SICE Journal of Control, Measurement, and System Integration
Online ISSN : 1884-9970
Print ISSN : 1882-4889
ISSN-L : 1882-4889
Volume 2 , Issue 1
Showing 1-9 articles out of 9 articles from the selected issue
INVITED PAPERS
  • Hideaki ISHII, Roberto TEMPO
    2009 Volume 2 Issue 1 Pages 1-9
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    Search engines utilize numerous measures to rank the webpages in the search results. At Google, the so-called PageRank algorithm provides crucial information by quantifying the importance of webpages. The PageRank values are considered to be objective since the algorithm requires only the data of the web link structure. In this paper, we first introduce the original PageRank algorithm and give a brief overview of the distributed randomized approach recently proposed by the authors. Then, we consider the problem of computing the variation in the PageRank values that can be caused by erroneous data in the web structure when some links are fragile. An efficient (centralized) algorithm in the form of linear programming is proposed. This approach employs results from the field of interval matrices. Numerical examples are given to verify the effectiveness of the approach.
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  • Hajime ASE, Tohru KATAYAMA
    2009 Volume 2 Issue 1 Pages 10-19
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    We derive a closed-loop subspace identification method based on a realization theory without using probing inputs, but with the assumption that there is a measurable disturbance that can be used as a test input for closed-loop identification. The orthogonal decomposition (ORT) technique is applied to obtain deterministic and stochastic components of the joint input-output process. An ORT-based closed-loop subspace identification method is then developed by combining realizations of the deterministic and stochastic components, followed by a model reduction procedure to obtain lower dimensional models. Some numerical results are included to show the applicability of the present method.
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CONTRIBUTED PAPERS
  • Jun UCHIDA, Yoshiyuki KARUNO, Hiroshi NAGAMOCHI
    2009 Volume 2 Issue 1 Pages 20-26
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    In this paper, we deal with a scheduling problem of minimizing the number of employed vehicles on paths. Let G=(V,E) be a path with a set V={vi|i=1,2,...,n} of vertices and a set E={{vi,vi+1}|i=1,2,...,n-1} of edges. Vehicles with capacity b are initially situated at v1. There is a job i at each vertex viV, which has its own handling time hi and deadline di. With each edge {vi,vi+1}∈E, a travel time wi,i+1 is associated. Each job is processed by exactly one vehicle, and the number of jobs processed by a vehicle does not exceed the capacity b. A routing of a vehicle is called one-way if the vehicle visits every edge {vi,vi+1} exactly once (i.e., it simply moves from v1 to vn on G). Any vehicle is assumed to follow the one-way routing constraint. The problem asks to find a schedule that minimizes the number of one-way vehicles, meeting the deadline and capacity constraints. A greedy heuristic is proposed, which repeats a dynamic programming procedure for a single one-way vehicle problem of maximizing the number of non-tardy jobs. We show that the greedy heuristic runs in O(n3) time, and the approximation ratio is at most ln b+1.
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  • Tharathip VONGSAROJ, Yasuhide KOBAYASHI, Hisaya FUJIOKA, Shigeo YANABE
    2009 Volume 2 Issue 1 Pages 27-31
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    In this paper, we consider a synthesis problem of digital controllers for speed tracking control systems of ultrasonic motors. In previous works, a continuous-time H control based synthesis involving the Tustin transformation has been utilized to solve the problem, where it has been empirically known that an over-estimation of a modeling error is needed to avoid speed fluctuations in a high frequency range. In this paper, it is shown that a desirable performance can be obtained by the sampled-data H control synthesis without such conservativeness in the modeling.
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  • Kenji SATO, Yuji YAMADA, Hisaya FUJIOKA
    2009 Volume 2 Issue 1 Pages 32-35
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    This paper proposes a method of discrete hedging by extending the MSOH (mean square optimal hedging) problem. In the proposed method, the risk of option sellers is minimized in terms of the mean square hedging error as in the MSOH problem, while it is allowed to rebalance with non-uniform intervals as opposed to the uniform assumption in the MSOH problem. The benefit of the extra freedom is demonstrated via numerical simulations.
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  • Yasushi KAMI, Eitaku NOBUYAMA
    2009 Volume 2 Issue 1 Pages 36-42
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    This paper is concerned with the mixed H2/H control problem with output-feedback. To propose a new iterative method for the problem we firstly construct a controller sequence which converges to the unconstrained globally optimal H2 controller. After then, using this sequence, we propose an iterative method for the mixed H2/H control problem. The advantage of our method is to guarantee that the obtained solution is either the globally optimal solution or a feasible solution in the neighborhood of the boundary of the H norm constraint. A numerical example shows the efficiency of our method.
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  • Gou NISHIDA, Takayuki TSUZUKI, Hisakazu NAKAMURA, Yuh YAMASHITA
    2009 Volume 2 Issue 1 Pages 43-49
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    This paper proposes a method of constructing weak control-Lyapunov functions for nonlinear systems by introducing a topological geometric assumption called a Morse-Smale system. A Lyapunov function is one of the most important tools to study stability and stabilization of nonlinear systems. However, a general way of finding Lyapunov functions has not been found yet. First, we confirm there is a weak Lyapunov function for Morse-Smale systems. Next, we define the escapability for singular structures of the weak Lyapunov function. If all singular structures are escapable, then the Morse-Smale system is a globally asymptotically stabilizable one. Finally, we present the method of constructing a set of weak control-Lyapunov functions to achieve global stabilization. The method is described in terms of a recursive sequence of singular structures. We call the sequence a weak Lyapunov filtration.
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  • Akira SHIMADA, Chaisamorn YONGYAI
    2009 Volume 2 Issue 1 Pages 50-55
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    A high-speed motion control technique for inverted pendulum robots, utilizing instability and a disturbance observer, based on the Kalman filtering technique, is introduced. Inverted pendulums are basically controlled as they do not topple. Shimada and Hatakeyama developed a contrary idea and presented a controller that deliberately off balanced the robot when it moved. To implement the idea, a controller was designed using zero dynamics, which was derived by partial feedback linearization. However, the control system was not robust or sufficiently reliable. Although they presented a revised method using H control law, it was complex. Shimada et al. also presented a design method for a disturbance observer using Kalman filtering. This paper presents the latest control technique, combining both control laws to solve the problem, and introduces an application with respect to inverted pendulum robots. It further shows experimental results to confirm its validity.
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  • Guanghui CEN, Nobuto MATSUHIRA, Junko HIROKAWA, Hideki OGAWA, Ichiro H ...
    2009 Volume 2 Issue 1 Pages 56-63
    Published: 2009
    Released: November 03, 2011
    JOURNALS FREE ACCESS
    Mobile robot localization is a problem of determining a robot's pose in an environment, which is also one of the most basic problems in mobile robot applications. Recently, introduction of particle filters becomes the most popular approach in mobile robot localization and has been applied with great success to a variety of state estimation problems. In this paper, an particle filter is applied in the authors' service robot position tracking and global localization. Moreover, the posterior distribution of a robot pose in global localization is usually a multi-model due to the symmetry of the environment and ambiguous detected features. Considering these characteristics, we propose an improved cluster particle filter to increase the global localization robustness and accuracy. On-line experiments based detailed analysis of coordinate errors and algorithm efficiency are given. On-line experimental results also show the efficiency and robustness of the approach in the authors' service robot ApriAlpha Platform.
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