Commercial vortex cannon from last year’s robot.
FRC Team 830 along with FRC Team 3322 are working on a show robot for the Detroit Maker Fair. Maker Works was even cool enough to give us a small grant to fab the robot! The working concept is a life-size animatronic dragon that shoots smoke rings. With my ample free time I’ve been figuring out how to make it happen using a combination of the standard cRIO FIRST platform and raspberry pi’s. Last’s year’s robot used a vortex cannon to knock over pac-man ghosts, but this year we wanted to go bigger. We are using the drive train from last year’s robot for the new dragon bot so we should have a lot more time to build cool animatronic stuff.
Hole in the bottom of the garbage can.
Vortex cannon diaphragm using 5mil sheeting.
I wanted to see how big of a vortex cannon we could build. Following some examples I saw on the internet I picked up a garbage can at Recycle Reuse and grabbed some 5 mil plastic sheeting I was using for the garden. This weekend we fabbed a prototype smoke cannon. The design is really simple, you just saw out a circle in the bottom of the garbage can and add a plastic diaphragm on the open side of the can (I secured it with some large rubber bands and duct tape). The trick is to provide a good amount of slack on the diaphragm.
The smoke machine makes the vortex rings visible. This weekend I tried to use some dry ice “smoke” to visualize the rings. The results weren’t that impressive, but playing with five pounds of dry ice was really fun (hint, if you put a quarter on dry ice it “squeals”). Today we tried using a professional fog machine and the results were much more impressive as you can see for yourself.
As for the rest of the animatronics we want the dragon’s eyes and eyebrows to move and for the dragon to play sounds. If we have enough time we want the dragon to have some “ground effects” LED lights. Right now the plan is to drive all of this off the GPIO pins on two raspberry pi’s. We plan to drive the pi’s off a separate router system connected to the cRio’s filtered 5V power supply (with a step up converter). The smoke ring mechanism and smoke generator will probably run off the cRio. The plan is to have each of the pi’s run a python script that provides access to PyGame (for sound), pi-blaster, and servo blaster. Tentatively I think we can use the Pika RabbitMQ library to move message between a client control application and servers running on the raspberry pi. Both the raspberry pi’s will be dispatched by running a client python app that also uses PyGame to grab input from the keyboard and a joystick. Right now we have a skeleton github repo for the project that should get filled out over the course of the summer. I must also add that I am really impressed with the AdaFruit Black Raspberry Occidentalis raspian distro. I am going to be gone for the next month so I can point the kids to the tutorials and let them go to town.
