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Volume 30, Issue 5
Displaying 1-16 of 16 articles from this issue
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Teruyuki IZUMI1994 Volume 30 Issue 5 Pages 485-491
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIt is necessary to investigate a natural frequency of a flexible link constituting a manipulator in order to control its flexural vibration. The natural frequency of the link is subjected to gravity if its flexibilty is increased.
This paper deals with a natural frequency of a flexible link which is set with an arbitrary angle of elevation. First it is assumed that a vibration superposes on a static deflection due to gravity. The differential equation and the boundary condition of the vibration under gravity are presented. The differential equation is related to a concentrated mass at the tip of the link and a distributed mass of the link. And it is shown that the boundary condition is a function of the angle of an elevation θ and a static deflection γs at the tip of the link. Second some frequency equations are derived by simplifying the differential equation, and the natural frequencies of the first mode are calculated. These frequencies are compared with experimental values. It is shown from the experiments that the natural frequencies are influenced by an angle (θ+γs) of the tip of a link and a distributed mass has to be taken into consideration.View full abstractDownload PDF (1182K) -
Kenichi KUROMORI, Takashi NISHIJIMA1994 Volume 30 Issue 5 Pages 492-498
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIt has been over 40 years since the electromagnetic flowmeter came into practical use. Since then many improvements have been made to the actual meter and many theoretical problems have been solved. Shercliff derived two-dimensional weighting functions and showed how sensitive a magnetic flowmeter with a uniform magnetic field would be to flow profile. A few authors obtained general solutions of the weighting function for the three-dimensional case. Furthermore, Smyth and Al-Khazraji calculated two-dimensional weighting functions for a flowmeter with finite electrode length.
However, most of these analyses are based on certain assumptions; such as point electrodes, nonconductive wall and/or two-dimensional analysis. If these assumptions are not satisfied, mathematical difficulties are encountered in solving the problem analytically.
This paper proposes a discrete approximation suitable for investigation of a magnetic flowmeter. This method simulates the conductive fluid inside a pipe by using virtual resister circuit network.
Applying this method to magnetic flowmeters which have wall contamination and which are connected with adjacent conductive pipes, approximate weighting functions are obtained. From investigation of calculated signal error with flow test the simulation method has been proved to be effective to predict the error in the case where complex boundary conditions are encountered.View full abstractDownload PDF (1176K) -
Hitoshi MAEKAWA, Kazuo TANIE, Makoto KANEKO, Natsuo SUZUKI, Chiyoharu ...1994 Volume 30 Issue 5 Pages 499-508
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe miniaturized version of a finger-shaped tactile sensor previously reported in scaled-up version is developed. The developed tactile sensor is capable of detecting the contact location and the normal to the surface of the object at the contact by applying optical phenomena. Infrared LEDs are installed for the light source at the edge of the hemispherical optical waveguide with elastic cover. A fiber optics plate (FOP) and a position sensitive detector (PSD) is employed for the image guide and the optical detector, respectively. The FOP consists of high-density bundled optical fibers and it can transmit the optical image from the optical waveguide to the surface of the PSD. The injected light from LEDs into the waveguide maintains total internal reflection at the surface of the waveguide and is enclosed within it. When an object comes in contact with the sensor, the cover depresses and touches the waveguide. At that moment, scattered light arises at the point of contact caused by the change of the reflection condition. The scattered light reaches to the PSD through the FOP and the position of the optical input is converted to the electric signal at the surface of the PSD. By processing this signal in the computer, it is possible to detect the contact location and the normal to the surface of the object.
The above-mentioned principle and the integrated structure of the developed sensor are described in detail, and the signal processing is formulated. Furthermore, the accuracy of the contact detection for static contact and the dynamic response for the intermittent contact of the sensor are experimentally evaluated.View full abstractDownload PDF (3207K) -
Yukio MATSUYAMA, Hisafumi IWATA, Hitoshi KUBOTA, Hidehiro IKEDA1994 Volume 30 Issue 5 Pages 509-518
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSAn automatic visual inspection system has been developed for Thin Film magnetic Head (TFH) wafers. Although there are only a few classes of defects to be detected, the difficulty of defect detection varies drastically depending on the location of the defect. When the optical characteristics of a defect and the underlying element pattern are similar, the defect becomes difficult to detect. To detect all defects reliably, we developed the following new techniques. (1) Optical enhancement: The wafer is illuminated by a slit-shaped light source from an oblique direction, and the scattered light is used for detecting flakes in the transparent protection layer. Reflected light from the surface is also used for detecting surface defects. Defects are easily extracted by thresholding the detected image. (2) Image processing: An element-to-element comparison method is employed to detect defects that cannot be enhanced optically. Many bright spots within the ceramic substrate cause discrepancies when compared. Local minimum processing is used for eliminating them and stabilizing defect detection.
The system has been evaluated in an actual production line and the defect detection rate achieved is approximately 13% higher than human performance.View full abstractDownload PDF (4135K) -
Kouji TSUMURA, Kazuo MUROTA, Toshiyuki KITAMORI1994 Volume 30 Issue 5 Pages 519-526
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper aims at extending the structural controllability/observability arguments hitherto developed for 1-D systems to multi-dimension systems. This amounts to investigating the “structural minor primeness” of a multi-variable polynomial matrix. A graph-theoretic criterion is derived for the “structural minor primeness” under the assumption that the nonzero coefficients are independent (in an algebraic sense). The criterion is effective for checking the “structural” controllability/observability of 2-D systems as it is expressed by means of the DM-decomposition of a bipartite graph and can be checked by an efficient algorithm. With possible minor modifications the criterion is applicable to various kinds of 2-D systems such as FM-model and time-delay systems.View full abstractDownload PDF (1589K) -
Atsumi OHARA, Izumi MASUBUCHI, Nobuhide SUDA1994 Volume 30 Issue 5 Pages 527-536
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper proposes a static state feedback controller design method for linear plants that are subject to polytopic uncertainty. Design specifications considered are robust H2-type disturbance attenuation and/or robust H∞-norm constraint with quadratic stabilization.
First, a new parametrization of stabilizing state feedback gains and its geometric structure are investigated. Next, conditions for quadratic stabilization and the robust performances are characterized by certain functions on the parameter space. By optimizing these characteristic functions, we can obtain state feedback controllers which satisfy prescribed design specifications. Since the parameter space and the characteristic functions are convex, the use of suitable convex optimization algorithms assures convergence to global optimum.
This design method is realistic and efficient for design problems which are difficult to solve analytically. Further, by optimizing maximum function of the characteristic functions, multiple specifications can be treated.View full abstractDownload PDF (1411K) -
Sadamu INAISHI, Hirofumi EGUCHI, Tadashi YAMASHITA1994 Volume 30 Issue 5 Pages 537-544
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA dynamic system model often contains some structured uncertainties which can be expressed by parameter perturbations. Keel et al. developed an algorithm for obtaining a robust state feedback controller, which is available to time-invariant system.
In previous paper, we extended this method to the system with time-varying uncertainties which are expressed by the linear combination of time-varing parameters and the time-invariant matrices characterizing the structures of uncertainties. As a result, we showed the sufficient condition for exponential stability of the time-varying system.
On designing a feedback controller, we can not always detect all of the state-variables in the system. Moreover, in order to attain a controller in low cost, the number of state-variables used in it is needed to be reduced.
This paper presents a new method which robustly stabilizes the system with time-varying uncertainties by use of a constrained state feedback matrix in which some elements are restricted to be zero, and provides the sufficient condition for the obtained feedback system to be exponentially stable.View full abstractDownload PDF (1403K) -
Takashi MIYAZAKI, Shigeyuki HOSOE, Feifei ZHANG1994 Volume 30 Issue 5 Pages 545-553
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn this paper we consider the H∞ control problem for a plant possessing zeros at infinity. Namely it is not assumed that direct-feedthrough matrices are of full rank. A necessary and sufficient condition is derived for the solution to exit. It depends on the solvability of two generalized Riccati equations. An algorithm is proposed with which the generalized Riccati equations can be solved by reducing them into usual Riccati equations. A parametrization is given for all compensators that are not necessarily proper. Also the existence of the proper compensator is proved. We use the properties of J-lossless matrix and the descriptor form representation to solve the problem.View full abstractDownload PDF (1312K) -
Tadashi ISHIHARA, Kazunobu SEKIGUCHI, Hikaru INOOKA1994 Volume 30 Issue 5 Pages 554-561
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe trajectory sensitivity method, which utilizes a quadratic performance index with the trajectory sensitivity term, is well known as an approach to design a regulator explicitly accounting plant parameter variations. However, most existing design methods are based on heuristic iterative algorithms that can not be guaranteed to converge. In this paper, for discrete-time systems, we formulate the trajectory sensitivity method as a parametric LQ problem. To solve the problem, we first propose an algorithm based on the iterative solution of two Lyapunov equations. Although this algorithm is practically efficient, its convergence can not be guaranteed theoretically. Then we propose a modification to guarantee the convergence. As an illustrative example, we give a design example for a simple second order system with an uncertain parameter.View full abstractDownload PDF (1378K) -
Toru FUJINAKA, Hiroshi SHIBATA1994 Volume 30 Issue 5 Pages 562-567
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn the Simplified Adaptive Control (SAC) scheme, the controlled object is usually assumed to satisfy the Almost Strictly Positive Realness (ASPR) condition. Thus, for a single-input single-output system, the applicability of SAC is limited to those plants with relative degree zero or one.
Parallel feedforward compensation has been considered as a means of applying the SAC to non-ASPR systems. This method, however, suffers from the fact that the controlled variable of SAC is the sum of actual plant output and auxiliary output, and it is not always easy to select an appropriate feedforward compensator.
This paper deals with a new method of applying SAC to non-ASPR systems with relative degree two and where the derivative signal of the plant output is available. It is shown that a complete tracking may be attained by this method. A simulation result is provided to illustrate the effectiveness of the proposed method.View full abstractDownload PDF (924K) -
Kisaburo HAYAKAWA, Hidenori KIMURA1994 Volume 30 Issue 5 Pages 568-576
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe input-output decoupling via state feedback for an automobile active suspension system is proposed based on the dynamic model of the automobile which was obtained using Kane's method. The method of decoupling proposed by Freund is used.
The aim of an automobile active suspension is to satisfy simultaneously ride comfort of passengers and road-holding. In conventional active suspension systems, road-holding is much better than passive suspension, but ride comfort of passengers is not so improved. The main reason is that each mode of body movements is controlled independently by using local models and the coupling among different modes of body movements is not taken into account. Therefore, it is important that each mode of them is controlled independently by a full dynamic model of an automobile to take these couplings into account.
First, a nonlinear model of an automobile motion is derived for the purpose of active suspension design based on Kane's dynamics and show the phisical implications of Kane's dynamics to the modeling. Next, it is shown that this model satisfies a condition for decoupling given by Freund which implies the adequancy of decoupling control for active suspension. Finally, we discuss the phisical meaning of decoupling condition in terms of Kane's dynamics.View full abstractDownload PDF (2323K) -
Fumihiro HOSOE, Tetsuro ODAGAWA, Shunji SHIMIZU, Shuichi INO, Takashi ...1994 Volume 30 Issue 5 Pages 577-583
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSTele-existence robots work in dangerous places while humans, which are operating them, are working in safe environments. In order to enable tele-existence robots to grasp or manipulate an object stably, obtaining tactile information and presenting the information to human is necessary. When a person grasps an object, the shearing strain is produced on the surface of the fingers. It is clear that the heavier the weight of the object, the larger the shearing strain becomes. To keep on grasping the object, he/she has to increase his/her grasping force according to the weight of the object. In order to make the tele-existence robot grasp something, the ability to detect the shearing strain is indispensable. As the shearing strain information is finally presented to the operator, the sensing ability of the robot needs to be as efficient as that of the operater. First, a psychophysical experiment was carried out to determine the human differential limen of shearing strain. The limen was found to be 200μm. Using this result, we designed a tactile sensor modelled after the human skin. Its sensing ability of shearing magnitude was 150μm and its shearing strain direction was 30 degree, which was superior to that of humans. The application of the sensor to a robot hand increased its effectiveness in adapting the robots grasp according to the varying weight of the object.View full abstractDownload PDF (2896K) -
Tatsuya SUZUKI, Shigeru OKUMA1994 Volume 30 Issue 5 Pages 584-593
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn the field of robotics, many researchers have focused on representation and analysis of an automatic assembly system. In the previous researches, however, no control-theoretic ideas for the assembly system have been found. In this paper, we study a closed-loop desired marking control problem for the automatic assembly system using the supervisory control technique. First of all, we represent the assembly system with a Petri net. Since the assembly Petri net has a “tree structure”, the assembly Petri net has some graph structural properties. Therefore, secondly, we comprehend these properties from a point of the formal language theory. As the result, we clarify that the solvability of the desired marking control problem depends only on the controllability of a control object, and that we can construct the supervisor for the assembly Petri net with a finite automata. Finally, we discuss the supervisor reduction technique and show the two concrete examples.View full abstractDownload PDF (1650K) -
Naoki MIZUNO1994 Volume 30 Issue 5 Pages 594-596
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper provides a simple implementation of internal model principle for model reference adaptive control systems, which allows for rejection of unknown deterministic disturbances. With proper modification of the disturbance model in the controller, the computational complexity is reduced.View full abstractDownload PDF (403K) -
Kouki SAKAMOTO, Yuuji HORIE, Hiroshi YOSHIDA, Tomoyuki MIYAZAKI1994 Volume 30 Issue 5 Pages 597-599
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSAn inverted pendulum system mounting a gyroscope was reported. The slanted pendulum was brought to be vertical by applying a control force of a gyroscopic moment. The state-space equations were derived to confirm that the system was controllable. The optimal regulator was designed and the region of its optimal poles was determined by simulation. In experiments with state feedback control obtained from those poles, the gyro-pendulum was kept upright more than an hour and half.View full abstractDownload PDF (332K) -
Ikutaka TERAKURA, Noboru OHNISHI, Noboru SUGIE1994 Volume 30 Issue 5 Pages 600-602
Published: May 31, 1994
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSWe present a mobile robot that can localize sound source. The direction is estimated based on time differences among signals received by a tri-microphone unit mounted on the robot. The robot can move toward the direction avoiding obstacles on the path.View full abstractDownload PDF (371K)
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