This paper presents a vibration control method for a wire changing its length such as an elevator cable and a crane wire. We propose a synthesis method of vibration controller considering a time-varying uncertainty directly and having the robustness for a variation of tension, a transition of frequency of resonance and a spillover of high order modes. The performance and robustness of the proposed control method is examined through the numerical calculation on variable conditions.

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In our paper Active-Passive Mass Damper are considered. The structure is the following; On the top of the vibration structure there are two additive cascaded masses, one mass denotes a Passive Mass Damper and the other one is an Active Mass Damper (AMD) on the passive mass damper. Switching control between TMD and AMD is expected better performance than ordinary AMD vibration control and TMD on the basis of the AMD's kinematic energy.

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Input shaping can be used to eliminate or greatly reduce residual vibration of flexible mechanical systems. The input shaping filter is based on the characteristics of the system, namely the frequencies and damping ratios. When the actuator saturates, the dynamics become nonlinear. As the nonlinearity increases, the effectiveness of standard input shapers tends to degrade. This paper presents a new class of input shapers that account for actuator saturation.

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This paper presents a novel active vibration control methodology termed "active boundary control"-ABC-which enables one to generate a desired boundary condition at any designated position of a target beam structure, thereby permitting the structure to possess desired properties characterized by the boundary conditions. It is found that applying ABC to the driving point of abeam where a disturbance force acts, suppression of all the vibration modes of a flexible beam may be achieved. It is also found that applying ABC to a current conventional boundary condition of a beam, a beam, a completely vibration-free state in the designated region of a beam can be realized.

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In this paper, we report a new control system for rotational cranes using a non-linear controller. Until now, the control problem of such a system has been treated by using a linear controller. However, the control systems designed by this method did not perform well. Although rotational cranes can be expressed as a non-linear dynamics system with infinite modes at high frequencies, it is impossible to make the model the same as the actual crane. We therefore considered an approximate non-linear model having similar performance as the actual crane, and applied a method we developed to convert the non-linear control problem to a linear one. The experimental results show that this approach is effective for the control of rotational cranes.

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An approach has been developed to design resonant vibratory equipment as self-sustained oscillating systems with electronic and electromechanical positive feedback and an actuator of a synchronous type. The feedback produces the exciting force by means of transformation and amplification of the motion signal. Autoresonant control relies entirely on the amplitude-phase characteristics of the vibrating system. Unlike amplitude-frequency curves, amplitude-phase curves of single-degree of freedom systems are single-valued and gently sloping near the resonance for many cases of practical importance regardless of Q-factor and nonlinearity of the vibrating system. The implementation of autoresonant control for the new nonlinear vibratory electro-mechanical systems is described.

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Pick-and-place processes are commonplace in manufacturing. A method has been devised for increasing the precision of these tasks using dynamic vibration absorbers to attenuate the dynamics induced by the step-like disturbances coming from the point-to-point reference commands. These novel absorbers are then combined with an intelligent choice of cycle time to produce enhanced performance of lightly damped manufacturing machines.

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A rigid (micro) robot mounted serially to the tip of a long, flexible (macro) manipulator is often used to increase reach capability, but flexibility in the macromanipulator can make them susceptible to vibration. A rigid manipulator attached to a flexible but unactuated base was used to study a scheme to achieve positioning of the micromanipulator combined with enhanced vibration damping of the base. The interaction forces and torques acting between the robot and its flexible base were modeled and studied. When these interactions are properly controlled, damping can be added to the base.

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This paper introduces a variable resistance type energy regenerative suspension using PWM step-up chopper. The energy regenerative suspension has nonlinear characteristics with dead zone for low speed motion. Hence the energy is not regenerated nor has it damping force. In order to overcome this problem, a step-up chopper is introduced between the actuator and the charging circuit. This chopper is controlled by velocity-dependent PWM signal to improve the damping characteristics and the efficiency of the regenerative suspension. The suspension system changes its height according to the carrier load. Hence linear AC motor is used to the isolation actuator. A simple experiment is performed. The results show better performance than the standard regenerative suspension.

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A practical and effective semi-active on-off control law is developed for vibration attenuation of a natural, multi-degree-of-freedom suspension system, when its operational response mode is available. It does not need the accurate system parameters and dynamics of semi-active actuator. It reduces the total vibratory energy of the system including the work done by external disturbances and the maximum energy dissipation direction of the semi-active control device is tuned to the operational response mode of the structure. The effectiveness of the control law is illustrated with a three degree-of-freedom excavator cabin model.

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An active vibration isolation system is proposed which uses an active dynamic vibration absorber as a servo accelerometer in a low-frequency range and as a vibration control device in a high-frequency range. The configuration of the proposed vibration isolation system is clarified. An experimental apparatus is developed for basic study. In this apparatus, a translational vibration in the vertical direction is actively controlled. The carried out experiments demonstrate that an active dynamic vibration absorber can operate as a servo accelerometer in a low-frequency range.

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This paper describes a new vibration control method. The distinctive feature of this method is the use of linear actuators and permanent magnets. Linear actuators actuate the magnets and control attractive forces which are used for reducing vibration through adjustments of the air gap between magnets and an object. To examine the performance of the proposed vibration control method, we consider a system modeled on an actual method, we consider a system modeled on an actual experimental device. Numerical simulations are carried out and the effectiveness of the proposed method is determined.

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Implantable left ventricular assist devices are powered by batteries. Their limited capacity has to be used as efficiently as possible. At the example of a MAGLEV centrifugal LVAD it was demonstrated that a drastic reduction of power consumption (50% in the bearing) could be achieved by vibration control. A vibration controller design for the non-linear plant is discussed, simplified and extended to four harmonics. Anew phase shift strategy is presented to eliminate time-consuming matrix operations. Based on this simplification the implemented algorithm applied on the bearingless slice motor allocates little memory and requires short computation time. Additionally, the decreased control currents lead to higher control margins of the power amplifiers and therefore to improved robustness.

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Wire-driven mechanisms offer great potential for the advancement of large-area manipulations. Unfortunately, the natural flexibility of wires requires vibration control techniques to ensure safety and efficiency. Since most large-workspace manipulations require human operation and lack pre-determined motions, many typical vibration control techniques are not applicable. Fortunately, input shaping allows for real-time vibration suppression and has been experimentally verified in many different applications. This paper will show that input shaping can also significantly reduce vibration in wire-driven mechanisms.

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This paper deals with the active control of progressive waves of a simply supported, lossless, thin distributed-parameter planar structure. It is the purpose of this paper to present a novel active wave control method for blocking the progressive wave, and thus a quiet zone (a specific region where vibration is to be prohibited) is produced. It is also the purpose of this paper to present a means to visualize wave propagation of the structure, whereby control effect for suppressing power flow in terms of vibration intensity, progressive waves, reflected waves and the combination of thereof becomes evident.

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This study considers the wave control of multi-story structures with the active mass dampers (AMD). A control design method for realizing the impedance matching controller by using the AMD is proposed. A controller is designed so that the controlled AMD has the property of the impedance matching controller at the higher frequency region including the resonant frequencies of the structure while preventing the drift of the mass at the lower frequency. Physical parameters directly used for designing the controller are only the actuator dynamics, therefore, the proposed method can be applicable for highly flexible structures. For the closed loop stability of the whole system including the structure, the notion of the Nyquist criterion is introduced. Experimental results are shown to prove efficiency

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This paper considers the active vibration control of a flexible beam using distributed parameter sensors from the viewpoint of active wave control theory. It is the pupose of this paper to present a new type of sensor which makes it possible to measure waves amplitude of a flexible beam in real time fore the application of the adaptive feedforward control system. Firstly, a novel wave filtering method using distributed parameter PVDF sensors is proposed which can be regarded as the integration of infinite point sensors, and have arithmetic calculation by being shaped on the basis of arbitrary functions. Furthermore, the characteristics of the wave filter are clarified. Finally, experiments on active wave control using the wave filter are conducted, and the control effects for suppressing the vibration of a targeted frequency are presented.

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In this review paper, it will be briefly surveyed current development of damping related technology which was mainly obtained through the works of JSME Damping Research Committee. After an overview of main research topics carried out by the members of the Committee, the report will describe the state of arts regarding research development of damping technologies. Firstly, investigation will be done on advancement of damping materials including both of metallic and nonmetallic materials. Secondly, innovative damping devices and seismic isolator proposed by the Committee members will be introduced. Particular attention will be focused on adaptive and magnetic dampers. Thirdly, some discussions will be done on vibration troubles and damping countermeasure which were reported through the questionnaire carried out in the Committee.

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Both passive and active shock isolation systems have been previously investigated. However, passive systems are limited in that they cannot adapt to different load conditions; active systems are not practical in many applications, as they may require large power supplies. Another solution to the problem is to implement a "smart" damping system, which typically requires little power, is controllable in real-time, and achieves nearly the same performance as an active system. This paper focuses on shock isolation using these "smart" damping devices. Following the basic problem formulation, the optimal design of passive and active shock isolators is given. These results are then extended to the "smart" (semi-active) shock isolation case. Theoretical analysis shows that if the linear spring stiffness is properly chosen and the control force is appropriately regulated, the shock isolator using "smart" damping can achieve optimal performance and has a better robustness than the passive shock isolator.

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A linear model is presented by a simple form for a two-dimensional magnetic seesaw damper using permanent magnets, which was proposed by Murakami and Satoh. The magnetic system is simplified with an equivalent magnetic circuit from which the incremental magnetic flux is described by the displacement of the moving core. Since the magnetic reluctance of magnet cores varies with frequency, the expression is formulated in the frequency domain. A numerical analysis follows with the measurement of the incremental magnetic flux.

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Various devices and equipment using ER effects have been developed and studied. When an ER fluid is used in shear mode, the ER fluid is filled between a pair of opposing parallel electrodes. We have proposed one-sided pattern electrodes that have many advantages. In this paper, four kinds of composition of electrodes including the both-sided electrodes and one-sided electrodes are considered. The electric fields are analyzed. The manifestation of ER effects is experimentally verified in four kinds of composition.

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Using the optimization algorithm, design parameters of Multi-Tuned Mass Damper systems composed of a few dampers (a-few-TMD systems) are optimized with respect to two kinds of robust widths. One is the robust width against the variance in the natural frequency of the structure and the other is that against the variance in the damping coefficient of TMD. A-few-TMD systems gain advantage over conventional single types in terms of these two robust widths. Through parametric studies, a set of robust design formulas for a-few-TMD systems with uniform mass distributions is derived. The design formulas cover the practical range of the mass ratio in control of civil structures (0.001 to 0.04) and are composed of functions of design conditions, that is, the total mass ratio and the required additional damping coefficient.

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Analytical methods for steady-state response of the piping system with various types of the nonlinear dampers are proposed. As one span model of piping system, a beam simply supported at one end, with the nonlinear dampers at the other end is dealt with. In this paper, impact damper and elasto-plastic damper are described as nonlinear dampers. The resonance curves and mode shapes are obtained by the method of approximate solution

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An optical radar sensor is described that scans space with a light beam in the shape of a quadrangular prism by using a cross-axis pendulous galvano mirror, and detects an object and measures the distance to the object according to the light reflected from the object. The basic requirements of safety assurance by space monitoring and the safety requirements of the radar sensor are logically defined. Examples are given of the concrete configuration and characteristics of the radar sensor. It is demonstrated that the optical radar sensor outperforms the camera studied as protective device in combination with image processing.

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This paper proposes a new type of seismic-type sensor based on the principle of servomechanism. The low natural frequency of the sensor is realized by using a positive feedback of the relative displacement and velocity signal, and a negative feedback of the relative acceleration signals between the measured object and the inner mass of the sensor. Based on this principle, a sensor with a light mass and hard spring was constructed. It is shown that a sensor of small size and which is lightweight can have a measuring frequency range in the low region. The results are demonstrated through both simulation and experimentation.

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This paper is concerned with the active tactile sensing using an artificial two-finger system together with the evaluation of human tactile sensation using the system. First, the samples such as newspaper, superfine paper, tracing paper, paper towel and toilet paper are pinched and/or stroked by the thumb and the forefinger of the volunteers, and their feelings of softness and roughness are obtained and classified with the use of the questionnaire. Next, the same samples are pressed and slid by the PVDF tactile sensor mounted on an artificial robotic two-finger system and the output signals from the sensor are collected and stored. Features on the collected data are then extracted by introducing the wavelet analysis and calculating the variance. They are compared with the evaluation of human fingers. Results of comparison show that the active tactile sensing using the artificial finger system well evaluates and describes the human tactile sensation.

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A new fluxgate sensor was developed for the high sensitivity for local field and insensitive against non-local fields (e.g. terrestrial field). The sensitivity was attained as high as 10 nT for real time observations with 30 ms filtering time constant with the very high spatial resolution of about 10 μm or less.

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To obtain high precision rotation with active magnetic bearings, high resolution sensor are needed. From a literature study, finite element modeling and mathematical derivations, the electrostatic principle of fringe capacitance is investigated. It is used for the design of an optimized sensor pattern. For a fixed sensing area of 75 [(mm)^2], different fringe capacitances have been realized on flexible and rigid PCBs varying the distance between two conductors (from 0.1 to 0.3 [mm]) and the width of the conductors (also from 0.1 to 0.3 [mm]).

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This paper deals with a nanometer-cutting machine with Stewart platform type parallel mechanism structure. The movable range of the prototype is 20 μm in the x- and y-directions and 100 μm in the z-direction. The resonant frequency of the prototype is approximately 85 Hz in all directions. The stage motion was controlled by the displacement feedback control of the link length. The standard deviation of motion error was 0.1 μm after the calibration. This stage was applied to a positioning device of the nanometer-cutting machine. Pockets could be machined on acrylic resin.

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The feasibility study has been investigated to build a small satellite (so called 'nano-satellite'), which has 3-kg mass and less than 30-W power, since October in 1998. The experimental 3-axes attitude control of the nano-satellite under micro-gravity field is conducted at in Japan Micro-gravity Center (JAMIC) in 2001. The small reaction wheel is used as an actuator for the attitude control and enables compensate the small residual deviation of the presume error. This project investigates the validity of the feedback control with sliding mode control because of the correspondence for the non-linearity of the control system and the excellence for robustness^<[1]>.

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A prototype magnetorheological (MR) damper was manufactured and its performance was studied. The magnetic circuit in the damper was designed to focus magnetic flux into the orifice by combining ferromagnetic and diamagnetic components and illustrating the magnetic flux lines using FEM. The damping force of the MR damper was experimentally measured for sinusoidal excitation under various amplitudes, frequencies and applied magnetic field strengths. The performance of this damper was analytically and experimentally compared with that of a damper which has the same structure except for not setting diamagnetic components around the piston.

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This paper describes a high-powered metal bellows type gas-liquid phase-change actuator. The bellows of the actuator has been welded many coned disc springs of SUS304,which has 18 mm in diameter and 26 mm in total length of bellows. The operating liquid is perfluorocarbon (C_5F_<11>NO). The actuator has a 10 Ω heater and a thermistor for measuring operating liquid. The circuit board has also been fabricated to control the pulse width of heating time in balancing between heating and cooling in the air. The motion of the bellows with the above circuit board has closely resembled to Boyle's law. We confirmed two kinds of axial forces, which are 100 N at 1 mm displacement and 20 N at 7 mm under pulse controlling on 80 ℃ with supply of 12 W.

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High frequency relative vibrations of closely spaced flat surfaces create a repelling force that can be used to hold the surfaces apart. As this research shows, the dynamics of the surrounding surfaces and enclosed air-layer are highly coupled. Contrary to what was assumed in the past, the division of the excitation frequency range into spring- and damper-like regions is inaccurate in the presence of vibration of mechanically flexible surrounding surfaces. A laboratory set-up was built and modeled by means of several coupled sub-models consisting of a piezoelectric part, a mechanical amplifier and the levitated object. while a finite-difference scheme is being used to compute the distributed pressure in the air-layer.

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A mass measurement system using the self-excited oscillation of a nonlinear system is developed. The system contains an on-off relay with hysteresis and switches force acting on the object in relation to the velocity of the object. The mass of the object is determined from the period of the oscillation. An apparatus with two voice coil motors (VCM's) is developed for experimental study. The VCM's work as a force generator and a velocity sensor. The effects of system parameters on measurement accuracy are studied experimentally. It is proposed to use one VCM as both forcer and sensor.

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A magnetically levitated stepping motor using high T_c superconductor has been studied. The levitated stepping motor consists of a cylindrical rotor with superconductors and a stator with eight electromagnets. The rotor measures 10 mm in diameter, 46 mm in length, and 18 g in mass. The superconductors of the rotor are field-cooled in liquid nitrogen with various field-cooling currents. The levitated rotor is driven by an eight-phase excitation with various driving currents. The rotation angle by each step is 90 deg. The rotor spins as the excitation phase shifts one by one. This paper discusses the dynamics of the motor driven by a new driving method.

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As the micro-technologies are developed in the precision manufacturing, the importance of micro actuator is increasing. But conventional actuators, piggy-back type or mechanical contact type, have limits to cope with demanded performance. As a solution, the magnetic suspension technology, showed much possibility, has been researched. This paper is about the design and control of a magnetically suspended linear actuator. The operating principle is explained with the magnetic force analysis. The control logic to achieve smooth motion is described. Finally, the experimental results are given.

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Estimations of calibration uncertainty in vibration acceleration standards are described. The sensitivity of charge amplifiers and parasitic motions of a vibration exciter are measured, and then a method of analysis of uncertainty is proposed. In the calibration of charge amplifiers, the calibration procedure is explained in detail, and several CAs (charge amplifiers) are calibrated in terms of the frequency sensitivity gain, the long-term stability, the linearity for input charge, and the linearity for gain setting. The maximum discrepancy in the sensitivity gain is 4% among the tested CAs. A sensitivity difference of 1.5% still remains when same type CAs are compared. It should be mentioned that a difference of 1.5% is not negligible. Such a large difference is not well known up to the present time. As for the evaluation of the vibration exciter, its parasitic motion is investigated using a dual laser doppler vibrometer (LDV). The parasitic motion mainly consists of transverse, rocking and bending motions. In order to evaluate the transverse motion quantitatively, the ratio of the vibration amplitude in the transverse direction to that in the longitudinal direction is measured as a function of the frequency. The ratio curve shows clear peaks at the resonance frequencies of the exciter. A novel method of estimating the uncertainty due to the transverse motion is proposed. Additionally, the effects of rocking and bending motions on acceleration measurement are discussed. To reduce the effects, a simple compensation method is adopted, and improved calibration results are obtained.

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Robot and virtual reality technologies may be applied to rehabilitation training, so that fewer human therapists are needed, training can be quantitatively evaluated for effectiveness, and training can be more enjoyable to patients. A training system to assist in rehabilitation can use robot or other virtual reality technologies, but it must be far safer than an ordinary industrial robot system. The authors have been studying actuators which are safe and easy to control, and have developed force display systems using such actuators. As an application of force display technology, they have developed a rehabilitation training system using ER actuators. The authors have also developed a computer program for the system which evaluates the physical capability of the upper limbs of patients and assists in their rehabilitation training. This paper is a summary of the basic experiments with the system and some virtual reality software and discussed its potency in rehabilitation use.

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ER fluid has rheological characteristics which can be controlled by the electric field. Using particle-type ER fluid, we developed a brake device. In this study, this ER brake was used in an isokinetic exercise system for rehabilitation training under restriction of constant rotational speed of a joint during exercise. Such a passive system using a brake is inherently safe for human use.

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This study possesses the same freedom degree as man's hand, and aims at the development of the upper extremity prosthesis where the noise is generated only by lightness. This thesis describes the mechanism to achieve the feature, the performance of the shape-memory alloy used, and the multi freedom degree, the system configuration, the grasp experiment of the object, and the policy in the future.

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In order to realize a wearable power assisting suit for assisting a nurse caring a patient in her arm, the power supply and control systems have been miniaturized. The new suit consists of shoulders, arms, waist and legs units and is fitted on her body. The arms, waist and legs have pneumatic rotary actuators driven directly with micro air pumps. The muscle forces are sensed with a new muscle hardness sensor utilizing a sensing tip mounted on a polymer thick film device. This paper gives the design and characteristics of the new power assisting suit verifying its practicability.

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The main purpose of this research is to develop a micro vehicle for severely disabled people because vehicles they can drive safely and easily are so limited in Japan. In this paper, the methods of designing manipulating system considering their physical abilities are written and a new counter-force-method suitable for them is proposed.

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In this study, the dynamic behavior of a non-linear full vehicle model having active suspensions and a controlled passenger seat is examined. The non-linearity comes from the dry friction on dampers. The suspensions considered are Mc Pherson strut type of independent suspensions. Three cases of control strategies are taken into account. First, only the passenger seat is controlled. Second, only the vehicle body is controlled. Then, both the vehicle body and the passenger seat are controlled at the same time. The method is chattering free sliding mode control, which is robust and successfully applicable to non-linear systems with superior performance. The time responses of the non-linear vehicle model due to road disturbance and frequency responses of the linear vehicle model are obtained for each control strategy. At the end, performances of these strategies have been compared and discussed.

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This paper presents a design method of nonlinear controller for semi-active suspension systems with Magnetorheological (MR) dampers having nonlinear properties. A dynamic model of the MR damper, which consists of a nonliear static element followed by a linear dynamic element, is introduced and then a control law based on the integral sliding mode control proposed by V. Utkin and J. Shi is presented. It is shown that the proposed model enables us to reduce so-called chattering, which takes place due to the nonlinear properties of the damper and high frequency switching of the sliding mode control. Although this model includes more modeling error than other rigorous ones in the literature, the use of this model makes it easy to design the sliding mode controller. Numerical Simulations illustrate the effectiveness of the proposed method.

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To evaluate the performance of a developed engine, the vehicle model constructed on a computer can be virtually reproduced using a low-inertia dynamo. This method does not require any devices of the actual vehicle except for the engine. In this paper, we show a control method of a low-inertia dynamo connected to an engine with a six-speed gear transmission through a flywheel with a spring and a damper (FSD) and a steel shaft so as to generate torque according to the vehicle model simulation. We regard the variation of the gear ratio with shifting of gears as the variable parameter in the system and apply μ synthesis to obtain a single controller that is applicable from the first gear to the sixth gear. Since the FSD stiffness is nonlinear, we also take its variation into account in the design of the controller. By carrying out simulations and experiments it is verified that the μ controller designed is effective.

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