基于高阶滑模变结构的挠性航天器大角度姿态机动控制研究

Variable Structure Control Study for Large-Angle Attitude Maneuver of Flexible Spacecraft Based on High Order Sliding Mode

考虑转动惯量不确定性和外界干扰条件下,对基于高阶滑模变结构的挠性航天器大角度姿态机动控制进行了研究。用四元数描述航天器的姿态运动学方程,为消除一阶滑模变结构控制律中因符号函数切换产生的高频抖振,用超螺旋算法设计了二阶滑模变结构控制器。超螺旋算法包括控制律的不连续时间导数和滑模变量的连续函数两部分,保证滑模相对阶次为2,无需滑模变量的时间导数信息,用连续的超螺旋控制律替代符号函数的切换部分,实现了二阶滑模变结构控制。仿真结果表明:算法对姿态机动控制力矩抖振的抑制作用明显,在相同的扰动和转动惯量不确定性条件下,基于超螺旋算法的二阶滑模变结构控制对挠性附件的振动抑制能力更强,抗干扰能力和鲁棒性更优。

The variable structure control study for large-angle attitude maneuver of flexible spacecraft based on high order sliding mode was studied under the uncertainty of rotational inertia and outer disturbance in this paper.The attitude kinematic equation of the spacecraft was expressed by quaternion.To eliminate the chattering problem caused by function switching in one order variable structure control law,the two order variable structure controller was designed by super-twisting algorithm. The super-twisting algorithm included two parts which were discontinuous time derivative in the law and continuous function of sliding mode variable.The relative order was guaranteed to be 2.There was no need for time derivative of sliding variable.The symbolic function was substituted by smoothing continuous super-twisting control law.The 2order variable structure control was implemented.The simulation results showed that the 2order control law proposed performed well in suppression of chattering for control torque in attitude maneuver.The 2order variable structure control based on super-twisting algorithm had better ability of vibration suppress,anti-disturbance and robustness under the same uncertainty of rotational inertia and outer disturbance.