Best sensor for detecting small and close objects

[Weird Fishes]

I am trying to figure out which type of sensor (and which model too, I suppose) would work the bet for detecting small objects (Lego bricks) on a white colour board by an autonomous robotic arm that will be approximately 5-10 cm from the ground(tip of sensor to board). What I don't know is whether a given sensor will be able to detect the brick, and be fairly accurate about it's position.

Any help would be greatly appreciated.

[Hawaii00000]

You might want to look into roborealm ( http://www.roborealm.com/ ). It uses a webcam and a laptop to process images. The other option is using a ir range finder like this...

[youtube]vbhMuPF0Qj4[/youtube]

[SmAsH]

does this sensor need to detect the color or the distance of the brick? have you considered sonar?

[superchiku]

hey if its coloured devce ..i can help u with image processing..i have devised a method for blob detection in opencv ...it really works gr8..and yes its faster then roborealm..

[Weird Fishes]

It doesn't need to detect colour. I've built a colour sensor already, and if I decide to include it it won't be on the end of the arm. I just ordered a sonar sensor from Pololu that claims it can detect small objects up to and touching it's face. I also have an IR sensor, so maybe I'll pair them. The IR sensor wasn't working very well before, but I think the voltage was out of range.

As for the camera, I don't think that's the best fit for this project(at least for now). I'm using an atmega168 and have little camera experience. Maybe version 3(this would be version 2 ).

Thanks

[GearMotion]

Perhaps think in stages. If you have a sonar sensor that gives you rough location, perhaps you can then supplement with a beam-break (IR or visible) sensor right on the robot arm.