挖掘机工作装置复杂轨迹跟踪实验

摘要

为实现挖掘机自动控制,对其进行了电液比例改造.建立了挖掘机工作装置的运动学模型及其电液控制系统的非线性模型,并通过实验验证了机理建模中指出的电液控制系统死区及动态特性不对称非线性.为满足地面平整作业,采用五次多项式插值法在笛卡尔空间生成了斗杆末端轨迹,并通过运动学模型获得系统关节空间轨迹.针对控制系统主要存在的死区和不对称非线性,设计了带死区补偿的分段PID控制器,通过对比实验,证明了分段PID比常规PID控制精度高,能克服系统的主要非线性特性.通过协调控制挖掘机工作装置三关节,实现了一个复杂轨迹的有效跟踪.%In order to control excavator automatically, an excavator was retrofitted with electro-hydraulic proportional control systems. Kinematic models for excavator' s mechanism and nonlinear model for its electro-hydraulic system was established respectively. The dead-band and asymmetry nonlinearities of the electro-hydraulic system which was deduced in the theory models was demonstrated by experiments. To satisfy ground-leveling task, a 5-order polynomial was used for path generation in Cartesian space, and the joint-space path was calculated by kinematic models. According to the dead-band and asymmetry nonlinearities of control system, a segment PID controller with dead-band compensation was designed. Comparison experiments demonstrated that segment PID overcame the majority nonlinearities effectively. It had better tracking performance than conventional PID. In conclusion, complex path tracking was achieved by coordinated control of the three working arms.