Author Topic: Grid Projection on the cheap  (Read 3369 times)

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Offline cyberjeffTopic starter

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Grid Projection on the cheap
« on: July 22, 2015, 03:01:08 AM »
Having a sense of spatial surroundings is not trivial.

You can however  map out the environment by projecting a grid on it. Laser grid projection is used in industrial robot vision to align parts. You can also calculate depth by the size of the squares and map contours.

There are a number of manufacturers of laser grid/spot projectors. What I haven't found is one priced in my ballpark.

Who knows of an affordable projector? Is there any software that  can be used with hobby robots?

Years ago, flea markets used to be awash in cheap laser pointers with interchangeable heads with a wide assortment of designs. So, this can be done, where is it?

Offline mklrobo

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Re: Grid Projection on the cheap
« Reply #1 on: July 22, 2015, 03:02:31 PM »
 ;D Hello!
I would offer an opinion, where permissible.
Yashamanic, on another post, is approaching the problem you indicated from another
point of view. He may solved the problem, but not posted it yet.  - ?  8)

Offline cyberjeffTopic starter

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Re: Grid Projection on the cheap
« Reply #2 on: July 22, 2015, 06:42:13 PM »
;D Hello!
I would offer an opinion, where permissible.
Yashamanic, on another post, is approaching the problem you indicated from another
point of view. He may solved the problem, but not posted it yet.  - ?  8)

Works for me. I have time.

I have no servos yet!

Jeff

Offline FIFO

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Re: Grid Projection on the cheap
« Reply #3 on: July 22, 2015, 08:09:35 PM »
Quote
Years ago, flea markets used to be awash in cheap laser pointers with interchangeable heads with a wide assortment of designs. So, this can be done, where is it?
You might be able to find something on ebay. I did a quick search and found this:

http://www.ebay.com/itm/New-GREEN-LASER-GRID-PEN-Pointer-Marker-Paranormal-GHOST-HUNTING-tool-/110961982067?pt=LH_DefaultDomain_0&hash=item19d5d97a73

If you scroll down on the page, you will find that the laser can project several different patterns, one of which might suit your need.
« Last Edit: July 22, 2015, 08:12:10 PM by FIFO »

Offline cyberjeffTopic starter

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Re: Grid Projection on the cheap
« Reply #4 on: July 23, 2015, 05:20:32 AM »
Quote
Years ago, flea markets used to be awash in cheap laser pointers with interchangeable heads with a wide assortment of designs. So, this can be done, where is it?
You might be able to find something on ebay. I did a quick search and found this:

http://www.ebay.com/itm/New-GREEN-LASER-GRID-PEN-Pointer-Marker-Paranormal-GHOST-HUNTING-tool-/110961982067?pt=LH_DefaultDomain_0&hash=item19d5d97a73

Thanks. Not quite what I want, but it may be the $13 solution for  the $150 part.

Laser patterns are called "structured light" and  is used not only in machine vision but MS  uses it in Kinect, which is their gesture sensor for XBox.

If you scroll down on the page, you will find that the laser can project several different patterns, one of which might suit your need.

Offline cyberjeffTopic starter

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Re: Grid Projection on the cheap
« Reply #5 on: July 23, 2015, 12:22:23 PM »
;D Hello!
I would offer an opinion, where permissible.
Yashamanic, on another post, is approaching the problem you indicated from another
point of view. He may solved the problem, but not posted it yet.  - ?  8)

Here is a setup on a beaglebone with structured light from a pico projector ($40 or so eBay)

http://www.hackengineer.com/hardware-overview/

The projectors aren't terribly bright so this would need color filtering to work on something closer to ambient. The article has a nice description on setting up openCV on the Beaglebone, which as I recall, was not trivial.

For my purposes, since my "catbot" is only a foot tall, I just need to know where things are sticking up out of the floor, x distance between vertical lines would be sufficient.

Jeff

Offline cyberjeffTopic starter

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Re: Grid Projection on the cheap
« Reply #6 on: July 23, 2015, 01:54:05 PM »
I've decided against the build your own computer vision.

I found this:

http://www.intorobotics.com/working-with-kinect-3d-sensor-in-robotics-setup-tutorials-applications/

This is the MS Kinect. The API also has speech recognition as well as being able to identify and track objects.

I've got a $34 used one on the way. It takes some horse power to run everything, perhaps:

http://liliputing.com/2013/12/odroid-u3-59-dev-board-with-the-power-of-a-galaxy-s3.html

Offline cyberjeffTopic starter

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Re: Grid Projection on the cheap
« Reply #7 on: July 23, 2015, 06:09:41 PM »
Kinect works with the Raspberry Pi B almost out of the box.  I'm going to give it a try.

My thinking of the moment is to use an Arduino Due for the mechanics and the Pi B for the vision. It would seem possible to run everything on the Pi but I think the Due is easier to use with the mechanics (and i2C), also the Pi will have it's hands full. 

Down the road (and not far down) the Beagle Bone x15 might be a choice.

I've toyed with openCV before on a few devices and have some Arduino experience but robotics is completely new and I have no experience. I don't mind being told if I'm on the wrong track!

At the moment the fun is beating the exasperation, but I know that will change! Everything is theory now, reality will intervene.

 


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