Zenith blind zone of two-axis stabilized platform

Zenith blind zone is a phenomenon which the line of sight can not track the target when the target maneuvers in the narrow offboresight of the missile. Utilizing the geometrical relation of photoelectric imaging guidance, the rectangular coordinates and polar coordinates stabilized platform were analyzed. Moreover, the models of zenith blind zone for polar coordinates stabilized platform were presented and the reason of this type of zenith blind zone was analyzed. Furthermore, the zenith blind zone for polar coordinates stabilized platform was simulated in three different rate conditions of target maneuver in Simulink environment of Matlab. Finally, a PID control approach based on variable parameters per different areas was proposed. Aiming at a vertical maneuver mode of target, this variable parameters based PID control method was simulated using Matlab in contrast to general PID control. The results show that the zenith blind zone models for polar coordinates stabilized platform conform to the actual situation and the variable parameter based PID control approach can improve the characters of the target tracking.