Abstract
〈Vol.1 No.4(2008.7)〉
Titles
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■ Range-Enlargement of Simplified Brillouin Optical Correlation Domain
Analysis Based on a Temporal Gating Scheme
The University of Tokyo・Kazuo Hotate, Hiroshi Arai, and Kwang Yong Song
This paper propose a method to enlarge the measurement range for Brillouin
optical correlation domain analysis (BOCDA) system simplified with time-division
pump-probe generation scheme. In this system, the pump and the probe lightwaves,
which are modulated in frequency with a sinusoidal waveform to localize
the stimulated Brillouin scattering (SBS) periodically, are additionally
gated temporally to select only one localized position. We successfully
measured distribution of fiber Brillouin gain spectrum over 250 m measurement
range with 8 cm spatial resolution. We also propose an optimization of
the time-gating scheme by applying separate time gates for the pump and
the probe waves and introducing unbalanced Mach-Zehnder delay line, by
which the performance was enhanced to 7 cm spatial resolution and 1 km
measurement range.
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■ Neural Computation Scheme of Compound Control: Tacit Learning for Bipedal
Locomotion
RIKEN・Shingo Shimoda and Hidenori Kimura
The growing need for controlling complex behaviors of versatile robots
working in unpredictable environment has revealed the fundamental limitation
of model-based control strategy that requires precise models of robots
and environments before their operations. This difficulty is fundamental
and has the same root with the well-known frame problem in artificial intelligence.
It has been a central long standing issue in advanced robotics, as well
as machine intelligence, to find a prospective clue to attack this fundamental
difficulty. The general consensus shared by many leading researchers in
the related field is that the body plays an important role in acquiring
intelligence that can conquer unknowns. In particular, purposeful behaviors
emerge during body-environment interactions with the help of an appropriately
organized neural computational scheme that can exploit what the environment
can afford. Along this line, we propose a new scheme of neural computation
based on compound control which represents a typical feature of biological
controls. This scheme is based on classical neuron models with local rules
that can create macroscopic purposeful behaviors. This scheme is applied
to a bipedal robot and generates the rhythm of walking without any model
of robot dynamics and environments.
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■ Properties of Zero-free Transfer Function Matrices
Australian National University・Brian D. O. ANDERSON and Technical
University of Vienna・Manfred DEISTLER
Transfer functions of linear, time-invariant finite-dimensional systems
with more outputs than inputs, as arisein factor analysis (for example
in econometrics), have, for state-variable descriptions with generic entries
in the relevantmatrices, no finite zeros. This paper gives a number of
characterizations of such systems (and indeed square discrete-timesystems
with no zeros), using state-variable, impulse response, and matrix-fraction
descriptions. Key properties includethe ability to recover the input values
at any time from a bounded interval of output values, without any knowledge
ofan initial state, and an ability to verify the no-zero property in terms
of a property of the impulse response coefficientmatrices. Results are
particularlized to cases where the transfer function matrix in question
may or may not have a zeroat infinity or a zero at zero.
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■ An Intelligent Cooperative System Using Fuzzy Instruction for Car-like
Driving
University of Tsukuba・Shenghao Zhou and Seiji Yasunobu
An impedance controller using fuzzy instruction to support human's operation in human-vehicle interaction is studied in this paper. Fuzzy instruction is a fuzzy set of control instruction candidates and is composed of satisfaction rating as membership value with the candidates. In order to examine the support performance of impedance controller, an effective car-like driving training system is established, and an intelligent cooperative system using fuzzy instruction is constructed. The intelligent cooperative system is applied to the training system to help trainee learn driving a vehicle safely, availably and quickly. The experimental results demonstrate that the intelligent cooperative system cooperates with trainee's operation according to the surrounding variation situation, and does adaptive support flexibly on a wide/narrow road through the car-like driving training system.
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■ Discretization Method of Continuous-time Controllers Based on Frequency
Response Fitting
Shinshu University・Yuichi CHIDA and Tomoaki NISHIMURA
In the present paper, a digital redesign problem that converts continuous-time
controllers into digital controllersis considered. A new discretization
method based on matching of the frequency response of a continuous-timecontrol
system is proposed. The frequency response is matched using the least squares
method based on data of discretefrequency points. The matching problem
is described using an LMI, and the stability condition of the closed-loop
systemand the redesigned controller are described as additional conditions
of LMIs. An optimizing problem described by someLMI conditions is solved
by an iterative procedure. Examples are presented that prove the superior
performance of the proposed method.
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■ A Formula for the Supremal Controllable and Opaque Sublanguage Arising
in Supervisory Control
Kyoto Institute of Technolog・Shigemasa TAKAI and Yusuke OKA
In this paper, we study a property of opacity in the language-basedframeworkof discrete event systems.The problem of synthesizing a supervisor that enforces opacityin a maximally permissive way is addressed.A maximally permissive opacity-enforcing supervisor is realizedby an automaton that generates the supremal closed controllable and opaquesublanguage of the generated language of the system.This motivates the study on computability of the supremal sublanguage.We present a formula for computing the supremal sublanguageunder some assumption on uncontrollable events.Whenever the languages under consideration are regular,the supremal sublanguage is effectively computed using the presentedformula.
▲ ■ Task-Space Iterative Learning for Redundant Robotic Systems: Existence
of a Task-Space Control and Convergence of Learning
RIKEN・Suguru Arimoto,
Ritsumeikan University・Masahiro Sekimoto and Sadao Kawamura
This paper presents a feasibility study of iterative learning control for
a class of redundant multi-joint robotic systems when a desired motion
trajectory is specified in task-space with less dimension than that of
joint space. First, it is shown that if the desired trajectory described
in task-space for a finite time interval is twice continuously differentiable
then a unique control signal describable in task-space exists despite of
the system joint-redundancy. Second, a learning control update law is constructed
through transpose of the Jacobian matrix of task-space coordinates with
respect to joint coordinates by using measured data of motion trajectories
in task-space. Third, the convergence of trajectory trackings through iterative
learning is proved theoretically on the basis of original nonlinear robot
dynamics in joint space..
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■ Model Representation of Multi-cyclic Phenomenausing Role State Variables-Model
Based Fast Idling Control of SI Engine-
Toyota Central R&D Labs., inc・Tomohiko JIMBO
and Nagoya University・Yoshikazu HAYAKAWA
The present paper describes a model representation of multi-cyclic phenomenafor
a multi-cylinderengine system. The model is simplified for implementation
as a practicalengine controller. The simplified modelwith physically meaningful
variables can be used in design consideringpractical objectives and constraints
moreeffectively. The proposed approach consists of two steps. First, anapproximate
analytical discrete crank anglemodel (i.e., a periodically time-varying
state space model) is derived fromthe conservation laws. Second, theconcept
of role state variables is proposed to transform the periodicallytime-varying
state space model intoa time-invariant state space model. The stabilizability
and optimality ofthe time-invariant state space modelimply those of the
periodically time-varying state space model. Thetime-invariant state space
model is usedto design cold start feedforward and feedback controllers.
▲ ■ Parametric Design of a Dual-rate Controller for Improvement in Steady-state
Intersample Response
University of Hyogo・Takao SATO
The present paper proposes a new design method for a dual-rate system,
in which a plant in continuous time iscontrolled by updating a control
input in discrete time, in which the sampling interval of the plant output
differs from theupdate interval of the control input. A dual-rate control
law that stabilizes a discrete-time closed-loop system is extended.One
of the advantages of such an extension is that the dual-rate control law
can be redesigned to be independent of thediscrete-time closed-loop system.
Consequently, the intersample response can be improved by making it independent
of the sampled response using the newly introduced design parameters. The
present paper proposes a design method for design parameters to improve
the intersample response in the steady state. Numerical examples are presented
to confirm the effectiveness of the proposed method.
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