Abstract: Aiming at the problem that the dynamic and static characteristics of the main spool of pilot electrohydraulic proportional valve are quite different in the process of left and right motion,the asymmetric characteristics of the left and right dead zones of the pilot spool of electrohydraulic proportional valve caused by machining and assembly tolerances were studied.An overall mathematical model of proportional valve with pilot asymmetric dead zone was established,the influence of the asymmetric dead zone of the pilot valve on the dynamic and static characteristics of the main spool was analyzed in the mathematical model,an asymmetric control strategy based on the asymmetric dead zone of the pilot valve and a variable gain dead zone compensation algorithm were proposed, that is, different dead zone parameters and controller parameters were set in the forward and reverse directions of the pilot valve. The control strategy was evaluated on the proportional valve test bench.The results indicate thatthe main valve spool overshoot is reduced by 80%, the steadystate error is reduced by 60%, the response time is reduced by 50%, etc. The dynamic and static characteristics of the main spool are significantly improved.
Key words: dead zone compensation; proportional valve; PID; asymmetric dead zone