Propeller-based Thermal Imager
Phil Pilgrim (PhiPi)
Posts: 23,514
I've been working on a possible new product for the Propeller: a 16x4-pixel thermal imager. Here's a photo of my hand-wired prototype plugged into a Prop BOE:
I wrote a Perl script to display the raw image data on my PC. Here's a video that demonstrates the unit capturing the heat from my hand and also from a hot soldering iron:
[video=vimeo;48896841]
In the video, I've expanded each pixel to a 3x3 array and interpolated the eight outer subpixels to give a smoother image. Although the resulting 48 x 12 image doesn't contain any more information than the 16x4 image, it does look nicer (i.e. less jagged).
Anyway, so far, so good. Correcting the raw image data for gain, offset, die temperature, etc., and converting it to actual pixel-by-pixel temperatures is the next step. The math to do so is a bit hairy, though, involving fourth powers and roots. This may be one case where I succumb to using floating-point math. Also, I want to be able to display the image directly to video and VGA, rather than depending on a PC. Being able to overlay the image on a video feed would be nice, too, although that would have to be done in grayscale, not color.
Stay tuned for further developments!
-Phil
I wrote a Perl script to display the raw image data on my PC. Here's a video that demonstrates the unit capturing the heat from my hand and also from a hot soldering iron:
[video=vimeo;48896841]
In the video, I've expanded each pixel to a 3x3 array and interpolated the eight outer subpixels to give a smoother image. Although the resulting 48 x 12 image doesn't contain any more information than the 16x4 image, it does look nicer (i.e. less jagged).
Anyway, so far, so good. Correcting the raw image data for gain, offset, die temperature, etc., and converting it to actual pixel-by-pixel temperatures is the next step. The math to do so is a bit hairy, though, involving fourth powers and roots. This may be one case where I succumb to using floating-point math. Also, I want to be able to display the image directly to video and VGA, rather than depending on a PC. Being able to overlay the image on a video feed would be nice, too, although that would have to be done in grayscale, not color.
Stay tuned for further developments!
-Phil
522 x 382 - 42K
Comments
http://www.robot-electronics.co.uk/acatalog/Thermal_Array_Sensor.html
It looks like the one you have will have a better resolution than that one. I can think of a couple robot projects I've done where this sensor would help.
Robert
I hope you develop it - yes, definitely get it on the shelf!
Any ideas yet about how sensitive it can be? What's the wavelength range?
http://www.irisys.co.uk/thermal-imaging/
It used a 16x16 IR array with 256 levels, and a germanium lens.
-Phil
I'm going to bet it's a MLX90620.
Here it is at DigiKey. I don't know why I'm surprised to see it cost as much as it does at $64.45.
Edit: BTW, this looks super cool.
Anyway, my initial plan is to design a board with a TO-239 socket to accommodate the sensor. That way, people can choose between the 40-degree model and the 60-degree model -- or anything else Melexis might come up with.
-Phil
Nevertheless, it looks like an awesome project.
I love this FAQ on page 37 of the data sheet:
I consider using MLX90620AAA to measure temperature within car compartment, but I am embarrassed about the Sun light that may hit the module. Is it a significant issue?
Yes, I was just pointing out that the effort and intelligence it takes to get that sensor to work with the Propeller, etc. is far from trivial. Phil needs to be compensated along with Parallax, and even though there might be discounts involved in buying a multitude of sensors, Phil needs to keep Browser happy in fancy shrimp and raccoon furs.
-Phil
-Phil
I've been playing around with the Propeller Backpack lately trying to create custom characters on the fly to generate an artificial horizon overlayed on my ELEV-8's video link.
This got me thinking about having thermal information overlayed on a live image of the object being measured(with the thermal sensor). I personally think it would be cool if your sensor board would work with the Propeller Backpack this way. Possibly even having the sensor on a daughter board that plugs into the Backpack's 12 pin connector. (Though now that I type this, I realize the sensor may need to be piggybacked on the video camera used to create the image.)
Anyway just some thoughts.
Thanks for continuing to make such cool stuff. I'll probably buy whatever you come up with next (I'm always glad when I do).
The sensor board is pretty much laid out. It will plug into the Backpack, Spinnret, and MoBo 12-pin connector. It will also have provision for plugging into a solderless breadboard, working with a pair of servo extension cables, and plugging into the mezzanine connector on the TSL1401-DB and PropCAM-DB for simultaneous visible and far-IR image captures. My thought is that it be a semi-kit, with all the SMD parts installed and the though-hole parts (connectors, TO-5 socket, and sensor) loose, so that users can configure it to suit their needs. It will work with both 3.3V and 5V systems, and on-board I2C pullups are jumper selectable, since some host systems already have pullups for SDA and SCL.
I think that pretty much covers the bases.
-Phil
Yup, I've been thinking the same thing!
-Phil
I wanted to persue thermal imaging a while ago, but did not have the experience to do so. However I did find a company that has quite a few thermal imagers.
It is my understanding that these sensors can ouput a couple different image formats over serial, spi, or i2c interface. The ones that caught my interest are the uncooled(thermal electric cooler-less) microbolometers. SOFRADIR- EC has an office in NJ with testing facilities, unlike ULIS which is based in France. I hope this is helpful!
And sorry, as you may know this is my first post on this forum... well on any forum.
SOFRADIR-EC website: http://www.sofradir-ec.com/
ULIS-IR website: http://www.ulis-ir.com/
SOFRADIR- EC uncooled microbolometers: http://www.sofradir-ec.com/products-uncooled.asp
Welcome to the forum! Are you affiliated with either of the companies you reference, by any chance?
Interesting, but I did not see any pricing info. Any idea what those things cost ... with lenses?
-Phil
Here is some Inspiration for you ...... as you mentioned overlays
[video=youtube_share;pIb1scnD67o]
re: A high speed I2C compatible digital interface
Maybe you could try 128 of them on the I2C interface * $64.45 * = $ 8249.60 LOL
That's impressive. And just think: if the Ardweeny can provide results like that, just imagine what Phil is going to get his Prop-based system to do.
If it was in a water proof container could it work through a lens of some sort? i.e. under water inspection of an object.