Circle Involute-Based Path Planning and Tracking for Impact Angle Control

In this paper, a guidance law considering impact angle constraint for missiles with time-varying velocity is proposed via geometric methods. The guidance concept is based on the geometric property of the circle involute. A simple path planning approach is proposed to find the desired involute trajectory that connects the missile and target while satisfying the impact angle constraint. Once the desired involute trajectory is determined, the reference line-of-sight (LOS) profiles with respect to the downrange are obtained consequently. Then, a robust guidance law is constructed to achieve the precise tracking of the reference LOS profiles that finally guides missiles with time-varying velocity to meet the impact angle constraint. Nonlinear simulations under various scenarios are conducted to validate the proposed guidance law.