PID练习
clc; clear N = 100; x = linspace(-3*pi,3*pi,N); % 目标值 % target_val = 20*ones(1,N); target_val = 5*sin(x); % 当前值 current_val =2; % PID 临时变量 integral = 0; last_err = 0; % PID 增益参数 Kp = 0.2; Ki = 0.1; Kd = 0.5; % 过程输出变量 方便绘图 PID_data = []; PID_data_noise = []; % 无噪声 100% 感知 100% 控制 for i = 1:N % 计算偏差 err err = target_val(i) - current_val; % 对偏差积分 integral = integral + err; % 对偏差微分 d_err = err - last_err ; % PID 比例+积分+微分 = 输出控制量 u_out = Kp * err + Ki * integral + Kd * d_err; % 在控制量u_out的作用下 当前值转移到下一个状态 current_val = current_val + u_out; % 数据保存 PID_data(i) = current_val; end % figure (1) % plot([target_val' PID_data']) % 传感器带噪声 measure_noise = rand() u_noise = rand() current_val = 0; for i = 1:N err = target_val(i) - current_val; % 传感器加噪声measure_noise measure_noise = 0.2*rand(); err = err + measure_noise; integral = integral + err; d_err = err - last_err ; u_out = Kp * err + Ki * integral + Kd * d_err; % 控制加噪声 u_noise u_noise = 0.5*rand(); u_out = u_out + u_noise; current_val = current_val + u_out; PID_data_noise(i) = current_val; end % figure (2) plot([target_val' PID_data' PID_data_noise'])
C语言版本
#include <stdio.h> #include<math.h> // PID 参数结构体 struct _pid { int pv; /*integer that contains the process value*/ //当前值 int sp; /*integer that contains the set point*/ //目标值 float integral; // 累计积分项 float pgain; // 比例系数 float igain; // 积分系数 float dgain; // 微分系数 int deadband; // 死区 int last_error; // 上一时刻偏差 }; // 全局变量 struct _pid warm,*pid; int process_point, set_point,dead_band; float p_gain, i_gain, d_gain, integral_val,new_integ;; /*------------------------------------------------------------------------ pid_init DESCRIPTION This function initializes the pointers in the _pid structure to the process variable and the setpoint. *pv and *sp are integer pointers. ------------------------------------------------------------------------*/ void pid_init(struct _pid *warm, int process_point, int set_point) { struct _pid *pid; pid = warm; pid->pv = process_point; pid->sp = set_point; } /*------------------------------------------------------------------------ pid_tune // PID 结构体参数设置 DESCRIPTION Sets the proportional gain (p_gain), integral gain (i_gain), derivitive gain (d_gain), and the dead band (dead_band) of a pid control structure _pid. ------------------------------------------------------------------------*/ void pid_tune(struct _pid *pid, float p_gain, float i_gain, float d_gain, int dead_band) { pid->pgain = p_gain; pid->igain = i_gain; pid->dgain = d_gain; pid->deadband = dead_band; pid->integral= integral_val; pid->last_error=0; } /*------------------------------------------------------------------------ pid_setinteg // pID 结构体积分项增益系数设置函数接口 DESCRIPTION Set a new value for the integral term of the pid equation. This is useful for setting the initial output of the pid controller at start up. ------------------------------------------------------------------------*/ void pid_setinteg(struct _pid *pid,float new_integ) { pid->integral = new_integ; pid->last_error = 0; } /*------------------------------------------------------------------------ pid_bumpless DESCRIPTION Bumpless transfer algorithim. When suddenly changing setpoints, or when restarting the PID equation after an extended pause, the derivative of the equation can cause a bump in the controller output. This function will help smooth out that bump. The process value in *pv should be the updated just before this function is used. ------------------------------------------------------------------------*/ void pid_bumpless(struct _pid *pid) { //偏差 = 目标值-当前值 pid->last_error = (pid->sp)-(pid->pv); } /*------------------------------------------------------------------------ pid_calc DESCRIPTION Performs PID calculations for the _pid structure *a. This function uses the positional form of the pid equation, and incorporates an integral windup prevention algorithim. Rectangular integration is used, so this function must be repeated on a consistent time basis for accurate control. RETURN VALUE The new output value for the pid loop. USAGE #include "control.h"*/ float pid_calc(struct _pid *pid) { int err; float pterm; //比例项 float dterm; //微分项 float result; // 输出结果 float ferror; //偏差 // 偏差计算 偏差 = 目标值 - 当前值 err = (pid->sp) - (pid->pv); if (abs(err) > pid->deadband) { ferror = (float) err; /*do integer to float conversion only once*/ pterm = pid->pgain * ferror;// 比例项计算 if (pterm > 100 || pterm < -100) { pid->integral = 0.0; } else { // 积分项计算 pid->integral += pid->igain * ferror; if (pid->integral > 100.0) { pid->integral = 100.0; } else { if (pid->integral < 0.0) pid->integral = 0.0; } } // 微分项计算 dterm = ((float)(err - pid->last_error)) * pid->dgain; // PID各项 综合 result = pterm + pid->integral + dterm; } else result = pid->integral; pid->last_error = err; return (result); } void main(void) { float display_value; int count=0; pid = &warm; // printf("Enter the values of Process point, Set point, P gain, I gain, D gain \n"); // scanf("%d%d%f%f%f", &process_point, &set_point, &p_gain, &i_gain, &d_gain); process_point = 30; set_point = 40; p_gain = (float)(5.2); i_gain = (float)(0.77); d_gain = (float)(0.18); dead_band = 2; integral_val =(float)(0.01); printf("The values of Process point, Set point, P gain, I gain, D gain \n"); // printf("%lf %lf %lf %lf %lf\n", process_point, set_point, p_gain, i_gain, d_gain); pid_init(&warm, process_point, set_point); pid_tune(&warm, p_gain,i_gain,d_gain,dead_band); pid_setinteg(&warm,0.0); //pid_setinteg(&warm,30.0); //Get input value for process point pid_bumpless(&warm); count = 0; while(count<=20) { // how to display output pid_init(&warm, display_value, set_point); display_value = pid_calc(&warm); printf("%f\n", display_value); //printf("\n%f%f%f%f",warm.pv,warm.sp,warm.igain,warm.dgain); count++ ; } }