Guidance law with multiple constraints and seeker field-of-view limit and the time-to-go estimation

The guidance law with impact angle constraint can enable missiles to hit the target in a designated direction,and the guidance law with impact time constraint can enable missiles to hit the target at a designated time.Compared with the traditional guidance approach(e.g.the proportional navigation guidance law),these guidance laws all result in additional maneuvers,which may cause the target to move out of the missile seeker's field-of-view(even for a stationary target).To solve this problem,by utilizing the nonlinearity of the cosine function,proportional navigation guidance law with a biased item composed of the seeker field-of-view limit and impact angle constraint is constructed firstly,and the time-to-go estimation of this guidance law is derived.Then,by adding the feedback of the time-to-go error,aguidance law with seeker field-of-view limit and both impact angle and impact time constraints is proposed.Simulation results show the validity of the proposed approach.