Abstract
An electro‐hydraulic servo position and pressure compound control method was investigated considering the working principle of a hydraulic stepping motor of a shield machine gripper shoe and its practical working characteristics in the supporting process. The control targets were to improve the support efficiency and reduce the disturbance of gripper shoes on the surrounding rock. In this method, a fuzzy switching controller was used to switch between electro‐hydraulic position control and electro‐hydraulic pressure control. Numerical and prototype simulation experiments were conducted on the control method. The theoretical analysis and experimental results showed that the control method could effectively convert the gripper shoes from an unsupported state to a supported state in a short amount of time, as well as realize surge‐free switching between position control and pressure control. Thus, disturbance of the gripper shoes on the surrounding rock could be reduced. The results of this study provide a theoretical basis for research on control strategies of hydraulic stepping propulsion of shield machines.
Highlights
An electro-hydraulic servo position and pressure compound control method was investigated considering the working principle of a hydraulic stepping motor of a shield machine gripper shoe and its practical working characteristics in the supporting process
Numerical and prototype simulation experiments were conducted on the control method. e theoretical analysis and experimental results showed that the control method could effectively convert the gripper shoes from an unsupported state to a supported state in a short amount of time, as well as realize surge-free switching between position control and pressure control. us, disturbance of the gripper shoes on the surrounding rock could be reduced. e results of this study provide a theoretical basis for research on control strategies of hydraulic stepping propulsion of shield machines
Introduction e supporting-propulsion-step-changing system is a key subsystem of open shield machines. e propulsion system consists of two sets of hydraulic cylinders arranged symmetrically on each side. e gripper shoe system includes a set of gripper shoe hydraulic cylinders and a set of torque hydraulic cylinders. e propulsion system provides the propelling force required for cutting tools to break the rock
Summary
Assuming that the electro-hydraulic servo valve is an ideal slide valve, based on the above analysis, the basic flow equation of the electro-hydraulic servo valve, the flow continuity equation of the hydraulic cylinder, and the equilibrium equation can be obtained as follows:. Where Ct is the total leakage coefficient of the hydraulic cylinder, (m3/(s·Pa)). E transfer function between the spool displacement and the output force of the hydraulic cylinder can be obtained by simplifying equation (1) by using the Laplace transform: P. To simplify the dynamic characteristics of the system, the transfer function of the electro-hydraulic servo valve is approximated by the second-order oscillation model. It can be seen that the requirements of the structure and parameters of the controller are different for the two control methods. erefore, it is impossible to simultaneously perform pressure and position control with only one controller
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