Week 16 - applications and implications (May 13)


To plan and document the final project integrating the range of units covered on the course.

Final project plan

What will it do?

A wearable rear brake light and proximity alert for cyclists.


The final project idea came from almost being run off the road by a car whilst cycling along a country lane and how the Pronghorn uses it rump to alert others and signal danger.

Who's done what beforehand?

The bike accessory market has seen new innovative products designed to increase a cyclist's visibility and safety. Several new products have used Kickstarter campaign's to get funded.

Velgo Commuter X4

The Velgo Commuter X4 is a successful Kickstarter project which gives added rear visibility for cyclists. The central light and harness create a larger area for cyclists to be seen by other road users. The harness is adjustable to fit on the body or rucksack, the lights have different modes and intensity and a USB rechargable battery gives up to 20 hours of run time. The product retails at $49.99 US and £49.99 UK.


The LucidBrake is an active brake light for cyclists. The LucidBrake 2.0 is a successful Kickstarter project as of May 2015. The product has a 3D accelerometer to sense deceleration and trigger the LEDs. It also has a number of beacon modes from off, flashing to steady. The product retails at $75 US.


The VISIJAX commuter jacket with turn signals. The rainproof jacket has LEDs on the front, rear and arms of the jacket, powered by a USB rechargeable battery. The LED arrays on the arm flash when the arm is raised for signalling. The product retails at $200 US and £129UK.


The Zackees are turn signal gloves and a successful Kickstarter project. The LED arrays on the gloves are triggered by pressing a button between the thumb and index finger. They also have an ambient light sensor for increasing visibility during the day. The product retails at $55-$65 US.

Other projects include Velodroom smart bicylce light, Open Source DIY Automatic Bike Tail Light 2.0, LED Matrix Bike Safety Backpack and Leah Buechley's turn signal biking jacket.

What materials and components will be required, where will they come from and how much will they cost?

The following table gives an initial budget for the project.

Materials/components Source Cost
FR1 3"x2", 2x FabLab inventory $0.36
LEDs, red, 30x FabLab inventory $3.90
ATMEGA328P-AU-ND FabLab inventory $1.92
Other electronic components FabLab inventory $2.00
Tri Axis Accelerometer MXR9159G FabLab inventory $9.34
Wiring pencil wire Farnell $1.00
Ultrasonic ranging module HC-SR04 eBay $2.99
Smooth-On SORTA Clear 37 FabLab inventory $8.00
3D printed buckle FabLab inventory $1.00
Vinyl FabLab inventory $1.00
Sub-total $31.51

Elastic webbing Abbey Saddlery $1.50

Li-Po rechargeable Battery 1200mAh Adafruit $9.95
JST PH Series PCB Header RS Components $0.12
Adafruit Micro Lipo USB Li-Po charger Adafruit $5.95
Sub-total $16.02

Budget total cost $49.03

The main costs are the rechargeable Li-Po battery and charger ($16.02), disposable batteries could be used to reduce this. The other major cost is the tri axis accelerometer ($9.34), there is another tri axis accelerometer in the FabLab inventory LSM303C $2.89 which I will investigate.

What parts and systems will be used?

Electronic systems diagram

Electronics systems diargram

Fab manufacturing process

Fab manufacturing process

What questions need to be answered?

  1. Use separate circuits boards for input and output devices or combine onto one board?
  2. How to embedd LEDs in silicon rubber and make them solderable.
  3. How to make charlieplex LEDs backplane - vinyl cut copper or wires.
  4. How to locate and fix circuit boards and battery inside casing.
  5. How to make casing flexible and allow for rigid ciruit boards inside.
  6. How to make casing for electronics watertight.
  7. How to access on/off/mode button through casing.
  8. How to adjust aim of ultrasonic ranging module.

What tasks need to be completed and what is the schedule?

Project plan

How will it be evaluated?

Feedback from cycling and triathlon club colleagues on features and usability and whether they would use one themselves.