ds1935’s blog

When playing with the paired heartbeat sensors at the show, my partner Zeke and Adam’s housemate Terry had a moment. It freaked Zeke out–he said it felt like they were lying in bed together, except of course they were standing a few feet apart touching some cardboard and plastic and barely know each other. It was disjointedly intimate, which is a nice reversal of the ways technology can sometimes take more-intimate experiences (such as conversation) and make them feel less intimate. or at least less embodied. Another friend said it felt like having sex.

It didn’t feel like having sex when we finally got the paired heartbeats working and tested them out–but on the other hand, working late into the night on a project is in its own way an intimate activity, so there wasn’t that total disjoint of suddenly and randomly connecting with someone else’s heartbeat.

There’s a germ of something going on here that ties into what I’ve been thinking about. I didn’t put as much into this project as it deserved, but at the end of it, I got some solid tech for reading heartbeats and (a bit after the fact) for sending the rhythm between locations. It can all use some tweaking, as well as some additional thought…

This project idea has two parts, one specifically collaborative and one a smaller individual application I am interested in.

Several of us in the collaborative mesh networking class are thinking about using different mobile/wireless sensors for indicating mood, stress, and/or autonomic function to control different applications (dance, a home environment, some sort of collective status for a fictional cult, ‘pets’ that respond to mood). so one part of the project will be working as a group to do some combination of developing mobile sensors for different aspects of mood (heart rate, galvanic skin response, consciously stating one’s mood) and developing protocols for how these sensors can send and share data. The ultimate goal will be to have a network of sensors that can share data in whatever ways each application ends up needing it. (This is all very sketchy and prospective at the moment, as we haven’t even met to begin working this out.)

On the individual side, I have this (probably deceptively) very simple idea of making paired mobile heartbeat sensors that transmit User 1’s heartbeat to User 2 (probably in a device that vibrates) , and User 2’s heartbeat to User 1. I am envisioning this playing out in 2 ways:

1. For people close to each other (i.e., within XBee mesh network range), User 2 would continuously feel User 1’s heartbeat, and vice versa.This would be simple beat detection, and transmission of the vibration whenever a beat is detected (probably with a little bit of noise/error correction). I’m curious if their heartbeats would synch up.

2.  I’d also like to make something that works over the internet. This feels cheesy to me, in part because part of my motivation for this arises out of being in a long-distance relationship and wanting the ability to transmit something more than text, voice, and video.

I was thinking, though, that this should *not* be a continuous transmission. Largely because even a good mobile sensor can get dislodged (or even just turned off), and of course a person’s net connection can go down or get turned off,  and I wouldn’t want to, say, have gotten used to someone else’s heartbeat and have it suddenly thud wildly then stop, and not have them at hand to make sure they didn’t just die on me. i’m exaggerating. but only slightly. so i think it woudl be better if the use were ‘i press a switch, and my heartbeat gets transmitted while i am holding the switch.’

also, to avoid weird results from lags in data transmission, it would make more sense to detect heart *rate* on this end, transmit the rate, and then translate the rate into felt beat. the rate detection should be sensitive enough to detect the heart rate variability that occurs with breathing, though… or maybe just operate at a bit of a time delay and send {beat, mswait} for each beat. plus error correction.

We’ll see how far I get by tomorrow evening.

I’m trying to detect my heart rate and develop some external response to variations–probably one response when i am particularly tachycardic, and one response when i am particularly relaxed.

As of Monday night, if I sit still, I can get a decent waveform and do slightly reliable beat detection (these are among the best results i’ve gotten. the first one is me, and the second is mike dory):

As of Tuesday night, I was able to have a self-contained (sensor, arduino, battery) module that detected my heart rate, identified beats, and activated a vibrating motor when a beat was sensed. Thus, a basic externalization of an internal sense.

This didn’t turn into any specific performance, but it’s part of a sensing system that I want to expand to include GSR, make wearable, and incorporate into a couple other projects.

I’m interested in seeing how my mood correlates with whether or not I am on my feet and when and how I am moving. I haven’t done that yet, but I have a feet-eye view of my life.

I hooked up 2 FSRs to each of my feet, one at the heel and one at the front. I used an old pair of Converse whose insoles are slowly falling apart, so I was able to prise the insole up and place the FSRs between the sole and the insole. I ran the flexible connector through rips in the fabric near the sole and connected the wires to long ribbon wires which run up my leg.

((photo))

((circuit diagram))

Currently, data from both shoes is feeding into the ADC ports of the Sparkfun datalogger and being recorded (at 10 Hz) as an array of bytes on an SD card. I added a potentiometer so I can (actively) indicate my mood.

I’m feeding this data into Processing (someone, please, give me a kick in the pants to move over to Eclipse!), parsing out the five pieces of information, and displaying it as follows:

The left strip is the front (left) and back of the left foot over time (the top is time 0, and the bottom is the end of the recording), and the right strip is the same data for the right foot. The colors are used to indicate my stated mood. There are some primitive zooming and scrolling options to allow a closer look:

Thus far, I have basically been able to visually identify when I am walking, and to a lesser degree when i am standing or sitting. I am particularly interested in when I am fidgeting, but I’m not as clear what that looks like.

The code needs a lot of work (I need to use objects a lot more heavily than I currently am), and I’d like to display this in three ways: as that larger graph (with an indicator of where in the graph one is looking), as a simultaneous closeup of a smaller section of the graph, and as an actual representation of feet with alpha as an indication of pressure, which can be seen changing over time.

Technically, I’m not convinced that the 5 inputs into the datalogger are entirely independent (the potentiometer is being wonky, which a potentiometer has never been for me before). Also, I *really* don’t think that indicating mood is the way to go. I am thinking of measuring heart rate and GSR as combined mood indicators (but am a little overwhelmed by finding and understanding op amps!), and then I think I will want to send all my data into Arduino, make the sense of it that I want, and then send it via serial into the datalogger.

Day 1: I DID NOT WANT to meditate. I procrastinated, I felt anxious, I finally sat down around 11:10 and set an alarm for 11:30. As is often the case, my brain went in waves between jumpier and quieter. I had a few moments of quiet. After a while I panicked that my alarm wasn’t going to go off and I would be trapped there for HOURS, so I opened my eyes and sat up about two minutes before the alarm was set to go off. After that I didn’t really want to do anything, so I went to bed early and lay in bed for a while and eventually fell asleep.