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针对有大型挠性附件的卫星高精度高稳定度姿态控制问题,提出了一种基于H_2/H_∞混合控制理论的控制器设计方法。为尽量减少控制器变量的影响以提高其性能,选择刚体卫星模型建立了控制模型,卫星三轴姿态解耦,基于H_∞方法分别设计了三轴控制器。引入三个输出量,考虑三者间关系,设计相应的加权系数,所得H_∞控制器在数学仿真中有较佳的控制效果。考虑实际工程中源于控制周期和执行机构非线性的大幅值高频干扰等因素,用两种方法进行改进:一是设计H_2/H_∞混合控制,抑制噪声的影响,减小输出力矩的振荡;另一是在控制器的速率输入端添加滤波器,防止转速飞轮的高频干扰力矩激发控制器或整个系统的振动。设计的控制器以被动振动抑制方法为基础,考虑现有星上单机的技术条件及速率闭环飞轮的输出特性,通过选择合适的性能输出和反馈信息,在较低的闭环控制系统带宽下实现了大型挠性卫星的高精度高稳定度姿态控制。由数学仿真给出了设计的控制器及其性能,仿真和半物理试验结果均表明设计的H_2/H_∞混合控制器的控制精度、稳定度和挠性振动抑制效果均明显优于传统比例积分微分(PID)控制器。
Aiming at the problems of high precision and high stability satellite attitude control with large flexible attachments, a controller design method based on H_2 / H_∞ hybrid control theory is proposed. In order to reduce the influence of controller variables to improve its performance, a rigid-body satellite model was chosen to establish the control model and the satellite three-axis attitude decoupling. Based on the H_∞ method, a three-axis controller was designed. By introducing three outputs, considering the relationship among them and designing the corresponding weighting coefficient, the obtained H_∞controller has a better control effect in the mathematical simulation. Considering the factors such as the large amplitude and high frequency interference in the actual project due to the control cycle and actuator nonlinearity, two methods are used to improve the system. One is to design the H_2 / H_∞ hybrid control to restrain the noise and reduce the output torque oscillation ; The other is to add a filter at the speed input of the controller to prevent the high frequency interference torque of the speed flywheel from exciting the vibration of the controller or the whole system. The designed controller based on the passive vibration suppression method, taking into account the existing technical conditions of the single on-board satellite and the output characteristics of the rate closed-loop flywheel, achieves the low closed-loop control system bandwidth by selecting proper performance output and feedback information High Precision and Stable Attitude Control of Large Flexible Satellite. The controller and its performance are given by the mathematical simulation. The simulation and semi-physical test results show that the control accuracy, stability and flexibility of the hybrid H_2 / H_∞ hybrid controller are obviously better than the traditional proportional integral Differential (PID) controller.