manipulator on the flexible object is assured