An Integrated System for Land Navigation

Abstract

Perhaps the most stringent requirement for land navigation is imposed by winter operations in the high arctic. The serious consequences of being lost or failing to find a supply dump in the arctic make reliability and accuracy vital necessities. A combination of circumstances conspire to also make the arctic a particularly difficult area in which to navigate by conventional means. Until GPS becomes fully operational, there will be no single system capable of continuously providing the necessary position and heading accuracy. Even then, reliability considerations will dictate that a self contained or autonomous backup be available, certainly for the military user. The Defence Research Establishment in Ottawa (DREO) has therefore developed a multi-sensor, optimally integrated navigation system to satisfy the present operational requirements of the Canadian land forces, which are most severe in the arctic. This system, called PLANS (Primary Land Arctic Navigation System) was designed to be a highly reliable, high- to moderately-accurate, automatic navigation system for all weather off-the-road use. Although designed primarily to meet an arctic requirement, PLANS would of course be just as applicable for desert navigation, or for any application in which reliability and accuracy are a priority, or where simpler and less costly methods are ineffective. PLANS combines several self contained sensors with two satellite receivers, using Kalman filter techniques to provide a continuous optimal estimate of position, height and heading. Time and attitude are also provided, along with waypointing functions. The self contained sensors consist of a gyrocompass/directional gyro unit, an odometer pickoff for speed, a magnetic fluxgate sensor (for which a detailed geomagnetic field model is used in the software) and a baroaltimeter. The satellite receivers are a single channel C/A-code GPS and a dual channel Transit. This paper describes the requirement, the difficulties in meeting this requirement, the design of a multi-sensor integrated system solution, some simulation results and some field trial results.