共位衍射电磁航天器成像过程中的小推力控制

Low-Thrust Control of Diffraction Imaging for Collocated Diffractive Electromagnetic Spacecraft

为了满足衍射成像系统在解决低轨遥感航天器覆盖范围小、目标重访周期长等问题的同时,而引入对航天器相对位置、姿态控制的需求。针对共位衍射航天器相对位置、姿态控制过程中传统推力器带来的羽流污染问题,采用电磁推力器和飞轮作为执行器,设计一种基于快速非奇异滑模的轨道控制器和基于PID的姿态控制器。所设计的快速非奇异滑模轨道控制器为共位衍射航天器频繁位置调整提供控制保障,基于PID的姿态控制器能够消除由电磁力耦合产生的电磁干扰力矩。研究结果表明:基于相对轨道动力学方程设计的快速非奇异滑模控制律鲁棒性好、收敛速度快,能够达到两颗共位衍射电磁航天器沿Z轴保持在10m相对距离的控制效果。在轨道调整过程中,其姿态能够通过PID算法稳定控制到期望姿态,使衍射成像结构一直保持不变,从而有效完成衍射成像任务。

In order to meet the requirements of the relative position and attitude control of the spacecraft in⁃troduced by the diffraction imaging system while solving the problems of low-orbit remote sensing spacecraft’s small coverage and long target revisit period,for the relative position and attitude control,the electromagnetic thrusters and the flywheels were used instead of traditional thrusters as the actuator to solve the problem of plume pollution.Furthermore,the orbit controller based on the fast nonsingular sliding mode control and the attitude controller based on the PID control law were designed for the electromagnetic spacecraft system.In this case,the orbit controller provides control support for frequent position adjustment of the geostationary orbit diffraction imag⁃ing system,and the attitude controller can eliminate the electromagnetic interference torque caused by electro⁃magnetic force coupling.The test results show that the fast nonsingular sliding mode control law based on relative orbit dynamics equation has good robustness and fast convergence speed.The orbit controller can achieve the con⁃trol effect on two collocated diffraction electromagnetic spacecrafts which allowed them keep a relative distance of 10m along the Z axis.In the process of orbit control,the attitude can be stabilized to the desired attitude through the PID controller,so that the diffraction imaging structure remains unchanged,thus completing the diffraction imaging task effectively.