[Chris Rybitski] developed this low-profile robot to help move scenery on stage. The test footage shows it to be spry and able to move hundreds of pounds of cargo. The demo shows the addition of a wooden platform about twice the length of the metal chassis with casters at each end to support the extra weight. It seems to have no problem moving around with the weight of a couple of human passengers on board.
Crafty systems for changing huge sets has long made the theater a natural breeding ground for hacks. Balanced turn tables, rails systems, and the like are common place. But we think this has a ton of potential. Right now the electronics seem convoluted, as there is an Arduino running the motors which connects to the LAN using an Ethernet shield and that Linksys wireless router.
We think he should patch directly into the serial port of the router. If he loads DD-WRT or OpenWRT he can easily make the remote control a web interface. We also wonder about the possibility of making it a line-follower that can precisely position itself automatically using patterns on the floor.
May be convoluted, but it sure gets the job done; not much else matters for a one-off creation.
Though it’s not the case here, if you’re moving a lot of data between MCU and router, I prefer Ethernet connections over serial. SPI is faster, and the extra buffer RAM on the Ethernet shield can make things easier too.
Seems to be a well thought out design. Would like to see the proto boards be replaced with a custom pcb, but that is just me! Anything that is constantly in motion means I wouldn’t trust the female headers to keep the wires from falling out. I also liked the consideration to use wifi because of concerns about interference with the wireless mics! Good job!
it would be way way cooler with mecanum or omi wheels
I think he would need 2 more motors for that
And mecanum wheels are hellishly expensive, even the lego ones.
Why not use wireless DMX-512 for control, as it is already abundant in theatre (albeit usually in wired form). The bot could then be controlled by the lighting desk.
there are plenty of wireless dmx units available however etc lighting boards are pretty locked down when it comes to adding anything other than lighting cues. also voiding the warranty to a $30,000 lighting console isn’t ideal. Also wireless dmx is not a secure communication There are a lot of other reasons but the short one is that it was easier to use wifi and interface with a pc. why fix something that isn’t broken.
Some of the newer boards allow you to “create” new profiles for devices. I readily admin I haven’t had that much chance to play with them, so they could still be fairly limited…?
Don’t forget that DMX-512A has no error correction, for lighting it isn’t as important, but for moving a setpiece I’d like something, even just a parity bit. Maybe I’m just too paranoid.
As a theatre technician, I want one. Or four.
The current methods of shifting large pieces of scenery (not counting carrying them or rolling them by hand) are flying them in and out with counterweight systems, or putting them on ‘dog tracks’. The latter requires building a false floor over laid track on the stage, and running powered ‘dogs’ that grab on to the set piece through channels cut in the floor.
I like the small cable tie visible under the deck – all it needs now is some duct tape, and the build is complete.
Why not use wireless DMX-512 to control the bot? It is abundant in the theatre (albeit not usually wireless). This could then be controlled from the lighting desk, and queued to move in between blackouts etc.
Replacement for the hacked Roomba
[quote]We think he should patch directly into the serial port of the router.[\quote]
I strongly disagree mike. Right now replacing or upgrading the communications for this thing is a matter of slapping a new router/bridge in and plugging in the ethernet cable.
Total time for replacement: 2 minutes.
Patching into the router requires adding a serial port, flashing a new firmware, installing the software and working out any bugs due to differences in the router.
When you’re using this for a theater production, you don’t have time to hack around with replacement parts.
You know, you could prepare one in advance. A “just in case” item, as it were. You could even make an entire spare robot! Imagine the possibilities!
I think a line on the stage floor for a robot to follow would be a distraction to those of the audience seated high enough to see it.
A lot of stage productions have various colors of tape on the floor to mark out stage props and actors marks just as in movie production. Not really a problem.
One idea would be black backed RFID tags taped to the floor to orientate the platform. Preprogram a vector to travel in, looking for a specific group of tags to park over.
Or you could use IR-reflective black tape, if such a product exists….
Strike tape is already used in theatre. It’s most commonly used to tell the human stage-hands precisely where to place a set piece. The audience doesn’t seem to notice, so I don’t see laying down a line of tape for a robotic stage-hand being that different.
In theatre there is no such thing as “spare”. “Backup” is sometime possible.
If you have a second robot built, there will be a need for that second robot.
As for the router, if there is an issue with a batch of bad NVRAM that expires at the same time on both the primary and the backup you have a buttload of work getting another setup.
Compare with the current system. Lightning or fire could take out the entire thing and he can rebuilt it in an hour or two with off-the-shelf parts.
The idea of not using DMX is that scenery automation needs to be ran by an individual operator whose sole responsibility is to ensure the safe operation of the equipment. This is for the actors and technicians as well as the equipment. All automation is typically ran by an individual operator.
As far as a tracking wire, it is plausible. This specific robot utilizes a electric dog fence and reciever to keep the robot from over running a target or going off the front of the stage.
I’d think a line follower would be challenging. Scenery changes are often done in an area that is as dark as possible. Any ambient light that manages to cross the stage would likely be brighter than the line itself. On top of that we have often distracted audiences to a degree during scene changes using lighting adjustments. Similar to magicians convincing you to look at one thing while the “magic” is happening somewhere else. I’ve had line followers make very entertaining choices when I take them off their lines. Those choices may entertain the audience in a very wrong way though. Not to mention really piss off/stress out one’s director.
I can wait to hear about people hacking the wifi to rearrange a theater set in mid show
I used to be a stagehand at the Dutch National Opera, and they have a system comparable to this but a lot larger.
It uses out-of-sightline reflectors and IR laser on the stage to orient and move around multiple objects, each weighing multiple tons if necessary, at the same time. It can be interrupted and overruled at any time from the terminal that also controls the light grid (not the lights themselves).
For the really heavy setpieces there is a compressed-air hovercraft system that can lift up to 15 tons and “float” it around.
great post