Three-dimensional Impact Angle Control Guidance Law for Missiles Using Dual Sliding Surfaces

Guidance law considering terminal impact angle constraints for missiles is proposed based on sliding mode control scheme with dual sliding surfaces. The merits of this method are that the angular constraints are satisfied prior to the impact and is maintained until interception with stable fashion. Therefore, excessive acceleration command at homing phase is not required. Based on the nonlinear three-dimensional equations of motion for the missile and stationary target, two acceleration commands, pitch and yaw channel command, are generated with the proposed guidance law. Dual sliding surface based guidance law without terminal constraints is also developed for the comparison purpose. Consideration on singularities are made and singular avoidance rule is inherited. To verify the effectiveness of the proposed scheme, 6-DOF numerical simulation is performed. Simulation results demonstrate that the guidance law has good performance in spite of the terminal constraints, nonlinearities, and cross-coupling effect of the engagement environment.