INTRODUCTION
The digital capture loop controller has two primary functions: I) to stabilize the inertial element in a torque-rebalance-loop, which maintains instrument null during all expected vehicle maneuvers; and 2) to process and form-at capture loop data for use by a navigation processor. Historically, classical techniques have been used in the controller design. In these implementations the average inertial input along a sensitive axis of the inertial element is approximated by the torque command, U. The torque command is a true indication of the applied inputs only if the loop is perfect. Any deviation from null as- a result of finite resolution, dynamic lag or overshoot in the command will result in an inaccurate approximation.