Simulink Control Design™ - MathWorks

Modeling Computational Delay and Sampling Effects

This example shows how to model computational delay and sampling effect using

Simulink Control Design.

Introduction

Computational delays and sampling effects can critically effect the performance of a

control system. Typically, the closed-loop responses of a system become oscillatory and

unstable if these factors are not taken into account. Therefore, when modeling a control

system, you should include computational delays and sampling effects to accurately

design and simulate a closed-loop system.

There are two approaches for designing compensators with the effects of computational

delay and sampling. The first approach is to design a controller in the discrete domain to

capture the effects of sampling by discretizing the plant. The second approach is to

design a controller in the continuous domain. This approach is sometimes more

convenient, but in this case you need to account for the effects of computational delay

and sampling. In this example, you apply both approaches to redesign a control system

using Simulink Control Design.

Simulating Using Discrete and Continuous Controllers

In the following example model, the initial compensator has the following gains from the

compensator in the example "Single Loop Feedback/Prefilter Design":

P = 0.0018222

I = 0.0052662

The first model has a discrete implementation of the control system.

mdl = 'scdspeed_compdelay';

open_system(mdl);

9 Classical Control Design