We wanted to build something new in the fitness world using hardwares, and do fund raising for student veterans in our school. I wasn't sure if anything useful would come out so I let my fantastic teammates decide. Between Ocululus Rift, Leap Motion, and... the Pebble watch, we picked the small and defiant.
What it does
It records your weight and prompts you to perform a punch, and then by creatively using the watch's accelerometer, you can obtain the maximum velocity of your punch. It's best used on a leather punching bag, or... a rolled sleeping bag would work! Sleep, what is that...?
How we built it
First we downloaded the Pebble Time Android app. Using that, we connected to the watch using Bluetooth. Then we studied Pebble's API since we weren't expert at Pebble products, but that's why we are here, to hack stuff! From there on, we dug deep into linear algebra, physics, electrical engineering and calculus in order to get this watch's accelerometer to do what we wanted, collect a series of movement signals as a base for calibration, then integrate to find the maximum velocity, upon which we can determine is the point of impact, and obtain the acceleration at that point. We wrote C in Pebble's cloud IDE, compiled the code on the cloud, ran it on Android and tested on Yi's pun... I mean sleeping bag.
Challenges we ran into
There were many technical difficulties. All three of us being software developers working on a physics heavy hardware project, and writing code in an unfamiliar programming language was a challenge.
Accomplishments that we're proud of
We were able to develop a working software that used the watch's accelerometer in a fun way, which is to measure the person's punch upon impact. We used mathematical models in our program to simulate the recoil of a punch by integrating acceleration to find the terminal velocity, thereby estimating the start frame of the recoil.
What we learned
Embedded systems projects require specific knowledge of the instruction sets since each set is different from another. Calculus classes are useful, and physics, writing, and... coffee.
What's next for Test Your Punch!
User input of his or her weight, and calculating force of impact based on estimates of the mass of a fighter's arm. Fundraising campaign to finance tutors for veterans who need help in school. A Hall of Famers RESTful API.