【Q12.4 A boiler output step response is shown below, where the boiler input signal is changed from 4 m³ per minute to 4.5 m³ per minute. The initial steady output water temperature was 85 °C. (a) Using the step response plot, determine the parameters of a first-order transfer function model, K, and t for the transfer function, G(s) = K(ts + 1). (b) It is proposed to use proportional control in a unity feedback control loop as shown. If the proportional gain is K = 4, use the transfer function you have found to show that the steady state offset to a reference change of 10 °C is 0.3 °C. Control engineering, Palgrave Macmillan, 2001. ProQuest Ebook Central, http://ebook.central proquest.com/lib/strativ/detail action?dociD-5297569. Tey What structural change to the controller would you recommend to completely eliminate the offset? Output temperature, "C Boiler temperature response 89 88.5 88 87.5 87 86.5 86 85.5 85 0 10 20 30 40 50 60 70 80 90 Time (minutes) K R(s) Кр TS+1 Y(s) Controller Process