Force unloading of a flexible manipulator link

A new approach to the design of light manipulator arms with long links is proposed in this paper. In contrast with traditional schemes, a flexible link is provided with a special force unloading system (FUS) having electrohydraulic drives. As a result, the static and dynamic errors caused by link structural deflections are minimized. Strategy of control the unloading actuators with measuring strain is developed. FUS dynamics is investigated by digital simulation and it is found to be an effective means to significantly decrease link flexibility and to dampen bending vibration. A digital controller for the FUS is suggested. The model of FUS dynamics is experimentally verified with a full scale prototype.