An improved adaptive sliding-mode navigation guidance law with variable structure

To make anti-tank missile(ATM)have the capability of low-altitude defense, and improve its hit accuracy to air maneuvering target, the simplified missile-target relative motion model of terminal guidance phase in longitudinal plane was derived. Based on the thread of annihilating the missile-target LOS angular-velocity, an improved adaptive sliding-mode variable-structure guidance law was designed. Meanwhile, the chattering phenomenon of variable structure was weaken by the integrated application of saturation function and improved variable switching term. Simulation results show that the guidance law has high accuracy at the time of attacking maneuvering air target, and the normal overload of guidance trajectory can be distributed reasonably by the guidance law. The results prove that the designed guidance-law is effective.