基于改进干扰观测器的虚拟轴机床滑模控制研究

Sliding model control scheme for virtual axis machine tool based on improved disturbance observer

圆弧齿轮加工用虚拟轴机床伺服系统存在的不确定性会影响系统的性能,从而降低圆弧齿轮的加工精度;同时,滑模控制中抖动现象会影响控制的精度和稳定性.为提高虚拟轴机床的加工精度和抑制滑模控制中的抖动现象,提出了基于改进观测器的滑模变结构控制算法来控制虚拟轴机床的伺服电机,算法中采用该干扰观测器对系统中的不确定性进行观测,利用饱和函数代替符号函数来抑制滑模控制中的抖动现象.推导了基于改进观测器的滑模变结构控制律,并证明了所设计控制器的稳定性;为验证算法的有效性,在MATLAB中进行了仿真,仿真结果表明:所提出的算法能够有效地观测系统中存在的不确定性因素,并抑制滑模控制中的抖动现象,系统具有较强的位置跟踪性能和抗干扰能力.

The uncertainties existed in the servo system of virtual axis machine tool that was used to process the circular arc gears will affect the performance of the system and reduce the machining accuracy of the circular arc gears,and the chattering phenomenon existed in the sliding mode control will influence the control accuracy and stability.In order to improve the machining accuracy of the virtual axis machine tool and reduce chattering phenomenon in the sliding mode control,an sliding model control scheme with improved disturbance observer was proposed to control the servo motor of the virtual axis machine tool.The disturbance observer was used to observe the uncertainties existed in the servo system of virtual axis machine tool in this algorithm and the symbolic function in the variable structure control was replaced by the saturation function to reduce the chattering phenomenon which was brought by the variable structure control system.The control law was deduced based on the improved observer of sliding mode variable structure,and the stability of the designed controller was proved.In order to verify the validity of the algorithm,the simulation was taken in MATLAB,the simulation results showed that the algorithm proposed could effectively observe the uncertainties in the system,and chattering phenomenon in the sliding model control was reduced,then the motor servo system had stronger position tracking performance and anti-interference ability.