I ought to explain that
Robot test 1.jpg is slightly oversize, because that's the size the meccano comes. The gold cog goes round clockwise, causing the feet to describe a flat ellipse, placing a foot on the ground in front of the other.
Robot test 2.jpg is a half-size mock-up of the same mechanism. The tubes on the side are part of a steering mechanism, and basically what this rig taught me was that this didn't work.
By the way, nothing wrong with Lego, I got meccano but Lego was mostly bricks when I was young. The danger comes when you say to yourself " I bet I could do that". Who knows were you will end up!
Phil "How did I tak myself into this" Palmer