Controlling a FIRST robot with a Lego RCX Controller?

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Posted by Lloyd Burns at 05/30/2001 10:52 AM EST


Engineer on team #188, Woburn Robotics, from Woburn Collegiate and TorDistSchoolBrd, ScotiaBank. OntPwrGen, Enbridge.


In Reply to: Controlling a FIRST robot with a Lego RCX Controller?
Posted by Andy Baker on 05/24/2001 3:17 PM EST:



: A local school is having fun with their lego league team here in Kokomo... but they want to drum up more interest and support.

: They have made various cool robots from the Mindstorms kit, and they've done alot of presentations, trying to get more students involved. Whenever they present one of their creations, they are having a hard time getting people to take them seriously and look at the robots for more than just toys.

: So, the team wants to be a little dramatic and really show the crowd something drastic during a presentation. They want to run their Lego Mindstorms robot, stop it, manually remove the RCX controller, insert the RCX controller into a big robot (a FIRST robot), and then have the big robot operate just like the Lego robot.

: The Lego team would like to do this... but we're not sure how. I would imagine that we would need some amplification of the signals from the RCX, and somehow link it to the Innovation FIRST controller. We have not investigated anything yet. Has anyone else done this? If so, do you have any suggestions?

: TIA,

: Andy B.

I did a search on "lego mindstorms" and found this site which deals with reprogramming the CPU - one reference therein :

"Paul Haas has figured out that the RCX generates a signal which can control a servo. His Hitec HS-300 servo responds to 1
millisecond (ms) pulses by rotating to one extreme and 2 ms pulses by rotating to the other extreme. You can make the RCX
generate pulses like that. It takes 3 resistors to get the voltage right and the wave form shape clean enough. His Servo is only
rated up to 6 volts, so he used 4 AA batteries for it. Now the servo goes to either extreme under the direction of the RCX. "


While this may not be what you had in mind, it does indicate the extent to which some folk will go. In order to drive the servo, he reprogrammed the CPU, and took the outputs off the board itself.