求
C(s) 令R(s)?0,N2(s)?0 N2(s)消去中间变量得
?TK0K1sC(s) ?N2(s)s(s?1)(Ts?1)?K0K12-7. 简化图2-59所示系统的结构图，并求系统传递函数
C(s)。 R(s)
解：
2-8. 试用梅逊公式列写图2-60所示系统的传递函数
C(s)。 R(s)
解：
(a)L1??G2G3H3, L2??G3G4H4
L3??G1G2G3H2, L4?G1G2G3G4H1
??1?G2G3H3?G3G4H4?G1G2G3H2?G1G2G3G4H1 P1?G1G2G3H4,?1?1
G1G2G3H4C(s) ?R(s)1?G2G3H3?G3G4H4?G1G2G3H2?G1G2G3G4H1(b)L1??G1H1, L2??G3H2
L3??G1G2G3H1H2,L4?G1G3H1H2
??1?G1H1?G3H2?G1G2G3H1H2?G1G3H1H2 P1?G1G2G3,?1?1 P2?G4G3,?2?1?G1H1
G1G2G3?G4G3(1?G1H1)C(s)? R(s)1?G1H1?G3H2?G1G2G3H1H2?G1G3H1H22-9.
求出图2-61所示系统的传递函数
C1(s)C2(s)C1(s)C2(s)、、、。 R1(s)R1(s)R2(s)R2(s)
解：
(a)??1?G1G2G3G4
C1(s)G1 ?R1(s)1?G1G2G3G4?G1G2G3C2(s) ?R1(s)1?G1G2G3G4?G1G3G4C1(s) ?R2(s)1?G1G2G3G4G3C2(s) ?R(s)1?G1G2G3G4(b)??1?G1G2?G4?G1G4G5H1H2?G1G2G4
C1(s)G1G2G3(1?G4) ?R1(s)?C2(s)G1G4G5G6H2 ?R1(s)?C1(s)?G1G2G3G4G5H1? R2(s)?C2(s)G4G5G6(1?G1G2)? R2(s)?2-10. 已知系统结构图2-62所示，图中N(s)为扰动作用，R(s)为输入。