Improvement of Air-to-Air Missile Guidance by an Imaging Sensor

The guidance of an air-to-air missile is investigated when the radar sensor is supported or replaced by an imaging sensor. The scenario covers the final approach of a missile in a head-on attack against a maneuvering combat aircraft. For flight under radar control, various guidance laws are considered, starting with proportional navigation. More sophisticated guidance schemes based linear quadratic optimization, pole placement and linear differential game reduce the miss distance to approximately one third. The glint limits further improvement of radar controlled missiles.An imaging sensor in the frequency band of visible light works on a noise level far below that of a radar. In a first step the electro-optica sensor and the radar with their associated filters are working independent- ly. They supply estimates of target's normal acceleration and line-of-sight rate as guidance signals to an augmented proportional navigation. The miss distance sinks to a value better than that for proportional navigation under radar control, but falls behind the performance of the sophisticated guidance schemes. Coupling of the filters reduces the error to vaues slightly below those obtained under radar control. In the last step of the investigation line-of-sight rate is taken from the imaging sensor and its filter. The smooth and hardly delayed guidance signals of the all optical system lower the miss distance to one tenth of the best achieved under radar control. This favourable result holds for a wide variation of relevant parameters.