Nowadays, Global Navigation Satellite System (GNSS) is the general technology selected to provide global threedimensional navigation in many different conditions. However, the interferences, including multipath effect and Nonline-of-sight (NLOS) reception, significantly limit its effectiveness. This study proposes GNSS/Odometer/Barometer integration to enhance the performance in GNSS domain. The accurate and frequent velocity measurements from an odometer can be used to act as a relative position constraint of the current position to the previous one. Additionally, the instantaneous-measured velocity can also be introduced as a constraint for the resultant of velocity in the threedimension. On the other hand, a barometer is a commonly applied and cheap sensor for height determination based on the measurements of atmospheric pressure. This relative barometric height estimation from a barometer can be considered as a height constraint between consecutive epochs, and reduce the severity of multipath/NLOS reception in the vertical. In general, the proposed integration with the constrained strategy outperforms conventional solution and shows a more reliable navigation solution. The statistical analysis shows approximately RMSE 5.5 m, 1.5 m, and 0.5 m for the 3-D position, cross-track error, and 3-D velocity, with 71.4% significant improvement of the maximum error over traditional GNSS filter. The experimental result exhibits the proposed integration is capable of allowing the application to locate a vehicle’s position on a particular road in GNSS-degraded environments.

Keywords: GNSS, multipath, NLOS, odometer, barometer