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This option can cause problems during the warm-up period if the vehicle
remains stationary for a long time and then drives suddenly
Note: The heading of most vehicles does change if the steering wheel is turned while the vehicle is stationary. Junctions and pulling out of
parking spaces are common places where drivers turn the steering wheel while not moving.
Garage mode
The Garage mode option is used to stabilise the RT’s outputs when GNSS is not available. For example, GNSS
can be blocked when the vehicle returns to the garage to have some modifications. Without Garage mode
enabled, the RT may drift too far and may not be able to recover.
When Garage mode is active, the RT applies a gentle velocity update and assumes that the vehicle is stationary.
This keeps the roll, pitch and velocity within acceptable limits while the RT has no GNSS. With heading lock also
enabled, the RT can also keep the heading accurate while stationary.
When using this option, try to keep the vehicle’s movement inside the garage to a minimum and exit the garage
through the same door the car entered.
Surface tilt
The surface tilt settings are used to compute the roll, pitch (and heading) compared to a flat inclined surface.
The roll and pitch from the RT products are measured compared to gravity. Most test tracks are built at an
angle so rain water runs off and the track dries faster. As the vehicle drives up the incline, the pitch shows a
positive value; as the vehicle drives down the incline the pitch shows a negative value; the value changes with
a sinusoidal pattern as you drive round a circle. The roll angle shows a similar effect.
Using the surface tilt option, the roll and pitch compared to the inclined surface can be output as well. The
NAVdisplay software contains a tool for working out the surface angles. NAVconfig can be used to configure
the surface’s angle if it has been measured already. These settings can be input in the Environment section
within NAVconfig. Figure 35 shows the Surface tilt properties settings.
Figure 35: NAVconfig surface tilt properties in the environment section within NAVconfig
Enter the heading (compared to true north) of the uphill direction and the gradient of the surface.
The RT does not change the roll and pitch outputs because of these settings. Instead there are additional
outputs, surface roll, surface pitch and surface heading that are output and the transformation is applied to
these outputs. Note that for surfaces with a small gradient the surface heading is almost the same as heading.
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