I remember that when I was a kid, in the 1980s, I had some toys made in Taiwan that basically worked like this: they moved forward uniterruptily until they bumped into an obstacle; then they moved back a few centimeters and then keep moving forward with an angle in relation to the original trajectory of 15-30º clockwise; unless they bumped something while turning back, so a forward movement was triggered, which made then move in a smaller angle.
With this routine, they could basically move everywhere in the house. I don't know very well their mechanism, all they had in common was was a wheel (or wheels?) under a metallic circle under the toy; or maybe an arc of circle where a wheel could change its direction by changing its position on the arc. My memory is fuzzy
Do you people have any idea of what was the mechanism of these toys? I am pretty sure they were quite simple as I don't remember seeing anything complicated inside them. Also, I am not a specialist in robotics, and I couldn't find anything about this type of thing by searching on google.