Use Matlab Function Block to plot into figure created by Matlab Script

Hello,

my plan is to create a figure with a Matlab script and then plot the results from my Simlink Simulation in this specific plot, using a Matlab function block.

Here is the script where the figure to plot the results is created:

ax1 = axes;
map_scales = imread("map_scaled.pgm");
imshow(map_scales, 'Parent',ax1)
hold on

My original idea was to use the ax1 in the matlab function block to plot the results in this figure. But this does not seem to work:

Here is a picture of the maltabl function block and the code inside it:

function path_plotting(x_pos, x_pos_prev, y_pos, y_pos_prev)
    x_coodinates = [x_pos_prev, x_pos];
    y_coodinates = [y_pos_prev, y_pos];
    plot(x_coodinates, y_coodinates, 'LineWidth', 2, 'Color', 'b', 'Parent', ax1)
end

Does anyone have an idea how to solve this?

Answer 1

[Simon Chan]

Try this in the function path_plotting

function path_plotting(x_pos, x_pos_prev, y_pos, y_pos_prev, ax1)
    x_coodinates = [x_pos_prev, x_pos];
    y_coodinates = [y_pos_prev, y_pos];
    plot(ax1,x_coodinates, y_coodinates, 'LineWidth', 2, 'Color', 'b')
end

[Jannis]

HI, thanks for you answer, but this does not seem to work. I think there might be no solution for my problem because simulink does not support the data type of an axes vairable.

I changed ax1 to a parameter data type and I received this error

See screenshot below

Answer 2

[Paul]

Hi Jannis,

I got this model to work

The code in the Matlab Function block is

function y = fcn(u,t)

persistent ax1

if isempty(ax1)
    ax1 = gca;
    set(ax1,'NextPlot','add');
end

plot(ax1,t,u,'r.')

y = u;

end

In your use case, maybe you can replace the ax1 = gca; with either your code, or a function that runs your code to create the image and return the axis handle. Anyway, I think that whatever you're trying to do is feasible.

[Jannis]

Hi Paul,

thanks for your comment. I will try your recommendation and will let you know whether it works

[Jannis]

Thank you very much this solves my problem