Satellites Autonomous Navigation With an Extended State and Disturbance Sliding Mode Observer Method

This paper considers the satellites autonomous navigation problem with an extended sliding mode observer method. First, on consideration that the relative dynamic equation of chaser and target spacecrafts refers to a nonlinear time-varying system, a transformation is performed on the original relative dynamic equation to obtain a linear time-invariant system with a nonlinear part. Second, an augmentation strategy is made on the new system to obtain a descriptor system. A new extended sliding mode observer is then designed for the descriptor system which can generate the simultaneous estimation of state and output measurement noise. Based on the observer estimates, the equivalent output error injection approach is used to estimate the space disturbance moment. Finally, an example is presented to demonstrate the effectiveness of the developed satellites autonomous navigation observer method.