Robot wheel design has been on my mind lately. We’ve been asked to take some robots down to a fundraiser for the Discovery Museum in Sacramento. I want to build something new for their event and was thinking about a robot that looks like a regular household item until you activate it. I’ll probably use a lunch box (my favorite chassis) or a brief case. But the design I have in mind needs to deploy its robot wheel before moving. Basically it needs to stand up and then move, and when deactivated it should sit down and just look like a regular object.
To do this I wanted a hinge mechanism that I could position electronically. Think of it like an aircraft wheel that is stored in the wheel bay when not in use. A hobby RC servo seemed like a good fit for the design. On the way to work I picked up some brass at the local hardware store and at the end of work I took a couple of hours to cut/drill the brass and solder pieces together. The prototype seems to work, and should be light weight. I stuck a knobby RC truck tire on this, but will use something lighter in the final design.
It took me a couple of tries to get the mechanics correct. I’ll do a mechanical design of this robot wheel on Google sketchup, since I need to fit four on the robot, and having some defined dimensions would help me do that. But overall it was a successful effort considering I spen just a couple of hours trying to put this together myself. I really like using brass since it is easy to work with and you can braze it with solder and a heat gun. It’s a poor man’s weld. I’m also quite proud of the hinge that is really just one brass tube that slides into another slightly larger brass tube.