磁悬浮准滑模目标跟踪控制器设计

Position Tracking Controller Design for Magnetic Levitation System Via Quasi-Sliding Mode

磁悬浮控制问题中,由于模型不确定性的存在,需要设计不依赖系统精确模型的控制方案。滑模变结构控制不完全依赖对象模型,具有响应快、结构简单的优势,但切换控制引起的抖振问题需要设法削弱,以保证闭环系统的鲁棒稳定性。首先以机理分析的方法建立单自由度悬浮系统的线性化模型,然后采用滑模控制方法设计了目标位置跟踪控制器。为了有效削弱系统输出的抖振现象,在滑模滑动控制阶段采用连续饱和函数的方式实现滑模面平稳切换。以46g小球在目标位置悬浮控制进行仿真以及多方案对比分析,结果表明,所得滑模控制器具有较好的目标跟踪性能。在输出端施加给定量2.5%幅度的随机干扰,系统显示出较强的鲁棒性。

Due to the uncertainties of plant models,control schemes that do not depend on the exact model need to be designed for the magnetic levitation system.Sliding mode variable structure control has less dependence on target models and has outstanding advantages such as fast response,simple structure,etc.Methods that can eliminate chattering caused by switching control should be given to ensure the closed-loop system to be robust stable.In this paper,a linearized model of a single degree of freedom levitation system was established by mechanism analysis.Then position tracking controller based on sliding mode control was designed.To eliminate chattering of the system output effectively,a continuous saturation function was adopted to deal with the switching control in the sliding stage of sliding mode control.Simulations and comparative analysis of different schemes of levitation system with 46 g sphere were completed.Simulation results show that the system with a designed quasi-sliding mode controller tracks the target successfully.With additive random disturbance which has a 2.5%amplitude of tracking signal to the output,the proposed method shows strong robustness.