Electro-hydraulic proportional control of thrust system for shield tunneling machine

In this paper, a thrust hydraulic system of shield tunneling machine with pressure and flow compound control scheme is proposed. In the control system, the task of real-time measuring of the pressure and the displacement of hydraulic cylinder in each thrust group is accomplished by pressure sensor and displacement sensor respectively, forming the closed-loop pressure and speed control with proportional valves. Thrust system mathematical modeling including hydraulic system and multi-cylinder acting dynamics is presented. Synchronization motion control between cylinders is also achieved by means of master–slave PID with dead band compensating displacement error. Experiments of thrust pressure and speed control as well as cylinder synchronization are conducted on the shield simulation test rig. The experimental results show that the proposed thrust hydraulic system and its control can meet the requirements of tunneling.