针对挠性卫星大角度姿态机动的振动抑制问题,提出了一种双回路鲁棒主动振动控制方法.首先,采用压电智能元件作为作动器和敏感器,通过求解一个带有线性不等式约束的最优静态输出反馈控制问题,给出了设计低阶振动模态最优正位置反馈补偿器的算法;然后,考虑到挠性结构模态不可测,给出了仅利用输出信息的自适应变结构姿态控制器设计方法,使闭环系统的轨迹渐近趋于滑动模态区,并且避免了确定不确定性和外干扰界函数上限的困难.最后,将该方法应用于挠性航天器的大角度姿态机动控制,并进行了仿真研究,结果表明,所提出的方法是可行而有效的.
This paper presents a dual-stage control system design method for the rotational maneuver and vibration stabilization of a spacecraft with flexible appendages embedded with piezoceramics as sensors and actuators. In this design approach, attitude control and vibration suppression were designed separately using lower order model. The design of attitude controller was based on adaptive variable structure control (AVSC) theory leading to a discontinuous control law. This controller accomplishes asymptotic attitude maneuvering in the closed-loop system and is insensitive to the interaction of elastic modes and uncertainty in the system. To actively suppress certain flexible modes, a modified positive position feedback compensator which adds damping to the flexible structures in certain critical modes was designed in the inner loop. The problem of determining the modified PPF gain is formulated as static output feedback problem. Numerical simulations are performed to show that rotational maneuver and vibration suppression are accomplished in spite of the presence of disturbance torque and parameter uncertainty.