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Dynamic characteristics of the over-actuated cutterhead driving system in tunnel machine

The cutterhead driving system of tunnel machine is over-actuated by redundant driving chains with inevitable load and parameter deviations. These deviations were rarely considered, and the researches on multi-motors synchronization and gear dynamics were usually isolated. In this paper, a novel electromechanical coupled model of the whole cutterhead driving system is established by connecting the vector-controlled motors via gear meshing system. Force transmissions between all coupled elements are investigated by analyzing rotational and translational dynamics, and the time-varying meshing stiffness and nonlinear backlash of both parallel pinions driving and multi-stage planetary reducer are considered. The phase and frequency features of meshing dynamics are also investigated. Comparative simulations are carried out with load and parameter deviations between multi-chains under two control structures, speed parallel control and torque master-slave control; some practical control principles are also concluded. The simulation results are verified and applied on a Φ2.5-m test rig. The consistent results indicate that, the meshing dynamics have the frequency components of carrier revolution and the meshing frequencies of both current planet and endmost pinion. Torque master-slave control could realize torque synchronization against all the adverse deviations while speed parallel control fails, and the vibration could be significantly reduced with lower rigidity in speed control.