A novel cutterhead cascade control strategy for hybrid-driving tunnel boring machines

Abstract

The electro-hydraulic hybrid cutterhead driving system is a newly developed innovative cutterhead driving system of tunnel boring machine. Regulating the cutterhead rotational speed, balancing the driving load and the torque control of the hydraulic motors are three essential issues of the electro-hydraulic hybrid cutterhead driving system to be addressed. The conventional synchronization method focuses on pure rotational speed regulation only and therefore causes serious unbalanced driving torque phenomena in the cutterhead driving system. In this article, a cascade control scheme is proposed which is, namely, grouped into three control levels. In the high level, a nonlinear disturbance observer–based integral sliding mode control strategy integrated with anti-windup technique scheme is proposed to guarantee the tracking accuracy of the cutterhead rotational speed. Furthermore, the total driving torque of the electro-hydraulic hybrid cutterhead driving system is estimated by the disturbance observer. The middle level is the driving torque distributor which generates the torque reference for each driving unit. Owing to the nonlinear characteristics of the hydraulic system, an adaptive robust controller is introduced to guarantee the output torque of hydraulic motors and to track the torque reference signal. The torque tracking performance of electromotors is guaranteed by the converter. The co-simulations are carried out to verify the effectiveness and performance of the proposed cascade control scheme. The results show that the proposed control system can guarantee the cutterhead rotational speed tracking performance while overcome the biased load problems in pinion–ring gear transmission system of electro-hydraulic hybrid cutterhead driving system.