Stability and measurement of seeker disturbance rejection rate parasitic loop

To study the stability of seeker disturbance rejection rate parasitic loop, models of disturbance rejection rate transfer function and parasitic loop were established for a typical gimbaled seeker. Two kinds of experiment systems for evaluating the stability of disturbance rejection rate parasitic loop were also proposed. Then, the characteristic of disturbance rejection rate transfer function was analyzed by using frequency domain methods. The effect of guidance parameters on the parasitic loop stability region was studied by employing Routh criteria. For an infrared imaging seeker with particular parameters, the disturbance rejection rate transfer function and stability of parasitic loop were analyzed under typical flight condition and the effectiveness of proposed test method for inspecting parasitic loop's stability was experimentally verified. The results show that the parasitic loop may go unstable in the middle frequency mostly. Both the guidance parameters and amplitude-phase characteristic of the disturbance rejection rate transfer function affect the stability of parasitic loop significantly.