How to find steady-error value from the response graph? is there any command to find the steady state error from the response graph?

G(s)=5/s^2+2s+25

[SARATHRAJ V]

s = tf('s');
sys=input('enter the funtion' );

Unable to run the 'fevalJSON' function because it calls the 'input' function, which is not supported for this product offering.

[y,t]=step(sys);
y(length(y))
plot(t,y);
xlabel('Time (sec)');
ylabel('Amplitude');
title('step responce');

Answer 1

[Arkadiy Turevskiy]

Your question is not formulated clearly. Did you mean steady-state value, not "steady-error value"? Assuming that's what you meant, the next clarification is steady-state value of a transfer function in response to what - is it in response to a step input?

If that's what you meant, then yes, you can do this like that:

>> s=tf('s');
>> sys=5/(s^2+2*s+25);
>> [y,t]=step(sys);
>> y(length(y))

ans =

          0.20

You can also right click on a step plot, "Charecteristics", "Steady-state", as shown below:

[Karrar]

What about the steady state error values, How to get them?

[Khadar Essa]

how did you get to this plot?

[Tunde Sulaimon]

What tool box is this?!

[Arkadiy Turevskiy]

My answer above us using Control System Toolbox.

To get a step plot in MATLAB do this:

s=tf('s');
sys=5/(s^2+2*s+25);
step(sys);

Answer 2

[Miswar Syed]

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?

[wint wah]

num=4;

den=[1 2 4];

sys=tf(num,den)

[Catherine Callaghan]

What would I set SP to if I wanted to represent a ramp input and parabolic input? Thanks.

Answer 3

[Ur rehman Waheed]

matlab command to find steadt state error from step response graph in matlab

>> sserror=(SP-(y1.data(end,end)))

where SP value is one when input is step input. y1 shows workspace value of step response. normally it comes during simulation from simulink.

[Josh McNamara]

Hi ,

Is there anything simular using 'lsim' command for a ramp input?

Regards,

Josh

Answer 4

[Amit Borole]

i need to find position constant of this