MATLAB and Simulink System Objects

by J Grant

A System object is a component you can use to create your system in MATLAB. You can write the code in MATLAB and use that code to create a block in Simulink. To define your own System object, you write a class definition file, which is a text-based MATLAB file that contains the code defining your object. Add your System objects to your Simulink model by using the MATLAB System block an Add other Simulink blocks, connect them, and configure any needed parameters to complete your model. Then Run your model in the same way you run any Simulink model. System objects let you implement algorithms using the MATLAB language. The MATLAB System block enables you to use System objects in Simulink. The MATLAB System block lets you: Share the same System object in MATLAB and Simulink, Dedicate integration of System objects with Simulink, Unit test your algorithm in MATLAB before using it in Simulink, Customize dialog box customization, Simulate efficiently with better initialization, Handle states, Customize block icons with port label and Access two simulation modes. Before you use a MATLAB System block, you must have a System object to associate with the block. A System object is a specialized kind of MATLAB class. System objects are designed specifically for implementing and simulating dynamic systems with inputs that change over time. You can develop a System object for use in a System block and interactively preview the block dialog box. This feature requires Simulink. With the System Block editing options, the MATLAB Editor inserts predefined code into the System object. This coding technique helps you create and modify your System object faster and increases accuracy by reducing typing errors. Using these options, you can also: View and interact with the block dialog design as you define the System object, Add dialog customization methods (If the block dialog box is open when you make changes, the block dialog design preview updates the display on saving the file) and Add icon methods. However, these elements display only on the MATLAB System Block in Simulink. Enumerated data is data that is restricted to a finite set of values. To use enumerated data in a System object in MATLAB or Simulink, you refer to them in your System object class definition and define your enumerated class in a separate class definition file. For System objects that are used only in MATLAB, you define global variables in System object class definition files in the same way that you define global variables in other MATLAB code. For System objects that are used in the MATLAB System block in Simulink, you also define global variables as you do in MATLAB. However, to use global variables in Simulink, you need to declare global variables in the stepImpl, updateImpl, or outputImpl method if you have declared them in methods called by stepImpl, updateImpl, or outputImpl, respectively. You can include System object code in Simulink models with the MATLAB Function block. Your function can include one or more System objects. Portions of your system may be easier to implement in the MATLAB environment than directly in Simulink. Many System objects have Simulink block counterparts with equivalent functionality. Before writing MATLAB code to include in a Simulink model, check for existing blocks that perform the desired operation. You can include individual System objects that you create with a class definition file into Simulink with the MATLAB System block. This provides one way to add your own algorithm blocks into your Simulink models. Generating code from MATLAB algorithms for desktop and embedded systems allows you to perform your software design, implementation, and testing completely within the MATLAB workspace. You can generate efficient C/C++ code for a subset of MATLAB built-in functions and toolbox functions, classes, and System objects that you call from MATLAB code.

306 pages, Paperback

Published March 7, 2018