Lab 08: Digital control

CHEN4011: Advanced modeling and Control

Objectives

1. To develop MATLAB Simulink model of continuous and digital control systems.
2. To simulate digital PI controller vs. continuous PI controller performance for different sampling periods T: 0.5, 1, 2.

Problem Statement

A continuous process is represented by the following transfer function:

\[ G_p (s) = \frac{5 exp(-2s)}{(7s+1)(s+1)} \tag{1}\]

Also, an output disturbance transfer function is given by,

\[ G_d (s) = \frac{1.4 exp(-3s)}{( 10s+1)} \tag{2}\]

For the digital PI controller implementation, use zero-order hold and sampler where the sampling period can be varied as mentioned in the objectives.

Tasks

1. Develop a Simulink model that contains the continuous and digital control systems. Provide the screenshot of the Simulink model in the report. [2 marks]
2. Tune a PI controller for the continuous control system, e.g., using Control System Designer. [1 mark]
3. Apply the PI controller tuning in (b) to the continuous and digital systems. For the digital system, switch the continuous mode to the discrete mode. [2 marks]
4. Compare the performance of the digital PI controller for the 3 different sampling periods mentioned above with the continuous PI controller. Plot the responses and give comments on the results. [5 marks]