关键词: 时滞系统, 模式切换, 负载口独立, 压力/流量控制

Abstract: The independent valve of the load port realized the decoupling control of the inlet and outlet orifices in the hydraulic systems, which might support a variety of control modes. However, due to the dynamic response and controller delay during switching, the system mode was easily asynchronous with the controller mode, causing pressure shock and instability problems. A stable switching strategy was proposed based on independent metering system. The strategy introduced the idea of "slow switching", considering system time-delay and combining Lyapunov stability theory, a boundary value solution method was proposed for the dynamic residence time of an asynchronous switching system based on mode correlation average residence time. The method obtains a shorter residence time than that of the traditional average residence time method. The stability control problem was solved under asynchronous switching of linear switching systems, which ensures the stability of switching instantaneously, and reduces the influences of residence time on system responses. Based on the excavation actions of bucket pole of rescue vehicles, the control strategy simulation verifies that under the conditions of time-delay, the pressure shock of hydraulic systems before and after mode switch is reduced by more than 80%, and the amplitude of the actuator speed oscillation is reduced by nearly 20%, which effectively improves the operation stability of the actuator of the rescue vehicles. 

Key words: time-delay system, mode switch, independent metering, pressure/flow control