Hi Nouman,
This error message indicates that your program is trying to call the function ExampleHelperRobotSimulator, which is a helper that ships in several ROS Toolbox examples, e.g. FeedbackControlOfAROSenabledRobotExample and GenerateCodetoManuallyDeployaROSNodefromSimulinkExample.
What may have happened is that you are using some code from those examples, but copied it into some other directory, or lost the original file. To determine the source of the issue, please try running the following in your MATLAB command console:
>> openExample('ros/FeedbackControlOfAROSenabledRobotExample')
>> FeedbackControlOfAROSenabledRobotExample
If that example is able to run then you should have everything you need going forward, otherwise you might be missing a ROS or Navigation Toolbox license. Please verify that you have both using the ver command.
Hope this helps,
Cameron
