IR Scanning Method Of Object Recognition

[davidthefat]

Originally Posted by CraigHickman

I work for a company (linked in my sig) that does Stereo Cameras. Stereo cameras allow machines to do exactly what you're hoping to do with this custom laser jig, but all in one nice and tight package. Here's a simple breakdown on how it works:
1. You know the distance between your camera's two lenses.
2. You can "measure" the distance between two features in an image.
3. Since you know the distance between lenses, the the distance in pixels between two features, through calibration you should be able to identify and quantify the distance between features. One "difference" is called a Disparity.
4. Using a nifty, already developed piece of software called SVS (credit to this goes to SRI's vision lab, more specifically Kurt Konolige, my boss), you can lay out an image that plots all Disparities in color to represent the depth and distance. A good example can be found here http://www.videredesign.com/index.php?id=65 if you're curious.

Vision is awesome, and can do just as much (if not more!) than some laser systems.

If you're hooked on lasers, go check out Hokuyo Automation's products. We use some of their laser rangefinders for our SLAM bots. They're a little pricy for FIRST, but man oh man are they cool.

I would LOVE to use lasers, unfortunately, its too expensive and its against FIRST rules, so I am trying this ghetto cheaper alternate using IRs

Originally Posted by davidthefat

I would LOVE to use lasers, unfortunately, its too expensive and its against FIRST rules, so I am trying this ghetto cheaper alternate using IRs

A few Sonar sensors on a gimbal ought to return enough range data to define the outlines of other robots... Pretty sure there's articles on the tubes about how it can be done.

Keep thinking outside the box!

[davidthefat]

Originally Posted by CraigHickman

A few Sonar sensors on a gimbal ought to return enough range data to define the outlines of other robots... Pretty sure there's articles on the tubes about how it can be done.

Keep thinking outside the box!

I was thinking of using sonar on the other sides of the robot and use it for general collision avoider type of thing, not sure how well thats going to work after the other team finds out that the robot moves away if they get too close... May be I can put an "aggressive" mode that chases every robot and rams into it for fun...

[davidthefat]

30 Milliwatt Continous Infra-Red Laser Module from http://www.amazing1.com/infrared-lasers.htm seems perfect for the job

[taichichuan]

The way we did this was to use one of the Sharp long-range IR scanners to find an object within range of the sensor. Basically, start at the far left angle of your servo (IR sensor is mounted on the servo) and jump every 5 degrees looking for something whose range indicates that it's close (uses an Analog channel for the voltages coming back from sensor and a formula to convert to distance). If you find something in range, start backing up until the distance falls off by a ball radius (this is the leading edge of the object). Then jump forward and do the same thing to find the training edge of the object.

Knowing the leading and trailing edges of the object as well as the closest distance (the closest face of the ball), you can use trig to calculate size of the object. If it's within the approximate size of a ball, then write the angle and distance to a message queue to be read by the robot control code to go kick it.

The whole detection is pretty fast (1.5-2 seconds) and could be made faster with multiple IR sensors scanning smaller sweeps. And, it is pretty good at being able to tell the difference between balls, robots and miscellaneous junk on the field. The code can be found here for your perusal...

http://www.chiefdelphi.com/forums/sh...ad.php?t=85509

Mike

[purduephotog]

One thing to think of is a Friend or Foe discriminator. An IR diode (s) emitting a certain frequency or IR reflective tape could be applied to alliance members.

Any camera with IR sensitivity (literally, anything) can discriminate that. If it can't, yank off the IR cutoff filter and slap in a piece of opticast IR plastic. In fact there are some IR goggles out at Target that are 50$ or so and excellent for IR. Identify the frequency and you know if the thing you're looking at is a Friend or Foe.

Of course, this also brings up ECM type opportunities- an IR emitter with sonar to 'jam' recognition. But I digress....