Experimental Study of the Direct Drive Hydraulic System with the Torque Mode

The torque mode is more suitable for the direct drive 6 degree of freedom (6-DOF) parallel mechanism than speed that both dynamic coupling and current among motors are easily solved, but its key parameters characteristics have never been studied, which important goals this paper. First hydraulic system 6-DOF simplified. Then transfer function with deduced together mode. Finally, comparative experiments conducted. Results show generally worse those mode, mainly determined by motor-pump second-order element composed two under-damped elements, proportion differentiation (PD) control strategy pressure feedback (DPF) useful practical effective methods still needed.