A new attitude controller was proposed for rigid-body spacecraft subject to input saturation and slow-varying disturbances. Based on the immersion and invariance methodology, the slow-varying disturbances were regarded as unknown parameters and the estimation equation was then derived independent of the control input. The controller was designed based on the estimation of the disturbances, which was simply in the proportional and differential form plus a disturbance compension term. By means of the immersion and invariance method, the following results were obtained: when the disturbance is varying slowly, the attitude tracking errors can be regulated to a ball near the origin that can be arbitrarily small by adjusting some parameters; when the disturbances are constant, the influence of disturbances can be completely eliminated and global asymptotical stability is obtained. Finally, simulations were presented to validate the effectiveness of the proposed control scheme.%设计了一种抗慢时变干扰的简单饱和姿态控制器.其基本原理是将干扰作为未知参数,然后利用浸入与不变流形的方法设计了独立于控制器的干扰估计器,从而再基于干扰的估计结果设计饱和控制器.该控制器形式简单,由比例与微分项和干扰补偿项组成,各部分物理意义明确.根据浸入与不变流形方法,通过严格的理论证明得到了如下结果:对于慢时变干扰的情况,通过调整控制干扰辨识收敛速度的参数,可以使得理论上的姿态最终控制误差任意小(实际仿真误差还受限于由数值稳定性决定的时间步长)；对于干扰为常值的情况,则可以完全消除干扰的影响,并获得系统状态渐近稳定的结果.最后通过数值仿真验证了控制方案的可行性.
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