Advanced Guidance Laws for Field of View and Impact Angle Constrained Engagements

Abstract

This thesis deals with the development of guidance laws for interceptors with seeker field-of-view (FOV) and impact angle constraints. Two classes of guidance problems, namely, field-of- view and impact angle constrained guidance; midcourse guidance of dual pulse interceptors with look angle constraints, are considered in this thesis. In the first problem, decision variables are lateral acceleration commands whereas the second problem has an additional decision variable of second thrust pulse firing time. For the first problem, three guidance laws are proposed using nonlinear control theory. These are (i) Backstepping control based guidance law (ii) Nonlinear mapping based guidance law for three dimensional engagements, and (iii) Partial integrated guidance and control based guidance law. For the second problem, singular perturbation technique is used to derive the guidance law. First, backstepping control based guidance law is proposed for impact angle and field-of-view constrained engagements in a planar geometry. The kinematic equations governing the problem are modified to strict feedback form for deriving the guidance law using backstepping technique. The look-angle, which is virtual input to the backstepping structure, is designed such that it is within the feasible domain and achieves the desired impact angle. Barrier Lyapunov functionals are used to derive a guidance law to track the virtual input without violating the field-of-view constraints. Further, capturability of the proposed guidance law is analyzed in the relative velocity plane. Simulation results are presented using a constant speed as well as a realistic interceptor model to show the efficacy of the guidance law. Next, backstepping control based guidance law is further extended to intercept targets in three dimensional space using nonlinear transformation. The interception geometry is controlled by defining impact angles in terms of flight path angles of interceptor and target...