空间机械臂面向太阳能帆板在轨清洁任务的擦抹力/位阻抗控制
FORCE/POSITION IMPEDANCE CONTROL FOR SPACE MANIPULATOR ON ORBIT CLEANING TASK OF SOLAR PANEL
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摘要: 卫星在载体位姿调整过程中燃烧的烟雾容易附着在太阳能帆板上, 若未对帆板定期清洁将导致其供电能力下降, 为此对空间机械臂执行太阳能帆板清洁任务进行了研究. 首先通过Lagrange方程法建立了空间机械臂系统动力学方程, 然后为了控制机械臂末端清洁装置的位姿, 基于运动学关系将动力学模型转换到惯性空间. 结合阻抗控制原理, 根据清洁装置位姿与其输出力之间的动态关系建立了机械臂的阻抗模型, 保证了清洁操作过程中输出力的稳定和精确控制. 为了防止清洁操作的各阶段切换时因系统状态突变导致输出力突变, 造成太阳能帆板的破坏, 基于障碍Lyapunov函数提出一种全状态约束控制策略, 其利用RBF神经网络对不确定系统进行拟合, 且结合虚拟控制力原理对设计的期望轨迹进行修正, 使得太阳能帆板的柔性振动能被抑制, 实现了对卫星与清洁装置位姿的高精度控制. 最后通过Lyapunov定理证明了系统状态的收敛性, 利用仿真分析验证了所提控制策略的有效性; 结果表明清洁装置的输出力控制精度优于0.5 N, 卫星与清洁装置的位姿控制精度优于0.1o和10−3 m.Abstract: The smoke generated by satellite during the process of position and attitude adjustment is easily attached to the solar panel. If the smoke is not cleaned regularly, it will lead to a decrease in the power supply capacity. Therefore, using the space manipulator to implement the task of cleaning the solar panels was studied. Firstly, the dynamic mode of the space manipulator system is established by Lagrange. Then, to control the position and attitude of the cleaning device at the end of the manipulator, the dynamic model is converted to the inertial space form based on the kinematics relationship. After, the impedance model is established according to the dynamic relationship between the position and output force of the cleaning device based on the impedance control principle to ensure stable and accurate control of the output force. In order to prevent the sudden change of the output force from damaging the solar panel due to the sudden change of the system state during the switching of each control phase of the cleaning operation, a full state constraint control strategy that the uncertain system is fitted by RBF neural network is proposed based on the barrier Lyapunov function. And on this basis, to achieve high-precision position and attitude control of the satellite and the cleaning device, the virtual control force principle is used to modify the expected trajectory of the design, so that the flexible vibration of the solar panel can be suppressed. Finally, the stability of the system is proved by the Lyapunov theorem, and the effectiveness of the proposed control strategy is verified by simulation analysis. The results show that the output force control accuracy of the cleaning device is better than 0.5 N, the position and attitude control accuracy of the satellite and the cleaning device are better than 0.1o and 10−3 m.