lecture on matlab simulink

7/24/2019 Lecture on Matlab Simulink

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ECE5143 Linear Systems and ControlLecture on Matlab/Simulink

Yongcan Cao, Assistant ProfessorDepartment of Electrical and Computer EngineeringUniversity of Texas, San Antonio


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Linear Time-Invariant Systems (LTI)

LTI systems: = + , = +

lsim (matlab command)

For example:A = [-1 0; 0 -1];

B = [1;1];C = [1 0];D = 0; sys = ss(A,B,C,D);For example, t = 0:0.01:10; u = sin(t); lsim(sys,u,t) simulates the responseof a single-input model SYS to the input u(t)=sin(t) during 10 seconds.

Other examples: step, impulse,


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Linear Time-Invariant Systems (LTI)

LTI systems: = + , = +

[u,t] = gensig('square',4,10,0.1);H = [tf([2 5 1],[1 2 3]) ; tf([1 -1],[1 1 5])];lsim(H,u,t);

Other methods: solving differential equations using ODE45.

[t,x]=ode45(@reactor,[0 10],[0.1;40],[],55);

function dx = reactor(t,x,Tj)

dx =[dCa;dT]


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Simulink


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S-function (M-file+Simulink)

What is S-Function? S-Functions is computer language description of Simulink block If written in MATLAB programming environment it is called M-file s-

function If written in C/C++ programming environment it is called C Mex s

function

What can S-Function Do? Allows you to add your own code to simulink model or environment Code can be written for continuous, discrete or hybrid system


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How does S-function work?Mathematically Simulink block consist of a set of inputs u, a set of states x, and set of outputs y

M-files:Initialization port widths, data types, sample time, memories allocation, execution order, evaluates b

parametersSimulation loop Execute block determined during initialization, computes/updates blocks states, deand outputs during a sample time


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Mobile Robot

= cos = sin

=

( , ) is the 2D location of the robot, is the heading of the robot,linear velocity of the robot, and is the angular velocity of the robot.


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Simulate a Robot using S-function

robot.m s-function describing robot kinematics w: linear speed w: angular speed


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Simulate a Robot with a Controller using S-function

robot.m: s-function describing robot kinematics ctrl.m: s-function describing the control input for the robot w: linear speed w: angular speed


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S-function Manual

http://www.mathworks.com/help/pdf_doc/simulink/sfunctions.pdf

lecture on matlab simulink

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