Auto Map provides an electronic mapping solution for in-vehicle applications, such as inter-State trucking.
Although expensive, the cost of this solution is adequately repaid after several trips, especially to new delivery/pick-up sites.
IVNS uses components of the Tracker Technologies AVL product such as the GPS receiver, DGPS receiver and also AVL CMS components, such as the mapping engine and electronic maps. Dead-reckoning capability is also included to minimize disruption in tunnels and when the satellite signal is insufficient to correctly locate the vehicle. Proprietary map-tracking algorithms are used to aid this process.
The Tilt Effect
The Earth's "magnetic poles", being where they are, give rise to a magnetic vector which is at an angle to the local horizontal plane over most of the Earth's surface. In temperate latitudes this angle can be large. For example, in Great Britain it is approximately 67 degrees to the horizontal, dipping to the north. This effect produces a significant bearing error of 2.35 degrees for an east-west tilt of 1 degree.
The compass must therefore be calibrated locally. This is a simple semi-automatic process that can be performed in a few minutes. This calibration is referenced to a horizontal plane which, although may be tilted, is itself not subject to variable tilting. For situations where the horizontal plane would be subject to variable tilting, gimballing is one solution to help maintain the horizontal plane level, with respect to the Earth's center of gravity.
The compass must be corrected for tilt from the horizontal plane as well as being compensated for the influence of nearby ferrous metals and static magnetic fields (which can be 10 times the strength of the Earth's magnetic field). Once this done, the compass is adjusted for a declination angle which offsets magnetic north to true north.
With SolidState this is a simple operation merely involving driving in a circle twice slowly and then heading in the direction of true north.
The fluxgate compass is used for dead-reckoning in Tracker Technologies
AVL and IVNS products. The fluxgate was was chosen over other
technologies due to low cost, good accuracy, and intrinsic foregivingness.
It has recently been re-engineered as a standalone product.