Dynamic coordinated control of attitude correction for the shield tunneling based on load observer

Attitude correction of the shield tunneling is more challenging than excavation ahead because it should regulate the postures of shield machine and realize dynamic coordinated control of the multicylinders. After the load characteristics are analyzed in detail, the dynamics of the shield postures are derived, by which can described the coupling effect of the equivalent loads and actuators. To eliminate the complexities of the control system, a double closed-loop controller structure is proposed that can deal with the coupling problems and nonlinear behaviors of the cylinders in outer and inner loops independently. Additionally, a sliding mode control scheme is adopted based on load observer which can effectively suppress the inherent chattering phenomena greatly. Such an observation method is proposed due to the fact that the loads acting on the shield body are unpredictable and slow changing. Our simulation results demonstrate that the proposed controller is simple, effective and powerful to perform attitude correction motion smoothly and accurately.