Force control of parallel link manipulator with hydraulic actuators

This paper proposes a force control algorithm for Stewart platform type of parallel link manipulators with velocity controlled hydraulic actuators. First, we design a control scheme for one degree-of-freedom, hydraulic actuator then we extend the control scheme to the parallel link manipulator. The hybrid force/position control scheme for parallel link manipulator is also proposed. The control scheme is designed based on velocity based force control algorithm, so that we can apply it to the parallel link manipulators with velocity controlled hydraulic actuators. The proposed algorithm is applied to the experimental system with six degrees of freedom and the experimental results illustrate the validity of the system.