My girlfriend is studying to be a teacher in art courses. Being a better student than I am she only had to retake a few exams during the summer holiday. One of them was the creation of an interactive project that included arts and mechanics.
Paddling a bike sure as hell is mechanics and instead of a workshop she wanted to build a game where someone has to padle a fixed bike in order to view a painting. The biker then must guess what painting it was and who it was from.
If the biker paddled to slow, or answered wrong on the question a part of the painting would get obscured. If he can’t see anything of the painting anymore the biker lost the game.
Keeping things simple we decided to use a simple powerpoint on a beamer and an extra layer in front of the beamers lens to do the obscuring part. (I was studying as well and not having to fiddle with image output by the beamer or the computer itself was a relieve)
Obscuring the view
I thought about a lot of principles to obscure the view, one of them was the actual use of mini curtains. After some trying though I couldn’t possibly find a fabric at home that was thick enough to block the light of the beamer and that was also light enough to “fall” beautifully when it was lowered.
Plan B was a lot more simple, we just cut out a circle shaped piece of cartboard and attached it to a servo. To save time I had my father build the frame on which we would mount the servo. (He helps me out with projects more often than I think).
A week before everything had to be done I took the frame to the city where I study. My girlfriend could start painting the structure and I could start fiddling with the code.
How a Fixed Bike works
First up was figuring out what kind of signal that fixed bike was sending. I was hoping it would just send 1 every time a magnet passed a sensor but was afraid it might work like a dynamo. Lucky me found that almost all fixed bikes send a 1 signal once every time you turn around the wheel.
So I cut the wires going to the unit on the screen, connected one wire with a resistor to a digital arduino input and the other one to 5V.
I made the script like so that you have a score going from 0 to 10. Padling would make the score go up with 1 and every 0.7 seconds the score would go down by 1.
I attached the servo to…..
Last thing to do was adding a button that would set back your time if you misanswered a question and a button for resetting the system. A lot of paddling and adjusting later my girlfriend finally settled that -2 on your score was sufficient.
I transfered the resistors to a perf. board together with some pinheaders. To finish of we made some ghetto style pushbuttons with WASKNIJPERS and DUIMSPIJKERS.
Overall this was a really simple build that is a lot of fun (for a while). The variaties are also limitless.. We’re thinking of making a summer version that would make a pump run and the person who’s the slowest would get wet.. Maybe we’ll tackle that next summer.
Keep on hacking