Synchronization Control of a Dual-Cylinder Lifting Gantry of Segment Erector in Shield Tunneling Machine under Unbalance Loads

Segment assembling is one of the principle processes during tunnel construction using shield tunneling machines. The segment erector is a robotic manipulator powered by a hydraulic system to assemble prefabricated concrete segments onto the excavated tunnel surface. Nowadays, automation of the segment erector has become one of the definite developing trends to further improve the efficiency and safety during construction; thus, closed-loop motion control is an essential technology. Within the segment erector, the lifting gantry is driven by dual cylinders to lift heavy segments in the radial direction. Different from the dual-cylinder mechanism used in other machines such as forklifts, the lifting gantry usually works at an inclined angle, leading to unbalanced loads on the two sides. Although strong guide rails are applied to ensure synchronization, the gantry still occasionally suffers from chattering, “pull-and-drag”, or even being stuck in practice. Therefore, precise motion tracking control as well as high-level synchronization of the dual cylinders have become essential for the lifting gantry. In this study, a complete dynamics model of the dual-cylinder lifting gantry is constructed, considering the linear motion as well as the additional rotational motion of the crossbeam, which reveals the essence of poor synchronization. Then, a two-level synchronization control scheme is synthesized. The thrust allocation is designed to coordinate the dual cylinders and keep the rotational angle of the crossbeam within a small range. The motion tracking controller is designed based on the adaptive robust control theory to guarantee the linear motion tracking precision. The theoretical performance is analyzed with corresponding proof. Finally, comparative simulations are conducted and the results show that the proposed scheme achieves high-precision motion tracking performance and simultaneous high-level synchronization of dual cylinders under unbalanced loads.

Development and simulation of magnetorheological damper for segment erector vibration control

In this paper, magnetorheological dampers are applied to a segment erector to replace passive vibration dampers. Because magnetorheological damper dynamics are highly nonlinear, design of a direct control system is impossible. To apply linear control theory directly to design the magnetorheological damper controller, the Takagi–Sugeno fuzzy model analytically represents the segment erector model. In addition, a disturbance observer based on a Takagi–Sugeno fuzzy controller is proposed for this system. Both simulations and experiments validate the performance enhancement and stability of the controller. The results show that the acceleration of the segment erector was reduced by 59.6% and 32.1% in oblique wave excitation and random excitation, respectively, compared to a conventional passive damper. The proposed fuzzy controller and magnetorheological dampers have great potential in practical applications because they can significantly improve the performance of a segment erector.

Paralleling Hydraulic Control of Variable Frequency Motor and Valve for the Swing Mechanism of Segment Erector

Aimed at achieving a high speed and precision circumferential positioning of pipe under low energy consumption, a paralleling hydraulic control of variable frequency motor and valve (PHC-VFMV) system is designed for the swing mechanism of segment erector. Firstly, with a view to the working principle of the swing mechanism, a hydraulic circuit of the PHC-VFMV is designed. Then, two sub-circuits of the hydraulic circuit are separately modeled and equipped with suitable controllers. Finally, one valve control (VC) system and the designed PHC-VFMV system are tested in AMEsim platform. Results show that, while guaranteeing a good performance of speed and accuracy, the PHC-VFMV could achieve a better performance in energy saving than VC.

Building of Fine-Tuning Mechanism Posture and Kinematics Model for Shield Segment Erector

The fine-tuning posture 3-SPS-1-S-type mechanism’s kinematics model and position mechanism for segment erector is built by creating general stiffness motion and revolution motion’s posture parameterized representations based on the Lie groupoids theory’s kinematic synthesis, the duality between parallel mechanism structure and performance and PRY angle coordination system’s kinematics analysis.