Improved heading using dual speed sensors for angular rate andodometry in land navigation

摘要

Two radar ground speed sensors are used in a land navigationsystem to provide improved heading by dampening erratic headings andremoving misalignments associated with magnetic compasses. Radar groundspeed sensors provide vehicle speed without contacting the groundsurface and are not subject to errors such as wheel slippage normallyassociated with wheel encoders or odometers. Differences between thespeed sensors provide a measure of angular rate which is input, alongwith magnetic compass heading, into a heading pre-filter. This providesan intermediate heading improvement by dampening the erratic magneticcompass heading outputs. The average of the speed sensors provide ameasure of distance traveled over a sample interval. Distance traveledand the heading pre-filter's output, are used to establish adead-reckoning navigation solution. This navigation solution is used asa reference state trajectory in a navigation Kalman filter algorithm,processing differential GPS positions as observations, to estimateposition, odometer scale factor, and heading misalignment errors. Theheading misalignment estimate is added to the heading pre-filter'sheading estimate to provide the final heading improvement for anoperator or vehicle guidance algorithm