Multi-Mode Load Control

In IMCS, the system degree of freedom (DOF) in the hardware increases from one to two. It first benefits the flexible configuration of individual flow paths, including regeneration and recuperation. In this chapter, multiple operating modes are established according to the achievable flow paths by the independent metering control. Considering the force and flow limitation of operating modes, the mode-switching logic is designed, such that the most efficient operating mode without losing controllability can be automatically selected. To solve an unstable and unsmooth switch, this chapter proposes a bumpless mode switch approach for the IMCS, which contains the dynamic dwell-time switch and a bidirectional latent tracking loop. The proposed strategy is verified by a mini-excavator. The comparison results show that the instability during mode mode-switching instant is eliminated, as well as the transitions of the cylinder velocity and pressure between the two modes are smoother. Meanwhile, the hysteresis of the mode switching caused by the dwell time is greatly decreased. In comparison to the conventional hydraulic control system, an IMCS could save energy without reducing the motion control performance using the proposed bumpless mode switch strategy.