                  ------------------------------------------
                  New TILShell+ features Simulation Facility
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Togai InfraLogic has announced TILShell+, the next release of the TILShell, the
graphical development tool for fuzzy expert systems.  TILShell+ has simulation
capabilities which allow the user to test and tune a fuzzy expert system to a
desired performance level from within the TILShell.  This facility eliminates
the need to convert the FPL (TIL's Fuzzy Programming Language) definition of
the fuzzy system into C code and then into executable code (see Figure 5 [not
supplied in this text-only version]) before the system may be tested.  The need
to write a separate C program to model the plant with which the fuzzy system
interacts is eliminated.  Fuzzy system development time is greatly reduced.  

The general process for defining a simulation is given in the following steps:

1) Define the inputs, outputs, and initial rules and membership functions of
   the fuzzy system.
2) Define the constants, constraints, and initial conditions of the system to
   be modeled in the Initialization Editor.
3) Define the relationships between the fuzzy system, timing parameters, and
   the modeled system in the Run Editor.
4) Define the timing parameters of the simulation in the Timing Dialog.
5) Choose to display either the Chart or  Watch windows, or both.
6) Choose which variables will be included in the Chart and Watch windows.
7) Choose Simulate from the simulation menu to activate the Simulation Tools.
8) Begin the simulation by pressing the Play or Step buttons in the Simulation
   Tools window.

The Model Editor
----------------

The Model Editor allows the user to mathematically describe a system which
interacts with one or more fuzzy systems defined in the TILShell.  This is
accomplished through a script language which is interpreted by the TILShell.  A
model is described in this script language in two separate sections, the
Initialization and Run sections.  

The Initialization section generally stores definitions of global constants and
initial conditions of the modeled system.  The Run section contains a
description of how the modeled system interacts with the fuzzy system, along
with time dependencies and any other applicable definitions.

The Timing Parameters Editor
----------------------------

The simulation timing parameters are defined in the Timing Dialog.  Simulation
Time, Sample Time, Simulation Cycles/Sample, and Simulation Cycles/Update are
all defined in this dialog.

The Chart Editor
----------------

Specifying which variables and what portion of those variables' range  will be
displayed in the simulation Chart window, along with various titles and
interval information, is accomplished through the Chart Editor.  A title for
the Chart, a horizontal axis variable, and at least one vertical axis variable
must be chosen before the Chart definition will be accepted.  Phase plane
plotting is just one option available to the user.  

The Watch Editor
----------------

The Watch Editor allows the user to designate which variables of the fuzzy
system and model will be displayed numerically in the Watch window during
simulation.  The fuzzy system input values, their membership belief values, the
values of the fuzzy system outputs, the activation level of each rule in the
fuzzy rulebase, all the user-defined model variables, and the built-in model
variables may be included in the Watch window.

The Chart and Watch Windows
---------------------------

After the Model, Timing, and Chart parameters have been defined, the user may
then choose to display either the Chart or Watch windows, or both.  The Chart
window displays user-specified variables in a graphical format, while the Watch
window displays numerical values of user-selected variables of the fuzzy system
and model. 

The Simulation Tools
--------------------

To run the simulation once all the parameters have been defined, the user
simply chooses Simulate from the Simulation Menu. Once Simulate has been chosen
from the Simulation Menu, either the Chart or Watch window, or both, will
appear on the screen, along with a window entitled Tools (see Figure 2 [not
supplied in this text-only version].)  The Tools window controls the flow of
the simulation.

The Control Surface Plot
------------------------

The Control Surface Plot utility gives the user a three dimensional overview
(see Figure 3 [not supplied in this text-only version]) of how the fuzzy system
responds to a wide range of inputs by plotting one of the outputs of the fuzzy
system against two of the inputs.  The user may specify which two inputs and
which output of the fuzzy system to plot, constant values for the other inputs,
the viewpoint, number of sample points on each input axis, domain of each input
axis, aspect ratio, aperture, and whether or not a frame is displayed around
the control surface.  These settings allow the user to achieve the desired
perspective and level of detail in the control surface plot.

The Test Project Dialog
-----------------------

The Test Project dialog provides a method of testing the fuzzy system's
response to specific input conditions.  The user specifies a value for each of
the inputs to the fuzzy system and then clicks the Run button to calculate the
membership belief values for each membership function of each input, the values
of the outputs of the fuzzy system, and the rule activation level for each rule
in the fuzzy rulebase.

The Test Model Dialog
---------------------

The Test Model dialog allows the user to test the model's response to a
specific set of input conditions in the same way the Test Project dialog allows
the user to test the fuzzy system.  The user specifies values for each of the
variables in the model, clicks the Run button, and the values of the model for
the that cycle are calculated.  

TILShell+ will be available August 1.  For information on updating your
TILShell to TILShell+, or for other product information, please call us.
--
Copyright (c) Togai InfraLogic, 1992.  All rights reserved.
Permission to freely distribute this document, provided that it remains
complete and intact, is hereby granted.
