best way to detect a ball?

[SomeSaba]

Hello

Ok, so theres a capret and a tennis ball on the carpet.

If i aim an IR sensor straight down and take a sort of "threshold" value of the distance to the ground, and use that to detect the tennis ball would it be better than an sonar sensor due to the curvature of the ball? Im just worried about the tennis ball is not reflective enough

thanks <3!

[Steve Joblin]

I would think that sonar would be a bit more reliable, but difficult to say... have you considered trying to detect the tennis ball by its different color than the background?  I wonder if a vision or color sensor wouldn't be easier and more reliable?

[Admin]

sharp IR would work . . . but as steve hinted at, Id use a colored ball with the CMUcam. This would be very reliable and not very difficult.

For example:
[youtube=425,350]rE6SJZC9eeo[/youtube]

[SomeSaba]

thanks for the replies!

At previous competitions the carpets have been anywhere from gray to green, if its green im afraid the tennis ball might blend in 

[bulkhead]

Just wondering, are you trying to build a completely autonomous robot to pick up the objects?  Because I think it would be much easier to just have someone drive it...most likely quicker too.

[SomeSaba]

i totally agree... but i want serverly challange myself and make a completely atuonomous robot designed for a competition where the robot has always been driven by the competitor.
Its my senior year i g2g go with a bang!

Imagine the event supervisors/audience watching all the robots, and then there's the sudden awe when they realize im not controlling it!

of course there's a very high chance for error... but i hope to work it out all the little details to make it perfect, and of course it wont a big enough bang if i dont get first place 

I'm very excited about this project <3

(BTW: are u a competitor too? which school are you from?)

[bulkhead]

That's cool.  I am a former competitor...mine was almost autonomous one of the years I did it, but that was before they moved the box.  I didn't get to run mine autonomously or even very quickly for that matter, but my team won so it was completely worth it. 

Making it autonomous this year is real challenge...have fun with that!

[Steve Joblin]

If the carpet is grey or green, it shouldn't matter as most tennis balls are fluorecent yellow, which is quite easy for a color webcam to discern.

[MaztorShake]

I know I'm new to anything robotics, but how exactly is the gameboy being used? Is there some link someone has bookmarked that I can read?