Abstract
〈Vol.4 No.3(2011.5)〉
Titles
[Contributed Papers]
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■ A Humanoid System Infrastructure: The RIBSI Middleware
Chiba Institute of Technology・Kengo TODA,Ken TOMIYAMA
A new middleware framework that is implemented as the RIBSI (Real-time
Interactive Behavior-Sensing Interface) middleware on our original humanoid
morph2 is proposed. A hierarchical control system architecture for humanoids
is developed for morph2 that consists of a device layer, a middleware layer,
which is the proposed RIBSI middleware, and an application layer. The RIBSI
middleware provides the upper layer of the humanoid system with individual
motor devices, integrated virtual action generation devices, individual
sensor devices and virtual sensors integrating sensor information. The
proposed middleware works as an infrastructure of the humanoid control
system, and can respond to asynchronous requests from the upper layer.
In order to verify the capabilities of the proposed middleware, the humanoid
control system implementing the RIBSI middleware is evaluated not only
on humanoid morph2 but also on a quadrupedal locomotion robot.
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■ A Condition for Better Estimation Using Asynchronous Sampling than Synchronous
Sampling
Tohoku University・Shogo ARAI,Hirosaki University・Yasushi IWATANI,
Tohoku University・Koichi HASHIMOTO
This paper investigates state estimation performance of sensor systems
with synchronous sampling and systems with asynchronous sampling. In a
sensor system with synchronous sampling, all the sensors work at the same
time. Sampling times of sensors with asynchronous sampling are determined
randomly and not constant. This paper shows that synchronous sampling does
not always yield better estimation performance than asynchronous sampling.
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■ Mixed-Integer-Programming-Based Approach to Optimal Design of Networked
Control Systems
Japan Advanced Institute of Science and Technology・
Koichi KOBAYASHI,Kunihiko HIRAISHI
A networked control system (NCS) is a control system in which plants, sensors,
controllers, and actuators are connected through communication networks.
In this paper, as one of the design problems for NCSs, we consider optimal
sampled-data control of linear systems with uncertain input delay and uncertain
sampling period. First, an input delay system is transformed into a discrete-time
system with parameter uncertainty. Furthermore, the obtained system is
expressed as a mixed logical dynamical model by using our previously proposed
modeling method. Next, a given continuous-time cost function is transformed
into a discrete-time cost function with parameter uncertainty, and the
optimal control problem is approximately expressed as a mixed integer programming problem.
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■ Passivity-Based Cooperative Estimation for Visual Sensor Networks: Averaging
of Multiple Target Objects Poses
Tokyo Institute of Technology・Takeshi HATANAKA,Masayuki FUJITA
This paper presents a novel cooperative estimation algorithm for visual
sensor networks. We consider the situation where multiple smart vision
cameras with computation and communication capability see different target
objects. The objective of the present algorithm is to meet two requirements:
(i) gaining estimates close to an average pose for static objects and (ii)
tracking of estimates to moving objects’ poses. In order to meet the requirements
simultaneously, we present a cooperative estimation algorithm based on
passivity of the kinematic model of rigid body motion. Though the present
algorithm embodies both properties from its structure, we restrict our
theoretical interests to averaging and provide an upper bound of the ultimate
error between the actual average and the estimates given by the present
algorithm.
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■ Quantized Average Consensus on Gossip Digraphs with Reduced Computation
Tokyo Institute of Technology・Kai CAI,Hideaki ISHII
The authors have recently proposed a class of randomized gossip algorithms
which solve the distributed averaging problem on directed graphs, with
the constraint that each node has an integer-valued state. The essence
of this algorithm is to maintain local records, called “surplus”, of
individual state updates, thereby achieving quantized average consensus
even though the state sum of all nodes is not preserved. In this paper
we study a modified version of this algorithm, whose feature is primarily
in reducing both computation and communication effort. Concretely, each
node
needs to update fewer local variables, and can transmit surplus by requiring
only one bit. Under this modified algorithm we prove that reaching the
average is ensured for arbitrary strongly connected graphs. The condition
of arbitrary strong connection is less restrictive than those known in
the literature for either real-valued or quantized states; in particular,
it does not require the special structure on the network called balanced.
Finally, we provide numerical examples to illustrate the convergence result,
with emphasis on convergence time analysis.
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■ A Distributed Consensus Algorithm via LMI-Based Model Predictive Control
and Primal-Dual Decomposition
Yamaguchi University・Yuji WAKASA,Kanya TANAKA,Yuki NISHIMURA
This paper deals with an output consensus problem of multiple agents and
first presents a centralized algorithm for solving it by a model predictive
control method based on linear matrix inequalities. It is shown that the
outputs of all the agents controlled by the presented method asymptotically
converge to a common point, i.e., a consensus point. Then two kinds of
algorithms for solving the consensus problem in a decentralized way are
presented by using primal and dual decomposition methods. In general, these
algorithms require a large number of iterations, i.e., a large number of
communications between agents. To cope with this communication burden,
a method that can reduce the number of
iterations and guarantee the convergence to a consensus point is proposed
by exploiting the property that the primal and dual decomposition methods
can give upper and lower bounds of the optimal value of the optimization
problem to be solved. A numerical example is given to illustrate the effectiveness
of the proposed method.
▲ ■ High-Precision Motorcycle Trajectory Measurements Using GPS
Keio University・Yuichiro KOYAMA and Toshiyuki TANAKA
A method for measuring motorcycle trajectory using GPS is needed for simulating
motorcycle dynamics. In GPS measurements of a motorcycle, both the declination
of the motorcycle and obstacles near the course can cause problems. Therefore,
we propose a new algorithm for GPS measurement of motorcycle trajectory.
We interpolate the missing observation data within a few seconds using
polynomial curves, and use a Kalman filter to smoothen position calculations.
This results in obtaining trajectory with high accuracy and with sufficient
continuity. The precision is
equal to that of fixed point positioning, given a sufficient number of
available satellites.
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■ AWearable Accelerometer Array for Human Movement Analysis Based on rBSN
Approach
Japan Advanced Institute of Science and Technology・Kohei MATSUMURA and
Osaka University・Tomoyuki YAMAMOTO
In this paper, we introduce a wearable accelerometer array system and propose
a method for analysis of human movements. While many studies of sensor
networks have aimed at scalability and/or accuracy, our concept is to introduce
“redundancy” in the array to measure movements in human bodies. In particular,
we gather data from as many points as possible, more than kinematic degrees
of freedom, and then obtain various information by data mining. We developed
an accelerometer array system based on our “redundant numbered BSN (rBSN)”
concept. It measures 46 channels of 3-axis
(15 channels of 6-axis) acceleration data in 1500Hz synchronously. We also
evaluate our accelerometer array system in two applications discuss the
applicability of our rBSN concept. Specifically, we describe methods to
estimate arm stiffness as well as center of gyration of human movement.
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■ On Equivalence between Critical Probabilities of Dynamic Gossip Protocol
and Static Site Percolation
Tokyo Institute of Technology・Tetsuya ISHIKAWA and Tomohisa HAYAKAWA
The relationship between the critical probability of gossip protocol on
the square lattice and the critical probability of site percolation on
the square lattice is discussed. Specifically, these two critical probabilities
are analytically shown to be equal to each other. Furthermore, we present
a way of evaluating the critical probability of site percolation by approximating
the saturation of gossip protocol. Finally, we provide numerical results
which support the theoretical analysis.
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■ Tracking of Human Groups Using Subtraction Stereo
Chuo University / CREST, JST・Yuma HOSHIKAWA,Yuki HASHIMOTO,
Alessandro MORO,,Kenji TERABAYASHI and Kazunori UMEDA
In this paper, we propose a method for tracking groups of people using three-dimensional (3D) feature points obtained with use of the Kanade-Lucas-Tomasi feature tracker (KLT) method and a stereo camera system called “Subtraction stereo”. The tracking system using subtraction stereo, which focuses its stereo matching algorithm to foreground regions obtained by background subtraction, is realized using Kalman filter based tracker. The effectiveness of the proposed method is verified using 3D scenes of people walking, which are difficult to track.
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■ Object Localization by Cooperation between Human Position Sensing and
Active RFID System in Home Environment
The University of Tokyo・Hiroshi NOGUCHI,
Taketoshi MORI and Tomomasa SATO
We propose methods for object localization by cooperation between human position sensing and active Radio Frequency Identification (RFID) system in a home environment. The traditional object localization methods based on received signal strength indicator from active RFID system suffer from the distortion of RF signal caused by human existence. Two proposed methods improve this problem using a human position sensing system and pattern recognition technique. One method selects the classifiers based on human position in object localization. The other method narrows location candidates using position data and detection data of human handling motion with the sensor embedded in the active RFID tag. The experiment in the human natural handling scenario demonstrated that the methods improved the performance of object localization in human existence.
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■ Performance Competition in Cooperative Capturing by Multi-Agent Systems
The University of Tokyo・Koji TSUMURA,Shinji HARA,
Sompo Japan Insurance Inc.・Keiichi SAKURAI and Chung-Ang University・Tae-Hyoung
KIM
In this paper, we deal with a problem to capture a target by linear multi-agent systems where the agents behave autonomously, whereas the target escapes with a reasonable strategy. We consider two cases for the dynamics of the agents and the target. First, for the simple dynamic case, we give a necessary and sufficient condition for the success of the capturing. Then, we extend the results to the general dynamics case and give similar sufficient conditions. The conditions clarify the performance competition between the target and the agents and we propose preferable strategies for them. We also demonstrate the results by using numerical simulations.
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