Stability and control of elastic-joint robotic manipulators during constrained-motion tasks

The effect of a major source of manipulator compliance, namely, the elasticity of manipulator joints, on the overall stability of robot manipulators during constrained-motion task execution is examined. The stability of the elastic-joint manipulator during constrained-motion contact is investigated separately for the case of two controls applied to the manipulator. Using results from the theory of singular perturbations, the stability of the robotic system is established with a `rigid´ control law applied. The stability of the robotic system is again established using this technique for the case of a `rigid´ control law with a corrective term applied to compensate for joint flexibility applied. It is theoretically established that the presence of joint elasticity does not lead to a destabilizing effect on the manipulator. Numerical simulation results for a two-degree-of-freedom flexible-joint manipulator during constrained-motion task execution confirm the theoretical results