www.pudn.com > truetime-1.2-compiled.zip > README

-----------------------------------------------
 TrueTime version 1.2
 Example: Distributed Control System
 Directory: $DIR/examples/distributed
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1. INTRODUCTION

This example simulates distributed control of a DC-servo. The example
contains four computer nodes, each represented by a TrueTime kernel
block. A time-driven sensor node samples the process periodically and
sends the samples over the network to the controller node. The control
task in this node calculates the control signal and sends the result
to the actuator node, where it is subsequently actuated. The
simulation also involves an interfering node sending disturbing
traffic over the network, and a disturbing high-priority task
executing in the controller node.


2. COMPILING THE SIMULATION FILES

2.1 Configuring the TrueTime Environment

    Before starting Matlab, you must set the environment variable
    TTKERNEL to point to the directory with the TrueTime kernel files:

        Unix/Linux: > export TTKERNEL=$DIR/kernel
        Windows:  Control Panel / System / Advanced / Environment Variables

    Then add the following lines to your MATLAB startup script. This
    will set up all necessary paths to the TrueTime kernel files.

        addpath(getenv('TTKERNEL'))
        init_truetime;

2.2 Compilation

    As described in the reference manual it is possible to write a
    TrueTime simulation (i.e. the code functions for the tasks and the
    initialization commands) either as m-files or as C++ functions.
    Both approaches are provided for this example and the compilations
    needed for the respective alternatives are described below.

    2.2.1 Matlab version
   
	TrueTime in the MATLAB version is compiled once and for all 
	by running the command make_truetime from the command prompt.
	This should be done the first time you are using TrueTime and
	no further compilation is then required.

    2.2.2 C++ version
    
        Compilation of the init scripts of the four computer blocks is
        performed by the m-file make.m. Run this file from the Matlab
        command prompt:

        >> make
    
        NOTE: If changes are made to the code functions or the
        initialization commands, the affected init scripts need to be
        re-compiled. Copy and paste from make.m to compile the
        relevant files individually.
    

3. SIMULATIONS

Open the model distributed.mdl to run the simulation. 

 - Run a first simulation without disturbing traffic and without
   interference in the controller node. This is obtained by setting the
   variable BWshare in the code function of the interfering node to
   zero, and by commenting out the creation of the task 'dummy' in
   controller_init. In this case we will get a constant round-trip delay
   and satisfactory control performance. Study the network schedule and
   the resulting control performance.

 - Switch on the disturbing node and the interfering task in the
   controller node. Set the variable BWshare to the percentage of the
   network bandwidth to be used by the disturbing node. Again study the
   network schedule and the resulting control performance. Experiment
   with different network protocols and different scheduling policies in
   the controller node.