空间电磁对接的非线性控制

空间电磁对接技术能避免诸如推进剂消耗、羽流污染和对接冲击等现有基于推力器对接所固有的不足，对接装置具有较高性价比，在小卫星领域具有广阔应用前景．空间电磁对接控制具有强非线性特性，论文综合采用反馈线性化理论及PD控制方法对该控制问题进行研究．首先基于反馈线性化理论线性化控制模型，根据空间电磁对接任务特性分析其适用性；基于线性化模型，将空间电磁对接路径跟踪问题转换为跟踪误差渐近稳定问题，采用基于扩展卡尔曼滤波的PD控制方法设计控制律；最后本文做了仿真分析，其中考虑了电磁力模型误差和地球非球形J2项的影响．理论研究与仿真分析表明：该控制方法能有效解决空间电磁对接控制的强非线性问题，对外界干扰、模型误差具有较好鲁棒性．

Nonlinear control of space electromagnetic docking

The space electromagnetic docking avoids the inherent shortages of the space docking based on thruster. Such shortages include propellant over consumption, plume contamination and docking impact. Electromagnetic docking devices are of high ratio of performance to cost, and will be widely applied to small satellites in the future. To deal with the strong nonlinearity in the control of space-electromagnetic docking, we employ feedback linearization and the PD control method. First, the control model is linearized based on the feedback linearization theory, and the feasibility of linearization is analyzed according to the characteristics of the electromagnetic docking. Secondly, on the basis of the linearized model, the path tracking problem is transformed to a problem of error stabilization, for which a linear control law is developed by using the PD control and the extended Kalman filter. Finally, the nonlinear space-electromagnetic docking simulation is performed and the results are analyzed, taking into account the additional electromagnetic force model error and the J_2 term of the gravitation. Theoretical research and numerical simulation analysis show that the strong nonlinearity of the electromagnetic docking can be handled by this combined control method, and a high robustness to the external disturbance can be achieved.