It must be that my previous question http://letsmakerobots.com/node/28808 was wrongly phrased as I am sure there are plenty of knowledgable people here. Anyway, I will try re-phrase my question.
Could anyone be so kind as to tell me what components would make for a complete navigation module. ie. a module that knows where it is.
I am asking in terms of a small household or garden robot so GPS is probably not relevant.