IMU Integration signals end to noisy GPS data…

GPS is the most accurate way to measure velocity… as long as view to the sky is clear.

Under bridges, near trees, or through built up areas, the quality of satellite signals degrades, causing ‘noisy’ measurements. In order to keep high GPS accuracy even where sky visibility is less than perfect, Racelogic has released IMU integration with the VBOX 3i GPS datalogger.

By blending GPS with data from an Inertial Measurement Unit, housing three gyros and three accelerometers, smoother, more reliable data is produced. The solution can deal with GPS dropouts lasting several seconds at a time, with high accuracy.

IMU integration realises the high accuracies that VBOX 3i can achieve even when external conditions are compromised, meaning that data has now become more reliable and easier to interpret.

VBOX 3i with IMU Integration…

• Uses a real-time Kalman Filter, which seamlessly blends GPS signals with data from an IMU (Inertial Measurement Unit)
• Produces a smoother velocity trace with even higher dynamic capabilities than GPS alone, due to the mutual corrections occurring  between the two data sources
• Can deal with GPS dropouts lasting several seconds at a time, with high accuracy
• Realises the high accuracies that VBOX 3i can achieve even when external conditions are compromised, meaning that data has now become more reliable and easier to interpret
• Uses separate modules: allowing for flexibility in vehicle placement with a number of mounting options
• Is compact – offers the ability to swap equipment between vehicles easily: meaning more time on the test track and less time setting up gear

How does IMU Integration improve the GPS data? 

Velocity

The graph to the right  illustrates GPS noise followed by drop outs lasting several seconds, incurred when driving on a section of road with very heavy tree cover, pictured above. The IMU integration (the blue line) decreases the noise for a more accurate reading, and maintains a precise velocity measurement throughout the GPS drop outs.

 Heading

The heading reading here (the blue line) is very consistent thanks to IMU Integration, providing more accurate results than the GPS only data, which exhibits some noise. Despite the low speed, (shown by the red line) the IMU Integration provides accurate, noiseless heading measurements.

Position

Mapping vehicle position along the heavily tree lined road as pictured above: the GPS signal incurs some drop outs and reflections, producing noisy position readings. However, as shown by the blue line, IMU integration corrects the position measurements, creating smoother, more accurate data.

 Acceleration

This graph illustrates longitudinal acceleration (measured in G-force) during an ABS brake stop – a very high dynamic test. The light grey line shows the GPS only data exhibiting a small degree of noise, whilst the darker line running through it illustrates the IMU Integration data, which provides a smoother, more accurate representation of the brake stop.