1. Workshop for Flipped Class
Based on students having completed the Chapter 15 e-Lesson before class
Chapter 15
Feedforward Control
Copyright © Thomas Marlin 2016

2. CHAPTER 15:FEEDFORWARD CONTROL
Workshop 9 – Concept questions about Feedforward
CLASS EXERCISE: SOME QUESTIONS ABOUT FEEDFORWARD CONTROL
Why do we retain the feedback controller?
When would feedforward give zero steady-state offset?
Why does the feedforward controller sometimes delay its compensation? Don’t we always want fast control?
What is the additional cost for feedforward control?
How can we design a strategy that has two controllers both adjusting the same valve?
What procedure is used for tuning feedforward control?

3. CHAPTER 15:FEEDFORWARD CONTROL Workshop 6 – Design Feedforward
Design one feedforward controller that will improve control performance and safety for the fired heater shown below with basic feedback already provided.

4. CHAPTER 15:FEEDFORWARD CONTROL Workshop 4 – Design Feedforward
Evaluate feedforward control for a disturbance in the heating medium pressure, P1. You may make no changes to the equipment. F 1 L 1
feed T 1
product TC 2 F 2 T 3
We have added a sensor for this disturbance P 1
heating stream

5. CHAPTER 15:FEEDFORWARD CONTROL
Workshop 3 – Design Cascade and Feedforward
Evaluate cascade and feedforward control for a disturbance in the heating medium inlet temperature. You may add a sensor but make no other changes to the equipment. TC 2 T 1 F 3 L
feed
product
heating stream

6. Workshop 2 – Understanding the Feedforward Compensation
Solve Cases II – VI defined in the table in Workshop 1 slides V CV D P D P FD FP Dm MV
???

7. Definition of Cases for Workshops 1 & 2 Solve Case I for Workshop 1
Workshop 1 – Understanding the Feedforward Compensation
Definition of Cases for Workshops 1 & 2
Solve Case I for Workshop 1
Case
Gain, -KD/KP = Kff
Dead time
Time constant I -1
D = P
τD = τP II
D < P
III
D > P IV
τD < τP V
τD > τP VI -2