PID on DriveTrain using NEO Motors and Spark Max

Technical Java
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1

Hello,

Our team is trying to use PID for the first time and we’re having some trouble with it. We are running the Rev Robotics Neo motors using the SparkMax motor controllers via CAN, and have two Neo motors on each side of the drivetrain.

Do we have to tune one motor at a time, or can we tune the PID numbers for both at the same time? We have tried to construct a CANPIDController using the Java API and put the constants on Smart Dashboard while plotting the encoder velocity values. We tried the online tutorials of PID tuning but the motors started to get too hot.

We have a few questions:

  1. Are there any step by step instructions for us to follow to tune pid given our situation?
  2. Do we just have to tune one motor at a time?
  3. Is there anything in our process that seems off or wrong?
  4. Does brake or coast mode on the motor controllers matter?

Thanks for any help in advance!

2
  1. I see you’re already following online tutorials. I have not seen anything which is NEO specific, so I’m giving #1 a no, as far as I’m aware.
  2. That shouldn’t be necessary. As (for forward or reverse driving) all four motors contribute equally to the same thing, you should tune the drive trains together.
  3. Seems OK to me.
  4. I’m not even sure if NEO has “brake mode”. Assuming it does, and is similar to brushed motors, it is a nonlinear departure and does not fit into the PID tuning parameters. On brushed motors, brake/coast mode only affects duty cycles sufficiently close to 0% (10% is the threshold IIRC.)