Should I revive my robot-building project, or...

Should I cannibalise the parts and embark on a brand new project that just flashed into my brain?

About a year ago, I started building what was intended to be an automomous robot vehicle; I have nearly all the parts I need and I have built the really tricky bits like the drive and suspension systems and the chassis and I have nearly all the electronic parts (the onboard computer is to be a stripped down old Pentium II PC) - it really just needs a bit of time putting together, then all the programming (plus some sensors that I haven’t figured out yet).

But I just had a neat idea for building a giant inkjet printer/plotter…

I thought it wouldn’t be all that hard to make a frame with balanced mechanism not unlike that on a professional drawing board, but driven by stepper motors, then use a print head that consists of spray paint cans actuated by solenoids. I was thinking of maybe an image area six feet square and making the device portable so that it could be used to paint murals. (I suppose with careful alignment, a larger image could be made up of 6’ panels).
I know the resolution would be pretty poor; probably two dots per inch or something, but that wouldn’t necessarily matter for an image that was intended to be seen from a distance.

What do you think? should I finish the robot or start on the printer; neither one is going to cost me more than the other to complete, but I can’t afford both at the moment.

You don’t give much detail about what is special about the robot project, so this may be a little biased, but the printer idea sounds truly fascinating.

From your description the picture I have in my mind is something like one of those flat-bed plotters but with spray cans instead of pens. Is that close to the mark? Perhaps an artists air brush might be easier to control and less liable to clogging. On the other hand spray cans gives it that extra bit of street cred.

If you could link it to a digital camera I would bet people would be transfixed as their portrait was grafitied before there eyes. If you don’t do it I hope somebody steals this idea 'cos I want to see it in action.

Yes, it would be exactly like a plotter; I have also considered the inclusion of a chunky marker so that it could plot the outline of an image then colour it in.

The reason for using spray cans is mostly economy - four colour printing with airbrushes would be too complex, the other reason that I wanted to use them is that the concept of the thing is kind of like an automatic ‘tagger’, although of course I would never use it to deface any property without the consent of the owner.

Yes, it would definitely be linked to some kind of image capture device and possibly equipped with a large roll of wide paper, so that a section can be pulled down, printed on and removed (maybe to create and sell giant arty portraits or enormous banners)

The robot project was to be something like a guard dog; the idea was that it would autonomously explore, map out and patrol a warehouse at night, responding to various onboard sensors (sound, heat, light) and capturing video footage of anything suspicious (which would be relayed wirelessly back to a secure storage area, in case intruders took it upon themselves to trash or steal the robot)and remotely alerting the person on call.
The starting point for the project was that I had a novel idea for how it might store and interpret the internal ‘map’ of its world, which is a little difficult to explain briefly.

Just outta curiosity, what were you gonna use for a power supply for the 'bot? That’s always where I get stumped. Batteries are heavy and don’t last, solar is inefficient and easily damaged, tethered sucks, gas sucks for indoors, nuclear is nice but a little out of my league. I can handle the programming and the sensors, but power always limits and makes me lose interest in the project.

just wonderin’.

Finish the original robot and then use it as an integral part of the printer idea.

I believe in finishing projects. If I was capable i’d personally finish the robot before I begin this grand automatic tagging machine(which btw sounds like an awesome machine. Send pics when done!).

it is going to run on batteries, deep cycle lead-acid to begin, but maybe something better (like Li-ion) later - it will only have about 30 minutes running time between charges, but that is OK as it will probably dock to top up at several points in the patrol zone.

herman_and_bill’s suggestion is not far from the one that got me started on the printer idea in the first place; GraffitiWriter

Stick with the automated robot idea. How the heck else can you become an evil overlord without faithful mechanical servants to serve you and terrify the cowering populace?

(And my smart-assery posting notwithstanding, keep us posted – frankly, either project sounds interesting, and I’m impressed with anyone who can take a project like this from start to finish. Very cool.)

Two robots operating in half hour shifts might work or possibly having a little “fetch” bot that brings out fresh battery packs and brings in the depleted ones for recharging.

I like herman_and_bill’s suggestion as well. You could do some cool things with the robot once you get it’s mapping and navigation down, then adding a “printer head” module to it - you could program the image you wanted it to paint, and it could automatically scale it to fit the “canvas” and whatnot. Painting on vertical suurfaces may be tricky though, but you could probably rig up a structure to accomodate it.

It seems the spray-paint printer is a reality:

I like the spray painter. I’ve always found robots to be rather boring excercise in mechanics - unless you can program some very interesting AI into it…

I think the spray-paint printer sounds really neat. But I would probably feel bad about not finishing the robot. So what I’m saying I would do is this: make the printer first, and finish the robot in the future.

And I’m amazed by the fact that you can do things like this! I don’t even know how a non-electric can opener works.