Continue to Site

Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Defining transfer function..

Status
Not open for further replies.

Johnson12

Mechanical
Apr 19, 2014
3
I am having a hard time understanding how i shall algebraically define the effect of disturbance and noise on a system.

Consider we have a system like this.

Hluwm.jpg


Where T[sub]d[/sub](s) is the disturbance, and N(s) is the noise.

How would shall i define the effect of the disturbance and noise for the overall system??

I am bit confused on how I should define it, and i would be very grateful if someone could explain how they define the equation which defines the effect on Y(s).
 
Replies continue below

Recommended for you

Is this for school? Wherever you got the picture from should have the equation to go along with, unless it's a homework problem.

TTFN
faq731-376
7ofakss

Need help writing a question or understanding a reply? forum1529
 
It's not homework, which is why no system definitions is included.
This is a theoretical question, on how anyone would do it.

 
?? So, where did the schematic come from? There are gobs of control theory sites on the web; have you looked at them?

TTFN
faq731-376
7ofakss

Need help writing a question or understanding a reply? forum1529
 
It's from Dorf&bishop...

I don't see how the answer from my book should help here.. Aren't there a general rule for deriving a equation which relate the effect of the inputs to the output of the system.

I could easily derive a formula for the closed loop transfer function and the output function for only R(s).
But i cannot derive the equation for the output where distubance and noise is includes.


I am only asking how you would derive an equation like that for multiple inputs.
 
Assuming the system is linear, you can apply the principle of superposition. Calculate the disturbance to output transfer function assuming the reference and noise signals are both zero. Calculate the noise to output transfer function assuming the reference and disturbance signals are both zero. The output signal will then be the sum of the products of the three transfer functions and their respective input signals.

xnuke
"Live and act within the limit of your knowledge and keep expanding it to the limit of your life." Ayn Rand, Atlas Shrugged.
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor

Top