Using an encoder with a two CIM gearbox

[otherguy]

Originally Posted by jhersh

The correct way to do this on board the Jaguar is to have the Jaguar firmware modified to include a "follow me" mode so you can implement a master and a slave Jaguar. Since that didn't happen for this year, the correct answer is to connect the encoder to the cRIO and to run the PID algorithm on the cRIO.

-Joe

Just to share our experience from last year. We ran into the same encoder splitting issue on our lift and drive train... We were not successful in splitting one encoder to two Jags but were able to get something to work that's along the lines of what you're describing as a "follow me" mode.

We set one motor controller up in a speed control mode over CAN. We then queried that "Master" controller's output voltage. Then commanded the "Slave" motor controller (in VBus mode) to the Masters' voltage.

This obviously is not ideal as the slave controller will undoubtedly lag the master, however it worked in our testing. That said, we ended up not implementing closed loop control on the Jags for other reasons, and ended up not driving the motors in this configuration during the competition season.

If you are tempted to use this method of Master/Slave control, be conscious of the traffic generated on the CAN bus, especially if you're using the RS232 bridge