Even robots need directions
by Wenche Gerhardsen (FFI)
The Norwegian Defence Research Establishment (FFI) develops navigation for autonomous systems below and above water.
"Navigation means finding your own position and orientation. It is something we need in numerous contexts," Kenneth Gade, researcher for the Maritime Systems Division, explains.
The current navigation group at FFI was set up in 1996, when researchers had to develop a navigation system for the autonomous underwater vehicle HUGIN.
Multiple user areas
"Our aim was to create something more than just a navigation system for HUGIN. We therefore developed a more general system that could also be used on land and in the air, the benefits of which have become obvious".
FFI's navigation programmes NavLab and NavP (see fact box) are used in many areas above water. Examples include hyperspectral imaging from aircraft, dynamic positioning of vessels, measurement of vibrations on Orion aircraft, augmented reality for military vehicles and synthetic aperture radar for unmanned aircraft.
Kenneth Gade, researcher for the Maritime Systems Division, FFI. (Photo: FFI)
"GPS is a very useful navigation tool, but unfortunately it doesn't work under water. That is why we have developed different technologies that are independent of GPS."
Even above water GPS signals can be interfered with or become jammed. The technology used by FFI researchers under water can also be used above water.
FFI's navigation system uses inertial navigation. It consists of inertial sensors as gyros and accelerometers, which measure rotation and acceleration. The most accurate gyros measure rotation with a measurement accuracy of less than a thousandth of the earth's angular velocity.
These instruments cannot be interfered with, unlike GPS signals and magnetic compasses.
The navigation is used to direct vehicles in real time. The navigation subsequently positions objects depicted by cameras and sonars, a requirement when making maps.
Where everything heads south
Other navigation constants are not always reliable either. Imagine you are on the North Pole, faced with a mathematical singularity: all directions lead south and longitude is undefined! It can result in some strange coordinates.
This phenomenon translates into larger areas around the poles, where navigation systems that work well elsewhere can suffer major failure or breakdowns. FFIs navigation system handles this issue.
"We have replaced longitude and latitude with our own coordinate, which we call the n-vector. It has the same properties all over the planet, whether at the poles, the equator or the dateline," Gade explains.