干扰观测器补偿的四旋翼飞行器自适应离散终端滑模控制

Adaptive Discrete Terminal Sliding Mode Control of Four-Rotor Aircraft with Disturbance Observer Compensation

传统的离散线性滑模应用于四旋翼飞行器控制具有跟踪误差大、响应速度慢、不能有限时间收敛等问题,针对具有外干扰、系统不确定和建模误差的四旋翼飞行器,提出了干扰观测器补偿的自适应离散终端滑模控制。首先,对一类包括四旋翼飞行器模型的离散化方程推导了终端滑模控制律,引入自适应律因子减小抖振,构造了以状态变量的平方作为干扰误差收敛速度的改进型离散干扰观测器,且证明了它的稳定性,再利用改进的离散干扰观测器获取未知干扰、不确定和建模误差的高精度估计,并用于控制器设计补偿项,提高鲁棒性和减小稳态误差,再对整个系统的稳定性做了严格的证明。最后将提出方法用于四旋翼飞行器控制,Matlab仿真分析表明,干扰观测器补偿的自适应离散终端滑模控制比离散终端滑模等其他控制方法具有响应时间更快、跟踪效果更理想、鲁棒性更强等特点,实现了在不确定干扰的情况下飞行器姿态的稳定控制。

When used in four-rotor aircraft control, the traditional linear discrete sliding mode has the shortcomings of large tracking error, low response speed, and long convergence time. Aiming at the four-rotor aircraft with outside interference, system uncertainties and modeling errors, we proposed a discrete adaptive terminal sliding mode control method based on disturbance observation compensation. First, the terminal sliding mode control law was designed to the discretization equation including the four-rotor aircraft model, and an adaptive law factor was introduced to decrease the chattering. An improved discrete disturbance observer was constructed by taking the square of the state variables as interference error convergence, and its stability was proved. The improved discrete disturbance observer was used to get high-accuracy estimation of the unknown interference, uncertainties and modeling errors, which were used for compensation in controller design. Thus the robustness was increased and the steady-state error was decreased. Finally, the proposed method was used for the control of four-rotor aircraft. Simulation on Matlab shows that：Compared with the discrete terminal sliding mode controlling method, this method has a faster response speed, better tracking effect, and higher robustness, which can implement stable attitude control of the vehicle in the presence of uncertain disturbance.