Evaluation of Workspace and Coupled Motions of an Electrohydraulic Parallel Manipulator

The focus of the present work is to evaluate the workspace and study the coupled motions of a multi-cylinder parallel manipulator constructed with industry grade double-acting single rod hydraulic actuators and low cost proportional valves. The coupled motions are generated based on an inverse kinematic model of the system and are realized in real time with the aid of proportional integral controllers maneuvering each leg based on the error between the generated leg demands and the present leg length positions obtained via the position sensors mounted on the hydraulic cylinders. The experiments performed on a real time laboratory scale setup reveals that high-precision 3D motions can be achieved on such low cost systems with the assistance of simple control schemes and intelligent design.