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<TITLE>Real-Time A.I.</TITLE>
<H1>
Real-Time A.I.
</H1>
<h2><!WA0><a href="http://www.cs.umd.edu/projects/plus/plus.html">Parallel Understanding Systems Group</a>,
Computer Science Dept., University of Maryland at College Park</h2>

<h2>Intelligent Real-Time Control:</h2>
<blockquote>
As Artificial Intelligence (AI) techniques become mature, there has
been growing interest in applying these techniques to controlling
complex real-world systems which involve hard deadlines.  
Unfortunately, many AI techniques are
characterized by unpredictable or high-variance performance, making
them unsuited to the performance guarantees required for real-time
control systems.  Most research on RTAI focuses on restricting AI
techniques to make them more predictable.
<p>
Our research to date has focused on a new approach, the Cooperative
Intelligent Real-time Control Architecture (CIRCA).  In this
architecture, an AI subsystem reasons about task-level problems that
require its powerful but unpredictable reasoning methods, while a
cooperating, parallel real-time subsystem uses its predictable performance
characteristics to deal with control-level problems that require
guaranteed response times.  We are investigating several aspects of
this architecture, including planning for real-time control tasks,
interfacing real-time and non-real-time subsystems, explicitly making
performance tradeoffs when resources are overconstrained, and utilizing
resources that become available dynamically.
<p>
Some of this work is being done in conjunction with the Real-Time
Intelligent Control project in the 
<!WA1><a href="http://www.cs.umd.edu/projects/amrl/amrl.html">Autonomous Mobile Robotics Lab</a>.
</blockquote>

<p>
<h2>Reasoning about Real-Time Competencies:</h2>
<blockquote>
In domains where the failure is to take appropriate and timely action is
potentially catastrophic, behavioral adequacy for a control system
cannot be established by testing alone. In addition
to the requirement of logical correctness, which is desirable for any
program, such mission-critical systems typically have strict temporal
constraints as well. Hard real-time systems have been developed to 
address these requirements, but achieving intelligent 
behavior in this context has proven probelmatic.
The requirement for hard real-time response is
clearly incompatible with the fundamentally time-bound, high-variance techniques
of classical AI, and the inability to precisely characterize the performance 
and resource requirements of current reactive systems makes them 
equally unsuitable for 
use in hard real-time systems. 
<p>
We propose to develop a system for 
representing the semantics of low-level competences and for reasoning
about their use in isolation and in combination. Such a representation
will allow principled proofs of the correctness of reaction-based systems,
as well as provide a formal basis for automated reasoning about the
use of reactive competences. This will support the use of engineered
reactive systems with guaranteed logical performance features
in a hard real-time context, while at the same time 
providing a link to classical AI methodologies. In short, this formal semantics
for reaction will bridge the gap between mission-critical domains and
deliberative AI techniques.
</blockquote>
<P>

<h2>Status/Availability:</h2>


<h2>Recent Papers:</h2>
<!WA2><a HREF="http://www.cs.umd.edu/users/musliner/papers/tsmc.ps.Z"> 
D. Musliner et al., CIRCA:  A Cooperative Intelligent Real-Time Control Architecture
<i>IEEE Transactions on Systems, Man, and Cybernetics</i>, Vol. 23 #6, 1993.
</a>
<p>
R. C. Kohout, J. A. Hendler, D. J. Musliner, and A. K. Agrawala,
<!WA3><a HREF="http://www.cs.umd.edu/users/kohout/Papers/rtss.ps"> 
Supporting Intelligent Real-Time Control: 
Dynamic Reaction on the Maruti Operating System</a>,
submitted to <i> Real-Time Systems Symposium </i>, 1994.
<p>
<!WA4><a HREF="http://www.cs.umd.edu/users/kohout/Papers/proposal.ps"> 
R. Kohout,
Representing Reactive Competences for Hard Real-Time Systems (Ph.D. Dissertation
Proposal)
</a>

<h2>People:</h2> 
<ul>
<li><!WA5><a href="http://www.cs.umd.edu/users/hendler/"><b>Dr. James Hendler</b></a>, PI
<li><!WA6><a href="http://www.cs.umd.edu/users/musliner/"><b>Dr. David Musliner</b></a>, Postdoc
<p>
<li><!WA7><a href="http://www.cs.umd.edu/users/kohout/"><b>Bob Kohout</b></a>, Graduate Student
</ul>