Vibrational Feedback Compass and Range-finder

Project Overview

We designed a vibrational feedback rangefinder for the blind. Signals from a headmounted ultrasonic rangefinder and a digital compass are continuously fed back into a DSP board stored in the backpack. There are 8 vibrational motors sewn into the harness. The four accross the chest communicate the output of the rangefinder to the user and four more around the waist indicate cardinal direction from the digital compass.

Objective

The objective of the ultrasonic rangefinder is to safely aid the blind. Generally, a visually-impaired individual heavily relies on a cane and other senses as they go about their daily lives. Our invention will NOT REPLACE the cane, but ASSIST in the user’s ability to travel independently and safely. Combining our invention with a cane, we believe that we have provided a positive addition to safety awareness

Challenges

Framework - finding a durable skeleton system flexible enough to accommodate users of varying sizes

Programming - Synchronizing activities between the rangefinder, compass and vibration motors.  Especially difficult was communication with the rangefinder.  We had to try 2 different models before we were successful.  

DSP - downsizing the DSP board to fit within the backpack, and giving it enough protection to withstand minor collisions.  

Electromagnetic interference with the compass - the steel backing on the DSP protection plate prevented the compass from working properly.  We had to remount the compass away from the DSP board, and it functioned correctly.   

Vibration motors failing - The motors fail for various reasons.  We had one fail internally from vibrating itself against the desktop while we were testing.  Another one failed because the soldering was not strong enough to withstand the bending forces we applied during wiring.  To alleviate this problem, we secured the wires with electrical tape.   

Wiring - With a goal of making our project portable and easy to mount, the wiring had to be able to be easily disconnected at certain points.  We solved this problem by using male-female extension cables, cutting them in half and using soldering them up to the necessary components.  The male-female section of the wires are now convenient connecting points that can be quickly released.  See the USB cable on the glasses for an example.