The Display Mannequin
With less than 12 hours remaining before our all-motivating contest deadline, we began work on our floor display. We made a mannequin to wear the Speed Vest by casting Brady, using Mark Jenkins’ packing tape sculpture technique (http://tapesculpture.org). Add one bicycle and one bicycle work-stand, and we were ready to wow the public.
It’s hard to know just how car drivers feel about the Speed Vest, but so far nobody bicycling while wearing it has been honked at or run over. Meanwhile, we’re now working on SpeedVest II, with four major areas of improvement:
- Wirelessness If the rider forgets he’s plugged into the bicycle when he dismounts, the electronics get yanked. In practice, this happens almost every time, and we’ve had to resolder the connectors three times already. SpeedVest II will use Zigbee wireless modules to transmit speed data from the wheel to the Arduino.
- Size In bicycle equipment, lightness is everything. The Arduino USB board is handy, but contains a lot of parts we don’t use. With a custom PCB design, we can get the whole system much smaller and lighter.
- Power The Arduino is powered by a 9V battery, but the EL wire inverter has its own AA battery and a separate power switch. The batteries run out at different times, and turning the unit on and off is a two-step process. Our improved single-board design will integrate the inverter, driven from the same power source as the rest of the board.
- Speed range Bicycles are fast, and getting faster! Our vest displays speeds up to 69mph, but the current bicycle land speed record is 81mph. (And that’s not even close to the drafting speed record of 152mph, set by a bicyclist chasing a specially designed car that pushed away the forward wind resistance.) So we’re redesigning our numeric display to show all speeds from 1 to 99 miles per hour. We hope that will suffice for normal use.
We handily accomplished our first mission: winning The Hub’s Bike Gadget Contest. W00t!
Then we set about testing the Speed Vest in real traffic. We’ve had great success with it, and the feedback from everyone who’s seen it has been wonderful. Many people want their own.
Also, simulating a wheel with your hands, and seeing how fast you can make the speed display go, has become a strangely compelling party game.
Download all project code, schematic diagrams, and templates at http://archive.makezine.com/19/speedvest.