基于干扰观测器的航天器非奇异终端二阶滑模控制

Non-singular terminal second-order sliding mode control of spacecraft on disturbance observer

为了消除干扰力矩和结构不确定性对卫星姿态控制性能的影响,本文提出了一种基于新型干扰观测器的非奇异终端二阶滑模控制方法.首先,文章设计了一种基于跟踪微分器的干扰观测器,来对卫星系统中的不确定项进行估计,利用估计值进行补偿,并保证估计误差在有限时间内收敛.在此基础上,文章设计一个非奇异终端滑模面,当系统到达滑模面时,姿态误差可以在有限时间内收敛,并利用二阶滑模趋近律设计控制器,保证系统在有限时间到达滑模面.在干扰观测器误差未完全收敛时,滑模控制器可以对存在的扰动进一步抑制,实现姿态跟踪系统的有限时间稳定,并通过李雅普诺夫方法严格证明了其稳定性.最后,仿真结果表明,干扰估计值误差可以在有限时间内收敛,证明了该控制方法对存在的干扰是具有较好的鲁棒性.

In order to eliminate the influence of disturbance torque and structural uncertainty on the maneuvering control performance of rigid satellite attitude tracking,a non-singular terminal second-order sliding mode control method based on a novel disturbance observer is proposed in this paper.Firstly,a disturbance observer combined with a tracking differentiator is designed to estimate the uncertain items in the satellite system.The estimated value is used for feedforward compensation,and the estimation error is guaranteed to converge within a limited time.On this basis,a non-singular terminal sliding mode surface is designed to ensure that the attitude error can converge in finite time when the system reaches the sliding mode,and the controller is designed by using the second-order sliding mode reaching law to ensure that the system reaches the sliding mode in a finite time.At the same time,the existing disturbance can be further suppressed when the error of the disturbance observer is not fully converged,and the finite-time stability of the closed-loop attitude tracking system can be achieved,and its stability is strictly proved by the Lyapunov method.Simulation results show that the error of the disturbance estimation value can be converged in limited time,which proves that the control method has good robustness to the existing uncertain disturbances,and the chattering phenomenon is obviously weakened because the disturbance is compensated.