锻造操作机相似模型逆动力学建模与非线性控制器设计

Inverse Dynamics Modeling and Nonlinear Controller Design of the Similar Model of a Forging Manipulator

锻造操作机是自动化锻造作业当中不可缺少的重要装备之一,在提高生产效率、保证加工质量等方面发挥了重要作用。为了提高锻造操作机的工作性能,针对某一型号的锻造操作机设计相似机构以便于开展试验研究。针对此相似机构,采用虚功原理方法建立其逆动力学模型。为减小机构动力学非线性对响应性能的影响,采用动力学前馈方法将钳杆按期望轨迹运动时所需的驱动力分配给各液压缸驱动单元,并以液压缸驱动单元位置动态性能的提高来改善钳杆的位姿跟踪性能。为此,考虑液压系统的非线性,利用反馈线性化方法将液压缸驱动单元转化为一个二阶线性系统,通过4个参数的设定来确定液压缸驱动单元的自然频率及阻尼比以及改善系统的动态响应过程。仿真结果表明了这种控制方法的有效性。

Forging manipulator is one of the most important equipment in the automation of forging operation,and plays an important role in improving productivity and ensuring manufacturing quality. To improve the forging manipulator＇s performance,a similar model of a forging manipulator is designed to facilitate experiments. The inverse dynamics of this similar model is obtained by using the principal of virtual work;and to decrease the negative effect of the nonlinearity of the mechanism dynamics,the dynamic feedforward control method is adopted,distributing driving forces,which are needed for the tongs carrier of the manipulator to generate desired motions,to each hydraulic cylinder. The tracking performance of the tongs carrier is chosen to be guaranteed by improving the position response performance of each hydraulic cylinder. So,by using feedback linearization method and considering the nonlinearities of hydraulic systems,a hydraulic cylinder system is transformed into a second-order linear system which can be easily adjusted by setting four parameters to get desired damp ratio and natural frequency and to improve the response dynamics. Simulation results finally attest the validity of the proposed method.