GPS Attitude Determination Reliability Performance Improvement Using Low Cost Receivers

Chaochao Wang, Gérard Lachapelle

Department of Geomatics Engineering, University of Calgary.

DOI:                 

Abstract

This paper describes different methods to improve reliability of attitude estimation using low cost GPS receivers. Previous work has shown that low cost receiver attitude determination systems are more susceptible to measurement errors, such as multipath, phase center offsets, and cycle slips. In some cases, these error sources lead to severely erroneous attitude estimates and/or to a lower availability. The reliability control in the attitude determination becomes imperative to users, as most attitude applications require a high level of reliability. The three methods tested herein to improve reliability are the use of a high data rate, fixed angular constraints, and a quality control algorithm implemented with a Kalman filter. The use of high rate measurements improves error detection as well as ambiguity fixing time. Fixed angular constraints in a multi-antenna attitude system is effective to reject incorrect solutions during the ambiguity resolution phase of the process. Utilizing a Kalman filter with a high data rate, e.g. 10 Hz, not only increases reliability through an increase of information, but also can improve accuracy and availability. The simultaneous utilization of the above methods significantly improves reliability, as demonstrated through a series of hardware simulations and field tests. The low cost receiver type selected is the CMC Allstar receiver equipped with a commercially available low cost antenna. Finally, the use of statistically reliability measures, namely internal and external reliability measures, shows the inherent limitations of a low cost system and the need to either use better antennas and/or external aiding in the form of low cost sensors.

Keywords

GPS, Attitude Determination, Low Cost Receiver

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Brown, R.G. and P.Y.C. Hwang (1992) Introduction of Random Signals and Applied Kalman Filter, Second Edition, John Wiley & Sons, Inc., New York
[2]	El-Mowafy, A, (1994) Kinematic Attitude Determination From GPS, Ph.D dissertation, UCGE Reports 20074, University of Calgary, Calgary, Alberta, Canada, 1994
[3]	Euler H.-J. and Hill C.D., (1995) Attitude Determination: Exploiting All Information for Optimal Ambiguity Resolution, Proceedings of the ION GPS-95, Palm Springs, CA, September, 1995
[4]	Hatch, R. (1991) Instantaneous Ambiguity Resolution, Proceedings of the IAG International Symposium 107 on Kinematic Systems in Geodesy, Surveying and Remote Sensing, Banff, Canada, September, 1990, Springer-Verlag, New York.
[5]	Hoyle, V., Lachapelle, G., M.E. Cannon and Wang, C. (2002) Low-Cost GPS Receivers and their Feasibility for Attitude Determination, Proceeding of NTM02, The Institute of Navigation, San Diego, CA, pp. 226-234 [http://www.geomatics.ucalgary.ca/research/GPSResearch/first.html]
[6]	Lu, G. (1994) Development of a GPS Multi-Antenna System for Attitude Determination, Ph.D thesis, Report No. 20073, Department of Geomatics Engineering, University of Calgary [http://www.geomatics.ucalgary.ca/links/ GradTheses.html]
[7]	Teunissen, P.J.G. and Salzman, M.A. (1988) Performance Analysis of Kalman Filters, Report of the Faculty of Geodesy, Delft University of Technology, Delft, The Netherlands.