Design and Simulation of three-dimensional guidance law based on Variable Structure Control

Inspired by the parallel approach method, as long as the angle of sight between the interceptor and the target is kept constant, the interceptor can hit the target accurately. In this paper, through the relative motion equation of interceptor and target in three-dimensional space, the state equation of line of sight angle change between interceptor and target is derived, and the controller is designed with variable structure control method to keep the line of sight angle constant, so as to achieve the purpose of interceptor hitting the target accurately. Theoretical derivation and simulation show that the designed controller can ensure that the azimuth angle of line of sight and the elevation angle of line of sight between the interceptor and the target remain constant, the interceptor hits the target accurately, and has strong robustness to the measurement error of target parameters.