Research and simulation of guidance law based on GPS/INS combination

In this work, the proportional navigation (PN) law with gravity compensated based on GPS/INS combination is formulated at first, and a guidance law is designed via Variable Structure Control (VSC). Secondly, as the primary reason of chattering in the traditional VSC, the input Relay-characteristic is improved in order to reduce chattering at the end time, and three continuous functions are given. To evaluate the performance of the two guidance solutions, a numerical simulation of the missile's guidance with a two-order dynamics of the autopilot is used. The results show that, guidance law based on VSC is faster than PN law. Moreover, the improvement has a great effect on reducing chattering at the end time, and the third method addressed by this work has a better result.