-
Terumasa NARUKAWA, Masaki TAKAHASHI, Kazuo YOSHIDA
2009 Volume 3 Issue 3 Pages
258-269
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
A two-dimensional rimless wheel provides a simple model of bipedal walking. The motion of the rimless wheel is stable, and this particular property has clarified the fundamental role of a swing leg in planar bipedal walking that addresses the problem of falling forward. In this paper, a three-dimensional rimless wheel is investigated as a simple model of three-dimensional bipedal walking. The 3D rimless wheel model is useful in understanding the essential dynamics of 3D bipedal locomotion. The model consists of two rimless wheels connected by a link at the center of the wheels, and flat feet connected to the spokes with springs. The first numerical stability studies indicated that the motion of the 3D rimless wheel could be unstable; however, numerical simulations and experimental results showed that for a given slope and physical parameters, including the spring constant at the ankles, a stable motion is obtained. This indicates the usefulness of ankle springs in providing stable bipedal locomotion in three-dimensions.
View full abstract
-
Takeshi KAWASHIMA
2009 Volume 3 Issue 3 Pages
270-281
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
In a car crash, permanent injury can be avoided if deformation of an occupant's rib cage is maintained within the allowable value. In order to realize this condition, the occupant's seat belt tension must be instantaneously adjusted by a feedback control system. In this study, a seat belt tension control system based on the active shock control system is proposed. The semi-active control law used is derived from the sliding mode control method. One advantage of this proposed system is that it does not require a large power actuator because the seat belt tension is controlled by a brake mechanism. The effectiveness is confirmed by numerical simulation using general parameters of a human thorax and a passenger car in a collision scenario with a wall at a velocity of 100 km/h. The feasibility is then confirmed with a control experiment using a scale model of about 1/10 scale. The relative displacement of the thorax model approaches the allowable value smoothly along the control reference and settles near this value. Thus, the proposed seat belt tension control system design is established.
View full abstract
-
Tao LIU, Yoshio INOUE, Kyoko SHIBATA
2009 Volume 3 Issue 3 Pages
282-295
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
To perform 3D ground reaction force (GRF) and moments measurement with a comfortable interface for the foot, this paper presents a new 3D force sensor cell designed using pressure sensitive electric conductive rubber (PSECR). A wearable force plate with a four-support mechanism was proposed for measuring triaxial forces and moments. A compact electrical hardware system including amplifier modules, conditioning circuits, and then a micro-computer controller was developed and integrated into the sensor system. A shoes-based sensor system composed of two developed force plates was constructed for GRF and moment measurement. Calibration experiments were conducted, and a stationary force plate was used as a reference device to verify the measures of GRF and moment using the sensor system in trials by a normal walking speed. The results show a good correspondence between the developed sensor system and the reference system, which was examined by a root mean square (RMS) difference of 7.2N for x-axial force, 11.1N for y-axial force, and 9.5N for z-axial force. The RMS difference of the measured x-, y-, and z- directional moments was 6.4Nm, 1.9Nm, and 1.4Nm, respectively.
View full abstract
-
Ting-Nung SHIAU, Chung-Hao KANG, De-Shin LIU, Tyau-Her YOUNG
2009 Volume 3 Issue 3 Pages
296-308
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
A verified hybrid optimization procedure, which combines the genetic algorithm (GA) with traditional optimization methods, is presented in this paper with a disc type piezoelectric motor. The optimization objectives include minimizing the frictional loss of the rotor and maximizing the efficiency and spin speed of the piezoelectric motor. The behavior constraints include spin speed, natural frequency, and stability. The Runge-Kutta method is applied to determine the dynamic response of this motor, and the Floquet theory is employed to analyze the motor's stability. The optimization algorithm (hybrid genetic algorithm, HGA) applies GAs to provide an initial design variables set, thereby avoiding the trial process; thereafter, traditional algorithms are employed to determine optimum results. With the single-objective and multi-objective optimizations by using the HGA, both the efficiency and spin speed of the motor can be improved, and the frictional loss of the coating can be decreased effectively, either individually or simultaneously. The designs of the designated performances can be derived as well.
View full abstract
-
Tetsuo SATO
2009 Volume 3 Issue 3 Pages
309-317
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
The present study aims at the design of the active control of machine tools' vibrations. The formulation of modal control for linear lumped parameter vibratory systems is offered. The electromagnetic exciters are developed to serve as active dampers for machine structures. A simple L-shaped beam structure is the object for the experiments and is mounted with two electromagnetic exciters. The behavior of the whole system is investigated by the model that is composed of the lumped masses and springs with 4-degree of freedom. The control system is designed through the investigation both by the root locus method and by the "MATLAB Simulink" simulation in which the elapsing responses,
C1(t),…,
C4(t) of all four modes and the vibratory waveforms,
W1(t),…,
W4(t) are computed. The best condition for the values of control parameters results by the simulation. In the experiment, the preparatory study for the vibration control of the L-shaped structure has been performed in advance to the investigation.
View full abstract
-
Jeang-Lin CHANG, Huan-Chan TING
2009 Volume 3 Issue 3 Pages
318-329
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
This paper presents an output feedback sliding mode control algorithm for linear MIMO systems with mismatched parameter uncertainties along with disturbances and matched nonlinear perturbations. A scheme of the output-dependent integral sliding surface is proposed and a control law is then designed to satisfy the reaching and sliding condition. Through utilizing
H∞ control analytical technique, once the system is in the sliding mode, the proposed algorithm can guarantee robust stabilization and sustain the nature of performing disturbance attenuation in terms of an algebraic Riccati equation. Finally, the feasibility of our proposed algorithm is illustrated using a numerical example.
View full abstract
-
Issam Abed SMADI, Yasutaka FUJIMOTO
2009 Volume 3 Issue 3 Pages
330-343
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
The purpose of this paper is to present a general framework for the design of a nonlinear disturbance observer for Euler-Lagrange systems, in particular, for mechanical, electro-mechanical, and power electronic systems. The generalized momentum plays a crucial role in realizing the proposed method, and the global stability is guaranteed under certain conditions. In the absence of parameter variations and/or model uncertainties, the proposed method guarantees global exponential stability. Otherwise, model uncertainties and parameter variations are merged with the input disturbance into a “lumped disturbance term”. Then under boundness assumption on the lumped disturbance term, the observer can asymptotically estimate to any desired accuracy the lumped disturbance. In the sequel of this paper, motivated by the proposed nonlinear disturbance observer, a robust tracking control for robot manipulators is proposed. Again, in the absence of parameter variations and/or model uncertainties, the global stability is guaranteed. Otherwise, using tools from singular perturbation theory, the proposed method ensures arbitrary disturbance attenuation, small tracking error, and boundness of all closed loop signals. The theoretical results are illustrated on friction compensation and robust tracking of two degrees of freedom planer robot manipulator with short comparison with a classical, linear disturbance observer.
View full abstract
-
(1st Report: Application to Swing-Up Control of an Inverted Pendulum System)
Motomichi SONOBE, Takahiro KONDOU, Nobuyuki SOWA, Kenichiro MATSUZAKI
2009 Volume 3 Issue 3 Pages
344-355
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
As a new control technique called the subspace control method is developed in an effort to carry out finely tuned control easily and efficiently for a complicated and large-scale mechanical system. In the subspace control method, the minimum and optimum subspace suited for the control specification is extracted from the entire state space by applying the concept of modal analysis, and feedback control based on the modal coordinate is performed in the subspace. The subspace control method takes advantage of the dynamic characteristics of the controlled object in the design of control system. In addition, decreasing the dimension of the controlled object based on the dynamic characteristics leads to simplification of the design of control system, reduction of mechanical overload caused by the control, and a reduction in consumed electric power. In the present study, in order to clarify the fundamental concept, the subspace control method is formulated for swing-up and stabilizing controls of an inverted pendulum system. The effectiveness of the proposed method is verified by numerical simulations and experiments.
View full abstract
-
(Second Report: Decrease in Formation Size)
Takuya YOKOYAMA, Katsuhiko YAMADA, Ichiro JIKUYA
2009 Volume 3 Issue 3 Pages
356-367
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
This paper proposes a basic method for designing a formation flight using Hill's equations of motion. This method involves a trajectory design for minimum fuel consumption during relative position change of spacecraft controlled by two impulses. The condition for minimum fuel consumption when the formation size is increased has already been examined. In this study, we consider the optimization problem to obtain the time and phase of the second impulse when the phase of the first impulse is given, during the decrease in formation size. In contrast to the optimum condition examined earlier, the optimum condition in this case is complicated. We have described the procedure to obtain the optimal solution. The results of our study show that the optimum condition determined previously is applicable to calculate the optimal cost in many simulation cases, whereas the new optimum condition is helpful to compensate the difference between them.
View full abstract
-
(Fundamental Characteristic and Vibration Control Performance of Pipe-Type-Damper)
Tomoyoshi WATAKABE, Satoshi FUJITA, Toshio OMI, Hiroshi KURABAYASHI, K ...
2009 Volume 3 Issue 3 Pages
368-379
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
The detached houses, in general, have the first natural frequencies in relatively higher range, and their structural deflection is small even though their response acceleration is high. Therefore, the deformation transmitted to damper becomes small, and the dampers have to be designed to obtain a desirable performance against such small amplitude vibrations. For this reason, the new type of damper having the displacement amplification mechanism was developed to solve this problem in this study (“pipe-type-damper”). This paper reports on the results obtained from experiments and analysis of a detached house model using the dampers. In the experiments, the trial damper of 10kN capacity was made, and the experiments were performed to investigate the fundamental characteristics of the pipe-type-damper. As a result, the properties of the pipe-type-damper were expressed by the fractional derivative 3-element model, its restoring force was proportional to the second power of amplification factor by the amplification mechanism. Analytical results obtained by considering the characteristics of damper showed that the pipe-type-damper had good vibration control performance.
View full abstract
-
Oleksandr MIKHYEYEV, Hiroki MORI, Takuo NAGAMINE, Mizue MORI, Yuichi S ...
2009 Volume 3 Issue 3 Pages
380-390
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
Friction-induced vibration often causes noise problems. When a plate-like object is rubbed by rubber, self-excited vibration is generated, which results in noise since plate vibration oscillates the air. For reducing vibration and noise, we investigate the characteristics of friction-induced vibration of a glass plate experimentally. Then, we study the effectiveness of a dynamic absorber mounted on the glass plate. The results demonstrate that the self-excited vibration is well suppressed by an absorber, and that absorbers with higher damping ratios are more effective than those with lower. The location of an absorber is also examined for reduction of vibration. Further, analytical study is performed to understand the mechanism of the vibration. We obtain an analytical model from observation and analyze the motion assuming bouncing vibration. Calculated results agree qualitatively with experimental ones.
View full abstract
-
Kenichiro OHMATA, Taichi MATSUOKA, Shinya KOHNO
2009 Volume 3 Issue 3 Pages
391-402
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
In this paper, a new type of arm-type damper consisting of two links and three joints (human type joints with friction) has been developed. The damper is able to suppress six modes of vibration of a machine, three in translational modes and three in rotational modes. The trial damper was made and its resisting force characteristics in three translational and three rotational directions were discussed theoretically and experimentally. The seismic responses of a three-degree-offreedom translational system and a two-degree-of-freedom translational-rotational system and the frequency responses of a single-degree-of-freedom translational system, which consist of a mass and four coil springs and supported by the damper, were measured using a three-dimensional permanent magnet type shaking table. The experimental results were compared with the calculated ones, and the effects of vibration suppression of the damper in three translational and rotational directions and the propriety of the calculations were confirmed.
View full abstract
-
Jianhong WANG, Datong QIN, Yi DING
2009 Volume 3 Issue 3 Pages
403-419
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
A mixed flexible-rigid multi-body model is presented to study the dynamic behavior of a horizontal axis wind turbine. The special attention is given to flexible body: flexible rotor is modeled by a newly developed blade finite element, support bearing elasticities, variations in the number of teeth in contact as well as contact tooth's elasticities are mainly flexible components in the power train. The couple conditions between different subsystems are established by constraint equations. The wind turbine model is generated by coupling models of rotor, power train and generator with constraint equations together. Based on this model, an eigenproblem analysis is carried out to show the mode shape of rotor and power train at a few natural frequencies. The dynamic responses and contact forces among gears under constant wind speed and fixed pitch angle are analyzed.
View full abstract
-
(Comparison between Experimental Results and Calculated Results)
Hiroyuki KIMURA, Tomoki IIJIMA, Shigenori MATSUO, Yoshiaki FUJITA
2009 Volume 3 Issue 3 Pages
420-428
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
An elevator rope in a high-rise building is forcibly excited by the displacement of the building caused by earthquakes and wind forces. This paper presents experiments involving free vibration and forced vibration of a rope for obtaining its natural frequency and damping coefficient. Experiments involving forced vibration of a rope whose length varies with time due to the up-and-down movement of a cage are also presented. Finite difference analyses of the rope vibration were performed by considering the time-varying length of the rope, based on the assumption that the movement velocity is constant. The calculated results of the finite difference analyses are in fairly good agreement with the experimental results.
View full abstract
-
François BESSON, Guy FERRARIS, Michèle GUINGAND, Jean-Pi ...
2009 Volume 3 Issue 3 Pages
429-440
Published: 2009
Released on J-STAGE: July 31, 2009
JOURNAL
FREE ACCESS
During the last decade, many new technical solutions dedicated to the comfort of automotive vehicle's drivers have raised, like Electrical Power Steering (EPS). To fulfill the more and more demanding requirements in terms of vibration and acoustics, the dynamic behavior of the whole steering is studied. The system is divided into dedicated finite elements (FE) describing the whole steering. The stress was first put on the gears models (worm gear and rack-and-pinion) and their anti-backlash systems as they have been identified as potential vibration sources. Mechanical non-linearities (clearances, non-linear stiffness) of the mechanical system are taken into account in these models. Then, this model allows simulating the transient response of the system to an input excitation. Each developed element is validated using a fitted experimental test bench. Then, the general model is correlated the same way. Hence models can be used to study the dynamic behavior of EPS systems or sub-systems.
View full abstract