The next step in my DC Motor Mobile Robot is to add the battery container. This is a 3D printer box that a slightly smaller 4 x AA battery holder fits into. I decided to use a smaller battery holder as the original one did not leave any room for putting some sides onto it. The downside of the smaller battery holder is that it doesn't have an ON/OFF switch but that should not really matter, once I have the controller added.
The battery holder fitted perfectly so what was needed next was a lid for it so that I have a flat surface on which to attach the rotating dome part. Again I have gone for an interference fit for the lid as it is the easiest approach. I have made the lip deeper than I usually use at 3.5 mm, to ensure it is stable when something else is added to the top.
Everything is still working, as after all, currently it is only four DC motors connected directly to a battery so there is little to go wrong. My next step will be to design and 3D print a dome that will fit on top of the battery lid. I have put a hole in the battery lid that is the same size as the arm parts of a micro step motor as I will be using this to rotate the dome. It does mean that the dome will only be able to move through an angle of 180 degrees, but that should be enough. In order to minimise the height of the entire mobile robot I will put the micro servo motor into the dome itself. Hopefully there will also be room for the Arduino controller as well. I have not always included routing points for all the wires that will need to connect from the DC motors to the dome, so I will have to fix them nicely on the outside, maybe with some small 3D printer covers to make everything look nice.
There will be some design issues as the current body of the DC motor Mobile Robot is rectangular but the dome will be circular. It might look OK. There is also the issue that the dome part may become too big to be made in one piece on my 3D printer. I might have to make it in two or more pieces, which will be tricky, or maybe go for some other curved surface, perhaps a segment or something. I will also need to ensure that the completed mobile robot does not become top heavy.