【摘要】 针对无人直升机姿态与高度系统存在未知外部干扰、输入饱和、姿态与高度约束等问题,本文提出一种具有输入输出约束的预设性能安全跟踪控制方法.首先,针对无人直升机的姿态与高度约束,通过设计一类边界保护算法,构建了新的安全期望跟踪信号.为了保证系统对于安全期望跟踪信号的跟踪性能,将预设性能函数与边界保护算法进行结合,并对跟踪误差进行转换.针对系统的输入饱和现象,使用Sigmoid函数进行逼近;同时,针对饱和函数的逼近误差与未知外部干扰构成的复合干扰,采用参数自适应方法对其上界进行逼近.然后,结合反步控制方法设计了安全跟踪控制器,并通过Lyapunov稳定性理论证明了闭环系统所有信号的收敛性,保证了无人直升机的安全跟踪性能.最终,通过数值仿真验证了所提控制方法的有效性.更多还原

【Abstract】 This paper deals with the problem of prescribed performance safe tracking control for the attitude and altitude system of unmanned helicopter with unknown external disturbances, input saturation, and constraints of attitude and altitude. Firstly, by considering the constraints of attitude and altitude, a safe desired tracking signal is constructed with the application of an output boundary protection algorithm. Furthermore, combining with the proposed output boundary protection algorithm, the prescribed performance function is developed to guarantee the tracking performance of the safe desired tracking signal. A Sigmoid function is utilized to tackle the problem of saturation input. To compensate the compound disturbances which include external disturbances and the estimation error of Sigmoid function, a parameter adaptive method is adopted to approximate its upper bound. Combining with the backstepping technology, the safe tracking controller is investigated. The Lyapunov stability theory is employed to guarantee the boundedness of all closed-loop signals and the safe tracking performance of the unmanned helicopter system. Simulation results of an example are provided to illustrate the effectiveness of the proposed control scheme.更多还原