CHE 493 – Process Dynamics and Controls Fall 2014 Homework #13 DUE: Wednesday, November 12th GROUP ASSIGNMENT (groups of 2) OPEN-LOOP CONTROLLER TUNING METHODS 1. The input-output response for a given process is shown below: a) Fit the input-output response to a FODT model. Write the process transfer function below: b) Using the Ziegler-Nichols open-loop tuning parameters, what are the controller values for a PI and a PID controller? PI: Kc = I = PID: Kc = I = D = c) Repeat part (b) for the Cohen-Coon tuning parameters: PI: Kc = I = PID: Kc = I = D = d) Plot the closed-loop output response, using the PID controllers in parts (b) and (c), to a unit setpoint change. Plot the two output responses on the same graph. CLOSED-LOOP CONTROLLER TUNING METHODS 2. Using the same process (i.e., transfer function) from the first page, develop PID tuning parameters using closed-loop oscillation-based tuning: a) With a P-only controller on your process, increase Kc until you see continuous oscillations in you output. Record your value of Kcu and Pu in space below: Kcu = ____________ Pu = _____________ b) Using your values of Kcu and Pu use Table 6-1 to find the optimal Ziegler-Nichols tuning parameters for a PID controller: kc = ________ I = ___________ D = ____________ ** Using these Z-N PID parameters, plot the closed-loop output response to a unit setpoint change. c) Using your values of Kcu and Pu use Table 6-2 to find the optimal Tyreus-Luyben tuning parameters for a PID controller: kc = ________ I = ___________ D = ____________ ** Using these T-L PID parameters, plot the closed-loop output response to a unit setpoint change.