Internal Model Principle:
Turn Output Regulation to Stabilization

• Name

Jie Huang

• Affiliation

Chinese University of Hong Kong

• Abstract

Stabilization and output regulation
are two fundamental control problems. The output regulation
problem aims to design a feedback controller to achieve
asymptotic tracking of a class of reference inputs and rejection
of a class of disturbances in an uncertain system while
maintaining the internal stability of the closed-loop system.
Thus the output regulation problem poses a more challenging
problem than the stabilization problem. A distinguished
feature of the output regulation problem from other problems
dealing with tracking and /or disturbance rejection is that
the controller must be able to handle a whole class of reference
input and / or disturbance signals that are generated by
an autonomous system called exosystem. For over three decades,
the output regulation problem has been one of the central
control problems. For linear systems, this problem was thoroughly
studied in the 1970s and the research on this problem has
led to one of the most celebrated linear control technique:
internal model principle.

Since the 1990s, the research on the output regulation problem
has been focused on nonlinear systems and it has been now
recognized that the key issue of solving the nonlinear output
regulation problem relies on an innovative extension of
the concept of the internal model from linear domain to
nonlinear domain. Indeed, the effort for establishing a
nonlinear version of internal model started in early 1990s
and the concept of internal model has been in the process
of constant evolving. This talk will be centred on the evolution
of the concept of internal model and will be divided into
the following parts. Part 1 is an introduction to the output
regulation and internal model design. In Part 2, we give
a new characterization of the internal model as follows.
First, we define an internal model candidate as any dynamic
system attachment of which to the given plant leads to a
so-called augmented system with the property that the stabilizability
of the augmented system implies the solvability of the output
regulation problem of the given plant and the exosystem.
An internal model candidate is further called an internal
model if it is such that the augmented system is stabilizable.
In short, an internal model candidate converts an output
regulation problem to a stabilization problem while an internal
model further guarantees the solvability of this stabilization
problem. In Part 3, we present a set of conditions for the
existence of internal model candidates as well as internal
models. Part 4 will show some applications of the internal
model approach including the synchronization of a chaotic
system to a harmonic system, disturbance rejection of the
RTAC system which is also known as the nonlinear benchmark
control problem, and the adaptive attitude tracking and
disturbance rejection of a spacecraft system. Finally, we
will close the talk by some remarks and open issues.

• Invited talk II

Recent advances in
networked control systems

• Name

Zengqi Sun

• Affiliation

Tsinghua University

• Abstract

Networked control
systems (NCSs) are one type of distributed control systems
when sensors, actuators, and controllers are interconnected
by a shared band-limited digital communication network.
The shared network will introduce new issues into the feedback
loop, such as time-varying delays and the potential loss
of information. The conventional control theories must be
re-evaluated before applying to NCSs. Due to the advantages
of NCSs in low cost, high utilization, simple installation
and great flexibility, etc., NCSs have been an attractive
research subject for researchers and important results have
been reported.

This presentation is organized in three sections. Section
1 presents a comprehensive overview of the current state
of research in the area of NCSs. In general, we will first
illustrate some of the problems encountered in NCS, including
network-induced delay, packet dropout, sampling period,
network constrains and scheduling. Then we will review the
modeling and analysis methodologies of NCSs under the effects
of the above problems, concentrating in methods and techniques
derived and implemented to improve the performance of NCSs.

In Section 2, emphasis will be given to the analysis and
controller synthesis of NCSs under effects of network-induced
delay and packet dropout. The existing approaches to handle
this problem in the literature will be introduced, focusing
on the stabilization and the optimization of linear NCSs.
Some progress on the control and scheduling co-design for
NCSs has also been addressed.

Two proposed methods for the analysis and design of NCSs
will be presented in details in Section 3. One is the H?
control problem for the NCS based on discrete-time Markovian
jump system with norm-bounded uncertainties. The upper and
lower bounds of the network induced delay of the NCS are
defined by an underlying Markov chain. The NCS is converted
to a discrete-time Markovian jump system based on the intervals
with norm-bounded uncertainties. The H? state feedback controller
is designed in terms of LMI using the stochastic Lyapunov
function approach.

The other proposed method is in stabilization of the NCS
via cone complementarity linearization approach. A discrete-time
switch model is proposed with time delay and packet dropout
considered by introducing lifting technique into NCSs. A
stability condition is derived for NCSs in terms of linear
matrix inequalities (LMIs) by defining delay-dependent Lyapunov
function and common quadratic Lyapunov function. The state
feedback controller design problem is then solved by exploiting
the cone complementarity linearization (CCL) method, together
with a sequential minimization problem subject to LMI constraints.
The proposed methodology have been applied to the application
of networked DC motor servo system and have shown promising
results.

This presentation will conclude with a discussion of possible
future development of the NCSs from a control perspective.

• Invited talk III

Cyberinfrastructure
Essential to 21st Century Advances in Science and Engineering
Education & Research

• Name

Balan Pillai

• Affiliation

Helsinki University of Technology

• Abstract

The broad infrastructure considered
necessary to capitalize on spectacular advances in information
technology has been termed cyberinfrastructure. Cyberinfrastructure
integrates hardware for computing, data and networks, digitally-enabled
sensors, observatories and experimental facilities; and
an interoperable suite of software and middleware services
and tools. Scientists and engineers need access to new information
technology capabilities; such as circulated wired and wireless
observing network complexes; sophisticated simulation tools
that permits exploration of phenomena which can never be
pragmatic or replicated by experiment. Computation offers
new models of performance and modes of scientific discovery
that deeply extend the limited choice of models that can
be shaped with mathematics alone, for example, chaotic behavior.
Smaller amount of researchers working at the frontiers of
knowledge can carry out their work without cyberinfrastructure
of one form or another. While hardware performance has been
exponentially ? with gate density doubling every 18 months;
storage capacity every 12 months; and network capacity every
9 months ? it has become clear that more and more capable
hardware is not the only prerequisite for computation-enabled
discovery.

This Talk would concentrate; on Cyberinfrastructure essential
to 21st century advances in Science and Engineering education
and researches.

• Invited talk IV

Humanoid Robotics

• Name

Kazuhito Yokoi

• Affiliation

National Institute of Advanced Industrial
Science and Technology (AIST)

• Abstract

With a physical form
similar to that of a human, humanoid robots can be used
as proxies or assistants to perform tasks in a real-world
environment on behalf of humans. Various humanoid robots
have been developed worldwide, and currently, humanoid robots
are able to work in our daily life environment. This talk
introduces some of the ongoing research and development
of humanoid, and discusses the problems, approaches and
applications for the next generation humanoid.
First, the history of humanoid robotics research is introduced.
It has been researched by a few research groups in the world
since 1970 as a kind of dreamy research target for robotics
researchers. However, after "Honda P3", a well-designed
humanoid robot which can stably and reliably walk, at the
middle of 1990s, it has been recognized as a robot which
may be able to be used practically near future and many
research groups began to develop the practical humanoid
robot. Ministry of Economy, Trade and Industry (METI) launched
a 5-year national project, "Humanoid Robot Project
(HRP)" in 1998. The objectives of the project were
to develop a humanoid which can be used as a research platform
to develop its new applications and also show how "the
human shape robot" is useful practically with several
application examples. As the results, the project developed
a new humanoid platform HRP-2 which has open software architecture
OpenHRP and several fundamental functions. Also, several
application examples have been developed and demonstrated
using real humanoid platforms developed in the project.
This talk will introduce some important results obtained
by the project.
Second, some of the humanoid research activities in National
Institute of Advanced Industrial Science and Technology
(AIST) and AIST-CNRS Joint Robotics Laboratory (JRL) will
be introduced. It includes various research aspects on "humanoid
motion control," "humanoid motion planning,"
"humanoid sensory-motor loop," and "programming
and software architecture of humanoid.
" Experimental results of humanoid robot HRP-2 will
be reported with videos.
Finally, technical problems to be solved, approaches for
further developments, sorts of applications, business models,
and a roadmap towards the next generation will be discussed.

Organized by ICROS(Institute of Control, Robotics and Systems)
Bucheon Techno Park 401-1506, 193, Yakdae-Dong, Wonmi-Gu, Bucheon-City, Gyeonggi-Do, 420-734, Korea
Phone : +82-32-234-5801/ Fax : +82-32-234-5807/ E-mail : conference@icros.org