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Volume 43, Issue 4
Displaying 1-14 of 14 articles from this issue
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Yuichi KURITA, Yoshichika IIDA, Roland KEMPF, Idaku ISHII, Makoto KANE ...2007 Volume 43 Issue 4 Pages 243-249
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSThe internal eye pressure is an important index for judging whether an eye suffers from glaucoma or not. The conventional eye pressure measurement is valid only under the condition that all subjects have the same structural eye stiffness. This paper challenges stiffness sensing of a living human eye by pressing with a contact probe. Prior to the experiment, a spherical model of an eye is developed and the analytical eye stiffness is introduced. The experiment is conducted based on the contact method where a contact probe is pressed on an anesthetized cornea. The deformation of the cornea is captured by a camera with high resolution during the experiment. The experimental results show that the measured stiffness nicely matches the analytical solution based on the constructed model.View full abstractDownload PDF (15739K) -
Wei QUAN, Katsunori SHIDA2007 Volume 43 Issue 4 Pages 250-255
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSThe paper presents a novel approach for flexion angle measurement based on the multifunctional technology, which is different from previous works with respect of its ability of measuring obliquity and bending direction simultaneously with a single structure. A flexible tube is utilized to imitate the status of skin on the elbow whose length varies with different gesture. Its flexible and compact character permits the biomechanical application and easy substitutional ability. Two angular parameters are converted to the linear movements of three iron wires, which are measured using inductive principle. We herein discuss the sensing structure, its geometric analysis, and the reconstructed equations. The estimated results of the built prototype prove the feasibility of the proposed approach.View full abstractDownload PDF (11618K) -
Nobuyuki TANAKA, Makoto KANEKO2007 Volume 43 Issue 4 Pages 256-263
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSThis paper discusses the evaluation of human skin dynamic characteristics by using the dynamic sensing system composed of an air jet supply for imparting a force to human skin, a line laser for making a line mark on skin surface, and a high speed camera for measuring skin deformation. To evaluate skin dynamic characteristics, we newly introduce the Deformation Shape Index (DSI=b1/2/d) where d and b1/2 are the defbrmation of the center and the half width at1/2d. We newly found that DSI recovers quickly for young subjects while it recovers slowly forseRior subjects.View full abstractDownload PDF (22458K) -
Koichi IGARASHI, Kenji KAWASHIMA, Tatsuya FUNAKI, Toshiharu KAGAWA2007 Volume 43 Issue 4 Pages 264-270
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSSome pneumatic systems require to measure the differentiated value of pressure with high resolution and high response. In former research, we have developed a pressure differentiator which is constituted of an isothermal chamber, a flow channels which make a laminar flow condition, pressure sensor and a diaphragm type differential pressure gauge. In this research, in order to reduce the number of the sensing elements and improve the resolution of the pressure differentiator while keeping the high dynamic characteristics, new pressure differentiator using micro fabricated hot wire anemometer is proposed and fabricated. Firstly, the principle of the new pressure differenctiator is discussed. Then, principle, fabrication process and characteristics of the micro hot wire anemometer. Finally, the results of performance tests are shown. The results indicate the high performance of the developed sensor.View full abstractDownload PDF (18540K) -
2. Output StabilityFumihiro SAKUMA, Laina MA2007 Volume 43 Issue 4 Pages 271-276
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESS0.65μm radiation thermometers are used as the standard thermometers at high temperatures. The stability of these thermometers influences largely the calibration uncertainty. Little information is available about the longterm output stability. Therefore, we studied the long-term output stability of ten 0.65μmradiation thermometers by conducting repeated calibration with the fixed-point blackbodies. Most radiation thermometers showed the tendency that the output signal increased in course of time. Some increases were ascribed to the filter wavelength change. When the center wavelength of the filter shifted to a longer wavelength, the output signal increased. Some thermometers showed a one percent decrease in a short period. These decreases were recovered after cleaning the objective lens. Therefore it is important to be careful not to contaminate the objective lens. The long term stability of the normal thermometer output is estimated to be within2% per year including the wavelength contribution and 0.2% per year for the gain contribution.View full abstractDownload PDF (4736K) -
Hiroto SAKAHARA, Yasuhiro MASUTANI, Fumio MIYAZAKI2007 Volume 43 Issue 4 Pages 277-284
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSMotion planning in dynamic environments is an important issue for autonomous mobile robot, and has been extensively studied for two decades. However, most of the existing methods repeat planning in short time, only looking around the current position of obstacles in the environment. In other words, they do not take into account the dynamic feature of environment. In our approach, we consider that the environmental changes are predictable in a short time interval, and regard the motion planning problem in a known dynamic environment as temporal spatial path planning problem. StRRT makes it possible to find a practically reasonable path for the robot with the limits of velocity and acceleration. It is also possible to choose the best among the paths by incrementally building a search tree in the allocated time. We demonstrate, using simulations, that StRRT can generate better trajectories in dynamic environments in comparison with RRT and a potential field approach. We also analyze the function of StRRT, considering perception and action constraints.View full abstractDownload PDF (22706K) -
Kiyotaka SHIMIZU, Kenichi TAMURA2007 Volume 43 Issue 4 Pages 285-292
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSThis paper is concerned with control of nonholonomic systems. As is well known, symmetric affine system is uncontrollable with continuously differentiable state feedback control. In this paper we apply Direct Gradient Descent Control (DGDC) for the symmetric affine system. DGDC is such a method that we manipulate control inputs directly so as to decrease a performance function by the steepest descent method. Note that the DGDC is a dynamic controller that we can adjust not only its gain parameter but also its initial condition. Then, not only controllable part of symmetric affine system is asymptotically stabilized by the DGDC but also uncontrollable part can be made to converge to the origin by choosing the initial condition appropriately. Applying the DGDC, we can control the symmetric affine system without transforming into the “chained form”. Simulation results for a four wheeled vehicle and flying robots demonstrate the effectiveness of the proposed method.View full abstractDownload PDF (2184K) -
Alali BASEL, Kentaro HIRATA, Kenji SUGIMOTO2007 Volume 43 Issue 4 Pages 293-302
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSThis paper studies MIMO (Multi Input Multi Output) learning control systems. It generalizes the well-known Feedback Error Learning (FEL) scheme to MIMO systems which are not necessarily biproper, and hence not invertible with properness. Assuming that a diagonal interactor is known, a pre-filter and an exact feedforward controller are designed to achieve FEL. Furthermore, adaptive feedforward controller based on FEL is derived using linear parameterization. Stability of the adaptive control law is proved with and without positive realness condition for strictly proper and biproper systems, respectively. Simulation results illustrate the effectiveness of the proposed method.View full abstractDownload PDF (7096K) -
Tomoaki HASHIMOTO, Takashi AMEMIYA, Hironori A. FUJII2007 Volume 43 Issue 4 Pages 303-310
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSThe stabilization problem of linear uncertain delay systems by means of linear constant memoryless state feedback control is investigated here. The uncertain parameters and the time delays under consideration may take arbitrarily large values. In this case, the locations of uncertain elements in the system matrices play an important role. It has been shown that it is a necessary and sufficient condition for the stabilization of time-varying or timeinvariant uncertain systems without delays to have a particular geometric configuration called ASC or GASC, respectively. For 3 dimensional systems, it is shown here that if time-varying uncertain delay systems have an ASC, then the systems are stabilizable with regardless to the upper bounds of delays and uncertain parameters. Moreover, it is shown that the time-invariant uncertain delay system having a GASC can be stabilized on the same argument. The results obtained here imply that the stabilizability conditions are not deteriorated by the existence of time delays.View full abstractDownload PDF (4716K) -
Takao NAMBU2007 Volume 43 Issue 4 Pages 311-316
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSIn feedback stabilization studies, a control scheme is designed so that the “state” of the system decays with a designated rate as t→∞. Thus the “output”, which is subordinate to the state, also decays at least with the same rate. We study in the paper a class of linear parabolic systems, and construct a specific control scheme such that the output decays faster than the state.View full abstractDownload PDF (642K) -
Shingo MABU, Yoshihiro IZUMI, Kotaro HIRASAWA, Takayuki FURUZUKI2007 Volume 43 Issue 4 Pages 317-322
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSA new evolutionary method named ‘Genetic Network Programming, GNP’ has been proposed. GNP represents its solutions as directed graph structures which have some useful features inherently. For example, GNP has the implicit memory function which memorizes the past action sequences of agents, and GNP can re-use nodes repeatedly in the network flow, so very compact graph structures can be made. In this paper, the stock trading model using GNP with Candle Chart is proposed and its effectiveness is comfirmed by trading simulations.View full abstractDownload PDF (3599K) -
Hirotaka KAJI, Hajime KITA2007 Volume 43 Issue 4 Pages 323-330
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSIn engineering, we often face to solve optimization problems of periodic functions having angles as decision variables. For example, a timing optimization for apparatus with cycling mechanism such as internal-combustion engine can be defined as an optimization problem of periodic function. In this paper, first, we discuss problems in optimization of periodic function by genetic algorithms (GAs). Second, to cope with such problems, we propose a new crossover operator for real-coded GAs for periodic function optimization. Finally, we show that the optimization problems of periodic functions are effectively optimized with the proposed method, and it also has some effectiveness in optimization with in bounded region.View full abstractDownload PDF (11914K) -
Yukinobu SUGIMURA, Takahiro OCHIISHI, Chikamune WADA2007 Volume 43 Issue 4 Pages 331-337
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSMany devices for assisting the elderly to stand up have been developed, but they move automatically without regard for the user's standing-up motion. In order to solve this problem, the user's motion must be measured simply and easily. However, there is no such measuring method, and we wish to estimate the standing-up motion based on information which is simply and easily obtainable. Therefore, we decided to use the plantar information, for the following reasons: 1) the COP (center of pressure) and VRF (vertical reaction force) of the plantar information are said to be influenced by the position of the body during the standing-up process; 2) the plantar information is obtained easily. In this study, we investigated the relationship between the standing-up motion and the COP/VRF to estimate the motion based on the plantar information. In order to reproduce a wide variety of standingup motions from a chair, 36different patterns of standing-up motion were included. We used our analysis device to calculate the COP and VRF, and a motion capture system to measure the standing-up motion, especially the positions of the head and hips. Prior to analyzing the relationship, we divided the standing-up process into two phases. The results for phase1revealed that the forward movement distance of the COP is relevant to the forward movement distance of the head, and that the integrated VRF is relevant to the upward movement distance of the head. The results for phase2revealed that the forward movement distance of the COP is relevant to the forward movement distance of the hips, and that the integrated VRF is relevant to the upward movement distance of the hips. These results suggest that it is possible to estimate to a certain extent the positions of the head and hips based on the plantar information.View full abstractDownload PDF (11689K) -
Tatsushi NISHI, Ryota MAENO2007 Volume 43 Issue 4 Pages 338-345
Published: April 30, 2007
Released on J-STAGE: February 25, 2013
JOURNAL FREE ACCESSIn this paper, we propose a decomposition and coordination method for timed Petri Nets to determine an optimal firing sequence to minimize the given objective function. The timed Petri Net is decomposed into several subnets in which the optimal firing sequence for each subnet is easily solved by Dijkstra's algorithm in polynomial computing time. The proposed method is applied to a flowshop scheduling problem. The effectiveness of the proposed method is confirmed by comparing the performance between the simulated annealing method.View full abstractDownload PDF (4981K)
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