Section 7.1 The Feature of Integrating Systems Steady-state Performance Consider the first-order integrating plant: G(s)-Ke-0s where K is the gain,0 is the time delay.Assume that the disturbance at the plant input is d'(s)=1/s.The effect of d'(s) on the system output can be equivalent to that of a disturbance d(s)at the plant output: 同=d)G=。 K It is seen that the system is in fact of Type 2.Only when the controller is designed for ramps,can the steady-state error caused by d'(s)vanish asymptotically 定9aC Zhang,W.D..CRC Press.2011 Version 1.0 8/79Section 7.1 The Feature of Integrating Systems Steady-state Performance Consider the first-order integrating plant: G(s) = K s e −θs where K is the gain, θ is the time delay. Assume that the disturbance at the plant input is d 0 (s) = 1/s. The effect of d 0 (s) on the system output can be equivalent to that of a disturbance d(s) at the plant output: d(s) = d 0 (s)G(s) = K s 2 e −θs It is seen that the system is in fact of Type 2. Only when the controller is designed for ramps, can the steady-state error caused by d 0 (s) vanish asymptotically Zhang, W.D., CRC Press, 2011 Version 1.0 8/79