针对并联机构传统控制器轨迹跟踪精度较低的问题,设计了一种基于并联机构动力学方程和比例切换控制律的滑模变结构控制器(SMC)。首先,建立机构的Matlab/Sim Mechanics仿真分析模型,采用微位移法求解并联机构的Jacobian矩阵及通过工作空间分析确定机构的最佳尺寸参数,为控制系统提供理论参考输入值。其次,设计滑模变结构控制器,运用Lyapunov函数证明滑模变结构控制器的稳定性;最后,建立机构的PID控制和SMC控制系统Matlab/Simulink框图,分别对其进行仿真分析与对比。结果表明,SMC控制器的轨迹跟踪精度比PID控制器的精度高,稳态误差小,且鲁棒性强,响应速度快,从而验证了SMC控制的有效性。
Because the conventional controller for parallel mechanism has low trajectory tracking precision,the sliding mode variable structure controller( SMC) is designed based on the dynamics equation of 3-RPS parallel mechanism and proportional switching control law. Firstly,the Matlab / Sim Mechanics analysis model of 3- RPS parallel mechanism is established,the Jacobian matrix of 3- RPS parallel manipulator is solved by using the micro- displacement method and the optimal size parameters of the mechanism are determined by workspace analysis,which are the theoretical reference values for control system. Secondly,the SMC controller is established,the stability of SMC controller is proved by using the Lyapunov function. At last,the Matlab / Simulink block diagrams of PID controller and SMC controller are respectively established,the effects of PID controller with SMC controller are compared and analyzed,the results show that the trajectory tracking precision of SMC controller is higher than the PID controller,and the SMC controller has smaller steady- state error,faster response speed and better robustness,and the effectiveness of the SMC control is verified.