飞行器自适应反推Terminal滑模轨迹跟踪控制

飞行器非线性动力学模型通常包含由未知外界干扰和未建模动态构成的非匹配不确定性。针对建立的飞行器纵向运动仿射非线性模型,提出了一种基于非线性干扰观测器(nonlinear disturbance observer, NDO)的自适应反推非奇异终端滑模(adaptive backstepping nonsingular terminal sliding mode,AB-NTSM)轨迹跟踪控制方法。设计非线性干扰观测器对未知干扰进行观测补偿,无需干扰上界先验知识。设计未建模动态自适应律,提高控制器对系统不确定性的鲁棒性。对3种不同情况的仿真表明,干扰观测器能够实现对不同干扰精确观测,仅在干扰突变时有较大观测误差。在不确定性影响下,采用提出的控制方法,系统能够实现对指定轨迹的稳定跟踪,并有效消除控制信号的抖振。

Adaptive backstepping terminal sliding mode control for aircraft trajectory tracking

Aircraft nonlinear dynamic systems usually include unmatched uncertainties consisting of unknown external disturbances and unmodelled dynamic terms. The affine nonlinear model of aircraft longitudinal motion is constructed. An adaptive backstepping nonsingular terminal sliding mode (AB-NTSM) control scheme is proposed for trajectory tracking, which is based on the nonlinear disturbance observer (NDO). Without the prior information of upper bounds of external disturbances, NDOs and adaptive laws are designed for external disturbances and unmodelled dynamic terms respectively, which can strengthen system robustness for uncertainties. Simulations of three kinds of cases are given, which demonstrate that NDOs can realize accurate observation of different kinds of external disturbances. Big observation errors only exist when the disturbance is discontinuous. Under the effects of system uncertainties, the proposed AB NTSM control scheme can realize stable tracking of desired trajectory, and the chattering of the system input can be effectively suppressed.