采用变速控制力矩陀螺的航天器自适应姿态跟踪和稳定控制研究

Spacecraft Adaptive Attitude Tracking and Stable Control with Variable Speed Control Moment Gyroscopes

研究以变速控制力矩陀螺群(VSCMGs)为主执行机构的卫星功率/姿态一体化控制(IPACS)问题。针对卫星的三轴稳定控制和相对惯性系的姿态跟踪问题分别设计了两类自适应控制器,二者都考虑了执行机构的动力学特性,并进行了稳定性的证明。其中前者采用相对姿态描述,可以避免三轴稳定飞行中因惯性姿态旋转方向的选择而引起的控制力矩突变;后者采用改进的罗得里格斯参数(MRPs)描述姿态,简化了控制器设计过程并避免了运动学奇异。对姿态误差的描述,前者采用小姿态角假设下的偏差形式,后者采用现时姿态与期望姿态之间的方向余弦矩阵,更具有合理性。设计了能够逃离奇异、并具有轮速平衡功能的VSCMGs的操纵律,并应用磁力矩器为VSCMGs进行动量卸载。最后,通过两个算例进行了仿真,验证了所设计系统的可行性和有效性。

This paper deals with the Integrated Power and Attitude Control System（IPACS） for spacecraft with single-gimbal Variable-Speed Control Moment Gyroscopes（VSCMGs） as main actuator. Two adaptive attitude controllers are designed, one for three axes attitude stable mode and the other for attitude tracking mode of the spacecraft. The dynamic characteristics of VSCMGs are considered in both controllers. The stabilities for both control systems are proved. For the former, the relative attitude description is used, so that the torque jump which may appear when choosing rotation direction in inertial attitude description is avoided. For the latter, the Modified Rodrigues Parameters（MRPs） are used to describe the attitude, thus the design procedure is simplified, and the kinematics singularities are avoided. For the former, the attitude error is provided in the form of subtraction based on the assumption of small attitude angles. For the latter, it is expressed by rotation matrix from desired attitude to current one. The steering law, which can escape the singularities of VSCMGs configuration and balance the speeds of rotors, is proposed. The 3-axis magnetic torquers are applied for desaturation of VSCMGs. Finally, numerical examples based on a small satellite on sun-synchronous orbit are provided, and the simulation results illustrate the feasibility and validity of the proposed control algorithms.