HIMM map making and localization

HIMM is a simple method specialized for sonars that can have vet good results for obstacle avoidance at a much lower cost that other techniques such as bayesian models 20220301203202.

HIMM is based on the sonar model 20220228203000, but only measures along the accoustic axis. It uses integers from 0 to 15 (can be stored on only 1 byte), and the updates are -1 for region empty and +3 for region occupied.

The update algorith is: grid*[*i*][*j*] = *grid[i][j] + I; 0 ≤ gri**d[i][j] ≤ 15 I = +3 if occupied, I = -1 if empty. So, for a measured reading on a cell, other cells will get an update of empty since are on the way to the occupied cell.

The reliability of the algorithm comes from, although measuring only the accoustic axis, measurements are quicker and with less delay, meaning more measurements and less gaps between each measurement.

Growth rate operator

One disadvantage is that some elements of the grid may get a few measurements that store a lower number that what really should be. Small obstacles also present a small profile on the grid. For this, HIMM uses a mechanism called Grwoth Rate Operator, where an extra step is used with a mask that checks neighbours to add the weight to the sensed element.

This has the advantage that obstacles are detected more easily, but false readings may persist longer since they have bigger numbers that have to decrease.

Notes References

20220228202048 Iconic localization and map making

20210514183815 INDEX - Robotics

References

(Murphy 2000)

Murphy, Robin. 2000. Introduction to AI Robotics. Intelligent Robotics and Autonomous Agents. Cambridge, Mass: MIT Press.