Simulink Control Design™ - MathWorks

Linearization of Multirate Models

This example shows the process that the command linearize uses when extracting a linear

model of a nonlinear multirate Simulink model. To illustrate the concepts, the process is

first performed using functions from the Control System Toolbox before it is repeated

using the linearize command.

Example Problem

In the Simulink model scdmrate.slx there are three different sample rates specified in

five blocks. These blocks are:

• sysC - a continuous linear block,


• Integrator - a continuous integrator,


• sysTs1 - a block that has a sample time of 0.01 seconds,


• sysTs2 - a block that has a sample time of 0.025 seconds, and


• Zero-Order Hold - a block that samples the incoming signal at 0.01 seconds.

sysC = zpk(-2,-10,0.1);

Integrator = zpk([],0,1);

sysTs1 = zpk(-0.7463,[0.4251 0.9735],0.2212,0.01);

sysTs2 = zpk([],0.7788,0.2212,0.025);

The model below shows how the blocks are connected.

scdmrate

In this example we linearize the model between the output of the Constant block and the

output of the block sysTs2.

Linearization of Multirate Models..................... 2-