Let's Make Robots!

What range sensors should I use?

Hi fellow LMRians!

 

I'm starting work on a 3Kg sumobot quite soon(gathering parts at the moment, going to do it right and have everything before I start building this time).

I would like to know your opinions on range/distance sensors, what's the best choice? I'm considering Sharp GP2D120 or the Sharp GP2D12 among the IR-sensors, but both those have their drawbacks. The GP2D120 just have 30cm max range, but the GP2D12 has a 10cm deadzone. I've also read that the Sharp sensors are quite slow.

On the sonar side I've also considered the HC-SR04, but I'm not sure, won't they be too slow, with the sending a ping, then waiting for the echo etc?

I remember from somewhere that most japanese teams use some really pricey sensor, anyone know what kind it is, perhaps I could replicate the circuit for a lower price :)