Arduino model for Robot use?

There are many models of Arduino boards from what I've read. (http://arduino.cc/it/main/boards) and (Arduino - Wikipedia) Speed, memory, and I/O vary in most. But I have found nothing that says what model is old and obsolete and what model is more recent, or what model is most useful for a given application. Is that information around?

I have no experience with Arduino at all, and I want to build a small robot for a few sensors and speed/direction control. Is there a model that is more useful, but not overkill? It would be nice if I could standardize on one that had broad applicability. Any suggestions - and reasons for your suggestion?

These are the current boards - http://arduino.cc/en/Main/Hardware.

An UNO will be fine for your small robot.

dxw00d:
These are the current boards - http://arduino.cc/en/Main/Hardware.

An UNO will be fine for your small robot.

Yes, I saw the hardware list.
The Uno recommedation seems OK. I'm concerned about the shields though; some may be designed for the larger processors. Without knowing what shield I'll need, its hard to pick the board, I guess.

Most shields are designed for the UNO or its predecessors. There aren't that many specifically designed for the Megas.

louarnold:
I have no experience with Arduino at all, and I want to build a small robot for a few sensors and speed/direction control. Is there a model that is more useful, but not overkill? It would be nice if I could standardize on one that had broad applicability. Any suggestions - and reasons for your suggestion?

If I was starting out from scratch, and wanting to build a robot, I might think about the Romeo arduino compatible from DFRobot (Romeo - a Robot Control Board with Motor Driver (compatible with Arduino) - DFRobot), since it is designed for motors, and you can get it with some robot kits. There are various shields that add motor support, but the Romeo has male pins for adding sensors directly, 2 motor ports, and an external power connection for adding multiple servos.

If you are the type that might fry your board, you might think about the Ruggedunio which is better because it better protected against high voltages (http://ruggedcircuits.com/html/ruggeduino.html).