Several recent advances in motion and vibration control technology are reported. Since it is far beyond the author's ability to cover the whole aspects of motion and vibration control technology, an overview of technological tendency is presented first, which is followed by reports on the recent works of the author.

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Contact processes may be represented by local discretization, by a rigid approach or by a mixed method using both ideas. For the dynamics of mechanical systems a rigid body approach is described achieving good results also for multiple contact problems. This paper considers mainly contacts in multi-body systems where the corre-sponding contact constraints vary with time thus generating structure-variant systems. The equations of motion for dynamical systems with such an unilateral behavior are discussed, solution methods and applications are presented.

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Current research in contact free levitation is in two directions : On one hand, there are open questions in the field of modeling and control, especially in advanced control schemes such as the "sensorless" or "self-sensing" approach of active bearings. On the other hand, the pressure towards reduced cost could make again passive contact-free levitation an interesting option, especially since there are new developments and potential applications in this field.

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In this paper, some recent results obtained for various aspects of the moving load problem are discussed. While encompassing a range of problems involving discrete subsystems traversing a primary distributed parameter system, a simple vehicle crossing a bridge is used herein to demonstrate various effects and their relative importance.

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In order to control the vibrations of adjacent buildings connected with control devices, this paper presents two methods for designing a semi-active controller with a variable damping device. Semi-active controllers are applied to control the vibrations of building structures. A semi-active device is defined as a type of passive element that has variable properties which may be changed according to external actions. In this study, a Magnetorheological Fluids damper is used instead of a variable damping device. Simulation results demonstrate the availability and possibility of semi-active control.

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The X-, Y- and Z-Tower office buildings of the Harumi Island Triton Square are located very close to one another. The distance between two of the three towers is as narrow as 13 meters. To increase the habitability of these buildings when they vibrate during a strong wind, they are equipped with active-damping bridges. Each active-damping bridge connects one building to another and actively controls expansion and contraction to reduce vibrations. In this paper, a general description of the buildings and equipment will be presented, following which an applied control system design method will be related. The paper will conclude with a report of tests on the actual buildings conducted to verify performance.

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The base isolation is a promising technique to eliminate the damage from ground motion. In order to improve the safety of a semi-active building, the magneto-rheological (MR) dampers are used to replace the traditional adjustable dampers. As the MR damper features nonlinearity, it is not easy, and even impossible, to apply the traditional control strategies on the basis of precise mathematical models. Hence, this paper presents an indirect adaptive control structure based on neural networks. This control structure consists of a neural controller, and a neural identifier which can estimate the back-propagation error of controller. The numerical simulations show that the new strategy is much better than the results of neural network controller without quadratic momentum term.

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This work develops a new type linear damper that uses MR fluid, consists of a number of plates with. MR fluid is filled in the damper, so that magnetic fields freezes MR fluid. Resisting torque (friction torque) is generated when the plates slide due to the shear of slits of the plates. It is proven that the presence of the damper affects the vibration of the plate as predicted by numerical simulations. The damper is maintenance free, and it is one of passive damper type with a good durability.

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A three-story structural model was equipped with Magnetorheologival (MR) damper, and the structural response was investigated under various excitations. The performance of the prototype MR damper was also studied under various conditions of amplitude, frequency and electric current to the coil in the damper. MR fluid is known as a class of functional fluid whose yield shear stress can be varied by the applied magnetic field strength. Because the maximum yield snear stress is far larger than ER fluid, whose propertied can be controlled by the applied electric field strength, MR fluid is thought to have great potential in applying in mechanical and civil engineering field. A neural network was applied to an adaptive vibration control system for the structure and the performance of the control system was verified by simulation and experiment.

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Many precise measurement devices or optical instruments are sensible to disturbances that are induced by environmental conditions. Therefore, such instruments have to be decoupled mechanically from the environment by means of vibration isolation. Because of the high requirements (high degree of isolation even at low frequencies), a sufficient vibration isolation can only be reached by using active elements. The process of realization of such an active vibration isolation system includes the choice respectively development of a suitable actuator, the modeling and verification of its dynamical behavior, the design of capable controller and finally the implementation of the vibration isolation system in the bearing system.

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This paper proposes a reduced-order physical modeling method for controlling the multi-modes of vibration of an active isolation system with an elastic table. In the lightweight isolation table, the elastic modes appear on the isolation table in a lower frequency domain. In order to avoid the spillover phenomena, the reduced order model, which includes elastic modes, is used in this modeling method. In this study, a reduced order physical model, expressed by 5DOF systems for controlling the multi-modes for designing the controller, LQ control systems, and a two-degrees of freedom control method with feedforward control are applied. Finally, the discrete model and the controller design are verified through numerical calculations and experimentation.

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The influence temperature can have on PZT actuators and sensors can be significant. The variations in these properties can ultimately affect the ability of PZT devices to actively suppress vibrations in flexible structures. To analyse the influence of these property variations, a reduced-order-lumped-parameter finite element model of a light, flexible structure was developed. The model is enhanced by including provisions for PZT actuators and sensors adhered to the structure as well as a damping term to account for material nonlinearities. These validated models assisted the development of an adaptive controller for the active vibration suppression of structures subject to significant temperature variations. The controller was found numerically and experimentally to improve vibration suppression performance over an equivalent fixed gain controller.

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The dynamic transfer equations of FBRE system excited by an off-center force are deduced according to the mechanical impedance method in this paper. FBRE system is composed of a machine, isolators and a flexible plate-like foundation. The characteristics of power flow of FBRE system excited by an off-center force are studied with the power transmitted to the foundation as the objective function. The difference and relationship of the effects between the symmetrical force and moment, and an off-center force are analyzed. The active control effects are also discussed.

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A suspension system is proposed whose compliance for direct disturbance forces is zero. The zero-compliance property is realized by connecting a conventional spring and an active suspension mechanism with a linear actuator in series. The active suspension is designed to have negative stiffness for disturbance forces acting on the suspended mass. The fundamental properties of the proposed system are studied both theoretically and experimentally.

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In this paper, a generalized theoretical model of floating raft vibration isolation system is presented, and the corresponding structural analysis method is developed to predict the power flow characteristics. Being based on the above, numerical calculation of the transmitted power flow for practical floating raft coupled system in engineering is performed to explore the effects of mount frequency and isolator damping on the flexibility of supporting structure and transmitted power flow within the overall system.

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Viaduct roads have wide applications in big cities carrying high traffic load in order to decrease the traffic density and to conduct the subways to highways. Viaduct roads are constructed by steel structures instead of concrete ones on areas of earthquake risks. The low weight of steel structures causes problems such as vibration and noise. There is an increasing demand especially in populated areas to suppress vibration and noise in highway roads for reducing noise related environmental pollution. In this research, it is demonstrated that modal separation and modal actuation of structural modes of a flat and curve roads using cluster filtering and cluster actuation depend on the existing modal symmetry axes. Every eigenfunction of a two-dimensional structure can be expressed in a form of the "(m, n) modes", m and n being modal indices. Simulation results obtained using FEM model of flat road show only the certain mode groups such as odd / odd, even / odd, odd / even, and even / even ones. When studying a curved viaduct road, it is possible to classify mode groups as odd / odd or even and even / even or odd.

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In this paper we propose a design method for active vibration isolation with a saturated input. Actuators have limitation of force or torque that can be generated in themselves. In order to overcome this saturation problem we introduce gain scheduling of a controller. The input saturation can be formulated as a nonlinear function and we use the hyperbolic tangent function that is continuous to the output of controller. By introducing this function we formulate the linear parameter varying system according to the input that the controller needs. The controller uses acceleration of the lowest story only as a feedback signal and is implemented to the experimental setup of a four-degree-of-freedom structure. We verify that the control performance is maintained even if a large earthquake comes so that the actuator is saturated, although the fixed H_∞ controller lowers the performance.

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Hanshin Awaji Earthquake (1995) caused enormous damage to Container Cranes at Kobe Harbor in Japan. After that, the horizontal type of vibration isolation system has been applied to the container crane as well as buildings and bridges. This paper presents a rocking type of vibration isolation system and its performance is investigated by nonlinear transient analysis of 3-D FEM comparing the horizontal type of vibration isolation system. The results of real size FEM analysis shows the availability of the rocking type of vibration isolation system as well as horizontal type of one. And we shows that the optimal damping parameter is determined by the conventional model of the rocking type of vibration isolation system.

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To join in the students racing car development program that is organized by the Society of Automotive Engineers, students at the Kanagawa Institute of Technology developed a formula-type racing vehicle with space-frame body structure. The vehicle is powered by in-line four-cylinder gasoline engine that is used as a load-carrying member of the frame. This design can cut much weight, but tends to invite heavy vibration because no resilient vibration insulator can be placed between the engine and the frame. To overcome this trade-off problem, structural dynamics modification technique was applied through FEM and experimental modal analyses. By this technique, very light structure was developed with such design features as aluminum alloy panels fixed to the frames and corner ribs. To suppress remaining noise and vibration by crankshaft second-order harmonics, and active dynamic damper system was installed. Using liquid filled cavity as a leverage mechanism, the dynamic damper was able to produce large counter force with relatively small electric current. In addition, the damper was controlled by adaptive feed-forward control scheme using engine tacho-pulse as the reference signal. By this arrangement, the active dynamic damper could track the second order harmonic. Though the active dynamic damper cannot control all the modes, this study demonstrated the potential of active dynamic damper when vibration insulator performance is limited.

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This paper presents a new method for motion and vibration controls of a three dimensional flexible shaking table. The shaking table is need of light weight for reproducing the earthquake wave and the variety of input signal exactly. However, then the elastic modes appear on shaking table in operating frequency region. So it is important to control the motion and vibration of shaking table simultaneously. The research purpose is to control the vibration and motion of the shaking table by using the reduced order modeling technique and LQ and LQI control theory. The modeling procedure and the control design are described. Control simulations on the discrete model are carried out to demonstrate the effectiveness of the method. Experimental work is shown to demonstrate a final verification.

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Analysis is performed to evaluate the response and control energy dissipation in actively controlled elastic structures during earthquake. Previous studies show that using optimal control algorithm gives optimal control results only in terms of the selected cost function, but it may not be the most efficient when the results are compared to another choice of cost function. In view of this shortcoming, the present research uses maximum control energy dissipation to define the most effective optimal linear control law, and results show that maximum control energy dissipation exists and it depends highly on the earthquake characteristics.

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This paper deals with cluster control to suppress structural vibrations occurring on viaduct roads because of vehicles' ride on them. A viaduct road has been modeled using finite element method to obtain the structural modes. Based on the finite element model of the flat road part, a cluster control method is introduced. The modes of flat viaduct road have been classified in four groups at first. Each group has been controlled separately using sliding mode controller (SMC). The control action is realized using cluster actuation. It is verified that cluster actuation and sensing based on SMC suppress considered structural modes without observation of spillover effects.

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In this paper, the active vibration controller design for isolation platform with digital signal processor implementation is presented. Three active vibration control techniques are compared in two control structures. In the feedforward control structure, adaptive controller using filtered-x least mean square algorithm with synthetic vibration reference is presented. In feedback control structure, the linear quadratic gaussian theory is used to employ for controller synthesis. Moreover, a hybrid control structure that combined feedforward and feedback control structures to obtain the desired robust performance and fast convergence is proposed. The experimental works are carried out to evaluate the proposed systems for reducing the vibration on test platform. The comparison of three control structures and experimental results are described in this paper.

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Applying the compressibility of air, the vibration transmissibility can be reduced by the passive pneumatic vibration isolator, but the vibration amplitude in the low frequency is still not decreased, even having resonance. Using active pneumatic vibration isolator the disadvantage of the passive system can be improved. The mathematical model of the pneumatic vibration isolator is built up and the characteristics of the effecting parameter are defined. Using off line method to identify the active valve controlled system, and design the adaptive controller to control the vibration isolator. The experiments show that the vibration amplitude of passive pneumatic vibration isolator in the low frequency can be decreased by active control.

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We introduced a method a method for analyze three dimensional distributions of electro static potentials and forces in a DNA molecule. A DNA molecule was expressed by a three layers cylinder so as to reflect the Debye-Huckel theory. The potential in each region was described by Laplace and Poisson equations. The Green function method was applied for the discrete helical charge distribution within a one helical turn of the finite cylinder. The calculated potentials and forces depended on the circumferential angles. The Present method, when it was improved, will be available for evaluating the free energy of the DNA molecule.

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A three-dimensional musculoskeletal model of human body with a command generator to the muscles is proposed to analyze biped walking in this paper. The original command generator is modified to allow larger delays in the transmission line of feedback passes. It is shown that an appropriate walking pattern can be obtained even in cases when there exist 5 msec delays in the transmission lines. This means that the proposed command generator suggests the structure of neural rhythm generator of human nervous system.

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This paper describes a numerical and experimental study of a double jointed fish robot utilizing self-excitation control. The fish robot is composed of a streamlined body and a rectangular caudal fin. The body length is 280mm and it has a DC motor to actuate the first joint and a potentiometer to detect the angle of the second joint. The signal from the potentiometer is fed back into the DC motor, so that the system can be self-excited. In order to obtain a stable oscillation and a resultant stable propulsion, a torque limiter circuit is employed. From the experiment, it is found that the robot can stably propel using this control and the maximum propulsive speed is 0.42m/s.

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We introduced the H2 control principle to evaluate the Calcium ion channel gating function by Allosteric modeling. Calcium ion selective channel was described by four identical subunits. The modeling was characterized by cooperative positional changes of voltage sensitive S4 molecule in each of the subunit and concerted conformational changes of all the subunits. We applied the H2 control strategy for minimizing the influence of noise on the out put as the functions of the Calcium channel. The temporal changes in amounts of any given conformation of the Calcium channel were computed with altering the weighting parameters of the control inputs, the state variables and the control inputs on the controlled out put z. As a result, the S4 molecules in each subunit of the Calcium channel seems to influence the disturbance of the temporal changes in amounts of the specific conformation of Calcium channel system.

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In order to stabilize the inherent unstable system like the inverted pendulum on a cart, severe judgment of situation by the operator is required. Accordingly, it can be expected that the human operators exhibit a complex behavior occasionally. This paper tried to identify the chaotic characteristics of human operation from the experimental time series data by utilizing fuzzy inference. It showed how to construct rules automatically for a fuzzy controller from experimental time series data of each trial of each operator to identify a controller from human-generated decision-making. Furthermore, it tried to identify the individual difference of human operator's behavior from time series data and acquire individual skill of human operator. It also investigated the chaotic behavior of human operator and the possibility of the formation of complex system composed of the human operator and the control objects. The operators in the experiment are skilled to some extent in stabilizing the inverted pendulum by training, and the data of ten trials per person were successively taken for an analysis, where the waveforms of pendulum angle and cart displacement were recorded. The maximum Lyapunov exponents were estimated from experimental time series data against embedding dimensions. It was found that the rules identified for a fuzzy controller from time series data of each operator showed well the human -generated decision-making characteristics with the chaos and the large amount of disorder. It was also found that the individual difference of the degrees of freedom and the amount of disorder in the system composed of the human operator and the control objects.

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In this study, a trajectory planning method of a CP control twp-link flexible robot arm by using the genetic algorithm is proposed. The flexible robot arm consists of a first rigid link and a second flexible link, and the desired trajectory is set to be a straight line. The numerical calculations have been carried out, and it is confirmed that the residual vibrations almost disappear, and the trajectory error can be considerably reduced.

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A multilevel hybrid genetic algorithm, which integrates genetic algorithms and traditional gradient-based optimal design methods, is investigated for solving the hierarchical optimization problem in structural control system design. A three-level mathematical model for the problem is developed in which the first level optimizes the controller number, the second level optimizes the positions of controllers in a structure, and the third level optimizes the parameters of controllers. The algorithm is applied to a 16-storey building excited by typical earthquake forces and controlled by a type of passive control device.

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In this paper, maximum efficiency operation of two types of permanent magnet synchronous machine drives, namely* surface type permanent magnet synchronous machine (SPMSM) and interior type permanent magnet synchronous machine (IPMSM), are investigated. The efficiency of both drives is maximized by minimizing cupper and iron losses. Loss minimization is implemented using flux weakening. A neural network controller (NNC) is designed for each drive, to achieve loss minimization at different speed and load values. Data for training the NNC are obtained through off-line simulations of SPMSM and IPMSM at different operating conditions. The accuracy and fast response of each of the NNC is proved by applying sudden changes in speed and load and tracking the NNC output. The drives efficiency obtained by flux weakening is compared with the efficiency obtained when setting the d-axis current component to zero, while varying the angle of advance "φ" of the PWM inverter supplying the PMSM drive. A NN is also designed and trained to vary φ following the derived control law. The accuracy and fast response of the NN controller is also proved.

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This paper reports the experimental tests conducted on the 5-storey benchmark model defined by Samali [1], using an Active Mass Driver (AMD) system, where the control action is achieved by using Fuzzy Logic controller and UTS state-of-the-art shake table facility. The performance of the Fuzzy controller is checked against Hachinohe 1968,and Northridge 1994 earthquake records as an excitation to the benchmark model. The advantage of the Fuzzy controller is its inherent robustness and ability to handle any non-linear behaviour of the structure. The results of the experimental tests show the ability of the adopted Fuzzy controller to reduce the building responses for the two earthquake records used.

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In this paper, an Active Mass Drive system (AMD) is used as vibration control device for reducing structural response of the UTS five storey international benchmark model under 1940 El Centro earthquake. A robust fuzzy sliding mode controller based on state feedback is proposed as control strategy for controlling the AMD and reducing structural response due to seismic loading. The controller, combining equivalent control, switching control and fuzzy logic control maximizes the advantages of sliding mode control and fuzzy logical control to provide robustness and at the same time minimize the chattering effects. A numerical simulation using MATLAB is conducted to compare the proposed control scheme to other control strategies in order to illustrate the effectiveness of the proposed control law.

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This paper is concerned with a research about fuzzy neural networks and application in fault diagnosis of rotary machine. To build robust fault diagnosis by neural networks, fuzzy neural networks are proposed. Fuzzy neural networks can memorize fault patterns and recognize fault patterns by association, and have good tolerance to unstable practical sample data. Through application in monitoring and fault diagnosis of pump sets of oil plants, it was verified that fuzzy neural networks are effective to handle practical sample data and make accurate fault diagnosis.

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For a linear system with matched uncertainty, an integral sliding mode controller using output feedback only is developed in this paper. Although the system contains an uncertain term, a novel state estimator proposed in this work is used to estimate the system states. The integral sliding vector and the corresponding controller are then designed using the estimated signals and the measured outputs. By introducing the initial condition of outputs in the integral sliding vector, out algorithm can guarantee the behavior of sliding motion starting from the initial time. Finally, a numerical example is demonstrated for showing the feasibility of the proposed scheme.

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This study focuses on the problem of robust output-sliding control design for a class of nonlinear time-varying systems. The switching functions are defined individually for each output channel and also prescribe the desired dynamics for the output errors in the sliding mode. An application to a two-degree-of-freedom manipulator indicates that the proposed switching control law drives the system state trajectories onto the chosen sliding mode in finite time and the output tracking can be achieved against a class of time-varying parameter variations and external disturbances.

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This paper deals with compensation for windup phenomena due to actuator saturation in sliding mode control systems with integral action. It is shown that the actuator saturation causes windup phenomena similar to integrator windup, which might take place in linear control systems with integral action, even if the linear component of the control input does not include any integral action. This means it is not sufficient just to apply the existing anti-windup methods for the linear controllers to the sliding mode controllers. In other words, the nonlinear component of the control input should be reconsidered. Therefore a simple modification for the switching function is presented in order to reduce the nonlinear component of the input during saturation. It is shown that this modification makes it possible to keep the plant state close to the ideal sliding mode. Simulation and experimental results show the effectiveness of the proposed method.

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It is well known that sliding mode control theory is effective to nonlinear system. Up to now, there are many approaches proposed to design hyperplane in sliding mode control theory, such as eigenvalue placement method, optimal control method, frequency-shaped method and so on. However these design methods of hyperplane used for linear model, so it is impossible to construct a precise hyperplane to a nonlinear system. On the other hand, back-stepping method, which also belongs to the nonlinear control theory, bases on the Lyapunov stability theory. We propose a design method of hyperplane by using back-stepping method, so that the hyperplane is nonlinear and no approximation. An example and experimental results are provided to illustrate the design method of hyperplane. In addition, we use J. J. E. Slotine's sliding observers theory to estimate the state variables of nonlinear system.

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The behaviors of particles in the flow is repeating several collision and friction each other. On that occasion, depending the materiality of particles, a contraction is actuated in elastically or non-elastically. A numerical simulation with Voigt model is done and added forces are divided into two directions, i.e. normal direction and shear direction. Voigt model has the friction slider to the shear direction. As the results, we corroborate the adaptability powder particles and motion control.

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This paper proposes a new state estimation using grey predictor in discrete-time system whose relative degree is more than one. To avoid using the differential operation, we apply the grey predictor of the grey system to design the new state observer. Based on the design of the new state observer, the state of the discrete-time system could be estimated accurately. Besides, the new state observer could incorporate the pole-assignment method to effectively stabilize the discrete-time system whose relative degree is more than one. a numeric example is used to demonstrate the success of the developed state observer.

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A procedure for the design of a robust μ-synthesis controller for position control is presented. It allows to overcome stability limitations usually occurring when PID-controllers are developed for systems with low-frequent flexible modes. The procedure is formalistic and can be used for SISO and MIMO systems in the same manner. An electro-mechanical torque measurement device is used as an example, and the controller implementation for this SISO system using analogue controller implementation for this SISO system using analogue components is demonstrated.

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Speed variation in a pump, a compressor or a wheel of electric vehicle often causes vibration and noise, which shorten the life of the machine. Although the repetitive control can suppress the speed variation, there are the following problems : ・If a reference velocity changes, the period of the speed variation changes and the effect of the suppression becomes bad. ・The tuning parameters are difficult to be tuned. In this paper, we propose a controller composed with PI controller and the controller suppressing the specified frequency waves based on the internal model principle. It is verified by simulations and experiments that the proposed method overcomes the above mentioned problems.

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This paper studies an optimal control of a golf swing robot that is used to evaluate the performance of golf clubs. Mathematical model of the golf club is derived by Hamilton's principle in consideration of the bending and torsional stiffness, and the eccentricity of gravity center of the club head on the shaft axis. The state variables that cannot be measured are estimated by state observer considering disturbance. Control torque is applied after the impact. LQR is applied to stop the robot during the follow-through. Numerical simulation is compared with experimental results by using a swing robot.

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In this paper modeling and vibration control problems are studied for aerial vehicles for the live-line maintenance work. In contrast with the bending stiffness of the boom. the mass of bucket is very heavy therefore bucket vibrations are caused by the change of the derricking angle or the rotation angle. Equation of motion for vibration suppression of aerial vehicle is derived in the case of simultaneous actions of derricking and rotation. Furthermore a velocity feedback control scheme is proposed based on the idea that the bucket vibration suppression is realized by increasing the damping ratios of the 1^<st> and 2^<nd> vibration modes. Here the bucket velocity is obtained from its acceleration signals. while actuators are small plungers attached to the derricking cylinder and the hydraulic motor for rotation. Simulation results illustrate the control performance and the closed-loop system stability of the proposed scheme.

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