Time-to-Go Estimate for Missile Guidance

Time-to-go is the time when the missile will arrive at the point of closest approach to the target. A good time-to-go estimate is important for the guidance laws that depend explicitly on the time-to-go. Two time-to-go closed-form solutions were developed and will be discussed here. One time-to-go estimate accounts for the missile-to-target accelerations. It provides an accurate time-to-go estimate if the missile and target accelerations are constants, or average missile and target accelerations for the flight can be estimated. The other time-to-go estimate accounts for future true proportional navigation acceleration. It provides an accurate time-to-go for a missile using true proportional navigation guidance. Both time-to-go estimates are very simple to implement.