ME 392 Adaptable Matlab Programing March 19, 2012 week 10

ME 392

Adaptable Matlab Programing March 19, 2012

week 10

Joseph Vignola

Assignments I would like to offer to everyone the extra help you might need to catch up.

Assignment 5 is due March 26, one week from todayLab 3 is March 28, one week from the Wednesday

File Names, Title Pages & Information

Please use file names that I can search for

For example

“ME_392_assignment_5_smith_johnson.doc”

Please include information at the top of any document you give me. Most importantly:

NameDate What the document isLab partner

Zip File With Everything

Make a zip file with everything relevant to the assignment and make the file names easy to search for

For example

“ME_392_assignment_5_smith_johnson.zip”

Please include :

Main document MS WordDataM-files including subfunctionVI’s including subs

Logical Programing Logical programing is more important than the actual assignments

This is the only way you will get to the point where you can write complex programs that control a multi-faceted system

Flight-control system on a planeComplex measurement system like an ultrasound scannerPower plant

Sub-functionsSub-functions do several things for you

Lets you quickly reuse code



Things like making the time and frequency vectors

function [f,t] = freqtime(si,N) t = [0:N-1]’*si; f = t/(si*si*N);








The sub-function is a separate m-file






The sub-function is a separate m-fileand in this case just three line long




The sub-function is a separate m-fileand in this case just three line long

As a general matter, variable names don’t need to be the same inside the sub-function as they are in the function that calls themSo you can have “t” in the subAnd “time” in the main program




The way subs work is that the first input to the function in the main program goes to the first input of the function

So you can have “t” in the subAnd “time” in the main program

A = 1;fc = 1000;[freq,time] = freqtime(dt,num_of_samp);signal = A*sin(2*pi*fc*time) + noise(1,N);SIGNAL = fft(signal)*2/num_of_samp; zf(1) = figure(1);clfza(1) = axes;plot(time,signal);grid xlabel(…za(2) = axes;plot(freq,abs(SIGNAL));grid xlabel(…




First input to first input


A = 1;fc = 1000;[freq,time] = freqtime(dt,num_of_samp);signal = A*sin(2*pi*fc*time); SIGNAL = fft(signal)*2/num_of_samp; zf(1) = figure(1);clfza(1) = axes;plot(time,signal);grid xlabel(…za(2) = axes;plot(freq,abs(SIGNAL));grid xlabel(…




First input to first input, second to the second






First output to first output






First output to first output, second to the second




Lets you quickly reuse code Lets you use code that you know works

You will be making time and frequency vectors for all the remaining labs and assignments


Lets you quickly reuse code Lets you use code that you know works

You will be making time and frequency vectors for all the remaining labs and assignments

You needed to scale, AC couple, integrate and plot accelerometer data for the last. There is no need to re-write all that


Lets you quickly reuse code Lets you use code that you know worksSimplifies the main program

This is not important if your code is only a few lines long



This is not important if your code is only a few lines long but if you are complex having discreet pieces make for much easier debugging



This is not important if your code is only a few lines long but if you are complex having discreet pieces make for much easier debugging

It is much easier on Therese or me to help if your code is simple to follow

Matlab PathFunctions look just like variables

So when you have a used defined function will first look for it as a variable

Then Matlab will look in the current directory (the one listed above the command window)

The Matlab will look, in order, in the directories in the path.

Setting the Matlab PathFunctions look just like variables

So when you have a used defined function will first look for it as a variable

Then Matlab will look in the current directory (the one listed above the command window)

The Matlab will look, in order, in the directories in the path.

Gain MeasurementAssignment 5 asks you to find a relationship between the input and the output for a shaker.

The relationship would be a measure of displacement of the shaker as a function of input voltage at several frequencies

The amplifier increases the voltage that comes out of the BNC 2120 box.

Gain MeasurementAssignment 5 asks you to find a relationship between the input and the output for a shaker. The amplifier input should not exceed about 0.250 volts and the frequencies should be in the audio band 20-20,000 Hz


All the power amps are a little different.



Gain should be about 10



Gain should be about 10 (dimensionless)

Look at the signalsIt is very important to look at the signals as you work


Be sure the power amp is at full gain


Be sure the power amp is at full gain

Look at the wiringBe sure the input selector is set to the something you are connected to

Documents

ME 392 Adaptable Matlab Programing March 19, 2012 week 10