Simulink: Update figure in matlab function

Hello,

i am trying to update a figure which is created in the InitFcn Callback, with another Matlab function in Simulink.

My InitFcn Callback runs a m file in which the figure is created and a first plot is made. I save this plot to a global variable.

During the simulation the x,y,z data of my plot is updated and i want do draw it in real time. So i tried to update the plot command with "set" command in another matlab function.

Background: It's a 6-DOF (Stewart) platform for a flight simulator and i want to draw the position of the platform in this figure. The position is read from a flight simulator program.

The Problem: I don't know how to update the plot in another matlab function. Or basically i don't know how to make an variable (which i created in the InitFcn m file) in another matlab function accesable.

figure_init.m creates the figure and make a first plot:

and in this function the plot should be updated:

Thank you for your suggestions!

Answer 1

[Fangjun Jiang]

This could work. The key is to declare a global variable in both the figure_init() function and update_plot() MATLAB Function block. You need to turn on hold, not sure how the figure would be refreshed though during simulation.

global fig;
fig=figure(1); hold on;

What I think you really need is this.

stream signal data to a MATLAB® callback function during simulation

[Gabriel]

Unfortunately I don't think this works. Because for global variables to access i need a Data store memory block. Without this i cannot access the variable in the function.

And here is the problem: The initial value of the data store memory block cannot be a figure handle (fig). I get an error. However there is a field for the data type and i don't think there is the data type assigned to a figure handle.

Regards,

[Fangjun Jiang]

Ok, I see. Not my recommended approach anyway. Thought it could work. What about just ploting to figure one, figure(1)?

[Gabriel]

Plot command is not a very time efficient solution. It's very slow...

not practical for real time drawing.

[Fangjun Jiang]

That was my concern too. But in terms of making it work, would making the global variable passing just a number work? What I meant was. It used to be this way. fig=figure(1). "fig" would be just the numerical number 1. Now it is a figure handle and its "value" is 1. In your update_plot() function, search the axes or line in figure 1, then use set() to update. Would that work?

[Fangjun Jiang]

It works. No need to use global variable. Just make sure all figures are closed before model simulation. If you really want to make it robust, I think you can use global variable to pass the figure number. In that case, you don't need to close or worry about other figures. Fig1=findobj(0,'type','figure','Number',GlobalFigureNumber);

%figure_init
figure(1);plot(1:3);xlim([1 10]);ylim([1 10]);

function y = update_plot(u)
Fig1=findobj(0,'type','figure');
Line1=findobj(Fig1,'type','line');
set(Line1,'XData',1:u,'YData',1:u);

y = u;

u is a digital clock thus its value is 1 at time 1, 2 at time 2, ... I see the figure line increasing as the simulation runs.

[Gabriel]

Yes i think that works!

Thank you very much.