基于matlab的控制系统与仿真-4

>> G1=zpk([-2],[0,-0.5,-0.8,-3],0.2)

G1 =
 
         0.2 (s+2)
  -----------------------
  s (s+0.5) (s+0.8) (s+3)
 
Continuous-time zero/pole/gain model.

>> G=feedback(G1)
>> pzmap(G)

>> syms K T;
assume(T<2&T>0);
assume(K>0);
isAlwaya((2+T)*(K+1)-2*T*K>0)
>>assume(T>2)
>d=(2+T)*(K+1)-2*T*K
>K=solve(d,K)
>T=(2+eps):0.01:10
>K=(T+2)./(T-2)

>> G1=zpk([],[0,-1,-10],50)

G1 =
 
        50
  --------------
  s (s+1) (s+10)
 
Continuous-time zero/pole/gain model.
G2=zpk([],[0,-1,-10],200)

G2 =
 
       200
  --------------
  s (s+1) (s+10)
 
Continuous-time zero/pole/gain model.
>>sys1=feedback(G1,1)
>>pzmap(sys1)
>>margin(sys1)

>>sys2=feedback(G2,1)
>>pzmap(sys2)
>>margin(sys2)

G=tf(conv([19 1],[0.44 1]),conv([0.625 1],conv([0.676 -1],conv([43.5 -1],conv([0.033 1],[0.0004 0.015 1])))))

G =
 
                                                  
                            8.36 s^2 + 19.44 s + 1
                                                  
  ---------------------------------------------------------------------------
                                                                             
  0.0002426 s^6 + 0.01647 s^5 + 0.8832 s^4 + 18.43 s^3 - 0.2936 s^2          
                                                                             
                                                                 - 43.5 s + 1
                                                                             
 
Continuous-time transfer function.

>> bode(G)
allmargin(G)

ans = 

  包含以下字段的 struct:

     GainMargin: [2.4020 78.1546]
    GMFrequency: [0.4163 32.1207]
    PhaseMargin: -180
    PMFrequency: 0
    DelayMargin: Inf
    DMFrequency: 0
         Stable: 0

>> G1=zpk([],[-1,-2,-5],100)

G1 =
 
         100
  -----------------
  (s+1) (s+2) (s+5)
 
Continuous-time zero/pole/gain model.

>> nyquist(G1)

G1 =
 
         500
  -----------------
  (s+1) (s+2) (s+5)
 
Continuous-time zero/pole/gain model.

>> nyquist(G1)

G=tf([1 15 16 200],[ 1 10 30.6 155 153.7 5.65])

G =
 
              s^3 + 15 s^2 + 16 s + 200
  --------------------------------------------------
  s^5 + 10 s^4 + 30.6 s^3 + 155 s^2 + 153.7 s + 5.65
 
Continuous-time transfer function.

>> nyquist(G)