Reliable Data in any Location
A 100 Hz GNSS receiver provides highly accurate measurements of position, velocity and distance in areas with a clear view of the sky. However, if visibility of the satellites becomes obscured when testing in locations such as tunnels, urban canyons or at test tracks with heavy tree cover, the accuracy of the data typically starts to drift.
By combining wheel speed data from the vehicle's CAN bus with GNSS and Inertial data from an IMU, the accuracy of the estimated speed and position can be maintained, even during prolonged periods without satellite signals.
The below images are from a test that was carried out through the East India Dock Tunnel in London, which is 400 m long. Using GPS only, the position was lost as the vehicle entered the tunnel. Adding IMU and wheel-speed data into the system resulted in the errors being significantly reduced and the vehicle was tracked through the tunnel with great accuracy.