機(jī)械控制工程基礎(chǔ)實(shí)驗(yàn)指導(dǎo)書分析解析

#num=K(j)*[0.0167,1];den=conv(conv([1,0],[0.03,1]),conv([0.0025,1],[0.001,1]));G=tf(num,den);y(j)=allmargin(G);endy(1)y(2)y(3)y(4)運(yùn)行結(jié)果：y=運(yùn)行結(jié)果：y=1x4structarraywithfields:GMFrequencyGainMarginPMFrequencyPhaseMarginDMFrequencyDelayMarginStableans=GMFrequency:602.4232GainMargin:455.2548PMFrequency:4.9620PhaseMargin:85.2751ans=GMFrequency:602.4232GainMargin:4.5525

PMFrequency:237.7216

PhaseMargin:39.7483

DMFrequency:237.7216

DelayMargin:0.0029

Stable:1ans=GMFrequency:602.4232GainMargin:2.8453

PMFrequency:329.9063

PhaseMargin:27.7092

DMFrequency:329.9063

DelayMargin:0.0015

Stable:1ans=GMFrequency:602.4232GainMargin:0.7588

PMFrequency:690.5172

PhaseMargin:-6.7355

DMFrequency:690.5172

DelayMargin:0.0089

Stable:0DMFrequency:4.9620DelayMargin:0.2999DMFrequency:4.9620DelayMargin:0.2999Stable:1系統(tǒng)開環(huán)傳遞函數(shù)為G(s)=系統(tǒng)開環(huán)傳遞函數(shù)為G(s)=100ks(s+5)(s+10)，繪制k=l,5,20時(shí)系統(tǒng)極坐標(biāo)圖，并利用Nyquist穩(wěn)定判據(jù)判斷閉環(huán)系統(tǒng)的穩(wěn)定性。代碼如下：clearz=[]p=[0,-5,-10]k=100.*[1510]G=zpk(z,p,k(1))[re1,im1]=nyquist(G)G=zpk(z,p,k(2))[re2,im2]=nyquist(G)G=zpk(z,p,k(3))[re3,im3]=nyquist(G)plot(re1(:),im1(:),re2(:),im2(:),re3(:),im3(:))v=[-5,1,-5,1];axis(v)gridxlabel('RealAxis')ylabel('ImaginaryAxis')text(-0.4,-3.6,'K=1')text(-2.7,-2.7,'K=5')text(-4.4,-1.6,'K=10')結(jié)果如圖5所示。圖5Nyquist圖三、思考與實(shí)驗(yàn)報(bào)告要求1、繪制二階系統(tǒng)的頻率特性圖并在bode圖上找出對(duì)應(yīng)于輸入不同頻率時(shí)