Design of Mid-Course Guidance Law Considering J2 Perturbation for Long-Range Fuel-Exhaustion-Shutoff Interceptor

In order to realize remote and high precision kinetic energy interception, a closed-loop mid-course guidance law based on general energy management (GEM) is designed to solve the problem of the exhaustion shut down of an interceptor with solid fuel engine under strong time constraints. In this paper, the impact of the non-spherical J2 perturbation on the trajectory is firstly considered to improve the algorithm of the Lambert problem and correct the deviation of the demand velocity caused by the Earth oblateness perturbation in the long-range interception, elevating the demand velocity accuracy by an order of magnitude. Then, an energy modulation angle virtual mapping relationship is presented based on the GEM to achieve the attitude command smooth transition during the energy modulation initial stage. And the near-off point thrust direction strategy is changed to solve the command divergence problem. The introduction of the accelerometer feedback in the guidance process enhances the robustness to the propulsion system parameters. Six-degree-of-freedom simulation shows that this guidance law is more accurate and adaptable than the conventional GEM guidance law.