将基于正交全局任务坐标系(GTCF)的非线性自适应鲁棒控制(ARC)方法扩展应用于二轴电液系统的轮廓运动控制,以解决精确轮廓控制的难题.构造二轴电液系统在笛卡尔坐标系下的非线性动力学模型,并将该模型坐标变换于正交全局任务坐标系中.针对此变换后得到的强耦合非线性动力学模型及其中存在的参数不确定性、不确定非线性和建模误差,利用非线性自适应鲁棒控制方法综合二轴电液系统的轮廓运动控制器.该控制器可以灵活地调整轮廓控制刚度与跟踪控制刚度,可在保证系统稳定的前提下尽可能地提高轮廓控制的性能.将所提控制方法与基于交叉耦合的自适应鲁棒轮廓运动控制方法进行对比实验,结果表明,所提方法即使在单轴跟踪误差较大的情况下仍然实现了更为精确的轮廓控制,在实验条件下轮廓误差的均方根值在15μm以内,表现出良好的轮廓控制性能与协调性.
The global task coordinate frame (GTCF) based nonlinear adaptive robust control (ARC) meth- od was extended to design a contouring motion controller for biaxial electrohydraulic system, in order to solve precise control problem of contouring motion. The nonlinear dynamic model of the biaxial electro- hydraulic system was developed in Cartesian coordinates, and the model is transformed into the GTCF. Considering the strongly coupled and highly nonlinear dynamic model of the electrohydraulic system ob- tained after coordinate transformation as well as parametric uncertainties, uncertain nonlinearities and ex- ternal disturbance inherently in the model, the nonlinear adaptive robust control method was adopted to synthesize the contouring motion controller. In the designed controller, contouring control stiffness and tracking control stiffness can be regulated flexibly, which will potentially improve system stability without losing contouring control performance. The proposed GTCF based ARC method and cross--coupled ARC method were compared in experiment. As a result, the root mean square values of contour error for circu- lar desired trajectory are less than 15μm while using GTCF based ARC method. The experimental results show that GTCF based ARC achieves satisfied contouring control performance and presents excellent coordinating ability.