J. J. Leonard and Hugh Durrant-Whyte, in the last decade, briefly described the general problem of mobile robot navigation by three questions:
"Where am I?"
"Where am I going?"
and "How should I get there?"
I was shocked to realize that these 3 basic questions which we, of course take for granted(!) are actually immensely complex implementations in robotic systems.
What I found interesting is that to date there is no truly elegant solution for the "Where am I?" part. A collection of many partial solutions can roughly be categorized into two groups: relative and absolute position measurements. Because of the lack of a single, generally good method, developers of automated guided vehicles (AGVs), unmanned flying vehicles (UAV's) and mobile robots usually combine two or more methods, one from each category. These two super-groups can be further divided into sub-groups as shows below.
