Test of Parasitic Loop Quality of Strapdown Seeker

In order to analyze the effect of disturbance rejection rate parasitic loop on strapdown imaging seeker, a model of disturbance rejection rate parasitic loop of strap-down seeker is established. Nondimensionalized method is used to obtain dimensionless characteristic equation, the effects of the guidance parameter and the scale factors and dynamic errors of gyro and seeker on the stability region of parasitical loop as well as the effect of parasitic loop on the dynamics of guidance system are studied by using Routh criteria, and the nonlinear models are established. Monte Carlo method is used to study the change of miss distance with scale factor and dynamics errors. A semi-physical open loop test system is established to appraise the quality of disturbance rejection rate parasitic loop. The research result shows that the scale error and the mismatch between the rate gyro and the detector are the main factors that cause the DRE parasitic loop. The numerical value of the error and mismatch decides whether the parasitic loop is positive or negative feedback. The stable domain of positive feedback is far less than that of negative feedback, while the miss distance is more sensitive to guidance system deviation. To improve the guidance precision, five axis turntable semi-physical simulation test system was used to test and calibrate the damping characteristics of parasitic loop, by which the parasitic effect can be eliminated by eliminating the scale error and the mismatch, or at least be reduced by constructing a negative feedback parasitic loop.