132 lines
3.3 KiB
C
Executable File
132 lines
3.3 KiB
C
Executable File
/*
|
|
* pid.c PID controller for testing cooling devices
|
|
*
|
|
*
|
|
*
|
|
* Copyright (C) 2012 Intel Corporation. All rights reserved.
|
|
*
|
|
* This program is free software; you can redistribute it and/or
|
|
* modify it under the terms of the GNU General Public License version
|
|
* 2 or later as published by the Free Software Foundation.
|
|
*
|
|
* This program is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* Author Name Jacob Pan <jacob.jun.pan@linux.intel.com>
|
|
*
|
|
*/
|
|
|
|
#include <unistd.h>
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <stdint.h>
|
|
#include <sys/types.h>
|
|
#include <dirent.h>
|
|
#include <libintl.h>
|
|
#include <ctype.h>
|
|
#include <assert.h>
|
|
#include <time.h>
|
|
#include <limits.h>
|
|
#include <math.h>
|
|
#include <sys/stat.h>
|
|
#include <syslog.h>
|
|
|
|
#include "tmon.h"
|
|
|
|
/**************************************************************************
|
|
* PID (Proportional-Integral-Derivative) controller is commonly used in
|
|
* linear control system, consider the the process.
|
|
* G(s) = U(s)/E(s)
|
|
* kp = proportional gain
|
|
* ki = integral gain
|
|
* kd = derivative gain
|
|
* Ts
|
|
* We use type C Alan Bradley equation which takes set point off the
|
|
* output dependency in P and D term.
|
|
*
|
|
* y[k] = y[k-1] - kp*(x[k] - x[k-1]) + Ki*Ts*e[k] - Kd*(x[k]
|
|
* - 2*x[k-1]+x[k-2])/Ts
|
|
*
|
|
*
|
|
***********************************************************************/
|
|
struct pid_params p_param;
|
|
/* cached data from previous loop */
|
|
static double xk_1, xk_2; /* input temperature x[k-#] */
|
|
|
|
/*
|
|
* TODO: make PID parameters tuned automatically,
|
|
* 1. use CPU burn to produce open loop unit step response
|
|
* 2. calculate PID based on Ziegler-Nichols rule
|
|
*
|
|
* add a flag for tuning PID
|
|
*/
|
|
int init_thermal_controller(void)
|
|
{
|
|
int ret = 0;
|
|
|
|
/* init pid params */
|
|
p_param.ts = ticktime;
|
|
/* TODO: get it from TUI tuning tab */
|
|
p_param.kp = .36;
|
|
p_param.ki = 5.0;
|
|
p_param.kd = 0.19;
|
|
|
|
p_param.t_target = target_temp_user;
|
|
|
|
return ret;
|
|
}
|
|
|
|
void controller_reset(void)
|
|
{
|
|
/* TODO: relax control data when not over thermal limit */
|
|
syslog(LOG_DEBUG, "TC inactive, relax p-state\n");
|
|
p_param.y_k = 0.0;
|
|
xk_1 = 0.0;
|
|
xk_2 = 0.0;
|
|
set_ctrl_state(0);
|
|
}
|
|
|
|
/* To be called at time interval Ts. Type C PID controller.
|
|
* y[k] = y[k-1] - kp*(x[k] - x[k-1]) + Ki*Ts*e[k] - Kd*(x[k]
|
|
* - 2*x[k-1]+x[k-2])/Ts
|
|
* TODO: add low pass filter for D term
|
|
*/
|
|
#define GUARD_BAND (2)
|
|
void controller_handler(const double xk, double *yk)
|
|
{
|
|
double ek;
|
|
double p_term, i_term, d_term;
|
|
|
|
ek = p_param.t_target - xk; /* error */
|
|
if (ek >= 3.0) {
|
|
syslog(LOG_DEBUG, "PID: %3.1f Below set point %3.1f, stop\n",
|
|
xk, p_param.t_target);
|
|
controller_reset();
|
|
*yk = 0.0;
|
|
return;
|
|
}
|
|
/* compute intermediate PID terms */
|
|
p_term = -p_param.kp * (xk - xk_1);
|
|
i_term = p_param.kp * p_param.ki * p_param.ts * ek;
|
|
d_term = -p_param.kp * p_param.kd * (xk - 2 * xk_1 + xk_2) / p_param.ts;
|
|
/* compute output */
|
|
*yk += p_term + i_term + d_term;
|
|
/* update sample data */
|
|
xk_1 = xk;
|
|
xk_2 = xk_1;
|
|
|
|
/* clamp output adjustment range */
|
|
if (*yk < -LIMIT_HIGH)
|
|
*yk = -LIMIT_HIGH;
|
|
else if (*yk > -LIMIT_LOW)
|
|
*yk = -LIMIT_LOW;
|
|
|
|
p_param.y_k = *yk;
|
|
|
|
set_ctrl_state(lround(fabs(p_param.y_k)));
|
|
|
|
}
|