Vex passive mogo transmission is back!

[technik3k]

@BottomNotch

so I use P control on the drive. this is the code I use to set the target based on the joystick.

			
fbcSetGoal(&driveLFBC, (int)getSensor(driveEncL) +
		      joystickGetAnalog(1, 3) + joystickGetAnalog(1,4));

fbcSetGoal(&driveRFBC, (int)getSensor(driveEncR) +
		     joystickGetAnalog(1, 3) - joystickGetAnalog(1,4));

though I don’t use trueSpeed this actually limits the the control value to 88 (with my current P term, if that were to change I would have to add a multiplier), which is probably a factor as to why it’s working so well for me. So I guess I do have a bit of extra math. Though I don’t limit the maximum power being sent for the mobile goal and I don’t have trouble intaking mogos at full speed (though putting them back down with cones on it is a different story :P.

Yes, it is good that you use PID, then the “I” should be able to adapt to variable load dynamically, and limiting slew rate will help to protect motors from sudden current spikes.

Then, I assume, you will use PID of some sort to control desired movement of MoGo lift as well.

However, the final step before sending power level to the motors should be to remap control values with true speed to correct for MC-29 motor controller’s non-linear characteristics. I may sound like a broken record, but this is very important to distribute load properly between drivetrain differential motors.

If you don’t do this step, then one of the motors could be pulling up to 20-25% higher load than its siblings (green vs blue lines on the graph), resulting in its PTC getting hotter, while it could be easily avoided.

It is very easy to add TrueSpeed to your program - one global array and a function with a couple of if() statements to check for sign and upper array bound. Just make sure you follow this workaround or latest version of RobotC may have issues uploading the code:

Cortex Slave CPU Error