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update pid, work version

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Alekseev
2025-05-21 18:24:53 +07:00
parent 484260d6cb
commit ff8192e65e
6 changed files with 134 additions and 97 deletions
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2
.gitattributes vendored Normal file
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# Auto detect text files and perform LF normalization
* text=auto

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PID Controller Implementation in Software.pdf Normal file
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91
PID.c
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@@ -1,55 +1,38 @@
#include "PID.h"
/*test push*/
void PIDController_Init(PIDController *pid) {
void pidControllerInit(PidController *pid, float Kp, float Ki, float Kd, float tau, float limMin, float limMax,
float limMinInt, float limMaxInt, float T) {
pid->Kp = Kp;
pid->Ki = Ki;
pid->Kd = Kd;
pid->KpDefault = Kp;
pid->KiDefault = Ki;
pid->KdDefault = Kd;
/* Clear controller variables */
pid->integrator = 0.0f;
pid->prevError = 0.0f;
pid->tau = tau;
pid->limMin = limMin;
pid->limMax = limMax;
pid->limMinInt = limMinInt;
pid->limMaxInt = limMaxInt;
pid->T = T;
pid->differentiator = 0.0f;
pid->prevMeasurement = 0.0f;
/* Clear controller variables */
pid->integrator = 0.0f;
pid->prevError = 0.0f;
pid->out = 0.0f;
pid->differentiator = 0.0f;
pid->prevMeasurement = 0.0f;
pid->out = 0.0f;
pid->enable = false;
}
float pidControllerUpdate(PidController *pid, float setpoint, float measurement) {
float PIDController_Update(PIDController *pid, float setpoint, float measurement) {
/*
* Error signal
*/
/*
* Error signal
*/
float error = setpoint - measurement;
/*
* Proportional
*/
/*
* Proportional
*/
pid->proportional = pid->Kp * error;
/*
* Integral
*/
/*
* Integral
*/
pid->integrator = pid->integrator + 0.5f * pid->Ki * pid->T * (error + pid->prevError);
/* Anti-wind-up via integrator clamping */
/* Anti-wind-up via integrator clamping */
if (pid->integrator > pid->limMaxInt) {
pid->integrator = pid->limMaxInt;
@@ -61,30 +44,19 @@ float pidControllerUpdate(PidController *pid, float setpoint, float measurement)
}
/*
* Derivative (band-limited differentiator)
*/
/*
* Derivative (band-limited differentiator)
*/
pid->differentiator = -(2.0f * pid->Kd * (measurement -
pid->prevMeasurement) /* Note: derivative on measurement, therefore minus sign in front of equation! */
+ (2.0f * pid->tau - pid->T) * pid->differentiator)
/ (2.0f * pid->tau + pid->T);
pid->differentiator = -(2.0f * pid->Kd * (measurement - pid->prevMeasurement) /* Note: derivative on measurement, therefore minus sign in front of equation! */
+ (2.0f * pid->tau - pid->T) * pid->differentiator)
/ (2.0f * pid->tau + pid->T);
/*
* Compute output and apply limits
*/
pid->out = pid->proportional + pid->integrator + pid->differentiator;
if (pid->proportional > pid->limMax) {
pid->proportional = pid->limMax;
} else if (pid->proportional < pid->limMin) {
pid->proportional = pid->limMin;
}
/*
* Compute output and apply limits
*/
pid->out = pid->offset + pid->proportional + pid->integrator + pid->differentiator;
if (pid->out > pid->limMax) {
@@ -96,10 +68,11 @@ float pidControllerUpdate(PidController *pid, float setpoint, float measurement)
}
/* Store error and measurement for later use */
pid->prevError = error;
/* Store error and measurement for later use */
pid->prevError = error;
pid->prevMeasurement = measurement;
/* Return controller output */
/* Return controller output */
return pid->out;
}

64
PID.h
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@@ -1,51 +1,43 @@
#ifndef PID_CONTROLLER_H
#define PID_CONTROLLER_H
#include <stdbool.h>
typedef struct {
/* Controller gains */
float Kp;
float Ki;
float Kd;
/* Controller gains */
float Kp;
float Ki;
float Kd;
/* Default controller gains */
float KpDefault;
float KiDefault;
float KdDefault;
/* Derivative low-pass filter time constant */
float tau;
/* Derivative low-pass filter time constant */
float tau;
/* Output limits */
float limMin;
float limMax;
/* Output limits */
float limMin;
float limMax;
/* Integrator limits */
float limMinInt;
float limMaxInt;
/* Integrator limits */
float limMinInt;
float limMaxInt;
/* Sample time (in seconds) */
float T;
/* Sample time (in seconds) */
float T;
/* pid coefficient offset for start pid */
float offset;
bool enable;
/* Controller "memory" */
float integrator;
float prevError; /* Required for integrator */
float proportional;
float differentiator;
float prevMeasurement; /* Required for differentiator */
/* Controller "memory" */
float proportional;
float integrator;
float prevError; /* Required for integrator */
float differentiator;
float prevMeasurement; /* Required for differentiator */
/* Controller output */
float out;
/* Controller output */
float out;
} PIDController;
} PidController;
void PIDController_Init(PIDController *pid);
float PIDController_Update(PIDController *pid, float setpoint, float measurement);
void pidControllerInit(PidController *pid, float Kp, float Ki, float Kd, float tau, float limMin, float limMax,
float limMinInt, float limMaxInt, float T);
float pidControllerUpdate(PidController *pid, float setpoint, float measurement);
#endif //PID_CONTROLLER_H
#endif

65
PID_Test.txt Normal file
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#include <stdio.h>
#include <stdlib.h>
#include "PID.h"
/* Controller parameters */
#define PID_KP 2.0f
#define PID_KI 0.5f
#define PID_KD 0.25f
#define PID_TAU 0.02f
#define PID_LIM_MIN -10.0f
#define PID_LIM_MAX 10.0f
#define PID_LIM_MIN_INT -5.0f
#define PID_LIM_MAX_INT 5.0f
#define SAMPLE_TIME_S 0.01f
/* Maximum run-time of simulation */
#define SIMULATION_TIME_MAX 4.0f
/* Simulated dynamical system (first order) */
float TestSystem_Update(float inp);
int main()
{
/* Initialise PID controller */
PIDController pid = { PID_KP, PID_KI, PID_KD,
PID_TAU,
PID_LIM_MIN, PID_LIM_MAX,
PID_LIM_MIN_INT, PID_LIM_MAX_INT,
SAMPLE_TIME_S };
PIDController_Init(&pid);
/* Simulate response using test system */
float setpoint = 1.0f;
printf("Time (s)\tSystem Output\tControllerOutput\r\n");
for (float t = 0.0f; t <= SIMULATION_TIME_MAX; t += SAMPLE_TIME_S) {
/* Get measurement from system */
float measurement = TestSystem_Update(pid.out);
/* Compute new control signal */
PIDController_Update(&pid, setpoint, measurement);
printf("%f\t%f\t%f\r\n", t, measurement, pid.out);
}
return 0;
}
float TestSystem_Update(float inp) {
static float output = 0.0f;
static const float alpha = 0.02f;
output = (SAMPLE_TIME_S * inp + output) / (1.0f + alpha * SAMPLE_TIME_S);
return output;
}

5
README.md Normal file
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# PID
PID controller implementation written in C.
Note on 'derivative-on-measurement': Since the 'error signal' effectively going into the differentiator does not depend on the setpoint: e[n] = 0 - measurement, and therefore (e[n] - e[n - 1]) = (0 - measurement) - (0 - prevMeasurement) = -Kd * (measurement - prevMeasurement). (Note the minus sign compared to derivative-on-error!)
I've included the minus sign in the code, so gains will have the effect as normal.