講演2: 船舶の非線形サンプル値制御 (Nonlinear sampled-data control for surface ships) (片山 仁志, 静岡大学; 15:15〜16:45)
講演3: A stability test for iISS networks: a brief summary (伊藤 博, 九州工業大学; 17:00〜17:45)
懇親会: 場所は当日お知らせします。 (18:00〜) 福岡市中央区天神近辺
参加者: Frederic Mazenc(INRIA), 片山(静岡大), 梶原(九大), 佐藤(広島大), 西村(山口大), 加藤(福工大), 伊藤(九工大) (以上敬称略) 問合わせ: 伊藤博 http://palm.ces.kyutech.ac.jp/~hiroshi
Abstract:
1. We consider three problems where time plays a central role. First,
we show that a time-varying interval observer can be constructed
for any time invariant exponentially stable linear system. The
construction relies on a time-varying change of coordinates which
transforms an exponentially stable linear system into a triangular
system. Second, we show how weak Lyapunov functions for
time-varying systems can be transformed into strict Lyapunov
functions by the addition of time-varying terms. Finally, for
systems belonging to a particular family of model of chemostat with
an arbitrary number of species, we solve the problem of ensuring
the persistence of the species by selecting, for the substrate
input concentration, a time-varying feedback. For each of these
problems we show that one cannot avoid using time in these designs.
Speaker's biographcal sketch:
Frederic Mazenc received his Ph.D. in Automatic Control and
Mathematics from the CAS at Ecole des Mines de Paris in 1996. He was
a Postdoctoral Fellow at CESAME at the University of Louvain in 1997.
From 1998 to 1999, he was a Postdoctoral Fellow at the Centre for
Process Systems Engineering at Imperial College. He was a CR at
INRIA Lorraine from October 1999 to January 2004. From 2004 to 2009,
he was a CR1 at INRIA Sophia-Antipolis. From 2010, he was a CR1 at
INRIA Saclay. He received a best paper award from the IEEE
Transactions on Control Systems Technology at the 2006 IEEE
Conference on Decision and Control. His current research interests
include nonlinear control theory, differential equations with delay,
robust control, and microbial ecology. He has more than 100 peer
reviewed publications. He coauthored a research monograph entitled
Constructions of Strict Lyapunov Functions.
2. 現在の制御系設計では、連続時間制御対象のデジタルコンピュータによる
制御 (サンプル値制御系) の設計は標準的である。本講演では、Nesic 等
により最近開発された近似離散時間モデルに基づく非線形サンプル値制御
系設計法の3自由度の (洋上) 船舶制御への適用を紹介する。
始めに、Nesic 等の結果を簡単にまとめ、全駆動船舶のサンプル値安定化
(定点保持) 制御系設計を紹介する。次に、より現実的な劣駆動船舶のサ
ンプル値通過点追従制御系設計を紹介する。通過点追従制御では、あらか
じめ与えられた通過点の間を結ぶ直線軌道み船舶を追従させるように操船
することが要求される。ここでは、船舶の目標surge速度とLine-of-Sight
ガイダンスアルゴリズムによる目標yaw角を与え、 surge速度とyaw角を目
標値に追従させるsurge制御則とyaw制御則をそれぞれ設計する。このとき、
サンプル値系及びサンプリング周期に陽に依存した離散時間系のカスケー
ド結合系の安定性理論により、船舶が目標直線軌道を追従できることを示
す。
For practical and modern control systems digital computers are
usually used as discrete-time controllers with samplers and
zero-order holds to control continuous-time systems. Such a control
system involves both continuous-time and discrete time signals in
a continuous-time framework and is called a sampled-data system.
In this presentation, sampled-data control problems for three
degree-of-freedom (3DOF) surface ships are considered by nonlinear
sampled-data control theories based on discrete-time approximate
models proposed by Nesic et al. First a summary of Nesic's results
is given. Then stabilization of nonlinear sampled-data fully-actuated
ships and way-point tracking control for nonlinear sampled-data
underactuated ships are considered. For way-point tracking control
of ships, it is required to control ships to track a straight-line
connecting two successively specified way-points. A desired surge
velocity and a desired yaw angle given by the Line-of-Sight (LOS)
guidance algorithm are introduced and then surge and yaw control
laws are designed. We can show that designed control laws make a
ship track a desired straight-line by using stability results for
sampled-data and parameterized discrete-time cascad interconnected
systems.
3. In this brief talk we consider dynamical networks consisting of
integral input-to-state stable (iISS) subsystems. A recent result
on the problem of verifying stability of the networks is presented
briefly. Basically, small-gain theorems in the literature had been
limited to interconnection of two subsystems and its multichannel
formulation. Several year ago, it was extended to large-scale
systems in arbitrary interconnection structure under the assumption
that subsystems are input-to-state stable (ISS). Stability problems
involving iISS subsystems have been much harder than ones for ISS
subsystems. This talk shows how we can go beyond the ISS by
presenting a novel way to construct Lyapunov functions of the
networks. The construction problem was not solved until the
emergence of the presented result even for ISS networks.
Last modified: Sun Mar 13 19:02:40 JST 2011