输入受限的非仿射纯反馈不确定系统自适应动态面容错控制

摘要

针对存在执行器故障和输入饱和受限的非仿射纯反馈不确定动态系统，提出了一种自适应动态面容错控制策略。在不损失模型精度和考虑系统输入饱和受限的前提下，基于中值定理将非仿射系统转化为具有线性结构的时变不确定系统，在此基础上，再利用参数自适应投影技术对有界不确定时变参数进行在线估计，参数估计误差和外界扰动采用非线性动态阻尼技术进行补偿，并利用双曲正切函数和Nussbaum函数处理系统输入饱和受限和控制增益函数方向未知的问题，同时将反演法和动态面法相结合设计鲁棒自适应控制器，消除了反演法的计算膨胀问题，并且在系统出现执行器失效故障的情况下可确保稳定跟踪。最后，根据解耦反推法，基于Lyapunov稳定性定理证明了闭环系统的半全局一致最终有界。仿真结果验证了所设计控制方案的可行性与有效性。%Adaptive dynamic surface fault-tolerant control is proposed for uncertain non-affine pure feedback dynamic systems with input saturation and unpredictable actuation failures. Under the consideration of input saturation, the non-affine system is first transformed into a time-varying system with a linear structure using the mean value theory without drop-out of nonlinear characteristics;then, the bounded time varying parameters are estimated by adaptive algorithms with projection, the estimation error and external disturbance are compensated by employing nonlinear damping technology. By combining backstepping technique with dynamic surface control (DSC), Nussbaum function and hyperbolic tangent function, the designed algorithm can not only deal with the input saturation but also overcome the“explosion of com-plexity”problem and the possible“controller singularity”problem. Furthermore, the proposed control is fault-tolerant. Finally, based on Lyapunov stability theorem and decoupled backstepping method, the semi-global stability of the close-loop system is proved. The simulation results demonstrate the feasibility and validity of the proposed control schemes.