Learn more about Simulink Control Design

frest.simCompare - Package: frest

Plot time-domain simulation of nonlinear and linear models

Syntax

frest.simCompare(simout,sys,input) frest.simCompare(simout,sys,input,x0)

Description

frest.simCompare(simout,sys,input) plots both

Simulation output, simout, of the nonlinear Simulink model
You obtain the output from the frestimate command.
Simulation output of the linear model sys for the input signal input
The linear simulation results are offset by the initial output values in the simout data.

frest.simCompare(simout,sys,input,x0) plots the frequency response simulation output and the simulation output of the linear model with initial state x0. Because you specify the initial state, the linear simulation result is not offset by the initial output values in the simout data.

Examples

Compare a time-domain simulation of the Simulink watertank model and its linear model representation:

% Create input signal for simulation
input = frest.createStep('FinalTime',100);

% Open the Simulink model
watertank

% Specify the operating point for the estimation
watertank_spec = operspec('watertank');
op = findop('watertank',watertank_spec)

% Specify portion of model to estimate
io(1)=linio('watertank/PID Controller',1,'in');
io(2)=linio('watertank/Water-Tank System',1,'out');

% Estimate the frequency response of the magball model
[sysest,simout] = frestimate('watertank',op,io,input)
sys = linearize('watertank',op,io)
frest.simCompare(simout,sys,input)

The software returns the following plot.