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Topic: Steady state error
Replies: 2   Last Post: Dec 12, 2012 3:18 AM

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justlooking for someone else

Posts: 77
Registered: 12/10/04
Re: Steady state error
Posted: Dec 12, 2012 3:18 AM
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Sorry, the closed loop transfer function's steady state error is:


If using an openloop transfer function, the function must first be closed
abs(1-dcgain(feedback(sys,1))) % for unity feedback

Alternatively if using an openloop transfer function with unity feedback, then the steady state step error is

where dcgain(sys) is the static error constant Kp

"A" wrote in message <ka9drm$n60$1@newscl01ah.mathworks.com>...
> The previous response to this is not correct. The steady state error can be calculated in two ways depending on the type of transfer function:
> abs(dcgain(sys)-1)
> for a closed loop transfer function
> Jon Carter <jdc298REMOVE-THIS@soton.ac.uk> wrote in message <38E0D27C.619EB741@soton.ac.uk>...

> > Hi
> >
> > I'm looking to calculate the steady state error of a transfer function
> > with a unit step input in Matlab. I can do this by using step() to draw
> > a plot of the response, but is there a function that would tell me the
> > error without needing to read it off graphically?
> >
> > Thanks,
> >
> > --
> > Jon
> > jdc298REMOVE-THIS@soton.ac.uk

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