10-04-2006 22:44

Mike

Re: paper: PID Control Theory for FRC Programming

Great job, helped me out a bunch.

10-04-2006 22:51

Tom Bottiglieri

Re: paper: PID Control Theory for FRC Programming

Just a note:

The equations given in text state the following:

POUT = KP * KERR

But your code shows the proper integer based math method of performing this expression.

POUT = KERR * KP

It's quite clear why the variables need to assume this order, but I did not find it documented that there IS a difference between the "text book" equation and your example.. (it is more accurate to "round" later in the equation, after your numbers have built up.)

Either way, great paper! I plan to include this in my "required reading" for new programmers on my team.

10-04-2006 23:59

Matt Krass

Re: paper: PID Control Theory for FRC Programming

Quote:

Originally Posted by Tom Bottiglieri Just a note: The equations given in text state the following: POUT = KP * KERR But your code shows the proper integer based math method of performing this expression. POUT = KERR * KP It's quite clear why the variables need to assume this order, but I did not find it documented that there IS a difference between the "text book" equation and your example.. (it is more accurate to "round" later in the equation, after your numbers have built up.) Either way, great paper! I plan to include this in my "required reading" for new programmers on my team.

11-04-2006 00:03

Greg Marra

Re: paper: PID Control Theory for FRC Programming

Well written and very clear!

You may want to consider adding some comments to the code examples, such as why you limit to +-127 in case any completely new FRC programmers read this.

12-01-2007 15:21

Mike

Re: paper: PID Control Theory for FRC Programming

I used this paper today as a reference when writing 237's PID control code.

Bumping it up to bring to the attention of other teams.

12-01-2007 17:51

Guy Davidson

Re: paper: PID Control Theory for FRC Programming

Thank you very much for this paper. This really helped me undferstand the concept of a PID, and will definetly be used when we write our PID code.

-Guy

19-02-2007 10:30

LieAfterLie

Re: paper: PID Control Theory for FRC Programming

Very helpful. You might want to move the P code example showing the #define KP 5 / 10 to between the P and I sections though, as it doesn't show I control.

I finally learned what this PID stuff is about, thanks.

You might want to also mention that since motor velocity control is a speed you're comparing encoder ticks per time rather than a target value that has a defined range, and therefore also give us a simple method for determining the range, such as maybe start at this many ticks per time period as the min/max, then scale it down when the motor is full and gives less than that number, then printf that max to initialize it to for future code so that it starts out at the right range. I know this really goes beyond the basic PID concept, but it is relevant to speed control.

19-02-2007 10:59

LieAfterLie

Re: paper: PID Control Theory for FRC Programming

Maybe even add some visual aids, graphs... ?

18-05-2007 13:30

kwilliam

Excellent paper!

Matt, this is an AWESOME paper! I wish I had read it earlier when I was learning PID control this year. I read this one instead and had the programming team read it, but your paper is an improvement. Wonderful explanations, good example code, and excellant usage scenarios! I will be sure to include a link to your paper in our own programming team's handbook.

18-05-2007 17:23

tseres

Re: Excellent paper!

...
[dotdotdot]
i'm a new programmer, and well, i don't understand how this works....i sort of understand the concept...you get feedback somehow from the robot....ya...that's about all i understand....

21-05-2007 09:46

Qbranch

Re: Excellent paper!

Quote:

Originally Posted by tseres ... [dotdotdot] i'm a new programmer, and well, i don't understand how this works....i sort of understand the concept...you get feedback somehow from the robot....ya...that's about all i understand....

21-05-2007 12:29

tseres

Re: Excellent paper!

thanks so much....although i wont be going to IRI...lol....but thanks

23-05-2007 17:25

tseres

Re: Excellent paper!

ahhhhh...after looking at a lot of other things....

so i guess PID is basically having software control the robot rather than just the PWM outputs are the same as the joystick values...so there's a layer of software that processes all the input and output data.

23-05-2007 17:54

JBotAlan

Re: Excellent paper!

Quote:

Originally Posted by tseres ahhhhh...after looking at a lot of other things.... so i guess PID is basically having software control the robot rather than just the PWM outputs are the same as the joystick values...so there's a layer of software that processes all the input and output data.

23-05-2007 18:27

tseres

Re: Excellent paper!

ya..i know it's not easy, but it is worth it. this year we didn't really have any PID, but the driving was sort of "software controlled". the only problem is we didn't have any sensors and our robot can't go straight. lately i have been developing omni code potentially for next year that uses a gyroscope. we dont need any encoders because the gyroscope algorithms/functions we made will automatically correct for any motor error.

23-05-2007 22:39

Alan Anderson

Re: Excellent paper!

Quote:

Originally Posted by tseres ...the only problem is we didn't have any sensors...

24-05-2007 03:28

Salik Syed

Re: Excellent paper!

I guess if all they really want to control is orientation that shouldn't matter.

But on the topic of the paper : great idea, I think the community needed a simple down-to-earth explanation. I know it was pretty overwhelming sophmore year trying to figure it out on my own without any real programming experience or calculus experience.

I also like how you gave a lot of ideas for applications, that is very useful... alot of people think PID is just useful for moving arms and such but it can be used for a lot of other things !