Bio-Feedback Meditation Bracer: Process

How can haptic feedback be used to improve our lives? How might it affect our health and our relationship with our bodies? As a sprint to create a feasible application for haptics, my team created a wearable device that tries to address those questions.

Continuing my exploration of haptic matrices, I joined Haiyi Huang, Dan Oved, and Asha Veeraswamy to see what we could ultimately create with a little more time and effort. One aspect of the matrix that afforded us greater flexibility was in how and where the motors vibrated. We agreed that an outwardly radiating vibration could be a calm yet observable motif to utilize. In a parallel conversation, we identified that we would need to organize the motors into sub-groups to conserve PWM pins in our micro-controller. This led to an arrangement of the motors organized in concentric rings.

Each ring of motors is fed by a single output pin of our micro-controller

We then crafted a quick prototype out of a piece of found leather.

Our meditation bracer prototype

This prototype had no functionality and was built primarily to test form factor and sensation. The vibrations of the motors were hard-coded into the prototype. User feedback was generally positive saying that the sensation was mostly pleasant. However, simply outputting the PWM signal directly from the micro-controller meant that the central motor was felt very strongly and the outer motors that shared a single circuit were not as noticeable.

In our next and final iteration, we revisited the wiring and introduced transistors to provide a more consistent power feed to the motors. This allowed each motor to have relatively the same amount of potential strength.

Our final version has transistors managing the power feed to each motor circuit

In this iteration, a heart rate sensor was introduced. The leather component was also recut and all of the wiring re-soldered making for a much cleaner build.

The new motor array and bracer
Cleaned up wiring. A couple of the motors stopped working, though.

The final product can be used as a meditation device with the understanding that once we have access to information about how the passive functions of our bodies operate, we can then affect those functions. A normal human’s resting heart rate is between 60-100 beats per minute. When one’s heart rate is greater than 80 beats per minute, the user can put on the meditation bracer which pulses in sinusoidal waves. This provides a breathing guide to the user that can then help the user to calm themselves. When their heart rate lowers to a resting rate range of  60-75 beats per minute, the vibrations will stop.

The meditation bracer

Additional user testing is necessary, but initial experiments appear to be promising!

Code:

https://drive.google.com/open?id=10blL9Sbe1vGR6RseN97FFWdx0bFdzLm3

Resources:

https://www.sparkfun.com/products/11574

https://github.com/WorldFamousElectronics/PulseSensorPlayground

https://pdfs.semanticscholar.org/4499/b10d4a22b52a0904569b9b0551d8e8409c91.pdf

https://learn.adafruit.com/haptic-headband/overview

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