非匹配不确定性下连铸结晶器振动位移系统准滑模控制

以伺服电机驱动的连铸结晶器振动位移系统为研究对象,针对系统中同时存在的匹配建模误差和非匹配外界时变扰动不确定系统,提出一种基于干扰补偿器的鲁棒准滑模控制方案.首先,针对非匹配外界时变扰动不确定系统,采用一种改进的解耦干扰补偿器,保证估计误差有界收敛;其次,采用一种新型的混合趋近律,将幂次趋近律与等速趋近律相结合,减小滑模面趋近时间;再次,基于切换函数设计扩张状态观测器用于观测系统不确定项(包括干扰补偿器估计误差及系统的匹配不确定性),并构建趋近律参数与不确定项的定量关系,以降低抖振,提高系统的控制性能和鲁棒性;最后,通过理论分析证明了闭环系统离散准滑动模态的稳定可达性.仿真分析结果表明了所提出控制方案的有效性.

Quasi-sliding mode control for mold vibration displacement system with unmatched uncertainties

With the continuous casting mold vibration displacement system driven by a servo motor as the research object, a robust quasi-sliding mode control based on the disturbance compensator is proposed for the system with match and unmatched uncertainties. Firstly, an improved decoupled disturbance compensator is adopted for the unmatched disturbance. The estimation error is convergent and bounded. Then, a new kind of hybrid reaching law, which combines the exponential reaching law with the constant speed reaching law, is designed to reduce the reaching time to the sliding surface. The extended state observer based on the switch function is designed to estimate the system states and the total system uncertainties (including the estimation error of the disturbance compensator and the system matching uncertainty), and then the relationship between the reaching law parameters and the total system uncertainties is established to reduce chattering and improve the system control performance and robustness. Finally, theoretical analysis proves the stability of the discrete quasi-sliding mode of the closed-loop system. Simulation results show the effectiveness of the proposed control scheme.