All issues
Volume 25, Issue 1
Displaying 1-20 of 20 articles from this issue
- |<
- <
- 1
- >
- >|
-
Masashi MIZUNO, Katsumi SUZUKI, Katsuhiro KOJIMA1989 Volume 25 Issue 1 Pages 1-6
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn the case of probe rotation type eddy current defect detection of round steel bars in hot rolling, the most serious problem is noise caused by vibration of round steel bars.
This paper reports the result of calculation and spectrum analysis of this vibration noise and improvement of defect detectability by characteristics extraction method using mini-computer.
By the calculation and spectrum analysis of vibration noise, it became clear that practical SN ratio of defect signal and the vibration noise is not obtained by conventional frequency discrimination method using band pass filter when the vibration amplitude is large.
To improve defect detectability, a signal processing to extract the characteristics of defect signal which are obtained by differential coil type probe were contrived and adopted to defect detection signals of round steel bars in hot rolling.
Consequently, SN ratio and defect detection rate have been improved about 40% and 50% respectively as compared with conventional frequency discrimination method.View full abstractDownload PDF (811K) -
Application to the Long-Period SeismometryAkiomi KIMBARA, Yoshihiro INOSE, Shigeru KUROSU1989 Volume 25 Issue 1 Pages 7-13
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis work is concerned with a long-period vibrometer using a gyroscope, the experimental device having demonstrated periods of 46 seconds and longer. Several types of the gyro-transducer have previously been built and some of technical problems have been clarified.
The topics in this paper are summarized as follows: 1) The more compact gyro-transducer in arrangement is designed. 2) The sensitivity of the gyro-transducer is further improved. 3) The limitations imposed on the performance are considered. 4) The problem of how other components of input acceleration influences the output signal is discussed. 5) The observation can be carried out without being disturbed by long-term drift due to the thermal effects etc.View full abstractDownload PDF (1734K) -
Kimio SASAKI, Shinji SASAKI1989 Volume 25 Issue 1 Pages 14-21
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSAcoustical passive imaging systems have been developed as one of the promising means of both extracting the precise information about noise sources and exploiting the sounded ones from mechanical systems and/or diagnosing the system malfunctions, because of the special features such that they can visualize the various states of acoustic or vibration sources without any affection on its stationary working conditions.
One of the most difficult problems in developing such imaging systems would be how to reconstruct super-resolved images of near-field sources against detection noises. In this paper, we propose a super-resolution imaging technique in acoustical passive imaging systems, that can stably reconstruct super-resolved images of near-field sources under the assurance of the expected SNR of images.
The basic ideas of the technique are on the use of spherical detection and least squared extrapolation of the detected hologram, by the effective utilization of the a priori information about the spatial finite nature of the object sources. That is, as the result of spherical detection the measured hologram can be approximated as the 3-D FT (Fourier Transform) of the object wave field to be imaged even in the near-field, so that the object spatial finiteness makes the extrapolation of the hologram measured in a limited area possible by the sampling theorem.
The principle of the proposed technique and its sensitivity to the additive noises are given theoretically, together with the numerical results which illustrate the properness of the theoretical developments. Also is ascertained the usefulness of the technique through experimental super-resolution imaging of fundamental sounded fields, by using a computeraided acoustical passive imaging system, designed and constructed to cover an audiofrequency region.View full abstractDownload PDF (1370K) -
Takehiro MORI, Hideki KOKAME1989 Volume 25 Issue 1 Pages 22-27
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSStudies on stability robustness issue in these years have been carried out towards two directions: researches to cope with unstructured bounded perturbations and those to tackle structured uncertainties. The latter approach was first triggered by the celebrated theorem by Kharitonov appeared in a Russian literature in 1978. The theorem claims that the strict Hurwitz property of real polynomials whose coeffcients fall into a hyperbox in the coefficient space is equivalent to that of polynomials corresponding to only four edges of the hyperbox. Since then, many attempts have been made to extend the theorem to various directions, together with its alternative proofs and applications, relating to stability robustness problems.
This paper also addresses an extension of the theorem, in the sense that the assumptions of the theorem are weakened or generalized. Namely, the case is considered when the strict Hurwitz property is replaced by “weak” one in the theorem, that is, one allows the roots of the polynomials within the closed left half complex plane. It turns out that the theorem still holds in an exact parallel way as expected. It is furthermore demonstrated that several additional results take place in this limiting case. Before stating the main results, an extension of Mikhailov's theorem, a classical stability criterion, is first made. With the aid of this extension, the results are proved and summarized in the form of two theorems.View full abstractDownload PDF (875K) -
Frequency Domain ApproachKeiji WATANABE1989 Volume 25 Issue 1 Pages 28-33
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper is concerned with continuous repetitive control systems for plants with delay. The stabilization of modified repetitive control systems with a low-pass filter in the servocompensator is considered on the basis of frequency response method. It is shown that a series compensation with small gain for repetitive control of delay-free systems is directly applicable to delay systems without any predictors, whereas the conversion speed is very slow. It is also shown that for giving good responses in the case of delay plants, a predictor is required for repetitive control systems with one degree of freedom in the presence of delay, and two predictors for the systems with two degrees of freedom. A scheme for repetitive control systems with predictors is presented. The steady state characteristics of the control system ard similar to those of delay-free case except that the output follows the periodic refrence input with delay.View full abstractDownload PDF (815K) -
An Approach via Nyquist Stability CriterionNaoto ABE, Kenko UCHIDA, Etsujiro SHIMEMURA1989 Volume 25 Issue 1 Pages 34-39
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSWe develop stability conditions for linear feedback time-delay systems under error in time-delay. The time-delay of a mathematical model does not coincide in general with that of the real plant. Therefore, if the mathematical model is used for control designs, resulting control laws do not necessarily guarantee stability of the real closed-loop system. The important step in our approach lies in descriptions of systems under error in time-delay; the time-delay error is described as an additive or multiplicative plant perturbation. These descriptions enable us to derive the stability conditions based on Nyquist stability criterion. From derived stability conditions, we evaluate the error tolerance of timedelay and consider stability margins for timedelay systems under error in time-delay.View full abstractDownload PDF (804K) -
Seiichi SHIN, Toshiyuki KITAMORI1989 Volume 25 Issue 1 Pages 40-45
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper presents continuous-time Model Reference Learning Control (MRLC), which is a redesign of the Learnig Control (LC) from the viewpoint of the Model Reference Adaptive Control (MRAC). Through the same trials as LC, using a similar adaptive law as MRAC, MRLC decreases the control error between the outputs of the controlled object and the given reference model when the control can be applied repeatedly as the trial.
Unlike LC and MRAC, MRLC, is able to treat time varying linear systems even if the output of the reference model varies every trial and the time varing system is unknown without it's relative degree and stable invertibility. It is proved that the output error converges to zero through trials under these assumptions. A simple numerical simulation is presented for the verification of the analysis.View full abstractDownload PDF (716K) -
Koichi OSUKA, Toshiharu SUGIE, Toshiro ONO1989 Volume 25 Issue 1 Pages 46-53
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn this paper, we propose a practical design method of a Fixed-Gain-Type controller (PD-controller) for manipulators. The controller has the following properties;
(a) The desired trajectory can be specified.
(b) The control accuracy can be specified.
(c) The convergence characteristics of initial error can be specified.
(d) The robustness to modeling errors and to measurement noises is ensured.
(e) The structure of the controller is simple.
The main idea of our method is that we take account of the work space of a practical manipulator precisely and adopt the Two-Stage Robust Tracking Control System (Two-Stage-RTCS) developed by the authors. The consideration of the work space is used for assuring the boundedness of state variable of the manipulator and the Two-Stage-RTCS is used for avoiding an excessive input torque to the manipulator. Further, we show that the controller based on the Computed-Torque-Method can be used as a robust controller.View full abstractDownload PDF (927K) -
Shogo TANAKA, Yasuyuki FUKUI, Tsuyoshi OKITA1989 Volume 25 Issue 1 Pages 54-61
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSFailure diagnosis is important from two aspects. The first one is an improvement on system availability, and the other, which is much more important, the protection against disasters. From this point of view, many failure detection methods have been developed until now. Especially, a generalized-likelihood-ratio (GLR) method is well-known for its most rapid failure detection speed for the dynamic systems whose mathematical models are known.
But, in its use, it has a drawback such that we must assume a priori several adequate hypotheses which are expected to model the actual anomalies or failures. Step hypothesis which models the anomaly function adding to the system by a step one has often been used for its convenience. But, we do not always have such a situation where the step hypothesis works well.
Thus, we propose here one approach which makes the most use of the information about the state and the input of the system to be able to detect even the anomaly which is hard to be detected by the step hypothesis, and finally show by numerical examples that the proposed method is effective.View full abstractDownload PDF (1068K) -
Tsuyoshi GOROMARU, Hideo HANAFUSA, Yoh YONEZAWA, Nobuhiro IWAKAWA1989 Volume 25 Issue 1 Pages 62-68
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSRecently, many steam-generating incinerator plants have been constructed for utilizing the heat energy in municipal refuse. In this situation, the improvement of abilities of the plants is becoming very important. Consequently, it is necessary to investigate several characteristics of the incineration process in the incinerator, and to develop a new automatic combustion control system in order to stabilize the steam flow rate.
In this paper, we propose a mathematical model which represents the incineration process for the reciprocating grate-type incinerator. We assume that the overall refuse on the furnace stoker is comprised of many refuse rectangular-column elements which are transferred in rows on the stoker. The combustion process of the refuse rectangularcolumn element consists of two processes; one is the drying process which is used to obtain both an ignition temperature curve and an endothermic (heat absorbing) rate, the other is the burning process providing an exothermic (heat releasing) rate. Many simplifying assumptions have been made to obtain the mathematical model. However, it is shown that the model is adequate to determine the ignition curve that is most influential in the overall incineration process, and to estimate the energy release rate along the stoker length.View full abstractDownload PDF (1066K) -
Fan LIU, Masaru UCHIYAMA, Kyojiro HAKOMORI1989 Volume 25 Issue 1 Pages 69-75
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSIn the initial paper, we have proposed a model-based method to measure unsteady flow in a pipe, in which, based on a distributed-parameter dynamic fluid model, velocity profiles are estimated by a Kalman filter. From then on, we extended the model-based method to the measurement of the entrance flow in a circular pipe. The extension was brought to success by linearizing the nonlinear Navier-Stokes' equation according to the fact that the entrance flow satisfies linear equations at its boundaries.
In this paper, we show the effectiveness of the linearization method for the estimation of the flow velocity profiles in the rectangular duct entrance. First, we linearize the momentum equation of the unsteady fluid in a rectangular duct by the proposed method and derive a lumped dynamic model with an unknown parameter by using the finite element method. Next, using this lumped model, we set up an extended Kalman filter algorithm to estimate the velocity profiles in the rectangular duct entrance. We verify the validity of the estimated results by comparing them with numerical solutions which are calculated by the finite difference method and have been proved to agree well with the real flow by experiments using a beam scanning LDV.View full abstractDownload PDF (924K) -
Takaaki KATO, Tatsuya NAKAJIMA, Shinichiro UENO, Hiroshi HAMAMURA, Kiy ...1989 Volume 25 Issue 1 Pages 76-83
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe use of pump controlled hydraulic servosystem has been increasing in recent years because its superior energy efficiency in comparison with a valve controlled hydraulic servomechanism, though the pump controlled system is inferior in dynamic response. The dynamic characteristics of servo-pump (a pump used in the pump controlled system) must be made clear in order to design the pump controlled servo-system and/or to simulate the response of such a system.
Purpose of this paper is to establish a dynamic model, including unknown parameter identification, of the servo pump.
Firstly, a mathematical model of the servopump was made referring the structure of the servo-pump. Secondly, error response of an actual servo-pump was measured and input signal to servovalve in the servo-pump was calculated. Finally, unknown parameters such as damping coefficient and equivalent compressibility of oil were identified by minimizing sum of squares of difference between theoretical and experimental values of frequency characteristics of servo-pump.
In most cases the identified parameters were found in reasonable range, and scatters were small. However, they became uncertain when input current to the servovalve was smaller than about 10% of the nominal current.View full abstractDownload PDF (894K) -
Takuya KAMANO, Takayuki SUZUKI, Kazuo YAMABOSHI1989 Volume 25 Issue 1 Pages 84-91
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper describes the effect of armature reaction and mutual induction (transformer action) on the steady state and the dynamic characteristics of the dc servo motors. To investigate the effect, the new models of the dc separately excited servo motor and the dc series servo motor are proposed. The propriety of the models is verified by comparison of the calculated results with the measured results. Furthermore, by using the models, the transfer functions between the applied voltage and the motor speed and the block diagrams of both motors are derived. The transfer functions are also verified by the experimental investigation.View full abstractDownload PDF (925K) -
Saburo RYUMAE, Yajiro MORITA1989 Volume 25 Issue 1 Pages 92-98
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper proposes a measurement theoretic framework in which the inter-relationship between inexact concepts and the fuzzy set theories is investigated. Each fuzzy set theory is a formal relational structure on the set of membership functions and regarded to represent the empirical relational structure of inexact concepts homomorphically. As the representation is uniquely characterized by permissible transformations on the set of membership functions, we construct some of them by using two types of mappings to show the sufficient conditions of the uniqueness. They are the endomorphisms on the universe of discourse where inexact concepts are defined, and on the image space of membership functions.
The discussion is also done about the scale of membership functional representation. Thus the capabilities and limitations of membership function in representing an inexact concept are pointed out explicitly.View full abstractDownload PDF (960K) -
Shiro HIKITA, Kiyotoshi KOMAYA1989 Volume 25 Issue 1 Pages 99-104
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA group supervisory control system is designed to perform efficient operation of multiple elevators, and its most basic function is to assign an appropriate elevator to a given hall-call.
In this paper, in order to improve elevator group control perfomance, we propose a new system which includes experts' knowledge in fuzzy rule-base.
In this system, when a new hall-call is generated, the rule which is adequate to the current traffic situation is selected. The elevator to be assigned to the hall-call is determined by the procedure written in the selected rule's conclusion part.
An example of computer simulation is shown to ascertain the efficiency of this system.View full abstractDownload PDF (854K) -
Modified KM-Algorithm and Its CriterionMasakatu MORII, Masao KASAHARA1989 Volume 25 Issue 1 Pages 105-111
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSEfficient encoding and decoding algorithms of the error correcting codes and the cryptosystems have been extensively studied. In general their algorithms are operated on finite fields, polynomial rings and integer rings. Therefore it is very important and interesting to investigate the efficient algorithms for the operations of the fields and the rings.
In this paper we have proposed two efficient algorithms of the modular calculations in polynomial rings over GF(2) and integer rings. Firstly, we shall discuss the fast algorithm, which has been proposed by Kashiwagi and Moriuchi in 1982, for the modular calculations in polynomial rings over GF(2). Unfortunately their algorithm cannot be fast enough unless the dividend is the sparse polynomial. We shall modify their algorithm so that it can be efficient in almost every case. Secondly, we shall show that the modified algorithm can be applied to the modular calculations in interger rings. Our algorithm is useful when enciphering and deciphering the practical RSA public-key cryptosystem using computer.View full abstractDownload PDF (770K) -
Circular Range Acquisition and It's Application to PolyhedraGen-ichiro KINOSHITA, Takashi YAMAGUCHI, Masanori IDESAWA1989 Volume 25 Issue 1 Pages 112-119
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSA method of feature extraction for 3-D objective surface by circular range acquisition is proposed and investigated. In the experimental system, circular range acquisition is realized by moving an optical range sensor mechanically along a circular path.
A prototype of an optical range sensor, which adopting a 2.0mW He-Ne gas laser as a light source, 342mm (length)×130mm (width) ×174mm (height) body size and 5kg weight was manufactured. This range sensor is mounted on the wrist of a SCARA robot (A 3020, Hitachi).
The range sensor is positioned sequentially at a point along the circular path with a given radius around the axis passing through the target point and detects the range to the corresponded point on the surface of an object.
The surface feature around the target point is identified by investigating the variation of the acquired range data along the circular path. Applying the above operation to the surface of an object to be tested, surface features of an object can be extracted. Surface features, such as planes, vertices and edges, are represented as a polar coordinates representation of the range variation along the circular path. Thus, the circular range acquisition and the feature extraction of the surface are applied to the different types of vertices on a polyhedra.
Moreover, the circular range acquisitions tracing on the edge line are carried out over the surface of an object and experimental results are reported.View full abstractDownload PDF (2143K) -
Eisyo KONDO, Yuziro SAKURAUCHI, Nobuko KUWANO, Kiyochika HOSHIKAWA1989 Volume 25 Issue 1 Pages 120-122
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThe proportion of the electric power to the hulled rice in the water was increased with the soaking time getting longer, during five days. But, the unhulled rice in the water had an inflection point with the changes of the soaking time, during 15 days.View full abstractDownload PDF (363K) -
Kenji SUGIMOTO, Yutaka YAMAMOTO, Toru FUJINAKA1989 Volume 25 Issue 1 Pages 123-125
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSThis paper clarifies the maximal area where poles are assignable when they are shifted by pairs by some optimal feedbacks. This area is obtained by using a complete solution to the inverse regulator problem.View full abstractDownload PDF (412K) -
Koichiro SHINADA, Tadashi EGAMI, Takeshi TSUCHIYA1989 Volume 25 Issue 1 Pages 126-128
Published: January 30, 1989
Released on J-STAGE: March 27, 2009
JOURNAL FREE ACCESSOptimal preview control with variable tracking speed is applied to robot manipulator trajectory control. Utilization of future information is effective. Determination of tracking speed is made by means of Bode diagrams of preview control system.View full abstractDownload PDF (441K)
- |<
- <
- 1
- >
- >|