For my unofficial contribution to the Picasso Design Challenge the holonomic mobile robot will support or carry a colour graphic display showing the magnified image of the artwork that is underneath. The four corner direction and drive motor units will maintain the orientation of the display as it moves about over the artwork. I haven't yet decided on how the movement should be controlled, it could be some systematic approach, or maybe random or even allow some user interface, perhaps via WiFi or Bluetooth.
The colour graphic display will need to be large enough to be visible from a reasonable distance with enough resolution to show useful information, plus, not be too heavy, not need a mains power supply and not cost too much money! I do have access to a flat screen PC monitor which has a 12V DC input but it is fairly large, probably a 18 or 19 inch display, with a wide bezel and is quite heavy. Rather than use that I have decided initially at least, to start with a much smaller 7 inch LCD graphics display, which is lighter, (only 380 g) has a smaller bezel, can be powered from a USB connection (to the Raspberry Pi) and comes with a Raspberry Pi casing already designed to be fitted to the back of the display. The resolution of 800 x 480 isn't as great as I would have liked, but with this smaller screen I think it should be OK. Life is usually a compromise afterall.
The displays arrives as a self-assembly kit, with laser cut plastic pieces. I hadn't realised this when I purchased it, thinking it was moulded pieces which would be stronger and smoother but it should still be OK.
It was relatively easy to assemble all the pieces although the instruction leaflet is quite small with some tiny diagrams. A good job I have a good magnifying glass. The instructions are OK but some common sense had to be utilised, so I'm hoping I got that part correct. I didn't have the Raspberry Pi to include into the assembly so I just put the case together without it, see below. I may have to dis-assemble it all again later but that should not be too much of a problem.
Not having a Raspberry Pi to hand to test it with I decided to just plug it into my Win 10 laptop to see if it would work, as it is a general HDMI display anyway. I was really pleased to see that it was immediately recognised by the laptop, with presumably the drivers already loaded into Windows and came up as a second display, mirroring what was on the main display. What was most satisfying was that the touch screen part was also recognised and seemed to work as well. My fingers are a bit too fat for fine control, but it does actually work. I didn't purchase it for the touchscreen part but it is nice to know that option is available, should I ever need it in the future.
The back of the display has the Pi case roughly in the middle and there might just be enough space for the four corner motor units, if I am careful. The cables connecting the display to the Pi are a little unsightly as they will stick out one side. I will have to think about what I can do to remediate this unsightly aspect.
I did have some parts left after assembling the display, one is a fan, presumably to try and keep the Pi cool as I guess a hot Pi may melt the plastic. plus what look like a couple of small heat sinks. Not sure where they might go. There was nothing in the instructions. Anybody any ideas?
So, the display has arrived and my next step will be to design and fix on the four corner units. That will just leave all the software and getting it all working together. Easy!
Dubbie
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