Research On Dynamic Characteristics And Trajectory Tracking Control Of Electro-hydraulic Thrust System On Shield Tunneling Machine

Shield tunneling machine is a complex construction equipment which is integrated with excavation, tunnel installation and navigation. Because of unpredictable underground environments, there usually exist unacceptable excavating errors and large ground deformations. Safety, high efficiency and high construction quality are of great importance in modern tunnel construction. This study focused on dynamics of the shield machine and control approaches on electro-hydraulic thrust system.The machine dynamic model was established to reveal the nonlinear coupling relationship between thrust force and the machine’s motion. A new approach on the machine tracking control was proposed. There are two characteristics of such approach. One is that there are good dynamic performances on pressure regulation. Current studies on pressure dynamic control are using servo valves. This study proposed a pressure regulation model which could be applied on proportional pressure valves. Adaptive robust control was applied on such model to enhance the dynamic performances. As comparison, dead band compensation and PID controller were also studied. Pressure regulation experiments on 1Hz sine wave tracking with amplitude of 1.5MPa were done. The results showed that normal controllers had 30° phase lag and 20% of amplitude attenuation. Adaptive robust control was almost able to achieve perfect control, enhancing the performances significantly. The other characteristic is that there are little effects on advancing speed when the machine is encountering sudden changing loads. Of all the load forces, friction force on the shield lining is the greatest one. Hence, the friction Stribeck effect is not ignorable. To handle this problem, a shield machine’s LuGre model was built to describe the friction force. Advancing speed controller with friction force feed forward compensation was designed. Simulations and experiments were done to validate the controller design. The highest position resolution was 0.2mm by using such speed controller. The proposed approach was a 3-dimension tracking error controller. It was able to make the machine excavation trajectory converge to the desired trajectory without overshoots. A new load simulation model was proposed to simulate different loads in complicated environments. It can be used to simulate the situation such as excavation in mixed stratum. A new loading system was proposed. The system can provide both force load and velocity load, which is capable of pressure regulation excavation mode and flow rate regulation excavation mode. The loading system is also able to provide active/passive loads.Chapters are briefed as follows.Chapter 1 is the introductions of the industry and current studies. Then the research points of this study were presented.Chapter 2 introduced two widely used electro-hydraulic systems on the machine. They are the pressure relief valve regulation system and pressure reducing valve regulation system. The working principles were explained. The key components, pressure regulation valves and flow rate control valve, were modeled. The steady state and dynamic performances were discussed. The commercial software AMESim was used to set up models for the two systems. And simulations with a tough excavation which has different stratum on excavating face were carried out. The results showed that the pressure relief valve regulation system had better performances.Chapter 3 mainly talked about the settings of test rig of the pressure relief valve regulation system, including mechanisms hydraulic systems and electrical system.Chapter 4 introduced compliance of shield tunneling machine at first. Then studies on thrust force control and advancing speed control were carried out. ARC was proposed to apply to pressure control by using a proportional pressure relief valve. ARC implements of first order model approximation and second order model approximation were presented. Simulations and experiments showed that ARC implements worked much better than the dead band compensation and PID controller. LuGre friction model was applied to the dynamic model of advancing control. The controller was designed by backstepping method. Speed regulation simulations and experiments were done and showed that such controller can regulate the advancing position error within 0.2mm during excavation.Chapter 5 is the tracking control study on the machine. A three-dimensional error dynamic model, with consideration of LuGre friction model, was derived. The design included three steps. Step 1 was to design desired inputs which were able to make errors converge. Step 2 was to design actual control inputs that could converge to the desired inputs. Step 3 was the implement by considering the actual disturbances. Simulations showed that the controller worked properly. At last some controller parameters were studied to show how they effected on the machine behaviors.Chapter 6 gives the conclusions and discussions on future works.