Strapdown seeker technology for the terminal guidance of tactical weapons

Strapdown or body fixed seekers with sufficient field of view for the terminal guidance of many tactical weapons are now approaching state of the art. Such seekers have a number of advantages over gimballed seekers, including increased reliability and unlimited line of sight rate capability. The major disadvantage is that inertial line of sight rates are not directly available for the implementation of proportional navigation. To form line of sight rates, the seeker output must be combined with inertial sensor measurements. This, however, results in a potential instability due to seeker gain errors. This problem has been minimized by a dither adaptive parameter identification approach for the measurement and correction of seeker errors. Simulation studies indicate the performance of such systems can be comparable to that of gimballed seekers. The basic principles and problems involved with mechanizing proportional navigation with strapdown seekers are considered and performance results for the dither adaptive technique are presented.