G E P1=-GG2,P2=-1,P3=G2G4,p4=-GG2GG4,△2=1 L=-GG, L,=GG2GG4, L=1, L4=-G3G4 C(S) GG2-1+G3G4-G,G,G,G R(S) G,G2+GG2G G4+G,G4 (c)信号流图如下 求C(s)/R(s) L=-GGH, L=-G,Gs, L=GG A=1-L-L-L+LL P,=GG2 C(s) GG(1-G,Gs) R(S)1+GG,H+G2Gs-GGs-GG2HG4Gs L=-GG2H, L=-G2G5, L=GGs △1=1-GG3,A2=1-GG3 C(s) G2+G3)(1-G4G5) N()1+GG,H+G2Gs-GG5-GGHGG1 1 2 2 3 3 4 4 1 2 3 4 1 1 2 2 1 2 3 4 3 4 3 4 , 1, , , 1 , , 1, i p G G p p G G p G G G G L G G L G G G G L L G G = − = − = = −  = = − = = = − 1 2 3 4 1 2 3 4 1 2 1 2 3 4 3 4 ( ) 1 ( ) C s G G G G G G G G R s G G G G G G G G − + − = + + (c) 信号流图如下 ` 求 C(s)/R(s) 1 1 2 2 2 5 3 4 5 1 1 2 L G G H L G G L G G , , p G G = − = − = = , 1 2 3 1 3 1 4 5 1 1 L L L L L G G  = − − − +  = − 1 2 4 5 1 2 2 5 4 5 1 2 4 5 ( ) (1 ) ( ) 1 C s G G G G R s G G H G G G G G G HG G − = + + − − 求 C(s)/N(s) 1 1 2 2 2 5 3 4 5 1 3 2 2 1 4 5 2 4 5 , , , , 1 , 1 L G G H L G G L G G p G p G G G G G = − = − = = =  = −  = − 2 3 4 5 1 2 2 5 4 5 1 2 4 5 ( ) ( )(1 ) ( ) 1 C s G G G G N s G G H G G G G G G HG G + − = + + − − G1 1 G2 1 R 1 C N G3 G4 −H −1 G5 1 GG3 4 1 R C 1 E −1 GG1 2 −1 1 1 −1 −1