steady state error command

Is there a command that will give the steady state error of the the response of a transfer function

Answer 1

[Paulo Silva]

SP=5; %input value, if you put 1 then is the same as step(sys)
[y,t]=step(SP*sys); %get the response of the system to a step with amplitude SP
sserror=abs(SP-y(end)) %get the steady state error

[Naufal Indrastoto]

I have already tried this and it says undefined function or variable 'sys'. Could please you explain more about it?

[Eric Chua]

sys is your transfer function

[HanJie Chong]

The result of this code is already in %?

EXP: 0.4= 40% or 0.4%

[Walter Roberson]

No, sserror would be absolute value, not relative value. You would have to divide by SP to get relative value as a fraction, which you could then multiply by 100 to get percentage.

[Mohammad Hosein Forghani]

Thanks, it worked for me

[irshad maz]

what is SP stand for Sir

[JAMES KEEN]

@irshad maz I believe it means setpoint i.e. the point of which you want the system response to settles at.

Answer 2

[Mohammad Hosein Forghani]

Another approach theoretically would be final value theorem, I might also implement that in MATLAB.