Inputting Transfer Functions in MATLAB - Rob's Guide

[rc flyer uk]

I have only basic MATLAB skills and need to input to transfer functions into MATLAB to determine a closed loop transfer function! But cannot find any simple books or guides to show me how to input the functions! One of the transfer functions i wish to input is:

G(p)=1/s(1+0.8+0.04s^2)

Some help of the method of inputing this, would be greatly apricated!

Cheers
Rob

 

[Cyrus]

A=tf([1],[0.04 0.8 1])

If you want the root locus just type in

rlocus(A)

Your system appears to always be stable and in the LHP for all positive values of gain K.

 

[tacman]

Hi Rob,

Thank you for reaching out for help with inputting transfer functions in MATLAB. I completely understand your struggle in finding a simple guide to help you with this task. Luckily, there are a few steps you can follow to input your transfer function and determine the closed loop transfer function in MATLAB.

Step 1: Define your transfer function

Before inputting the transfer function in MATLAB, you need to define it. In your case, the transfer function is already defined as G(p)=1/s(1+0.8+0.04s^2).

Step 2: Create a transfer function object

In MATLAB, you can create a transfer function object using the "tf" command. The syntax for this command is "tf(num, den)", where num represents the numerator coefficients and den represents the denominator coefficients of your transfer function. In your case, the command would be:

G = tf([1], [1 0.8 0.04])

Step 3: Calculate the closed loop transfer function

To calculate the closed loop transfer function, you can use the "feedback" command in MATLAB. The syntax for this command is "feedback(sys1, sys2)", where sys1 and sys2 are the transfer function objects of your open loop system and feedback loop system, respectively. In your case, the command would be:

Gclosed = feedback(G, 1)

Step 4: View the result

To view the closed loop transfer function, you can use the "tfdata" command in MATLAB. The syntax for this command is "tfdata(sys)", where sys is the transfer function object you want to view. In your case, the command would be:

tfdata(Gclosed)

This will give you the coefficients of the closed loop transfer function in the form of a cell array.

I hope this helps you input and determine the closed loop transfer function in MATLAB. If you need further assistance, I recommend checking out online tutorials and resources or reaching out to the MATLAB community for help. Best of luck!