how to plot bode plot(frequency plot) in simulink ?

I have simulink model

and i want to plot bode plot for output sensitivity . Normally output sensitivity measure from output to additive noise. In model i have put linearization pints at output and additive noise but i am not getting how to plot bode response for this ? can anyone tell ?

Answer 1

[Ryan G]

Why do you need the additive noise to find the bode plot? I would first suggest using the linear analysis tool.

First you want to determine what response you are looking for. Do you want the open loop plant response? The close loop response with the controller? I don't see anywhere you can actually command your controller to do anything.

If you want the frequency response over the plant, set the input to the plant as an open loop input point and the output of the plant as an open loop output. If you want the overall system response you would determine the input to the controller and set that as the input point and you would use the output from the plant as the output point.

[Aniket]

Thank you

I want to get the response of output sensitivity

normally in matlab we can write direct equation

s = 1 / (1+ G * C)

but i am not getting how to do it in simulink means where should i put linearization points to get output sensitivity response ?

[Ryan G]

Check out this example for a typical controller/plant steup. You see the controller in series with the plant and the summing junction allows the user to define a point for the controller to control to. In your current model, there is no way to add a setpoint to the controller (normally via summing junction error). That is where you would add the input point.

[Aniket]

helloi have added sum point and my controller is parallel to plant. I am using LQG contoller for this.

here is my model and i am implemnting model for disturbance rejection. for this where should i put input/output points for output sensitivity and output complimentary sensitivity ?