Auto-focus, HandyCam, and where are the kits?

I am also suprised that there aren't hacks or kits for this...

If you want autofocus assembly, tear apart a polaroid camera. The lens has motorized focus with an encoder to let your computer know how far it has moved.

Rich

vision kits

complete

machine

servo/circuit

As a programmer why not use these cheap Handycam things than? I had thought of using my video camera and a video frame grabber. This is usually part of a PC tuner card. However it requires something called TWAIN and I don't have the beginners books on this sort of stuff.

- John

Rich,

Have you done this? If so, do you have a write up on your web site? I'd love to see it and I bet so would Circuit Cellar and Servo magazine.

Also, wants a Polaroid model # that's a good one to tear up.

Thanks.

I hooked one up and got it to move (computer controlled) hbridge, 2 outputs and 1 input are all that is required for computer control.

I couldn't get it to focus the gameboy camera. Might be difficult to match the autofocus lens with a camera. I didn't get into the math of lenses though.

I never tried to use the input from sonar to position the lens because I couldnt get the camera and lens to get a non-blurry image. this would prolly be the best way to go. take a measurement with sonar, adjust lens accordingly (just like the camera worked)

Any polaroid sonar camera will work. They all adjust the lens according to sonar measurement.

Rich

John,

A couple of reasons:

1)

I'd like to try my hand at emulating stereo vision. I may be out of my depth here, but here's my idea and I'm betting some of the higher end vision robots like Rodney Brooks' COG do something like it.

a - Tear out two Handycam or other camera auto-focus/zoom lens + camera assemblies. b - Mount them on a flat panel, with a pair of two-axis turrets (rotate and swivel), independently adjustable. That way I can angle the eyes like a person does at a desired target. c - Grab frames from both cameras d - Find a decent sized colored blob (a ball most likely) that exists in both frames e - Adjust each camera's rotate, swivel, and focus until the blob is at the center of of both frame grabs as best as possible, using an advanced dithering algorithm to vary each parameter (rotate, swivel, focus). Also adjust the focal length of each camera by trying to achieve same approximate distance to each [north, south, west, east] border of the frame. Use each camera's zoom until those values match between the frames. This is done so that each camera has about the same focal length. Best in this case to choose a percent of frame the blob should occupy, zoom the "dominant" camera (left or right) until blob occupies that much of the screen, and then simply match the other camera to it.

With any luck, that would approximate the depth perception of a mammal. Then angular shift measurements could be made to do all kinds of fun measurements.

2)

Mounting issues and size. I want to have them on the robot so they can't be too heavy and I want it to look at least a little "cool". Also if there's too much weight, the battery life of the unit will get hammered.

Thanks,

Rich,

Ok thanks! I'll check eBay for some used items. Any warnings about current so I don't fry the item? Do you know how much current the unit requires to operate?

Robert.

camera batteries are 6volt I think.

the lens focus motor is probably

3 to 6 volts.

Rich

1) the lens just isn't focusing on the place in space where your imager is. Use a piece of scotch tape to form a visable image.

2) The lens itself will not auto focus. You need the sensing circuitry to tell the lens' motor and drive where to go.

Why don't you just start out with two handi cams mounted on servo pan/tilt mounts and work with these until you finally get something workable. Then you can strip the cams to make them smaller. If it doesn't work out, then you can sell them cheap on ebay to the next robot tinkerer or general home user. You can also use a servo to operate the zoom in/out buttons on many cams.

Robert Oschler wrote: [...]

Whew. Ok. Not exactly sure what you are hoping to do. I try to stick to the "keep it simple" principle. This means a fixed focus and plain old pan,tilt for the eye. I have enough trouble with the software without making the hardware more complicated :)

- John

If you want to hack a camcorder on your next robotic project, search for a unit that can show live video but has some problem with it that makes the owner want to sell for cheap (or even give away). The most common problem with camcorders that can still show live video is that the unit won't record, which is fine for robotic use since you'll probably gut out the mechanical parts anyway to reduce the size and weight. Every week at work I see people bring in camcorders for repair that are out of warranty and would cost more to fix than it does to buy a new one. Sometimes the customers just throw them away, sometimes they take 'em home, throw 'em a closet and forget about 'em, and sometimes they sell 'em dirt cheap for parts. Check your local "forsale" newsgroup and post a want ad asking for broken camcorders that still show video. (I did that last month and got 4 offers. The one I finally bought cost me $10.)

Remember that the equipment for your next project doesn't always have to be new or fully functional to be useful.

~WEC

That's a great idea!

Thanks.