A redundantly actuated PRPRP radial mechanism in the segment erector of a shield machine for synchronization control

Abstract

The shield machine is a heavy construction machine for tunnel excavation, and the segment erector is an important subsystem of the shield machine. It is difficult to achieve precise control in the 6-DOF (degree of freedom) erector in the 2-DOF 5-bar radial mechanism. Hence, this paper proposes a redundantly actuated PRPRP radial mechanism for the segment erector. When the redundant actuator is unlocked, the radial mechanism is able to adjust its posture, which has two degrees of freedom. On the other hand, when the redundant actuator is locked or produces enough pre-tightening tensile force, the PRPRP mechanism can ensure the synchronization of the two driving hydraulic cylinders along the radial direction based on the mechanical structure, which has one degree of freedom. The redundant actuator also facilitates the equal application of two flexural torques at the hydraulic cylinders; thus, preventing the overload of a single cylinder.

Keywords

redundant actuation / parallel mechanisms / five-bar mechanisms / segment erectors / shield machines

References

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Acknowledgements

We gratefully acknowledge the support provided by the National Basic Research Program of China (Nos. 2007CB714007 and 2011CB706503), the National Natural Science Foundation of China (Grant Nos. 51075357 and 51005199), the Fundamental Research Funds for the Central Universities (No. 2010QNA4026), the Postdoctoral Science Foundation of China (No. 20100471717), and the Zhejiang Provincial Natural Science Foundation of China (No. Y1090512).

RIGHTS & PERMISSIONS

2014 Higher Education Press and Springer-Verlag Berlin Heidelberg