Missile autopilot design based on second order sliding modes control

The difficulties in designing an effective load control missile autopilot arise from highly nonlinear and non-minimum phase plant characteristics because the missile acceleration is regarded as output. To avoid the instability problem associated with unstable zero dynamics, a modified second order sliding mode controller was proposed through reconstruction of the novel sliding surface, and the suitable commutation logic of control law was introduced to prevent an uncontrollable growth of uncertainties, then the system zero dynamics can be stabilized by pole assignment. The simulation results show the validity of the proposed method in trajectory tracking and chattering attenuation.