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Biking Assistance System

Make biking safer and more efficient
Mid 2016

Once the brake is applied, all the kinetic energy will be wasted into heat. To make the best use of the recyclable energy, I have designed a biking assistance system, powered by the energy regenerated from applying brakes, that makes biking safer.

 

Early development

 

Initial thought

To make use of the kinetic energy, one good way is to convert it into electricity with a generator. However, the generator has a big resistance (mainly iron loss and friction loss in the gearbox) even under zero load, so it is necessary to separate it from the bike when not in use. My idea is to use a clutch.

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Clutch

The car clutch, obviously, is too complex. To make the clutch simple, my idea is to use rubber wheels. One rubber wheel is connected to and rotates with the front wheel and the other rubber wheel is connected to the shaft of the generator. To engage the wheels, my idea is to attach the generator to a rail fixed on the bike and move the rail up with something to engage the generator. The best way to move the rail in a bike, obviously, is using a brake lever.

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Prototype

An additional brake lever is installed. When this brake is applied, the brake rope will pull up the rail which is connected to a generator. The rubber wheel attached to the generator will then engage with the rubber wheel fixed on the front wheel. The front-wheel pushes the generator to rotate and the generated energy is used to power an LED. The LED has an internal DC converter and powers the LED when the bike is at above 10kph.

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Final product

 

Modification

Several months after finishing the prototype, I modified it to be an assistance system which includes a generator with clutch that generates electricity when needed, a radar that detects incoming bikes (since Chengdu has a huge number of bikes going on the streets), an adjustable spoiler that increases down-force (although not really useful) and an LED light.

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How it works

The potentiometer controls the angle of the spoiler. The supersonic sensors detect the incoming bikes and the LED will shine once distance gets small. If the incoming bike is even closer, the alarm will sound but it can be turned off by the red switch in the upper left picture. The other red switch controls the light.

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Electronics

This is the wiring diagram designed using Fritzing. The generator is connected to the DC-DC converter to stabilize and lower the voltage that it delivers because this time, most electronics could only work at 5V.

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Unsolved problem

One thing is very interesting, that whenever I turn on the switch and connect the generator to the battery to charge it, the generator's rotational speed is forced down to the zero-load speed of the generator at the voltage of the battery. Professor Lanzara from UC Berkeley told me that there is most likely a feedback loop in the DC-DC converter that makes it happen, however, I have not had a chance to go home and fix it.

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