为加快Terminal滑模收敛速度,并避免控制器奇异,首先分析了Terminal滑模产生奇异的原因,基于李代数给出Terminal滑模控制器非奇异判据。然后,设计了两种新型非奇异快速Terminal滑模,其收敛速度在任意点均快于现有标准快速Terminal滑模;给出了收敛时间公式。将新型快速Terminal滑模与动态滑模相结合,避免了控制器抖振,设计了近空间飞行器快、慢回路控制器。采用改进的非线性干扰观测器逼近近空间飞行器复合干扰,进一步提高控制精度。基于Lyapunov理论,严格证明了系统的稳定性。最后,进行了仿真验证。
To accelerate the convergence of a terminal sliding mode and avoid the singularity of the controller, an analysis for the cause of singularity in terminal sliding mode is presented in this paper. Based on Lie algebra,the nonsingular criterion is provided for the terminal sliding mode controller. Thereafter, two novel nonsingular fast terminal sliding modes are designed with convergence speed faster than that of a normal fast terminal sliding mode at any points. The formula of convergence time is derived. The new fast terminal sliding mode is combined with the dynamic sliding mode to eliminate chattering. Then, controllers are designed for the fast loop and slow loop of a near space vehicle. In order to improve the control effect, a nonlinear disturbance observer is used to approximate the compound disturbances. By means of the Lyapunov theorem, the system is proved to be stable. Finally, simulation is conducted.
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