[Mike Betts]

Originally Posted by BurningQuestion

1) Would you recommend the use of mechanical or optical sensors?

2) What are the benefits of one over the other?

4) do you think it is better to make your own or buy one?

6) What does "PC Mount" mean? What does it mean to have a horizontal mount or a vertical mount or just a mount?

8) Of the above, what could be used with a FIRST robot?

11) how many "clicks" per revolution would you recommend? This encoder would be used for the drive train most likely, not for the angle of an arm. (meaning that the encoder doesnt need to be as accurate as one you would use for an arm)

-- Jaine

Jaine,

1,2&4) I recommend optical encoders. Much easier to use and more reliable (less moving parts).

6) PC stands for "printed circuit" and is meant to mount on a PC Board. The other common mount is called a "panel" mount. Panel mounts are normally easier for a FIRST team to use. Horizontal and vertical mean exactly what they sound like. Choose one of each and look at the picture.

8) It varies from year to year according to the rules. Last year, DigiKey was an approved source. There was also cost restraints...

11) The number of clicks per revolution depends on how many revolutions per second the encoder will see and how you are processing data. The 2004 Bobcat used 256 clicks per revolution on an encoder which rotated at less than 10 revolutions per second (max). This meant that the processor had to update (count) a maximum of 2560 times a second. Not a problem for the PIC18C...

Check out Kevin Watson's web site for a good example of how to use optical encoders and interrupts with the RC controller.