自动控制原理（双语教学）：9.10.3.3

Solution 9.10.3.3 S G a = a G @G @a = a a s(s + a) @ @a a s(s + a) = s(s + a) 1  ;as s 2 (s + a) 2 + 1 s(s + a)  = s(s + a) " ;as + s 2 + as s 2 (s + a) 2 # = s 2 s(s + a) = s (s + a) S T c a = a T c @T c @a = a a s 2 + as + a @ @a a s 2 + as + a = s 2 + as + a 1  ;a(s +1) (s 2 + as + a) 2 + 1 s 2 + as + a  = (s 2 + as + a) " ;as;a + s 2 + as + a (s 2 + as + a) 2 # = s 2 (s 2 + as + a) S G K = S T c K =0 since there is no dependence on K: