Compensation for the Body-Coupling in the 2-Gimballed Seeker Homing Loop on BTT Missile

It is observed that if the 2-gimballed seeker is stabilized using rate gyros mounted along its primary axis, line of sight change measured in the seeker is induced by the rolling due to the bank-to-turn(BTT) steering as well as the actual change. This body-coupling within BTT homing includes the spurious target maneuver effect and the coupling loop due to the rate gyro misalignment. In this paper we formulates the linear BTT homing loop model with a 2-gimballed seeker including those body-coupling effects. With the model, we analyze the effects of the couplings, and show that the roll rate coupling to the rate gyro for the stabilztion of gimbal could seriously deteriorate the homing loop stability. And we propose a direct linear compensator for the coupling to recover the stability.