PROJECT AURA// bicycle safety-light system

In the editorial Infographic Of The Day: How Bikes Can Solve Our Biggest Problems
Cliff Kuang, founding editor of Co.Design (an online subsidiary of Fast Company [magazine written for progressive business leaders] that explores the intersection of business and design), discusses inforgraphics made by Healthcare Management Degree. The infograph data walks through statistical analysis arguing the point that increased cycling as transportation would solve several of America’s problems.

70% of America’s car trips are shorter than 2 miles~10-minute bike ride
50-90% of air pollution is caused by automobile emissions =health issues
20 bikes can be parked in 1 car space =compact design
projected reduced medical costs statistics =air pollution and obesity related illnesses

He poses two important questions in relation. How do you get the government to take this seriously? “How do you make cyclists safer without making drivers feel like they’re under attack? The answer to that question could hold the key to our biking future.” Enter Project Aura:

PROJECT GOAL: create a responsive lighting system responding to a cyclist’s actions.

1: Admit you know nothing. “All our preconceptions of what could work were way off.” However, this does not mean defeat: “but, we have goal and a vision. That’s what counts.”

2: purchase test materials & setup work/testing station.

3. begin testing hypotheses.

“Each LED group of three = .72 watts and 12 of these groups require 8.64 watts. An average casual biker around 153 lbs outputs about 210 watts. Though it might not sound that much, it is actually almost 3x’s the usual output of the hub generator.”

4. prove theory.

“A hub dynamo (electrical generator) can power the LEDs.” Using 38 LEDs the resistance was enormous which would tire a biker. The team decided to add some smoothing capacitors (device used to store electric charge, consisting of one or more pairs of conductors separated by an insulator; from AC to DC, moderates the change in output voltage/current; can be used as temporary battery; it reduces the flickering of the lights for steady output) and tuning capacitors (a variable capacitor whose capacitance (measure of electrical energy stored) may be repeatedly changed mechanically or electronically; used to vary the resonant frequency of an oscillatory circuit) to help the resistance problem.

5. refine theory for application.

Testing 1 LED strip showed it could handle voltage fluctuation of the dynamo from 13VDC and up.

Building the slipring (disc with concentric copper channels mounted at the hub of the wheels, to transfer power from the frame to the moving wheel). “A 4 channel slip ring, 1 to supply the +12v to the LEDs, and then the LEDs have three color channels, which in total will give us the option of producing 7 different colors.” The process entails transferring a slipring pattern onto a copper plated board, then soaking the board in an acid solution that eats the exposed copper, leaving the copper covered by the pattern.

6. begin prototype refinement & construction.

Solder wires to the LEDs, making each wheel light strip.

7. more construction.

mount copper runners to the fork of the bike frame to contact with the slipring. The contacts are made of phosphor bronze (a highly conductive, springy material) with a silver coated head (providing smoothing gliding contact across the copper rings to reducing wear).

8. testing prototype at construction phases.

Conveniently the red channel requires less current than the others, so when the bike slows the wheels continue to glow red.

9. complete prototype.

Connect wheels creating the power system, add kill switch, disc brakes, and diffusers.

10. Test ride.



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