Simulink® 7.1

Product Description

• Introduction and Key Features
• Creating and Working with Models
• Defining and Managing Signals
• Running a Simulation
• Analyzing Results

Running a Simulation

After building your model in Simulink®, you can simulate its dynamic behavior and view the results live. Simulink software provides several features and tools to ensure the speed and accuracy of your simulation, including fixed-step and variable-step solvers, a graphical debugger, and a model profiler.

Using Solvers

Solvers are numerical integration algorithms that compute the system dynamics over time using information contained in the model. Simulink provides solvers to support the simulation of a broad range of systems, including continuous-time (analog), discrete-time (digital), hybrid (mixed-signal), and multirate systems of any size.

These solvers can simulate stiff systems and systems with state events, such as discontinuities, including instantaneous changes in system dynamics. You can specify simulation options, including the type and properties of the solver, simulation start and stop times, and whether to load or save simulation data. You can also set optimization and diagnostic information for your simulation. Different combinations of options can be saved with the model.

End-to-end, multirate defense communications system, modeled in Simulink using Communications Blockset™ and Signal Processing Blockset™. Simulink solvers automatically determine when to call each block's methods. Click on image to see enlarged view.

Debugging a Simulation

The Simulink debugger is an interactive tool for examining simulation results and locating and diagnosing unexpected behavior in a Simulink model. It lets you quickly pinpoint problems in your model by stepping through a simulation one method at a time and examining the results of executing that method. (Methods are functions that Simulink uses to solve a model at each time step during the simulation. Blocks are made up of multiple methods.)

The Simulink debugger lets you set breakpoints, control the simulation execution, and display model information. It can be run from a graphical user interface (GUI) or from the MATLAB® command line. The GUI provides a clear, color-coded view of the model's execution status. As the model simulates, you can display information on block states, block inputs and outputs, and other information, as well as animate block method execution directly on the model.

Simulink debugger GUI used with a multirate control system. You can step through the simulation one method at a time or run to breakpoints. Click on image to see enlarged view.

Executing a Simulation

Once you have set the simulation options for your model, you can run your simulation interactively, by using the Simulink GUI, or systematically, by running it in batch mode from the MATLAB command line. The following simulation modes can be used:

• Normal (the default), which interpretively simulates your model
• Accelerator, which speeds model execution by creating compiled target code while still letting you to change model parameters
• Rapid Accelerator, which can simulate models faster than Accelerator mode but with less interactivity by creating an executable separate from Simulink that can run on a second processing core

You can also use MATLAB commands to load and process model data and parameters and visualize results.

Profiling a Simulation

Model profiling can help you identify performance bottlenecks in your simulations. You can collect performance data while simulating your model and then generate a simulation profile report based on the collected data that shows how much time Simulink takes to execute each simulation method.

Next