A theoretical and experimental investigation is conducted into impact oscillations between a pantograph and an overhead rigid conductor line in a railway current system. The contact problem is modeled as impact oscillations of an intermediate spring-supported flexural beam excited by an oscillating plate. A numerical calculation using the modal interation relationship equations, which describe the modal velocities after the impact as functions of velocities before impact, are made to clarify the impact oscillations with multiple modal vibrations. Moreover, we conducted an experiment using a similar model based on the analytical model. Qualitative agreement was demonstrated between the experiment and theoretical results.

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Impact vibration of cantilever beams with collision wall, that is set with almost no clearance, was treated as an example of impact vibration of strongly unsymmetrical system. Vibrations in the wide excitation frequency range from near 1st natural frequency to near 2nd natural frequency were investigated. The followings were made clear from the numerical analysis: (1) Near 2nd natural frequency, the internal resonance between the 1/7-th sub-harmonic vibration of 1st mode and the primary resonance of 2nd mode is occurred. Because the vibration has a feature of the 1/4-th sub-harmonic vibration, vibration amplitudes become large at the excitation frequencies near 1/4, 2/4 and 3/4 times of 2nd natural frequency. (2) The even order sub-harmonic vibrations of 1st mode occur. (3) The amplitude of the vibrations mentioned at (2) becomes large, if its frequency is close to those of the vibrations mentioned at (1) occur. It is supposed that the energy of the primary resonances of 2nd mode flows into the even order sub-harmonic vibrations of 1st mode through the odd order sub-harmonic vibrations of 1st mode.

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In this paper, we discussed the mechanism of periodic modulation phenomenon with energy exchange in a multi-vibro impact system using Grover wave algorithm. We assumed the proportional viscous damping, which acts as perturbation to the state transition matrix of the system. We show that the change of energy transfer velocity depends on the perturbation and state vector. The state vector with perturbation presents clockwise type and anti-clockwise type rotation in regard to its time evolution. We obtained the analytical expression of the periodic modulation mechanism of energy exchange by using perturbed wave algorithm.

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We discuss the dynamic complex contact behavior between a stator and a liner that sticks to a rotor of an ultrasonic motor. We already proposed a numerical technique using the Finite Element Method on the basis of incremental theory to analyze the nonlinear behavior for a non-rotating rotor. In this paper, we expand this numerical technique from a non-rotating rotor to a rotating rotor and propose a numerical technique to analyze the dynamic behavior of this complex contact zone. Moreover, we clear the dynamic contact mechanism and the driving characteristics of the ultrasonic motor such as the dependency of driving torque on the maximum frictional coefficient.

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This paper deals with the quenching problem of electromagnetic vibration of the motor using dynamic absorbers. The iron stator of motor is modeled by circular ring, and the two dynamic absorbers are installed on the outside of the circular ring. The solutions of forced vibration of the system are obtained by the theoretical analysis and the finite element analysis followed by the numerical simulation. Following was made clear from these analyses: (1) By installing two dynamic absorbers leaving an angle that is not equals to the one between any loops of the mode to be quenched, the amplitude of the iron stator becomes zero theoretically around the circumference of the circular ring, namely, the iron stator is perfectly quenched. (2) By installing two dynamic absorbers leaving an angle that is equals to the one between loop and node of the mode to be quenched, the quenched region near resonance frequency becomes the largest one. (3) In the frequency region that is higher than natural frequency, if manufacturing error is considered, the natural frequency of the dynamic absorbers must be a little higher than the frequency of electromagnetic force. (4) The results obtained by the theoretical analysis and those obtained by the finite element analysis followed by the numerical simulation were in good agreement qualitatively.

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A labyrinth piston compressor is one of the important reciprocating machines because it can supply a large amount of oil-free gas. It is important to improve its stability and to reduce its resonance amplitude if we plan to increase its rotating speed in order to improve its efficiency. Bending stiffness of its piston rod fluctuates as its crank rotates. Thus, this compressor can be modeled as a parametric excitation system when its bending vibration mode is considered. Unstable regions near the rotating speed corresponding to twice natural frequency divided by arbitrary positive integer value becomes larger as a fluctuation ratio of stiffness becomes increases. These regions become small as corresponding rotating speed decreases or damping ratio increases. Not only typical resonance but also subharmonic and superharmonic resonances occur when the fluctuation ratio of stiffness increases and damping ratio decreases. In unstable and resonance vibration, the component of the natural frequency harmonic vibration is dominant. Thus, its vibration can be reduced by using a dynamic vibration absorber whose stiffness and damping are determined under conditions that the fluctuation ratio of stiffness and the damping ratio of the compressor are zero.

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This paper proposes a passive type undumped dynamic absorber which has a vibration control effect for a certain frequency ranges. We designed the kinematic chain which changes a natural frequency of a plate spring tracking an excitation frequency variation with gap and verified this frequency-tracking system experimentally. This kinematic chain is applied to a passive type undumped dynamic absorber.

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This research deals with numerical analysis of effects of a vibration absorber on the amplitude of nonlinear oscillation in a high-Tc superconducting magnetic levitation system. High-Tc superconducting levitation systems have very low damping and stable levitation without control. In such low-damped systems, complicated phenomena of dynamics can be easily generated by nonlinearity of the magnetic force. Our previous research showed that, if the frequency of vertical excitation is in the neighborhood of double the natural frequency in the horizontal direction, horizontal oscillation can occur parametrically through nonlinear coupling between vertical motion and horizontal motion. This research investigates an effect of a vibration absorber on the parametrically excited horizontal oscillation of the levitated body. We calculated numerically the dynamics of the rigid body which is levitated by the magnetic force acting between superconductors, which are fixed on shake table, and magnets, which are fixed to both the ends of rigid body. A simple damped horizontal pendulum is attached to the main system as a vibration absorber, so that it is linearly coupled with horizontal motion of the main system. Numerical results proved that this kind of vibration absorber is effective in reducing the amplitude of a parametric resonance in a high-Tc superconducting levitation system.

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This study assumes the data measurement at the time of the true operation and is a thing for the non-linear vibration system to receive random input. Harmonic content occurred due to a non-linear characteristic and clarified it by higher order spectra analysis about the main resonance and the subsidiarity of main frequency ingredient intervals. In addition, in numerical simulation, I showed that it was effective as technique of being the estimate that was the robust method in the additive noise and the non-linear linear identification. Finally, I clarified that it was possible for identification to be right without making a wrong decision by using a by spectrum about 2 dof linear vibration system that the natural frequency ratio became at 1:2.

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The main purpose of the current study is to model and identify vibrations in mechanical systems subject to arbitrary external excitations. In this paper, we apply our method based on infinite impulse response digital filter technology - termed time-frequency analysis - to analyze nonlinear vibrations. Firstly, we consider transient and nonstationary forced vibrations of weekly nonlinear systems having a single degree of freedom. With the use of time-frequency analysis method, secondly, we analyze transient forced vibrations for primary and secondary resonances, which is unable to be analyzed by a fast Fourier transform (FFT) analysis. Thirdly, we discuss the passage of the system through resonance when the frequency of the excitation is varied. Moreover, the proposed analysis has the advantage over FFT analysis that we can also analyze transient and nonstationary vibration phenomena.

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In this paper, we compare results of Short Time Fourier Transform, Wavelet Analysis, Time-Frequency Analysis based on Digital Filter and High Order Spectrum Analysis, and discuss on effectiveness and problems of these methods of analysis for non-linear system. The Time-Frequency Analysis, based on the well-known digital filter, is expected improvement of frequency resolution of transient phenomena. And High Order Spectrum Analysis is expected direct evaluation of non-linear vibration. First, we constitute three kinds of numerical model including nonlinear element and simulate vibration responses for exciting input that frequency characteristic changes. Then, we apply four kinds of analytical methods to those results and discuss on effectiveness and problems of these methods of analysis for non-linear system.

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In this study, I assume true operation and perform analysis non-linear vibration in the random input and examination. The non-linear characteristic paid attention to repulsion properties by the magnetism and produced an experimental model. I estimated a nonlinearity characteristic (soft spring) that I showed a method to estimate a non-linear characteristic statistically and the effectiveness and depended on the amplitude for by using higher order spectra(ex. Bispectrum) analysis and I showed what the characteristics to be subordinate to each other such as harmonics vibration and the fraction next vibration could grasp by bispectrum mainly on the main resonance experimentally and finally I estimated a nonlinearity parameter in this vibration system experimentally and examined the equivalent nonlinearity characteristic that considered the band in random data.

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In the present study, the critical axial depth of cut at the onset of chatter in the end milling operation determined by Akaike's Information Criterion (AIC) was evaluated. AIC was applied to the time history of tool vibration displacement in order to determine the critical axial depth of cut. The axial depth of cut that makes the value of AIC minimum was defined as the critical axial depth of cut. Comparing with the critical axial depth of cut obtained using the presented AIC method and that by detecting the emergence of the amplitude of the chatter frequency, there are fairly good agreements in both results.

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The present study investigates the effect of multiple dynamic absorbers on both regenerative chatter and forced chatter. The stability lobe of the regenerative chatter with considering the effect of the intermitting cutting is obtained by the time domain analysis. It is shown that the resonance caused by the forced chatter, at the spindle speed of the local maximum of the chatter stability lobe, can be controlled by the dynamic absorbers. Furthermore it is made clear that the dynamic absorbers have a significant suppression effect on not only the regenerative chatter but also the forced chatter.

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Pattern formation Phenomena due to time delay often occur in contact rotating system. In previous study, we have been established a stability analysis method based on the existence condition in stable and unstable boundary not only in a single-DOF system but also in a multi-DOF system which all time delays is same. And, last year's report showed the possibility theoretically to apply to the stability analysis method for a system including difference time delay. In this report, we verify the availability experimentally to apply to the stability analysis method for a system including difference time delay and compare experimental results with theoretical ones of a system including difference time delay. In addition, we confirm the validity of dynamic absorbers for a system including difference time delay. As an example, we take 4 Rolls 3-DOF system that two viscoelasticity rolls rotate while contacting directly.

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While operating the contact rotating systems, a periodic polygonal deformation pattern is formed on the peripheral surface of a roll. Such phenomena is called the pattern formation phenomena. The occurrence mechanism of pattern formation phenomena for contact rotating systems was clarified by regarding the cause of phenomena as the unstable vibration generated in a time delay system. Linear analysis is sufficiently effective in order to estimate the occurrence region of the unstable vibration. However we confirmed the vibration behavior resulting from nonlinearity, such as that a frequency response shows the characteristic of a soft spring, a jump phenomenon, and higher harmonic resonance, in the experiment of a pattern formation phenomenon due to viscoelastic deformation. In this report, the authors add the adequate nonlinearity to viscoelastic part and analyze the vibration behavior of the systems. We apply analysis for nonlinear viscoelastic model by Runge-Kutta-Gill method and it compares with an experimental result.

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This paper analyzes the natural vibration of a single carriage of linear roller guides. The carriage was excited by an impulse hammer through an added mass and its response was detected by an accelerometer. The acceleration was analyzed by an FFT analyzer. The linear roller guide has three rigid body modes. The motion directions of these modes are roll, pitch and radial direction. The natural frequencies and compliances were measured changing the added mass. The mathematical model of carriage was proposed for identifying the natural frequencies, compliances and damping ratios of each mode. This mathematical model includes the roller model. The contact stiffness between roller and raceway is modeled as linear spring. Moreover, assuming the vibration damping is caused by interaction of roller and raceway, the damping force is modeled. This mathematical model can calculate the natural frequencies and compliances well. And the damping capacity of carriage is evaluated as damping ratios of each mode.

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The authors previously developed the SA/GA hybrid optimization method using a procedure of mesh size change, which is very effective method for the simultaneous optimization of the topology and geometry of a two-dimensional framed structure. However, the region searching the optimum solutions can vary depending on the types of the search individuals generated stochastically in the early stages of the SA and GA operations. Consequently, it is necessary to conduct multiple trial calculations in order to obtain the Pareto-optimal solutions globally and accurately. In the present study, therefore, the two calculation techniques are newly introduced into the previous method in an attempt to improve the computation efficiency. One is aimed at generating search individuals with a great diversity of topologies during the initial stage of the iterative calculation, and the other is aimed at preventing the search individuals with the potentiality of generating the non-dominate solutions from disappearing by competition between search individuals. The validity of the present algorithm is confirmed by the results of numerical computations.

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Dynamics and running stabilities of railway bogies with a link structure are affected by coupling motion between the roll of bogies and the yaw of wheelsets, and the coupling motion depends on the offset angle of link on equilibrium position. This study constructs a model of a railway bogie, which have the link structure, to consider coupling motion between the bogie-roll and wheelsets-yaw, and investigates the traveling stability of the bogie model by time historical responses and eigenvalue analysis by using a linearized mathematical model with the link structure. First, this study shows that the proposed bogie model expresses the effects of coupling motion between bogie-roll and wheelsets-yaw. Next, this study shows that the relationship between the critical speed for stable running and the curvature radius of the track, and the effect of displacement, which is generated by moment input in the roll-direction of the bogie, to the traveling stability and safety are investigated.

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Response distribution of a nonlinear system subjected to non-Gaussian random excitation is investigated. The excitation is a stationary stochastic process characterized by the non-Gaussian probability density and the spectral density with a wide range of bandwidth. Both bimodal and Laplace distributions are considered as the non-Gaussianity of the excitation. A non-Gaussian stochastic process is generated by calculating an Ito stochastic differential equation in which the drift and diffusion coefficients are determined by the desired probability density and spectral density of the process. Monte Carlo simulations are carried out to obtain the stationary response distributions of a linear system, a Duffing oscillator and an asymmetric nonlinear system subjected to the non-Gaussian excitation. The response distribution varies markedly depending on the bandwidth and non-Gaussianity of the excitation. Furthermore, the asymmetry of the system makes the response distribution asymmetric shape irrespective of the bandwidth of the excitation.

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Non-Gaussian response characteristics of an asymmetric nonlinear system subjected to nonwhite random excitation are investigated. Applying a previously developed analytical method, which contains moment equations method and non-Gaussian equivalent linearization technique, stationary responses are numerically computed. Non-Gaussian indicators i.e. skewness, kurtosis and equivalent linear coefficients which are defined by the 3rd and 4th order moments are considered. Responses in a family of the asymmetric parameter of the system and the dominant frequency of the excitation are plotted onto a diagram as the map of non-Gaussianity. Numerical results demonstrate the effects of bandwidth and amplitude of the excitation, as well as the asymmetric properties of the system and the dominant frequencies of the excitation, upon the non-Gaussian response characteristics.

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Since the reduction gears of motors in robotic arms have rotational stiffness, residual free vibration occurs in robotic arms after the motor stops. Therefore, it cannot shift to the next operation until it is completed by vibration and causes decline in working efficiency. As method to suppress vibration is the input shaping method, the input shaping method is effective for suppression of residual vibration in machining tools. However, this method can be applied only to time-invariant system. Since robotic arms operate changing a posture, natural frequency changes. We model robotic arms with two flexibility and consider notch filter to intercept two natural frequency in a frequency domain. Therefore we change into the mode coordinate system from the physical coordinate system and consider conservation of energy of equation of motion, an improved is proposed for suppression of residual vibration to time-variant systems. The effectiveness of the proposed method is verified through simulation.

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Various robots have been researched and invented along with improvement of actuators. However, gigantic robot is not possible to be built with ordinary robot structure which is based on a series of rigid links connected by actuated and passively compliant joints. Square-cube law confines the limitation of size. To make up more than 10m height humanoid robot, we apply Tensegric structure which is offspring of Tensegrity for the structure of the robot. In Tensegrity, form is achieved by using a disconnected set of rigid elements connected by a continuous network of tensile elements. Tensegrity structure is so light that the king size structure can be constructed neglecting the square-cube law. This paper introduces an idea of the structure of the modular tensegric parts which configure the massive size robot.

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In a control method of a manipulator, it is important that an end effector can softly touch a subject. In order to realize a control for flexibility of a hand, a control with an artificial muscle actuator has been executed. However, the artificial muscle actuators are known to have a problem in controllability because they have nonlinear viscoelastic properties. This study shows simultaneous control of manipulator posture and joint stiffness using the artificial muscle actuators. It is realized by using a simple feedback control system. We also deal with the method to obtain the ellipse that indicates the stiffness characteristic of the end effector. Moreover, the control method is used for leg control of a walking robot. The control performance of the proposed method is verified by simulation.

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This paper proposes a new fast computation method for 1-DOF hydraulic arm dynamics on multi-domain. First, it is confirmed that the popular and conventional state-space equation has two conserved quantities even in the presence of mechanical damping. Second, the state-space equation of hydraulic arms is converted by a coordinate transformation using the conserved quantities. Third, the converted state-space equation and the conventional state-space equation are compared with each other with respect to computation time. The validity of the proposed computation method is confirmed by numerical experiment. The computation time is reduced by 49% on average in initial response and 43% on average in disturbance response.

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Generally, when we try to swing up pendulums one by one in a multiple inverted pendulum system and to stabilize them, we have a problem that the control inputs to stabilize pendulums and to swing up a pendulum interfere. To solve this problem, we proposed the subspace control for stabilizing the system and the method to swing up a pendulum by nonlinear resonance based on Jacobian elliptic function, and we have achieved some results about applying their method to various inverted pendulum system. In this report, we apply these methods to a parallel-serial inverted pendulum system and verify the effectiveness of the methods by numerical simulation and experiments.

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This paper describes how to develop a closed-loop controller generating competitive motions in the coupled inverted pendula model. For this purpose, we proposed an intelligent controller consisting of a classifier, a selector and an impulse generator. The classifier is identified by off-line learning of impulse responses of the model to output the indexes of equilibrium points starting from given initial conditions. The selector binarizes a series of the indexes by replacing the desired index with 1 and the others with 0. The impulse generator outputs an impulsive force when the selector outputs 1. Then, applying the obtained intelligent controller into each of pendulums of our model independently, we numerically demonstrate that the controlled model can produce competitive motions. However, since the performance of our method depends on resolution of the training data in O(n^4)-order, improving performance may cause computational time explosion. To solve this problem, we finally propose a simple method of adding a time delay element by which the control performance can improve with low resolution training data.

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In this paper, we perform bifurcation analysis on instability arising in a pair of acrobots connected by a mechanical coupling. For this purpose, we propose a coupled acrobots model consisting of two identical acrobots stabilized at their standing position in terms of feedback control and connect them with the mechanical linkage composed by a linear spring and a linear damping. It is shown numerically that the proposed model exhibits four types of dynamics such as a simple-stable, a buckled-stable, a simple-vibration and a buckled-vibration response when the strength of coupling changes. Then, we employ bifurcation diagrams to examine correspondence between the coupling strength and the resulting dynamics. For more detailed feature of the change of stability, we also derive bifurcation sets with respect to the linear spring and damping coefficient. The result shows that the parameter condition of each dynamics can be divided by supercritical pitchfork bifurcation set and supercritical Hopf bifurcation set.

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This paper describes elicitation process of the optimum landing motion of a biped robot. Firstly, modeling of the contact between foot and cushioning material is discussed. A nonlinear viscoelastic contact model is introduced with considering of experimental results with human. Secondly in order to calculate the optimal landing process, a criterion consists of a sum of joint forces and torques is proposed. The features of derived optimal landing process is illustrated in comparison with experimental data measured by human landing experiments.

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In this study, we propose a new mobility device using tether (Tether Space Mobility Device, TSMD) for outer space. TSMD is the mobility device that moves user by taking-up the tether which is attached to the wall of the structure. This system has to contain the control system. So we applied two types of control system, arm control and taking-up control. Arm control reduces variation of posture by changing direction of tensile force autonomously. Taking-up control helps arm control by cause deflection and tension of tether deliberately. In this study, we designed the prototype of TSMD and produced it. The fundamental experiments of TSMD are performed by duplicated two-dimensional microgravity with the air bearing and the flight-table. From the result of experiment, it is found that proposed control system is effective. The effectiveness of control gain is also investigated.

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Recent years, it has been required accurate and agile attitude control of satellites. For this purpose, the necessity of Control Moment Gyros (CMGs) has been increasing, which can generate much higher torque than Reaction Wheel which is used for conventional spacecraft actuator. CMGs have singularity problem that they cannot output desired torque when they try to output high torque. When CMGs close to singularity, it's dangerous that its gimbal moves very quickly and widely. It is necessary to avoid singularity. In this paper, we focus on singularity and CMGs' angular momentum and propose a singularity avoidance method by planning path in angular momentum space. Because output torque from CMGs depends on path of angular momentum, we plan the angular momentum path that avoids singularity and its length is short as possible by application of A* algorithm. It is shown from the simulations that the proposed method can realize singularity avoidance and low gimbal drive.

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This paper proposes a novel lightweight robot arm for astronautical development by using honeycomb structure. In astronautical development, all the launched objects should possess lightweight and compact to save launch cost. For this purpose various lightweight materials have been developed. Honeycomb structure is one of such lightweight material and already used in astronautical field mainly for large panels. In this study, we propose to apply honeycomb structure to realize lightweight and compact arm.

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This research proposes a relative position and attitude control method using magnetic force with dipole magnets for formation-flighting spacecrafts without reaction wheels. This technology can be widely applied to re-configurable space structures that architect or/ re-structure themselves by assembling basic structural units. One remarkable benefit is that this control method can extend mission term in comparison to conventional control methods with magnetic force because spacecrafts never require any types of fuel for position controls or unloadings. This paper focuses on current control of dipoles which produce strong nonlinear magnetic forces and suggested a way of linearization of a nonlinear system for control. Also feasibility of this method and controllability are investigated, then the series of attitude control simulation are shown, and the next step for developing this technology will be discussed in the following chapter.

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To use elliptical vibration, we can supply and separate the work which material and shape is similar at the same time. When the vertical vibration of elliptical vibration is larger than 1.0G, works jump and the characteristics of transportation change considerably. But some works don't jump because negative pressure is caused on contact face. As a result, it is possible to separation and transportation by the presence of jump. However, it is difficult to separate works with little difference or tiny works. In this study, we try these works by changing driving frequency. First, we examined that the influence of driving frequency on jump limit. Next, we examined that the influence of driving frequency on stability of the separation or velocity. Finally, from a result of these examinations, we choose optimal driving condition of the tiny work with little difference in the face side and reverse side. In this condition, we try separation and transportation a lot of works at fast and stable using elliptical vibration.

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Many cranes are used as transportation devices in wide industrial fields. Especially, the overhead crane is known as a famous example of cranes. When the trolley moves and the length of the wire rope changes at the same time, undesired vibration with variable frequency occurs, since the natural frequency of the crane changes with the length of the wire rope. For safe and efficient operations, it is necessary to control the motion and reduce the vibration. However, it is difficult to suppress the vibration with ordinary linear time invariant controller because of nonlinearity of the cranes. Therefore, in this study, we first derive an analytical model of the overhead crane as a linear parameter varying (LPV) system. Then, we design the controller using Dual Model Matching (DMM). The effectiveness of the controller is verified through experiments.

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Mechanical elements such as rope and pulley systems are widely used in elevators and hoist machineries. For these machineries, it is necessary to perform the behavior analysis for emergency stop in order to ensure safety. "Slip" may occur between the rope and the pulley at the emergency stop, and it depends on the frictional characteristics. Since behavior of the contact between the rope and pulley is complex, it had not been studied enough so far. In this study, we propose a simple modeling of the rope and the pulley by spring-mass system through multi-degree-of-freedom approach. In the model, friction is acting on each mass. Numerical simulation is performed to evaluate the slip distance. In this study, the condition for the rope finally stopping at the emergency brake is investigated. Otherwise, the rope does not stop and it falls. We solve the equation of motion numerically by the Runge-Kutta method with fourth order.

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This paper deals with a wave control strategy for multiple pendulums system by the lateral motion control of the support. The multiple simple-pendulums system to which the controlled multiple pendulums system is virtually connected can give the lateral movement of the support of the controlled system based on the wave propagation. By assuming the wave solution of the equation of motion of the n-th pendulum of homogeneous simple-pendulums system, counting from the bottom one, has wave propagating characteristics inherent to the number 'n', the transfer function between the angles of pendulums connected next to each other can be expressed explicitly in time domain. This transfer function (impulse function) and the measured angle of uppermost pendulum give the lateral motion of the support to realize wave propagating in the controlled pendulums system. As this control includes no position control of the support, position and velocity feedback control inputs are added. The performance of wave control may become lower by adding the motion control input; however, we have the advantage to realize both wave control and support position control by one actuator of the support movement. An optimization in the wave and motion control has been conducted by tuning the feedback coefficients. Numerical simulation has been done based on the presented strategy.

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This study addresses the design of a camera stabilizer in order to stabilize the captured image from a camera on the daruma type mobile robot. The daruma type mobile robot means the two wheeled inverted pendulum type mobile robot with self-righting mechanism. The daruma type mobile robot is applied as a tour guide robot aimed at the explanation of several exhibits in the science or art museum. This robot is able to recognize an exhibit by using the image processing a prepared maker for every exhibits. The camera mounted on the daruma type mobile robot oscillates because of the acceleration and deceleration of movement, and captured an unstable images. This paper describes about the design of a camera stabilizer for the daruma mobile robot. In consideration of the structural limitation of the robot, we proposed the camera stabilizer which adopted passive mechanism. Modeling of the daruma type mobile robot included the camera stabilizer was derived. From theoretical simulations for the frequency characteristics and stability of the robot dynamics, the design parameters were indicated for the camera stabilizer. The simulation results for movement of mobile robot showed the feasibility for the vibration suppression and the image stabilization by using the proposed camera stabilizer.

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Recently, robots not only have been researched and developed actively but also have replaced humans in several fields such as the service and medical industries. For robots to coexist with humans and provide support, they must have human-like dexterity and should be very safe. Therefore, pneumatic artificial actuators are used to develop safe and lightweight robot. However, the relationship between the internal pressure and contraction ratio of pneumatic artificial actuators is nonlinear, with a hysteresis characteristic and a dead zone. Moreover, the nonlinear characteristics of pneumatic actuators change with the applied load. By such characteristics, controlled performances of equipments mounted pneumatic artificial actuators are unsatisfactory. In this study, we proposed a hysteresis model that can express the change in these hysteresis characteristics, and we constructed a position and force control system that integrated this hysteresis compensation by using the proposed hysteresis model.

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This paper deals with a control method for an achieving walking not to follow the desired angle of the rotating links between support phases. As a trajectory following control for omni-directional walking of a six-legged robot, LQI control system to follow the target orbit of the position of the center of gravity and the yawing angle of the body which was designed in a world coordinate system was designed. By using 3D model of the six-legged robot, the effectiveness of the proposed control method was examined in the case that the reference orbit was semicircle of 0.5m radius and S-turns of 0.5m radius. As a result, the validity of the proposed control method was verified.

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This paper proposes a position tracking controller for a skid-steering vehicle robot based on the back-stepping method with the Dynamic Surface Control (DSC). Since the mathematical model of this robot can not be expressed in the so-called strict feedback form, there are many potential controllers to achieve robust position tracking even based on the BS method. It is shown through numerical simulation that the proposed controller is one of the robust controllers at the presence of model uncertainty with respect to the ground condition.

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This paper proposes an evaluation method for maneuverability of pleasure boats in order to develop an electronic control steering system of those boats. Based on usability as addressed by ISO9241-11, some evaluation criteria such as effectiveness and efficiency are defined for a task of obstacle avoidance and course return. For safety and repeatability, the simulation with a simplified ship simulator, which is composed a manual hydraulic steering system as hardware in HILS, is performed instead of experiments. As a result of the simulation to show design principle of the electronic control steering system, it is found that the usability of the manual hydraulic steering system deteriorates in the case of emergency avoidance. In particular, the wakes of the course return after the emergency avoidance are caused to be periodic by time delay in the dynamics of the pleasure boat. Therefore, it is found that the electronic control steering system of pleasure boats should have compensation for the time delay.

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This paper presents the method of semi-active control design considered with characteristic of earthquake motion and sensors placement for 4-story base isolated structure with 4 oil dampers whose damping coefficient can be changed at two steps. This method uses information of both sensor placement and structural response in the control design at the same time. The relationship between the sensor placement and control effect come out in this paper. The genetic algorithm is applied to multi-layered neural network and this algorithm is used to adjust the neural network parameters in learning. We can realize reduction of the structural response to use more sensors and the relationship between the sensor placement and control effect under three different earthquake motions by the proposed control design method.

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The active seismic isolation system and the active seismic vibration control system have now been focused on because of the recent big earthquake disaster. These active control devices usually regulate actuators within structures by using a computer which processes earthquake input waves monitored with sensors. Although these systems have an advantage that a control program can be designed freely, maintenance of the computer leaves a problem to be solved when a programmer becomes absent. In this study, a novel seismic control device, in which spool valves controlled electrically are replaced with mechanical links directly driven by earthquake waves, is proposed to solve this problem.

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In this paper, a novel combination of structures for connected-control mechanism(CCM) is presented. By coupling base-isolation and ordinary structures, the vibration suppression effect of ccm is expected to be expanded, while the stroke of base-isolation layer is hopefully suppressed. Experimental structures and ccm mechanism using magnetic dampers are built and excitation experiments are carried out. The effectiveness of ccm applied to base-isolation and ordinary structures is confirmed.

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On March 11^<th>, 2011, the Pacific coast of Tohoku Earthquake caused damages to Industrial facilities with a seismically isolated structure. For that reason, in order to improve the safety evaluation methods on the current isolation systems, a new estimation using higher earthquake standards inputs are required. This paper deals with the earthquake response analysis of the seismic isolation equipment for nuclear power plants using laminated rubber bearings. The high amplitude of this new input shows a hardening property of the rubber bearing in the horizontal direction and a softening property in the vertical direction. So far, the horizontal and vertical directions analyses are considered independently, but in reality, there is a mutual influence between the horizontal and vertical behavior. Consequently, in this paper, the analysis of the coupling between those two directions will be carried out. Then, after comparing these two approaches, the utility of considering this dependency will be estimated.

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In this paper, a base isolation system with restorative mechanism using sliding bearing is developed, and the dynamic characteristics of this system were evaluated by excitation experiments. Increasing the thickness of sliding bearing edge that makes contact with surface of the lower plate, the damping ratio and the coefficient of static friction became large. However, the natural frequency is independent of the thickness of sliding bearing edge. In the case that the thickness of sliding bearing edge is 0.5mm and the damping ratio is 0.8, the peak acceleration amplitude of response waveform decreases into about 20% compared to input wave using artificial seismic wave. On the other hand, it decreases into about 70% compared to input wave using observed seismic wave. To decrease the friction force, it needs to change the material of slide bearing.

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In order to prevent a resonance on the small base isolation system using friction bearings, a bearing ball of this device is changed to a marble plate type and to a bearing ball with rubber ring. As the results by excitation experiment using seismic wave, the damping ratios of this system were increased. The natural frequency in case of the marble plate was increased. It was depending on the radius of the marble plate. However, in case of the bearing ball with rubber ring, the natural frequency was little changed. In the case that the thickness of rubber that makes contact with the spherical concaves plate is 1.0mm, the peak acceleration amplitude on the base isolation system has decreased to 40% compared to the input wave. The bearing ball with rubber ring is better than other bearings on this system.

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This paper deals with two dimensional base-isolating device for sick person's bed in ambulance. This device does the reduction response acceleration by using pendulum type inclination chassis on horizontal direction. And, this device does the reduction of relative displacement and response acceleration by using restorative force from compression spring and friction force on vertical direction too. The performance check of a base-isolating device is shown from experiment in a base-isolating device by an ambulance and Conduct simulation analysis and the experiment using vibration exciter using the experimental result by an ambulance.

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In this paper, we propose a new position control system for a dynamic absorber using a neural oscillator synchronized with a structure. The neural oscillator is one of the nonlinear oscillators whish has a property of synchronizing with special external oscillation. In this study, by taking an advantage of the property, we have been developing a new system to control the dynamic absorber. The developed system has led the auxiliary mass for the dynamic absorber to the preset target position by using a PD controller. However, the method could not dissapate the vibration energy of the structure, appropriately. Then, in this paper, we make an improvement to move the auxiliary mass to the target position through the pre-scheduled path. In addition, we also propose a method that the oscillator starts the oscillation after detecting the response of the structure. On this occasion, we take a measure to avoid improper start-up by sensor noise. This paper shows the validity of the proposed system by numerical simulation.

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