Design of a hydraulically actuated 3-DoF translational parallel manipulator

The paper presents the design solution, kinematic structure, simulation and experimental control tests of a hydraulically actuated three degree of freedom (3-DoF) translational parallel manipulator (TPM). The TPM consists of a base (fixed) platform and a moving platform connected by three serial chains. The closed kinematic loops of the TPM utilize 3-RRPRR serial chains with revolute R joints and prismatic P joints. Herein, the active prismatic P joints are hydraulic actuators. To ensure the required accuracy of the trajectory tracking of the TPM end-effector, a control system to synchronize the position of the three hydraulic actuators was proposed. The suggested synchronization controller employs cross-coupled control (CCC), and guarantees the asymptotic convergence to zero of both hydraulic actuator position errors and synchronization errors.