Three dimensional retro-PN based impact time control for higher speed nonmaneuvering targets

In the implementation of modern guidance laws, especially in impact time constrained engagement scenario or multiple agent salvo attack scenario, a good estimate of time-to-go is extremely crucial. The most widely used time-to-go estimate range over closing speed has several limitations. Very few work is there in existing literature which actually try to estimate the time-to-go. Most of them are meant for the engagement of lower speed target with a higher speed interceptor. However, in the current defence scenario, targets of higher speed than the interceptor is a reality. This paper first discusses a recursive time-to-go estimation method for three dimensional engagement of a Retro-PN guided interceptor with higher speed non-maneuvering target and then presents a navigation gain scheduling algorithm to achieve the interception at a pre-specified time. The effectiveness of the time-to-go estimation method and the gain scheduling algorithm is justified with simulation results.