EP 314LAB 6 Closed Loop and Controller Design

Block Diagram & Controller Design

EP314 Lab Timeline

LAB 1 & 2 -Introduction to MATLAB

Interface, code, function, graph, Simulink, etc.

LAB 3, 4 & 5 - Modelling of Chemical Process

ODE, Transfer Function, Open Loop Analysis, Sensitivity analysis, etc.

LAB 6 ,7,8 & 9 - Closed Loop and Controller Design

Block diagram, controller design, Performance Analysis, Criteria of Good controller, Stability Analysis, etc.

NO LAB

LAB 10 - Advanced Control System

Feedforward, Cascade and Ratio controls.

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NO LAB

2 3 4 5 6 7 8 9 10 11 12

Construct a Simulink block diagram for the control system shownbelow. Design the P controller which gives the offset less than20% of unit step R.

Exercise 1: Design Conventional P Controller

Note: Observe what happen when the value is increased

Exercise 1 : Solution1. Create Control system as below

2. Change value until you reach offset < 20% of R

Develop PID controller block

1. Start Simulink

2. Formulate PID equation into Simulink block diagram

() = +1

0

+

Required block diagram:

Construct a Simulink block diagram for the control system shown below.

Exercise 2: Design Conventional Controller

()

Compare the performance of conventional controller underZN tuning method.

Ziegler-Nichols (Z-N) Rulesclosed-loop tuning method

Target : and Steps:

1. Remove the integral and derivative modes of the controller, leaving onlyproportional control.

2. Select a value of proportional gain , disturb the system, and observethe transient response.

Continue increasing the gain in small steps until the response first exhibits asustained oscillation.The value that correspond to the sustained oscillation are the ultimate gain and the ultimate period .

Step 1: Apply P Controller, Kc

= 2 = 4 = 8 = 10

Exercise 2 : Solution

At = 10,Control system produce sustain oscillation response.

SaveAs: LAB6_ex2.mdl

Step 2: Find Ku and Pu

Exercise 2 : Solution

= = 10

=9.445 1.845

4= 1.9

Hint: Use Data Cursor & hold Alt for multiple point

Step 3: Apply Z-N Controller Setting

------------- Z-N Controller Setting --------------Controller Kc TauI TauDP controller: 5 inf 0PI controller: 4.5 1.5833 0PID controller: 6 0.95 0.2375

Answer

Exercise 2 : Solution

Exercise 2 : Answer

Challenge

Design conventional controller to meet the control system requirement as below:

Zero offset with settling time less than 6s and maximum overshoot of 20%.

Challenge : solutionControl System Performance: Zero offset with settling time less than 6s and overshoot of 20%.