基于先行PID控制实现对液位控制附matlab代码

%PID Controler Based on Ziegler-Nichols clear all; close all; sys=tf(400,[1,30,200,0]); figure(1); rlocus(sys); [km,pole]=rlocfind(sys) wm=imag(pole(2)); kp=0.6*km kd=kp*pi/(4*wm) ki=kp*wm/pi figure(2); grid on; bode(sys,'r'); sys_pid=tf([kd,kp,ki],[1,0]) sysc=series(sys,sys_pid) hold on; bode(sysc,'b') figure(3); rlocus(sysc); %PID Controler (2001/9/6) close all; ts=0.25; sys=tf(1,[10,2,0]); dsys=c2d(sys,ts,'z'); [num,den]=tfdata(dsys,'v'); u_1=0;u_2=0; y_1=0;y_2=0; x=[0,0,0]'; error_1=0; for k=1:1:1000 time(k)=k*ts; %rin(k)=1.0; rin(k)=0.5*sin(0.025*2*pi*k*ts); %Linear model yout(k)=-den(2)*y_1-den(3)*y_2+num(2)*u_1+num(3)*u_2; error(k)=rin(k)-yout(k); x(1)=error(k); % Calculating P x(2)=(error(k)-error_1)/ts; % Calculating D x(3)=x(3)+error(k)*ts; % Calculating I M=2; switch M case 1 %Using PID u(k)=kp*x(1)+kd*x(2)+ki*x(3); case 2 %No PID u(k)=error(k); end u_2=u_1; u_1=u(k); y_2=y_1; y_1=yout(k); error_1=error(k); end figure(1); plot(time,rin,'b',time,yout,'r'); xlabel('time(s)');ylabel('(rin,yout)'); figure(2); plot(time,rin-yout,'r'); xlabel('time(s)');ylabel('error'); %PID Controler Based on Ziegler-Nichols clear all; close all; ts=0.25; sys=tf(1,[10,2,0]); dsys=c2d(sys,ts,'z'); [num,den]=tfdata(dsys,'v'); axis('square'),zgrid('new'); figure(1); rlocus(dsys); [km,pole]=rlocfind(dsys) wm=angle(pole(1))/ts; kp=0.6*km kd=kp*pi/(4*wm) ki=kp*wm/pi dsys_pid=kp+kd*tf([1,-1],[1,1],ts)+ki*tf([1,0],[1,-1],ts)*ts; dsysc=dsys*dsys_pid; figure(2); rlocus(dsysc); axis('square'),zgrid;