Automatic trajectory tracking control of shield tunneling machine under complex stratum working condition

Abstract Automatic trajectory tracking control is a significant task of thrust system during tunnel excavation. Tasks of steering and posture adjustment of the shield machine can be achieved by properly adjusting the distribution of thrust pressure in corresponding working zones. Principle of hydraulic thrust system and hydraulic load simulation test rig of shield machine are illustrated at first. Then a set of scientific and complete orientation and posture rectification strategies has been put forward to eliminate the position and angle deviations simultaneously. Based on construction site investigation, mechanical structure diagram and kinematics model of the thrust system have been established. Then, the numerical results of path planning under steering or rectifying working condition are demonstrated. An integrated control system, which consists of one trajectory planning controller for both cylinders and an individual cylinder controller for each of hydraulic cylinders, is proposed to achieve the automatic control of the thrust trajectory. A cascade control strategy, which comprises feedforward controller of fixed-value compensation and feedback controller of Variable-gain proportion–integration–differentiation (PID), is applied to achieve the precise tracking control of the given trajectory. Experimental studies on automatic trajectory tracking control under several typical working conditions are done at last.