Experiments with flexible manipulators

Abstract A robot system is considered which consists of two elastic links (bending and torsional deflection), three flexible joints for elbow and shoulder and two rigid joints for the gripper. This leads to eight degrees of freedom for the rigid body motion of the system, five of which are assigned to motor torque inputs. The remaining three dof describe the gross motion of the system in space. They are superimposed by small elastic deflections. The aim of the present investigation is to evaluate an optimal endpoint control (gripper movement) for a prescribed path in space or on a given surface including a prescribed force which acts on the gripper. The control is hereby divided into three steps, only one of them being on-line calculated and thus coming out with minimum effort. The results are proven by several experiments like fitting a snapper, moving a liquid-filled glass along a spatial path and surface polishing.