针 对 运 动 目 标 的 可 观 性 增 强 非 线 性 最 优 制 导 律

This paper proposes a nonlinear observability-enhancement optimal guidance law for moving targets of the missiles with strapdown seekers. Firstly，a nonlinear relative motion model between the missile and the moving target is constructed based on a virtual relative coordinate system with its origin fixed at the target，so that the linearization process can be avoided under the condition of small-angle assumption. Secondly，the integral of the LOS rate is leveraged as the measure of target observability based on the Cramer-Rao lower bound theory. The performance index to be optimized is designed by considering target observability，guidance accuracy and energy consumption. In addition，the dependence on the time-to-go is removed by utilizing the relative range as the independent variable. The analytical solution for the guidance law is derived by using calculus of variation. The simulation results show that the proposed guidance law can intercept moving targets using bearing-only measurements. Compared with the observability-enhancement optimal guidance laws based on the linearized model，the proposed guidance law can enhance the system observability more significantly，which results in a smaller value of the estimation error of guidance information，faster convergence，and higher hit accuracy of the missile.