Skip navigation
kyle90

Week 10! - Wrap-up

Posted by kyle90 Sep 13, 2018
Back in July, our team set out to build an assistive device that could improve the lives of people with certain medical needs. We decided that our project would be a system that could tell if someone has fallen down, and automatically get them help if they need it. With an aging population, and many elderly people electing to live independently, people falling and becoming injured is certainly a growing problem. Based on our research, it looked like all medical alert devices on the market still ...
The Arduino MKR1000 has the ability to send and receive serial data, and this is used to communicate with and control the GSM board. In this way it can initiate phone calls, as well as send and receive text messages. The audio comes from the DAC pin and into the microphone jack of the GSM board (currently via a wire that is soldered in place underneath it). The Arduino also gets the raw analog data from the three axes of the accelerometer. It adds these together for an overall acceleration measu ...
With the code written, power circuitry set up, audio amplifier built, cell network connection tested, accelerometer function verified, and project box 3D printed, what more is left but to assemble it and make sure it all works? And this is precisely what we did - after some delays for family matters and beginning a new school year.   When designing the enclosure we wanted to make sure it was as small as possible, so that the user wouldn't have to carry around a huge obtrusive box on their ...
  More to come in a couple of days as we enter the final countdown before the new school semester starts. All the components are ready now and just need to be assembled. ...
Everything is really starting to come together now! On the fall detection side of things, we built a test rig to hold the accelerometer and a spare Arduino, for calibrating the axes and doing some drop tests. This was constructed from Lego bricks, which have the advantages of being quick to assemble and disassemble, and keeping everything at known right angles. The "X" on the front is to remind us that the positive X axis is in that direction.   We also bought a SIM card so that the GSM ...
With Dan returned from his vacation, we had a meeting to integrate all the code we had written so far, work on the circuitry, and begin the design for the case that will house the device when it is done. The code went together easily enough, though there were some bugs we had to work out. The first was that the Arduino audio library seems to interfere with the tone() function which will send a simple square wave to a piezo buzzer. We decided that if we were going to have full audio output anyway ...
One of the things our device will need to accomplish is reading a wave file (the pre-recorded help message) from the SD card and playing it back so that it can be used by the GSM module, which expects an analog waveform. While it has historically been difficult to use Arduino boards for audio output, the updated 32-bit processor found on the MKR1000 can be used for this, by using the public domain AudioZero library.   How is audio stored?   Sound moves through the air as pressure wav ...
We haven't done much in the past week because Dan is in Europe for a long-awaited family vacation. Back home, Kyle has been looking over the math for the accelerometer.   Vector Calculus: Hard For People, Easy For Computers   We wondered if we could make the fall detection more reliable or use less processing power by, for example, using a smoothed velocity measurement rather than an integrated position measurement. Time will tell what actually works best with our hardware and in the ...
In our most recent project meeting, we focused on determining which tasks were going to be the most difficult so that we could prioritize them. There are two things that we think will test our technical skills the most:   1. Integrating accelerometer data   Since we are not using any kind of absolute position sensors, we will need to calculate position from acceleration by taking a double integral. This is complicated by not having an associated gyro, but we are hoping that we can ma ...
After coming up with our design proposal, our team met up to discuss the plan for the next ten weeks. We set some basic parameters for how we are going to build our device so that we could then figure out a schedule that will allow us plenty of time to build, program, and test our wearable fall detector prototype.   How will it be built?   Our initial thought was that we might put the accelerometer in something like a necklace, and have it connected to the microcontroller, battery, e ...