OxTS has developed new velocity calculation algorithms for the RT2500 that improves the velocity accuracy by more than 30%. The improvements are obtained by processing the raw GPS measurements using more accurate algorithms, giving velocity accuracy from the RT2500 that approaches 0.1km/h. This is part of a larger set of work which will allow the RT products to continue to correct the inertial algorithms when there are fewer than 4 satellites.
Currently the improved velocity calculations are only possible using RT Post-process. Future versions will allow the improved algorithms to run in real-time on RT2500 products that have the faster processor (TP500) in them. Older RT2500 products can have their processor upgraded as part of an extended calibration.
Advanced settings are required in order to select this new processing method. By default the normal processing algorithms are used. We are also working towards differential corrections on the RT2500 and we are hopeful of being able to get accuracies better than 1m CEP from the RT2500 with differential corrections in the future.
Using an RT3003 in 2cm mode as a reference in a 20 minute test of constant driving, the two algorithms showed:
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Velocity improvements are important because the velocity error is a key component of slip angle. By improving the velocity calculation in the RT2500 the slip angle measurement has also been improved. This will allow more people to use the RT2500 for accurate slip angle measurements, reducing the cost of slip angle measurement in the future.
For information on how to use the new velocity processing algorithms contact support at OxTS.
Graphs showing the error of the RT2500 compared to an RT3003 using RT Post-process and the new processing algorithms.