measure the ROS loop time in simulink

I am trying to figure out my control loop time in simulink for controlling my simulation using MATLAB 2021a.

I am using the loop control rate block found in these closed loop control example here

The comments say:

    %   The rate control may not be effective if the simulation model is too
    %   complex to be handled at the desired rate. To check the rate control
    %   performance, consider output rateObj.LastPeriod. Ideally it should be
    %   close to SampleTime during most part of the simulation.

How do I actually output/access the rateObj.LastPeriod in the model so I can make a historgram of the control rate?

Answer 1

[Abhijeet Gadkari]

Hello Nathaniel,

The Simulation Rate Control block used in this example is a MATLAB System Object.

You can modify the stepImpl method of this system object class, ExampleHelperSimulationRateControl.m, to add an output argument as below.

        function r = stepImpl(obj)
            %stepImpl Regulates simulation update
            if coder.target('MATLAB')
                obj.RateObj.waitfor();
                r = obj.RateObj.LastPeriod;
            else
                r = nan;
            end
        end               

Save the ExampleHelperSimulationRateControl.m class and re-open the model.

You should now see an output port on the Simulation Rate Control block, as shown below.

-Abhijeet

[Nathaniel Goldfarb]

thank you so much. this worked perfectly