Making a galvanic skin response sensor.

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tjbaldy
Posts: 2
Joined: 05 Apr 2013, 15:29

Making a galvanic skin response sensor.

Post by tjbaldy »

Hey there!

I'm new to programming on the NXT Lego Brick and I'm trying to follow this: http://www.extremenxt.com/gsr.htm

I have done everything apart from creating the 'simple' data logging program that creates the text file that holds the raw sensor data values. I've played around with the data logging programming and I know that running the touch sensor through a data log will automatically create a text file. However, I don't know how to create a text file based on the program I've made for the galvanic skin response program.

When I run a normal touch sensor data log it always comes back with 0 constantly. But when I run the program from the website I get values between 900-1100 which is what I should be getting! So the program does work.

So to summarise: How would I make the data logging file that uses the program I've made from the website above.

Thank you :)
circuitmage
Posts: 68
Joined: 14 Dec 2012, 17:56
Location: Austin, TX

Re: Making a galvanic skin response sensor.

Post by circuitmage »

Hoping someone with more experience will chime in here...

I've been doing datalogging with Robolab and the NXT Edu software (which has a separate datalogging program).

If you are recording datalog information, it should appear in the datalog memory of your NXT. You can then upload that to your PC programmatically (via blocks in Robolab, for example) or with an option at the top of the NXT software window.

I think there is another way to do it, if you are not using the NXT Edu software (retail NXT version)....that info is also out there on the webs.

Edit: Here is some good datalogging information, also check this site out for lots of other information http://www.teamhassenplug.org/NXT/DataL ... ogging.htm
tjbaldy
Posts: 2
Joined: 05 Apr 2013, 15:29

Re: Making a galvanic skin response sensor.

Post by tjbaldy »

Thanks for the reply. If you look on the guide there's an option to download a more complex program that does the same job but shows more information on the Lego Brick as it runs. I've decided to use this now instead as it gives more user feedback. I'm using the education version too. I've been playing around with the data logging and have been able to upload the resulting text files to my computer easily. I've also been able to import a text file into Excel so that I can make a scatter graph from the data. All this was fairly straightforward. The problem I'm having is modifying the program so that it writes a text file with the values being shown on the NXT Lego Brick.

The more complex program (that I'm now using off the website) looks like this;
Image

On the picture you can see what I've added to try and get the file writing to work. And to my shock it does work and writes the RAW sensor values to the file. However, it constantly writes the values and there is no time gap in between each reading which is what I need. My guess is that it is really simple to do but as I'm new to this I'm unsure what to do next.


EDIT: Not sure why the image link isn't showing so here's the image url - http://postimg.org/image/fcb8vtx6b/
circuitmage
Posts: 68
Joined: 14 Dec 2012, 17:56
Location: Austin, TX

Re: Making a galvanic skin response sensor.

Post by circuitmage »

Ok, so first thing...I actually still have the blue Rat Shack biofeedback machine. I used it alot to explore meditation in those days. Flashback....

Second, nice erotic pictures...oh you mean the top one...ok. So, at first glance, if it is working but going to fast...in his write up, his datalogging program recorded data every 10 seconds, so you need to add a wait block in there, or have the loop sample every 10 seconds. Maybe try 5 seconds too, or different things.

Without a wait block or other method of pausing, the NXT samples nice and fast, and you will run out of your 4600 data sample storage quickly.
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