Characteristics of Systems Feasible for Inertial Navigation of Submarines

Abstract : This report is the result of a study of possible submarine inertial navigation methods. Prior investigation has narrowed the field of inquiry to gravity-field navigation, and pointed to a system design based on a stable vertical element which is essentially an equivalent pendulum with eight-four- minute-period characteristics, a so-called Schuler-tuned system. The equivalent pendulum is represented by a controlled member which is oriented by accelerometer-monitored gyro units to indicate the vertical. The accelerometer units furnish data, which, after processing, are used to precess the gyro units and drive the controlled member so that it responds to changes in the vertical direction as the ship moves along its course over the surface of the Earth. The gyro units also, in conjunction with the same controlled member drives, simultaneously isolate motions of the base from the controlled member. This kind of vertical indicator is described in detail in the report, with the discussion including such problems as the effects of damping, uncertainties in component outputs, and inaccuracies in inputs from external sources. With this system, Schuler tuning eliminates the requirement for precise external compensation. The optimization of system parameters is discussed, and numerical values are given for optimum parameters.