自适应二阶动态terminal滑模在近空间飞行器控制中的应用

为克服滑模抖振,设计了二阶动态terminal滑模,得到在时间本质上连续的控制器,并使滑模面在有限时间内收敛.然后采用非线性干扰观测器逼近复合干扰,通过在控制器中设置自适应补偿项,放宽了非线性干扰观测器的假设条件,不再要求复合干扰变化率为零.基于李雅普诺夫理论,严格证明了系统稳定性.最后将提出的控制方案应用于近空间飞行器姿态角跟踪仿真实验,仿真结果表明了该控制方案的有效性及优越性.

Application of adaptive second-order dynamic terminal sliding mode control to near space vehicle

A second-order dynamic terminal sliding mode control is proposed for near space vehicle which has characteristics such as violent changes of aerodynamic parameters, high nonlinearity, strong coupling and uncertainties. To achieve high control precision and overcome chattering which usually exists in conventional sliding mode control, second-order dynamic sliding mode control is combined with terminal sliding mode control. The terminal sliding mode control speeds up convergence of tracking error and the second-order dynamic sliding mode control obtains continuous controller in time domain by embedding discontinuous functions into the first-order differential of controller and also makes sliding surface and its some order derivatives equal to zero. Consequently, nonlinear disturbance observer is used to approximate compound disturbance. Adaptive compensation term, which relaxes the prerequisite of nonlinear disturbance observer, is added to controller. Finally, the simulation applied to near space vehicle demonstrates the superiority and effectiveness of the control scheme.