Effect of parasitic loop on strap-down seeker and compensated with identification method

In order to analyze the effects of disturbance rejection rate parasitic loop on strap-down seeker, the model of homing loop with strap-down seeker is established. Then a nondimensional model is derived. With Routh criteria and coefficient freezing method, the influence of the time to go, guidance parameter and a scale factor error on the stability of the guidance loop are studied. The adjoint method is used to derive the influence of the scale factor error on miss distance. Based on the identification theory, an identification method to identify the scale factor is presented. The study shows that the scale factor sharply decreases the guidance system stability of a strap-down seeker, and increases the needed flight time. With the identification method, the scale factor can be identified accurately. Thus it can be used to compensate the strap-down seeker. The research can provide technology reference to strap-down guidance system design.