Adding Stereo Imaging to the Lynxmotion AL5C

My target now is to add stereo imaging to my robot arm. So to explain this I’ll make parts corresponding on each step, and make posts out of this, to ease comprehension and navigation on the blog…

But hey !! What’s « stereo imaging » ?? It’s an algorithm to infer 3D data from two images of a same scene, but taken at two different know points. It then gives a 2D image in grayscale like this famous one :

Stereo Imaging - Disparity map

You’ve got on top, the left and right image taken from two close points in a room.
On the bottom, the result : on the left, noisy image from the algorithm, on the right, the filtered result. (Image credits : http://afshin.sepehri.info/projects/ImageProcessing/ColorCalibration/color_calibration.htm)

The white color stands for closer objects, the darker it is, the further it is from the camera.
As you can see, it’s a powerful algorithm that allows to have the 3rd dimension, the depth from a scene. We can imagine using the produced data with object recognition algorithms or to help a robot to move itself in space avoiding obstacles, or maybe also in SLAM agorithms (SLAM stands for Simultaneous Localization and Mapping).

So, I started searching for a good camera. It has to be small enough to fit two of these in the robot arm, provide good quality images, have an auto focus feature…  And also, affordable ! That’s a lot of criteria isn’t it ?

After spending some time searching, I finally found the Logitech C525 which has it all !
I also searched on the web some information on what the cameras had inside to see how the PCB and the sensor looked like to have an idea for integrating the cameras on the robot arm (for example locate mounting holes, sensor position…).
There’s one video which helped me a lot to see what’s in the webcam, it’s here : www.youtube.com/watch?v=mBwH2hqGkck‎ thank you Peter !
Oh and, little detail on the webcam, it has an internal microphone, so later I could play with sounds too, in stereo !

Logitech C525

So, the Logitech C525 is an HD camera featuring 720p image resolution, auto focus and it’s quite affordable costing some 40€ each… For full specifications, see the official Logitech website.

Finally I bought two of these webcams. Next post will show you how to hack the webcams to install them on the robot arm ! Interesting part ha ? See that next time !