Discrete to continuous in Simulink.

Hi, I use PID controller to control the input voltage (Ui) of the servo valve to adjust the spool displacement [-10< Ui <10 (V)].

I coded Ui =[-10:0.01:10]; and Simulink show the error: "Encountered unknown exception". So i think that discrete value from Ui can't calculate for the continuous system ( have PID controller and Intergator). It has any block or code to make Ui become continuous? Thank you for help.

[Paul]

Ui is a gain that takes (what I assume to be) a scalar signal and expnands it to a signal with 2001 elements, which I doubt is desired. What is Ui supposed to do? Limit the output of the PID Controller to lie between -10 and 10? Something else?

[Nguyen Hieu]

Ui is a term in math equation to calculate the Spool displacement. That equation is in a 1/4 car model, the movement of Spool generate control force to make the car more balance.

[Paul]

Why would UI be -10:.01:10? Maybe if you show the actual math equation we can figure out how to model it in Simulink.

[Nguyen Hieu]

Math equation is: @Paul

[Paul]

Apparently Ui is supposed to be scalar, but its coded as a 2001-element vector. Why is it coded as a vector?

Answer 1

[Abderrahim. B]

Hi!

Use d2c and/or c2d functions in a MATLAB function !

Check out the link below, some others methods to do this conversion are listed there.

Link: Continuous-Discrete Conversion Methods

Note that most of these methods require Control System Toolbox.

Hope this helps

[Nguyen Hieu]

My code is:

U =[-10:0.1:10];

Ui=d2c(U);

And Matlab show:

Error using d2c (line 33)

Not enough input arguments.

Error in half_car_supension (line 16)

Ui=d2c(U);

Can you help for this. Thank you.

[Abderrahim. B]

d2c and c2d accept model object as input, will not work in your case. To convert a vector(discrete) to continuous use quantizer and zero-order hold blocks.