F11_ECH157_Quiz2 - University of California Davis...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: University of California, Davis Department of Chemical Engineering & Materials Science ECH 157 – Process Dynamics and Control Fall 2011 – Quiz # 2 Instructions: This is a 30-minute closed-book closed-notes quiz. Please print your name on all answer sheets, label the problems clearly and put them in the right order. Read all questions carefully; answer them concisely and neatly. Point values for each problem are based on 10 points total for the quiz. Good Luck!! Problem 1: The question has been raised whether an open-loop unstable process can be stabilized with a proportional-only controller. Ysp Gp = K 1−τ s G c = Kc Y Fig.1 (a) [3 points] For the process and controller shown in Fig.1, find the range of Kc values that yield a stable closed-loop response. (Note that τ is positive.) (b) [3 points] For K = 10 and τ = 20, find the value of Kc that yields a pole at s = - 0.1. What is the offset for these conditions? (c) [4 points] Suppose that you had designed the controller neglecting the dynamics of the measurement sensor. Would the controller still yield a stable closed-loop response when the sensor is in the loop? To check the "robustness" of your design, suppose that the sensor dynamics can be modeled by the following transfer function: 1 Gm ( s ) = τm +1 Find the general conditions on Kc and τm for stability if the system is as shown in Fig.2. Show for τm = 5, that your value of Kc from part (b) does or does not still yield a stable system. Ysp Gp = K 1−τ s G c = Kc Gm Fig.2 Y ...
View Full Document

{[ snackBarMessage ]}

Ask a homework question - tutors are online