GPS limitations resolved by INS combination

Comparisons of vehicle test speed measurements by GPS (Global Positioning System), which is increasingly used in several motorsport disciplines, and INS (Inertial Navigation System) have shown that a combination of both technologies achieves the optimum short- and long-term precision. The tests were conducted in the UK using a new, low-cost, full-motion test system, 'RT3100', developed by Oxford Technical Solutions to achieve a speed accuracy of 0.1kph

Mar 20, 2003, 6:09 PM

Despite the reliability of GPS transmissions, reception can be interrupted by local obstructions such as tree cover, bridges and buildings. When this occurs, a standalone GPS navigation system will lose its short-term measurement precision, which may make the test mission invalid.

Conversely, with a combined system, the INS is 'on-line' continuously. When GPS signals are corrupted or disappear for short periods, the INS will continue to perform full-motion measurements to a high accuracy. When the GPS signal is recovered, it can be used to correct the longterm drift of the INS inertial components (gyros and accelerometers) using a powerful Kalman filter algorithm.

An illustrated report of the testing is available on Oxford's website.