Journal of System Design and Dynamics
Online ISSN : 1881-3046
ISSN-L : 1881-3046
Volume 6, Issue 5
Special Issue on D&D2011
Displaying 1-18 of 18 articles from this issue
Special Issue on D&D2011
Papers
  • Claudiu Valentin SUCIU, Yuta KIMURA
    2012 Volume 6 Issue 5 Pages 538-554
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    Colloidal dampers are able to dissipate large amounts of mechanical energy without significant heating, and such result is surprising since traditional hydro-pneumatic absorbers transform almost integrally the dissipated energy into heat. Trying to get deeper insight into this phenomenon, in this experimental work, using a thermographical method the temperature distributions on the external surface of a colloidal damper are recorded during its forced heating followed by its natural cooling. Employed compression-decompression cylinder is axially divided into two chambers, one of constant volume and the other of variable volume. Silica particles are introduced inside the cavity of fixed volume (silica tank), and a micro-filter is used to separate it by the chamber of variable volume, in which only water is supplied. Two main heat sources are identified at the silica tank (colloidal effect) and the packing used to seal the cylinder (frictional effect). Tests prove that heating/cooling through colloidal effect is much slower than heating/cooling through frictional effect. However, depending on the working frequency, generated heat power through colloidal effect can exceed the generated heat power through frictional effect. Based on the experimentally observed slow speed of heating/ cooling through colloidal effect, one suggests that silica tank can be regarded from a thermal standpoint as a thermostat. Mechanism of energy dissipation is justified based on the molecular and cluster vibration modes of the liquid water, variation of the radiation absorption coefficient of liquid water versus the electromagnetic wavelength, and changes in the arrangement of water octamers.
    Download PDF (870K)
  • Claudiu Valentin SUCIU, Tsubasa TOBIISHI
    2012 Volume 6 Issue 5 Pages 555-567
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    Common autovehicle suspensions employ hydro-pneumatic absorbers placed in parallel with compression springs that provide the necessary restoring force. Since the spring can be omitted, compact and lighter design can be achieved by using the recently proposed colloidal suspensions. In this work, frontal and rear colloidal suspensions were designed to replace the classical suspensions, and tests of an autovehicle traveling on normal road with an asphalt step were performed. From the impulse response of tested autovehicle one evaluates its comfortableness, both based on the K factor method and based on the equivalent acceleration recommended by the ISO 2631 standard. Such testing method allows comfortableness evaluation without using an expensive test rig on which the autovehicle is placed over four actuators and excited to simulate the real road conditions. Results obtained are firstly validated in the case of classical suspensions consisted of oil dampers mounted in parallel with compression springs. Then, colloidal dampers with and without attached compression springs were evaluated. Relationship between the travel speed of the autovehicle and the level of vibration perception, as well as the influence on the sickness, concentration and health was obtained for various values of the tire inflation pressure. Ride-comfort decreases at augmentation of the travel speed and the tire inflation pressure. Although the colloidal suspension was found to provide inferior comfortableness than the classical suspension, results obtained are encouraging, since better performances are to be expected by optimal design of the colloidal spring.
    Download PDF (525K)
  • Yasutomo KANEKO
    2012 Volume 6 Issue 5 Pages 568-582
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    Recently, DS (Directionally Solidified) and SC (Single Crystal) alloys have been widely applied for gas turbine blades instead of CC (Conventionally Casting) alloys to meet the requirement of the high temperature operation and to improve the thermal efficiency. The SC blade consists of one columnar grain, and the DS blade consists of several columnar grains where the growing direction of the columnar crystal is set to the direction of the centrifugal force. Therefore, the vibration analysis of the SC and DS blades has to be carried out, taking account of the anisotropy. In this study, first, the effect of the anisotropy of elastic constants on the vibration characteristics of the SC and DS blades are investigated in detail. Second, the validity of the assumption of the transverse isotropy for the DS blade is examined, carrying out the Monte Carlo simulation. From these results, it is concluded that the actual DS blade can be treated as a transversely isotropic material.
    Download PDF (2475K)
  • Kanjuro MAKIHARA, Shigeru SHIMOSE, Shinsuke TAKEUCHI, Junjiro ONODA
    2012 Volume 6 Issue 5 Pages 583-596
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    We report herein our innovative self-powered digital autonomous system for vibration control using a digital micro-processor. Our unit is a completely self-powered control system that does not require an external power-supply. Because this digital, self-directive, self-powered system is programmable and can be used to implement versatile control schemes. Our digital-autonomous controller is much more advanced and progressive than conventional analog-autonomous controllers. Moreover, our digital system can be implemented in multiple-input multiple-output systems (MIMO) to suppress even complicated structural vibrations. This is quite useful for energy-saving or energy-shortage systems, such as large space structures, artificial satellites, and isolated lunar bases, which are vulnerable to long night-time exposures without solar power. Experiments demonstrate that displacement is reduced to as much as 35%. Energy dissipation in experiments is measured using various methodologies. Finally, we investigate the influence of the voltage offset of the AD port of the microprocessor on both estimation error and suppression performance.
    Download PDF (1208K)
  • Tetsuya WAKUI, Naoki IMAIZUMI, Ryohei YOKOYAMA
    2012 Volume 6 Issue 5 Pages 597-615
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    A model-based performance monitoring method for heat utilization processes in distributed energy systems is developed in this study. It is characterized by introducing dynamic compensation, where the response lags of heat exchangers to variations in their operating conditions are identified as first-order lag elements, and the output process variables estimated using a static input-output model are revised on the basis of these identified response lags. The estimated values of the output process variables are compared with their measured values in order to detect device failures. A numerical simulation of a heat utilization process in a gas engine cogeneration system containing a radiator with a considerable response lag reveals that the developed performance monitoring method has sufficient estimation accuracy in terms of the output process variables and ability to detect device failures, including a deterioration in the heat transfer performance of the radiator and heat exchanger, in a dynamic state.
    Download PDF (3035K)
  • Junji YOSHIDA, Yoichi ONISHI, Yuya NARITA
    2012 Volume 6 Issue 5 Pages 616-625
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    In this study, we considered accuracy evaluation indices for operational transfer path analysis (TPA) that employs the principal component regression method, and we verified their reliability. To evaluate the accuracy of TPA, the consistency of the response signals, in which the calculated response signal from the TPA model is compared with the measured response signal, has been frequently used in the past. Also, some cases use the condition number that indicates the inverse matrix condition used in the calculation procedure of the acceleration transfer function. In addition to these accuracy evaluation indices, a correlated principal component number (CPCN), which indicates the number of principal components that correlate with the response signal generated at the running test, has been proposed. The reliability of these accuracy evaluation indices has been verified through a simple simulation. The results show that the two conventional indices (the consistency method and the condition number) do not satisfactorily evaluate the accuracy. However, a CPCN can indicate the frequency bands where the TPA accuracy is high or low. Consequently, the new index was found to be a suitable index for evaluating the accuracy of the operational TPA.
    Download PDF (943K)
  • Yohei HOSHINO, Kyohei KATAYAMA, Yukinori KOBAYASHI, Takanori EMARU, Yo ...
    2012 Volume 6 Issue 5 Pages 626-640
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    This study presents an Active Wheel Damper (AWD) unit that can be easily mounted on flexible structures such as cantilever beams. The AWD uses a gyro sensor to directly measure the absolute angular velocity, which is the rotational velocity of the slope angle of a deflection curve caused by the flexible vibration of the structure, and can be used to realize a skyhook control by the direct feedback of the angular velocity. This study proposes a Sky-hook With Adaptive Disturbance Cancellation (SWADC) control—which is constructed as a combined skyhook control and an adaptive disturbance cancellation control system—to enhance the capability of the AWD unit to suppress vibrations. An adaptive algorithm, which estimates the frequency of vibration of a structure in real time, is derived on the basis of an adaptive notch filter algorithm. The estimated frequency is used to model a disturbance observer that estimates harmonic disturbances. This study demonstrates the vibration-suppression performance of the AWD unit by numerical simulations and experiments.
    Download PDF (2171K)
  • Tatsuya KOYAMA, Mitsuo ABOSHI
    2012 Volume 6 Issue 5 Pages 641-654
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    As undulating wear on an overhead rigid conductor line grows up, arcs due to contact loss occur frequently between the conductor line and a pantograph. The arcs cause extreme wear of the conductor line and contact strips of the pantograph. However, mechanism of the undulating wear formation has not been clarified. In order to clarify this, the authors investigated state of sliding surface of overhead rigid conductor lines on commercial lines and dynamic characteristics of a pantograph. These results indicate that the dynamic characteristics of the pantograph and the distance between pantograph heads play a causal role in the undulating wear formation. Periodic unevenness is formed by mechanical wear due to the dynamic characteristics of a pantograph, in particular anti-resonance phenomenon of the pantograph affects this process significantly. Once the undulating wear amplitude grows to the extent that the pantograph cannot keep contact with the conductor line, arcs due to contact loss frequently occur at concave portion of undulating conductor causing extreme undulating wear. The wavelength of the extreme undulating wear is related to the interval of the pantograph heads.
    Download PDF (1013K)
  • Wataru ADACHI, Nobutaka TSUJIUCHI, Takayuki KOIZUMI, Kouzou SHIOJIMA, ...
    2012 Volume 6 Issue 5 Pages 655-664
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    In walking analysis, which is one useful method for efficient physical rehabilitation, the ground reaction force, the center of pressure and the body orientation data are measured during walking. In the past, these data were measured by a 3D motion analysis system consisting of high-speed cameras and force plates, which must be installed in the floor. However, a conventional 3D motion analysis system can measure the ground reaction force and the center of pressure just on force plates during a few steps. In addition, the subjects' stride lengths are limited because they have to walk on the center of the force plate. These problems can be resolved by converting conventional devices into wearable devices. We used a measuring device consisting of portable force plates and motion sensors. We developed a walking analysis system that calculates the ground reaction force, the center of pressure, and the body orientations and measured a walking subject to estimate this system. We simultaneously used a conventional 3D motion analysis system to compare with our development system and showed its validity for measurements of ground reaction force, the center of pressure and posture of lower limb.
    Download PDF (1216K)
  • Yuya EZAKI, Hideo TERASAWA, Takuma WADA
    2012 Volume 6 Issue 5 Pages 665-675
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    This study evaluates the strength of tapered roller bearing loaded vibrations. We modeled tapered roller bearings with a flexible multi-body model and calculated the retainer stress by mechanical simulation. The simulation results show that retainer stress increased when the rollers vibrate in the yaw direction, and the largest part of the stress was the root of the retainer bridge. We also evaluated the fatigue strength based on the calculated stress of the retainer with this simulation. However, since such a simulation with a flexible multi-body model was very time-consuming, we could not calculate the stress in various conditions. To solve the time-consuming problem, we confirmed that the major frequency of the stress in the retainer bridge's root is below the first natural frequency of the retainer and found that this simulation can be calculated by the solid body model to save time. We calculated the root's stress of the bridge per unit force by static analysis with the force calculated by solid body model analysis. Using this solid body model, we calculated the force between the retainer and the rollers in various conditions and learned that it increased depending on the vibration acceleration, the rotation speed of the inner race, and the radial force; it did not increase depending on the rotation direction of the inner race. We also identified the acceleration level at which the bearing is likely to experience fatigue failure.
    Download PDF (1416K)
  • Kiyoshi AIDA, Koutaro KAWAMURA, Yuichi HIYOSHI, Satoshi FUJITA, Keisuk ...
    2012 Volume 6 Issue 5 Pages 676-684
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    This paper deals with vibration displacement prediction formulae based on energy balance for boiler structures. The boiler structure is a coupled structure, which consists of the boiler, its support structure and seismic ties installed between the boiler and the support structure. Vibration displacement prediction formulae based on energy balance originally developed by Akiyama, H. et al. were for non-coupled structures such as multi-story buildings with elasto-plastic dampers. The formula could predict the vibration displacements using energy spectra as earthquake inputs. However, the formulae was not applicable to the coupled structures such as the boiler structures. Considering 1st natural mode of the coupled structure enabled authors to develop the prediction formulae for the boiler structures. The formulae developed by authors were verified with time history analysis results using a lumped mass vibration model of the boiler structure.
    Download PDF (477K)
Papers
  • Gong DAOXIONG, Pan QI, Zuo GUOYU, Li XINGHUI
    2012 Volume 6 Issue 5 Pages 685-699
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    A self-balancing unicycle robot, which has a wheel for balancing and moving in the longitudinal plane (pitch angle) as well as a vertical flywheel for balancing in the lateral plane (roll angle), is studied in this paper. The non-linear dynamic equations of the unicycle robot on slope are analyzed using the Lagrangian dynamic formulation, then a linear model of the robot is derived at the equilibrium point, and linear quadratic regulators (LQR) are designed to control the robot on slopes with the angle of inclination varying from -11° to 11°. Simulation and physical experiment results validated that the unicycle robot can achieve good performance both on level plane and on slope. As far as we know, this is the first report of an autonomous unicycle robot moving and balancing on slope.
    Download PDF (634K)
  • Takaaki KATO, Takeshi MIZUNO, Yuji ISHINO, Masaya TAKASAKI
    2012 Volume 6 Issue 5 Pages 700-712
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    Multiple electrostatic suspension suspends multiple floators with a single power amplifier. The controllability of double parallel suspension was previously analyzed and the conditions to be controllable were shown. To ensure the analytical results, single-DOF suspension systems were fabricated, and a double parallel electrostatic suspension system consisted of these systems. The feasibility of double parallel electrostatic suspension was demonstrated experimentally. Dynamic characteristics of double parallel electrostatic suspension were studied based on step responses and frequency responses.
    Download PDF (1757K)
  • Saifudin RAZALI, Keigo WATANABE, Shoichi MAEYAMA
    2012 Volume 6 Issue 5 Pages 713-728
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    This paper proposes an unscented transformation for a FastSLAM framework. The unscented transformation is used to estimate robot poses in conjunction with generic particle filter used in standard FastSLAM framework. This method can estimate robot poses more consistently and accurately than the use of single standard particle filters, especially when involving highly nonlinear models or non-Gaussian noises. In addition, our algorithm avoids the calculation of the Jacobian for motion model which could be extremely difficult for high order systems. We proposed two different sampling strategies known as a symmetrical and a spherical simplex to unscented transformation to estimate robot poses in FastSLAM framework. Simulation results are shown to validate the performance goals.
    Download PDF (1247K)
  • Takaaki KATO, Takeshi MIZUNO, Yuji ISHINO, Masaya TAKASAKI
    2012 Volume 6 Issue 5 Pages 729-739
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    Voltage control using a variable capacitor and floator position estimation are proposed for designing a low-cost electrostatic suspension control system. When an electrostatic actuator and a variable capacitor are connected in series to a constant power supply, the voltage applied to the suspension system can be changed by varying the capacitance of the variable capacitor because the electrostatic suspension system can be treated as a capacitor. Moreover, the voltage is determined by these capacitances and so the floator position can be estimated from the voltage applied to the suspension system and the capacitance of the variable capacitor. The proposed voltage control system enables electrostatic suspension without a high-voltage amplifier or direct floator position detection. Therefore, this control system can reduce the total cost of electrostatic suspension systems. The principle of the proposed self-sensing control is described using a basic electrostatic suspension model. The position of the floator was estimated according to this principle. Self-sensing suspension was achieved by feeding back the estimated signal.
    Download PDF (1990K)
  • Renpeng TAN, Shuoyu WANG, Yinlai JIANG
    2012 Volume 6 Issue 5 Pages 740-753
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    A cushion robot with omnidirectional wheels is developed to support in-room movement of the elderly. Because the cushion robot works in a narrow, complex surrounding, it must accurately follow the target direction to avoid repetitively switching drives and to guarantee user safety. However, the user seated on the cushion robot causes a load change and a shift of the center of gravity (COG) of the whole system, which decreases the path tracking precision. To address this issue, an adaptive controller is designed to enable the cushion robot to accurately follow the target direction. The adaptive law can estimate the load and the position of the COG shift on-line, and can control the system so that it accurately follows a reference path generated to reach the target. Simulations and experiments are executed under the no-load condition and the load condition. The simulation and experimental results demonstrate that this control scheme effectively deals with the load change and the COG shift. Therefore, the cushion robot is reliable and convenient for assisting in-room movement of the elderly.
    Download PDF (810K)
  • Makoto TAWARA, Satoshi SUZUKI, Kenzo NONAMI
    2012 Volume 6 Issue 5 Pages 754-766
    Published: 2012
    Released on J-STAGE: December 28, 2012
    JOURNAL FREE ACCESS
    An attitude sensor mounted on an unmanned system requires to have high accuracy in attitude estimation under a dynamic acceleration environment for autonomous attitude control. To estimate the attitude, an attitude sensor needs to detect the direction of gravity from measured accelerations, which include dynamic accelerations. However, accelerometers are usually sensitive to both gravity and dynamic accelerations. In this paper, two attitude estimation algorithms with a quaternion based on the extended Kalman filter are described and compared. One of the proposed algorithms uses a pre-filter. In this approach, measured accelerations are filtered by the pre-filter and classified into gravity and dynamic accelerations. Using only the measured gravitational accelerations, an EKF can estimate the attitude with high accuracy. In the other approach, the EKF includes a dynamical model of acceleration disturbance. It can estimate both the attitude and the acceleration disturbance. The comparative experiments with hand motion, moving vehicles, and UAVs, were carried out to evaluate these algorithms. In the result of pre-filter method, estimation errors were accumulated in long-term acceleration disturbance. Meanwhile, the EKF algorithm with a dynamical model of acceleration disturbance provided accurate results in each experiment. As a result, we concluded the latter method is well suited to a dynamic acceleration environment for unmanned systems.
    Download PDF (1352K)
feedback
Top