Nonlinear differential games guidance law based on SDRE with terminal impact angular

The problem of intercepting a maneuvering target at a terminal impact angular is discussed in the nonlinear differential games framework. A feedback form solution is proposed by extending the state-dependent Riccati equation (SDRE) method to nonlinear zero-sum differential games. An analytic solution is obtained for the SDRE corresponding to the impact-angle-constrained guidance problem. The impact-angle-constrained guidance law is derived using the line-of-sight rate and projected terminal impact angle error as the state vectors. Local asymptotic stability conditions for the closed-loop system corresponding to these states are studied. Time-to-go estimation is not explicitly required to derive and implement the proposed guidance law. Finally, through mathematical simulations, the derived guidance law is tested under four scenarios of target maneuvering: nonmaneuvering, step maneuvering, sine maneuvering and the best control maneuvering. The simulation results show that the guidance law have good effects for different maneuvering targets and can satisfy terminal impact angular constraint requirements. © 2016, Editorial Office of Systems Engineering and Electronics. All right reserved.