Todd et al (1994) have shown that evolutionarily shaped blind action may suffice to keep some animals alive. For some insects for example, the environment is not interpreted as a map, and they survive only with a triggered response.
But a slightly more elaborated navigation strategy dramatically enhances the capabilities of the robot. Cognitive maps (Tolman 1948) enable planning capacities, and use of current perceptions, memorized events, and expected consequences.
A good algorithm in robotic mapping may combine the information from the past, the present and the future (Trullier et al. 1997).
The problem can be decomposed in three processes (Levitt and Lawton 1990 ; Balakrishnan et al. 1999) : map learning, localisation, path-planning.
When it moves, the robot integrates its position by counting the number of wheel turns it has done. This corresponds to the idiothetic source. It can give the absolute position of the robot. But it is subject of cumulative error which can grow fast.
The allothetic source corresponds to the sensors of the robot, like a camera, a microphone, laser, sonar, ... The problem is the "perceptual aliasing". This means that two different places can be perceived the same. For example, in a building, you can't know where you are only with the visual information, because all the corridors look the same.
Many techniques use probabilistic representations of the map, in order to handle uncertainty.
There are three main methods of Map representations:
These employ the notion of a grid, but permit the resolution of the grid to vary so that it can become finer where more accuracy is needed and more coarse where the map is uniform.
An important additional problem is to determine whether the robot is in a part of environment already stored or never visited, that can be solved, i.e., using electric beacons.
For the metric representation of the map, the robot can find short cuts in the map.
For the topological representation, the problem of path planning is a classical problem of finding the shortest path between two nodes in a graph.
Electric beacons also has been proposed for cheap robot navigational systems.
Human presence detection: the navy has tri-service responsibility for EOD-related science and technology development.
Oct 01, 2011; The ability of man-portable robots to effectively address life-threatening hazards like improvised explosive devices (IEDs) on...