G1=tf(1,1 10);G2=tf(1,1 1);G3=tf(1 0 1,1 4 4); numg4=1 1;deng4=1 6;G4=tf(numg4,deng4);H1=zpk(-1,-2,1);numh2=2;denh2=1;H3=1;nh2=conv(numh2,deng4);dh2=conv(denh2,numg4);H2=tf(nh2,dh2);sys1=series(G3,G4);sys2=feedback(sys1,H1,+1); (结构图化简及闭环传递函数的求解）sys3=series(G2,sys2);sys4=feedback(sys3,H2);sys5=(G1,sys4);sys5=series(G1,sys4);sys=feedback(sys5,H3) /zeta=0.707;num=16;den=1 8*zeta 16;sys=tf(num,den);p=roots(den) t=0:0.01:3; （特征根）figure(1)impluse(sys,t);grid impulse(sys,t);grid （单位脉冲响应）xlabel(t);ylable(c(t);title(step response);xlabel(t);ylabel(c(t);title(step response);figure(2)step(sys,t);grid （单位阶跃响应）xlabel(t);ylabel(c(t);title(step response);figure(3)u=t;lsim(sys,u,t,0);grid （任意输入响应）xlabel(t);ylabel(c(t);title(step response);/K=20,40;Gc=tf(1,conv(1,0,1,2,10);for i=1:2 （开环增益对系统的影响）G1=tf(K(i)*1,1,1,5);G0=series(G1,Gc);G=feedback(G0,1);figure(i);bode(G);gridEnd/G=tf(1280,640,1,24.2,1604.81,320.24,16); figure(1) margin(G);（对数幅频曲线与实轴交点横坐标为截止频率，相频曲线与-180交点为幅值1） figure(2) nyquist(G);（奈奎斯特曲线，在开环幅相曲线或对数幅频曲线基础上补画使闭合）Axisequal/G1=tf(2000,-4000,conv(1,0,0,1,1);伯德图即对数频率分布图，包括对数幅频和对数相频G2=tf(1,1,10,400);G=series(G1,G2);bode(G);grid/G=tf(1,4,1,4,20); (零极点分布图和开环根轨迹图) figure(1) pzmap(G); figure(2) rlocus(G);