Fixed-Point Blockset

Simulink Model of a Feedback Design

Run the Simulink model of the feedback design by launching the MATLAB Demo browser and selecting the Scaling a Fixed Point Control Design demo. Launch the Demo browser by typing

• demo blockset 'Fixed Point'
  

at the command line, or by opening the Demos block found in the Fixed-Point Blockset library. Alternatively, you can access the model directly by typing its name at the command line:

• fxpdemo_feedback
  

The demo's .mdl file automatically runs the M-file preload_feedback, which populates the workspace with the required parameter values. The feedback design model is shown below.

The model consists of the following blocks and subsystems:

• Reference

• This Simulink Signal Generator block generates a continuous-time reference signal. It is configured to output a square wave.

• Sum

• This Simulink or Fixed-Point Blockset Sum block subtracts the plant output from the reference signal.

• ZOH

• The Simulink or Fixed-Point Blockset Zero-Order Hold block samples and holds the continuous signal. This block is configured so that it quantizes the signal in time by an amount tsamp = 0.01 second.

• Analog to Digital Interface

• The analog to digital (A/D) interface consists of a Gateway In block that converts a Simulink double to a Fixed-Point Blockset data type. It represents any hardware that digitizes the amplitude of the analog input signal. In the real world, its characteristics are fixed.

• Controller

• The digital controller is a subsystem that represents the software running on the hardware target. Refer to Digital Controller Realization.

• Digital to Analog Interface

• The digital to analog (D/A) interface consists of a Gateway Out block that converts a Fixed-Point Blockset data type into a Simulink double. It represents any hardware that converts a digitized signal into an analog signal. In the real world, its characteristics are fixed.

• Analog Plant

• The analog plant is described by a transfer function, and is controlled by the digital controller. In the real world, its characteristics are fixed.

• FixPt GUI

• This block launches the Fixed-Point Settings interface.

The model also includes three scopes, which display the reference, plant input, and plant output signals.

Overview

Simulation Setup