高超声速飞行器有限时间LPV滑模控制器设计

Design offinite-time LPV sliding mode controller for hypersonic vehicle

摘要:

高超声速飞行器在机动飞行时易受到外界扰动,若采用传统的状态反馈控制方法,闭环控制系统极易引起振荡,无法满足机动飞行指令信号跟踪的精度要求；若采用传统的滑模控制方法,由于系统存在奇异值的问题,且计算过程较为复杂,控制系统不易于实现.针对上述问题,考虑高速机动飞行控制实际要求,提出了一种基于有限时间时变滑模的线性变参数(LPV)控制器设计方法并应用于高超声速飞行控制.首先不考虑外界扰动,通过传统的状态反馈控制方法使系统保持稳定.然后,在扰动存在的情况下,通过选取一个特殊的滑动函数,设计有限时间时变滑模控制律.为减小系统的抖振现象,引入饱和函数来替换控制律中的符号函数.经理论推导证明了闭环系统中的所有信号都是有界的,并且可以在预定的时间内将跟踪误差控制在零点的一个很小的邻域范围内.仿真验证结果表明,高超声速飞行器机动飞行条件下的状态量可在有限时间内稳定跟踪参考指令信号,且有效地抑制了闭环系统的振荡现象,验证了本方法所设计控制器的有效性.

Abstract:

Hypersonic vehicle is susceptible to external disturbances during maneuvering. If traditional state feedback control methods are used, the closed-loop control system can easily cause oscillations and fail to meet the precision requirements for the tracking of maneuvering flight instructions. If traditional sliding mode control methods are used, the problem of singular value will emerge in the system and the calculation process is more complicated, thus the control system is difficult to implement. In view of the above problems and considering the actual requirements of high-speed maneuvering flight control, this paper proposes a designed method of the linear parameter varying (LPV) controller based on a finite-time time-varying sliding mode and applies it to hypersonic vehicle control. First, the system was kept stable by traditional state feedback control methods without taking the external disturbances into account. Then, in the presence of perturbations, a finite-time time-varying sliding mode control law was developed by selecting a special sliding function. In order to reduce the chattering phenomenon of the system, a saturation function was introduced to replace the signed function in the control law. Theoretical derivation proved that all the signals in the closed-loop system are bounded, and the tracking error can be controlled to a small neighborhood around the origin in a predetermined time. Simulation results show that the states of the hypersonic vehicle could stably track the reference signal within a limited time, and the oscillation phenomenon of the closed-loop system was effectively suppressed. These properties verified the effectiveness of the controller presented in this paper.