Nonlinear Modeling and Analysis of Electro-hydraulic Proportional Control System for Excavator
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摘要: 为实现挖掘机自动控制,对其加装了电液比例阀。为有效分析系统,分别建立了电液比例阀及阀控非对称液压缸的非线性模型,由此得出整个系统的非线性状态空间模型。通过仿真实验表明,系统中死区非线性会引起方波跟踪的稳态误差和正弦跟踪的滞后及平顶效应,阀控非对称缸正反向响应特性存在差异。针对系统中存在的本质非线性特性,采用了带死区补偿的分段PID控制算法。对比实验表明:该控制策略能有效地克服系统死区非线性及不对称性带来的影响。Abstract: In order to control excavator automatically, an excavator was retrofitted with electro-hydraulic control system. Nonlinear models for electro-hydraulic proportional valve and valve-controlled asymmetric cylinder were built respectively, and then the nonlinear state space model for the whole system was achieved. Simulation experi-ments showed that the steady error, delay and flat-headed effect were aroused by the dead-band nonlinearity, and also testified the dissymmetry character of valve-controlled asymmetric cylinder. According to the nonlinear charac-ter, a piecewise PID with dead-band compensation was adopt, and the comparison experiment showed that the pro-posed controller could overcome the affects of dead-band and asymmetric nonlinearities.
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