Skip to content

Instantly share code, notes, and snippets.

Embed
What would you like to do?
PID C++ implementation
.DS_Store
/**
* Copyright 2019 Bradley J. Snyder <snyder.bradleyj@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef _PID_SOURCE_
#define _PID_SOURCE_
#include <iostream>
#include <cmath>
#include "pid.h"
using namespace std;
class PIDImpl
{
public:
PIDImpl( double dt, double max, double min, double Kp, double Kd, double Ki );
~PIDImpl();
double calculate( double setpoint, double pv );
private:
double _dt;
double _max;
double _min;
double _Kp;
double _Kd;
double _Ki;
double _pre_error;
double _integral;
};
PID::PID( double dt, double max, double min, double Kp, double Kd, double Ki )
{
pimpl = new PIDImpl(dt,max,min,Kp,Kd,Ki);
}
double PID::calculate( double setpoint, double pv )
{
return pimpl->calculate(setpoint,pv);
}
PID::~PID()
{
delete pimpl;
}
/**
* Implementation
*/
PIDImpl::PIDImpl( double dt, double max, double min, double Kp, double Kd, double Ki ) :
_dt(dt),
_max(max),
_min(min),
_Kp(Kp),
_Kd(Kd),
_Ki(Ki),
_pre_error(0),
_integral(0)
{
}
double PIDImpl::calculate( double setpoint, double pv )
{
// Calculate error
double error = setpoint - pv;
// Proportional term
double Pout = _Kp * error;
// Integral term
_integral += error * _dt;
double Iout = _Ki * _integral;
// Derivative term
double derivative = (error - _pre_error) / _dt;
double Dout = _Kd * derivative;
// Calculate total output
double output = Pout + Iout + Dout;
// Restrict to max/min
if( output > _max )
output = _max;
else if( output < _min )
output = _min;
// Save error to previous error
_pre_error = error;
return output;
}
PIDImpl::~PIDImpl()
{
}
#endif
/**
* Copyright 2019 Bradley J. Snyder <snyder.bradleyj@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#ifndef _PID_H_
#define _PID_H_
class PIDImpl;
class PID
{
public:
// Kp - proportional gain
// Ki - Integral gain
// Kd - derivative gain
// dt - loop interval time
// max - maximum value of manipulated variable
// min - minimum value of manipulated variable
PID( double dt, double max, double min, double Kp, double Kd, double Ki );
// Returns the manipulated variable given a setpoint and current process value
double calculate( double setpoint, double pv );
~PID();
private:
PIDImpl *pimpl;
};
#endif
/**
* Copyright 2019 Bradley J. Snyder <snyder.bradleyj@gmail.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "pid.h"
#include <stdio.h>
int main() {
PID pid = PID(0.1, 100, -100, 0.1, 0.01, 0.5);
double val = 20;
for (int i = 0; i < 100; i++) {
double inc = pid.calculate(0, val);
printf("val:% 7.3f inc:% 7.3f\n", val, inc);
val += inc;
}
return 0;
}
To compile library:
g++ -c pid.cpp -o pid.o
To compile example code:
g++ pid_example.cpp pid.o -o pid_example
@vtellier

This comment has been minimized.

Copy link

vtellier commented Jan 30, 2017

Thanks a lot!

I would just suggest to check the Dt term as it might lead to a division per zero:

if(dt == 0.0)
    throw std::exception("Impossible to create a PID regulator with a null loop interval time.");
@AGenchev

This comment has been minimized.

Copy link

AGenchev commented Dec 2, 2017

It works - nice :) :+1 . Now it's a good starting point for speed optimization like fixed point implementation for FPU-less MCUs.

@Tbone2401

This comment has been minimized.

Copy link

Tbone2401 commented Aug 12, 2018

Can I ask why you decided to create 2 classes for this?
I don't know the in and outs of c++, but I'm wondering :)

@nullbus

This comment has been minimized.

Copy link

nullbus commented Sep 5, 2018

@Tbone2401 It is called PImpl. See https://en.cppreference.com/w/cpp/language/pimpl for more information :)

@LiuJungle

This comment has been minimized.

Copy link

LiuJungle commented Dec 2, 2018

nice, it is a good tutorial to learn the C++ implementation of pid controller.

@brztitouan

This comment has been minimized.

Copy link

brztitouan commented Feb 13, 2019

Hello, dt value is in ms ? or in second ? Thank you

@qiweiyang2018

This comment has been minimized.

Copy link

qiweiyang2018 commented Apr 18, 2019

@brztitouan That depends on your own situation. If you use s or ms, just scale all other parameters accordingly.

@Purpleshadz

This comment has been minimized.

Copy link

Purpleshadz commented May 2, 2019

I am struggling to find the cmath header. Where could I find this file?

@oldrev

This comment has been minimized.

Copy link

oldrev commented Jul 25, 2019

Hello, I did a fixed-point version:

My Gist

@EserFromCambridge

This comment has been minimized.

Copy link

EserFromCambridge commented Sep 17, 2019

Hello,
May I ask the license of this library if you don't mind ?

@chris-praxis

This comment has been minimized.

Copy link

chris-praxis commented Oct 30, 2019

Maybe "dt" should be passed in to calculate since it's likely to change at least slightly.

@bradley219

This comment has been minimized.

Copy link
Owner Author

bradley219 commented Nov 18, 2019

Hello,
May I ask the license of this library if you don't mind ?

added license to source files

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.