I recently built an eight wheeled snake bike, and that was based on a smaller version I built some time ago. And before that I built a worm robot which moves by expanding and contracting. This is known as a system of Peristalsis, which from Wikipedia, is defined as a radially symmetrical contraction and relaxation of muscles that propagates in a wave down a tube.
While I was researching these projects, I came across another experimental robot which uses a wave motion, with the wave running down its body, to propel it forwards. This is a bit like how snakes actually move, Well, the ones without wheels or legs of course.
My original plan for this project was to make a surf board you can ride on the land, but using a mechanical wave like this to propel me along, and use a large set of mountain board wheels for steering. However, I thought I’d try to make a smaller version of this mechanism first so see where the potential problems could be.
It looks like the mechanical wave is formed by a thing that looks a bit like a giant corkscrew, which simply rotates inside a flexible track, so I 3D printed a former which I used to try to bend some wire around. I wanted this to be quite stiff though because in my version it has to support the whole weight of the machine, so I used 4mm diameter stainless steel rod. This was pretty hard to bend into shape by hand, and my resulting screw shape doesn’t quite match the former or the original CAD design, but we’ll see what problems that causes later.