论文部分内容阅读
针对空天飞机再入飞行阶段存在模型参数不确定和外部扰动情况下的姿态跟踪控制问题,分析、建立了考虑地球自转的空天飞机六自由度动力学模型;以此为基础,利用非线性三阶扩张状态观测器可实时在线估计姿态角速度和系统扰动的显著优点,导出了适用于控制系统设计的数学模型;利用该模型,设计了一种基于非线性三阶扩张状态观测器的快速光滑终端滑模控制算法。然后,基于李雅普诺夫理论,严格证明了系统的稳定性。控制算法利用快速光滑终端滑模控制无需惯常终端滑模控制所需的控制量系数矩阵的求逆计算,提高了控制算法的计算实时性;同时,采用光滑滑模趋近律能够在有限时间内收敛到滑模面且有效地消除抖振,对系统的参数摄动及扰动具有很强的自适应性。仿真结果表明,相比基于非线性三阶扩张状态观测器的传统非线性反馈控制算法,文中所提出的控制算法调整时间短,超调量小,并且具有良好的跟踪精度,具有一定的工程应用价值。
Aiming at the uncertainty of model parameters and the problem of attitude tracking control in the reentry flight phase of the space shuttle, the six-DOF kinetic model of the space shuttle considering the earth rotation is established. Based on this, The third order extended state observer can estimate the significant advantages of attitude angular velocity and system disturbance on-line in real time. The mathematical model suitable for the design of control system is deduced. By using this model, a fast and smooth method based on nonlinear third order extended state observer Terminal sliding mode control algorithm. Then, based on Lyapunov theory, the stability of the system is strictly proved. The control algorithm improves the real-time calculation of the control algorithm by using the fast and smooth terminal sliding mode control to inversely calculate the control coefficient matrix needed by the conventional terminal sliding mode control. At the same time, the smooth sliding mode approach law can be used within a limited time Converges to the sliding mode surface and effectively eliminates the chattering and has strong self-adaptability to system parameter perturbation and disturbance. The simulation results show that compared with the traditional nonlinear feedback control algorithm based on the nonlinear third-order extended state observer, the control algorithm proposed in this paper has short adjustment time and small overshoot, and has good tracking accuracy and has some engineering applications value.