View Single Post
  #1   Spotlight this post!  
Unread 24-01-2012, 07:13
NotInControl NotInControl is offline
Controls Engineer
AKA: Kevin
FRC #2168 (Aluminum Falcons)
Team Role: Engineer
 
Join Date: Oct 2011
Rookie Year: 2004
Location: Groton, CT
Posts: 261
NotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond reputeNotInControl has a reputation beyond repute
Re: 2012: Tuning the Jaguar's Speed Control PID Loop

Quote:
Originally Posted by Ether View Post
Some questions:

What wheel were you using?

What speed(s) were you controlling at? What was the approximate voltage at each speed?
I was using a 5in. colson wheel and controlled the motor speed between 500 rpm and 2500 rpm. I was not able to record voltage data because as mentioned, the interface I was using was through BDC-COM.

Quote:
Can you estimate the approximate transfer function from speed command to measured speed?
The answer to this question would also answer your other question on the voltage at each speed. I have not done the complete testing yet, but the transfer function is obviously non-linear. Which could be reasons for spikes in rpm around the set point. Ideally, a speed controller will clamp its output to the last output once the setpoint was reached, to prevent these fluctuations due to non-linear motor controllers.


Quote:
Did you collect any data, such as time traces of speed command and speed output (for step commands or sinusoids).
Sounds like your looking for information on rise time and settling time? Because I was running the Jag using BDC-COM, I wasn't able to record actual output information (unless there is a feature I am unaware of).

I tuned the gains of the controller to have a rise time of about 0.3 seconds and settle just under 1 second. Just visually, I would say settling time was closer too 2 seconds. When I run the setup on the CRIO, where I can log output data from the Jag I will be able to graph it and view true rise time and settling time for the response.

I am confident that the Jag will perform well under certain applications. It is my personal stance as a Control Engineer to have filtered feedback signals, and account for external disturbances if I need too with additional control, which the Jaguar can't do. I am confident the Jaguar can perform good speed and position control, but a smooth response where the controller is not being overworked may be hard obtain because the Jaguar does not allow the user to account for the variable non-linear effects. For FIRST purposes, I think the Jags can accommodate.

Hope this helps,
Kevin

Last edited by NotInControl : 24-01-2012 at 07:34.
Reply With Quote