I wanted to have a go at the Month of Robots for two main reasons. Mostly is that I really like making robots and secondly that it is a year since I started joining in the Project14 activities. The problem I was having was thinking of a robot that I could create that would be different to all my other robots, still be a fun robot, and that I could make it within the timescale available. For many days and nights I pondered what sort of robot I could make without much success and then I thought, why not make a robot that has many other robots within it, a SuperRobot. Obviously it would have to mainly be a mobile robot (just because they are the best) and I wanted something bigger than my usual ones, so a large base seemed like a good idea. I have some spare MDF so that sorted that. Then I just have to think of as many other robots as I might be able to make within the timescale. To make this easier I decided to take some existing products, mainly children's toys as these come with good external covers and hack them about until they do something robot like. I have two trains that run on the well known wooden rails, plus some talking farm animals. I also want to make some actual robots as well so hopefully at least one robot arm, and possibly another smaller mobile robot as well - which would be as good a small mobile robot as I can make. See below for the components that I was able to gather together to start with.
The first thing to do was to make the base move about. I wanted it to be simple to I have decided on two plastic casters at the front (cheap) and two small DC motors with gearboxes and tyres at the back (because I had them). I wanted to have some significant ground clearance underneath the platform, just in case I decided to put some other robots underneath, plus I didn't want to cut notches into the base board for the wheels. So the DC motors had to be upright and hence required a 3D printed holder. After several attempts I managed to design something that actually seemed to work (thanks for the advice from other Element14 participants on reducing the infill on 3D printed - it did seem to work better). I also had to 3D print some blocks for the castor wheels to lift up the front end to the same height as the back. I got those right first time!
Then it was just a matter of drilling some holes in the base board (not as easy as it sounds as the board is quite big and difficult to move, but I did manage to get it onto my pillar drill for the big holes -- just! Then it was off to the shops to buy some M3 and M4 screws as I just didn't have any of the required length and it all went together. See video below.
There was a problem with the battery and the two DC motors in that the weight of the base board was just too much for 6 Volts. I did have a 12 V lead acid battery lying around so I tried that. It zoomed away with a distinct ozone/heating smell. I think 12Volts might be too much so I cobbled together a 9 Volt supply from a 6 V (4xAA) and a 3V (2xAA) just to see if it would work. Which, as you can see in the video, it does, mostly. When a reasonable load is added to the base plate then it struggles to get going. Much of this is down to the carpet it is travelling on but this is my test room so it has to work in here. And, if it works with this carpet it will work in most other areas as well.
So the base board is working, but with some limitations, but it is good enough so that I can start adding some other robots. I may have to replace the motors with something more powerful and mechanically stronger at a later date.