Microvibration control technology has been rapidly becoming important in a number of fields including superfine technology in semiconductor manufacturing and microgravity research experiments in space. In this paper, an active 6DOF microvibration testing device using air actuators is studied from the view point of control system design. The control system proposed in this paper consists of 3 control functions: a dual model matching controller, an on-line feedforward controller using disturbance information, and a multi axis off-line feedforward controller to generate a modified reference input using experimental data. The effectiveness of the proposed control system is verified through reference following experiments when adevice for vibration test in equiped on the table.

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Recently, it is required to reduce the vibration of the optical disc drive such as CD/DVD-ROM with high transfer rate. This paper describes a new vibration reduction method by blending dynamic damper and automatic balancer so as not to increase the weight. We optimizied the natural frequency of dynamic damper which concerns relocate of balacing mass of automatic balancer. In consequence, the vibration of this drive was reduced by half of conventional drive at 11OOOr/min speed.

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Entitled magnetic seesaw damper has more than ten times larger damping coefficient compared to conventional ones provided that the same volume of magnets are used. In frequency region of earthquake, or under several Hz order region, the damping coefficients of this damper are more higher. In this paper, it is shown that maximum damping forces of this damper becomes nearly 40 percent of magnetic attractive forces, analytically. Experimental data of the case where this damper is applied to a 843[kg] vibration isolation table are given.

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The original magnetic seesaw danper has two magnetic paths which branch off from magnetic pole pieces via gaps. In other words, between two yokess, exists a permanent magnet having two pole pieces. Each side has two gaps which increase or decrease oppositely to the other side gaps, i.e., all four gaps change their length due to extermal vibration. Therefore, its rather tedious to adjust strength of mechanical spring constants to overcome unstable force. In this paper, it is proposed that any one side gaps is fixes to a constance, introducing simple structure and easy adjustment. However, some decrease of damping are unavoidable. Some experimental data are given.

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Active mass damper (AMD) mounting on the cage of super- high- speed elevators has been developed for the purpose of reducing horizontal vibrations of cages excited by forced displacements from elevator guide rails. By anticipated disturbances, such as, the cage excitation by passenger or vertical vibration of the cage, the control stability of AMD could be disrupted, which was especially sensitive to gravity components detected by acceleration sensors. Therefore, a new AMD controller, which was designed based on LQ optimal control theory, and the installation of high pass filters were considered. Excellent advantages of the AMD system having the proposed control synthesis were successfully demonstrated by numerical simulation and also actual high speed elevators running in the field, and the stability of the controller and the reduction of 30-40% in horizontal vibration were finely realized.

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Maghetorheological fluid (MR fluid) is known as one of highly functional materials, and apparent viscosity of MR fluid can be varied in accordance with the applied magnetic field strength. Adapted for a damper, a variable mechanism can be given to the damper. In this paper, MR damper was constructed and its characteristics were examined. Furthermore, a neural network was applied to vibration control system of model structure with MR damper and vibration control experiment was conducted.

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This report is studies on the methods of the control of liquid surface wave control in the case of an incline-type automatic pouring machine. The machine has two inputs, transfer for going to pouring place and rotation for pouring into the molds. When the motion is designed to move quickly, rotation and transfer generate big waves. But the transfer pattern is previously known, a predictive control method can be applied. The transfer pattern is fixed, so the transfer pattern can be used to reduce waves. The predictive control purposes that the container makes to move by aimed angle and to goal position without generating waves as much as possible. Finally we demonstrated the usefulness of the approach presented in this paper through the control simulation and the experiment

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A semi-active control strategy using variable dampers had been applied for vibration control of actual buildings and vibration isolation of vehicles. In these systems, natural frequencies are very low. Thus, we thought it was very interesting that the semi-active control using variable dampers was applied for structural control whose natural frequency was high like 10-20Hz. In order to confirm possibilities of semi-active control in high frequency, we performed experiments using the variable damper and the single degree of freedom structure. In this paper, experimental results and the characteristics of variable damper will be shown. Validities and problems of variable damper for semi-active control will be described bellow.

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This paper describes experimental results of structural control using MR damper. First, the controller for the MR damper will be discussed. Next, device performance test results will be shown. Finally, semi-active vibration isolation controller will be applied to 3-DOF structure that supported by rubber and MR damper. Tracking control system with force feedback shows a good performance for the nonlinear controller of the MR damper. The experimental results will show that the semi-active control strategy with MR damper is fit for the sky-hook controlled vibration isolation system on broad band.

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It paid attention to the vibration generated when walking in the flooring and the walking feeling. The amenity evaluation of both was examined. Different structural floorings were prepared and the walking experiment was done. At this time, the vibration of the flooring was measured at the same time with two or more acceleration sensors. The evaluation item of the walking feeling paid attention to the deflection of the flooring and the remainder condition of the shake. Then, the following became clear since the correlation of the vibration and the walking feeling of the flooring were examined. In a little amplitude of the flooring, amenity is sensitively evaluated. It paid attention to not only the vibration of the flooring but also the rigidity and the design indicator of a pleasant floor structure was proposed.

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This paper describes a prototype model of active control system for reducing transmitted noise, which is caused by floor impulse and perceived at the downstairs room. The active control system actuated by bi-morph piezo-electric elements are installed in the intermediate space between the upstairs floor and the downstairs ceiling. The bi-morph piezo-electric elements are reinforced for improving bending strength by polyethylene plate with low bending stiffness. H-infinity robust feed-back control system is designed assuming application of four actuators and four sensors to eliminate the sensor signal. Control experiment is conducted to prove the effectiveness of the control system.

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This paper describes active noise control with intelligent compound structure. Intellectual compound structure is the panel which contains sensors and actuators in itself. This panel consists of a sheet of piezoelectric plate, which contains electric pole domain in the surface, and two sheets of thin stainless plate for reinforcement of bending strength. We apply robust IMC control system, which performs as howling cancelling and also rejecting the effect of disturbance. We conducted the control experiment to verify the effectiveness of the IMC.

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Recently, manufacturing industry uses a vibrating feeder that applied resonance phenomenon. However, there is a possibility of shattering delicate objects since the vibrating feeder contains multidimensional vibration. In this study, a new conveying system using Linear Stepping(Pulse) Motor(LPM) is proposed. This new conveying apparatus system contains only horizontal vibration. Controllability for LPM is much better than conventional vibrating feeder, as we can easily order a new feeder to appointed feeder velocity directly. On the other hand, the conveying motion of specimen is calculated analytically. By linking the LPM drive simulation with conveying simulation, the coupled system simulation is constructed. When a command for velocity is given to LPM, the coupled simulation of this system is able to solve a conveying motion of specimen in the block. The usability of coupled conveying simulation in determining feeder velocity for desired conveying velocity was confirmed.

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A magneto-electric composite element of two functional materials: giant magnetostrictive (GMM) and piezoelectric materials, is developed for coil-less magnetic force control. This force control is based on the inverse magnetostrictive effect of GMM and realized by composing a closed parallel magnetic circuit with a permanent magnet in magnetic yoke. The magnetic force between two yokes can be adjusted by controlling the strain in the magnetostrictive rod. For the purpose of efficiently controlling the strain of the GMM rod, a magnetp-electric composite element is constructed, in which the two functional materials: a giant magnetostrictive rod and a stack piezoelectric actuator, are mechanically coupled via strain. The magnetization in the GMM rod can be controlled by adjusting the voltage of the piezoelectric actuator. It is confirmed that this element works to adjust magnetic force and has wide frequency bandwidth. As an application of this element, a magnetic levitation system is proposed and the movable yoke was levitated by simple PD control. This system has advantages of low power consumptions and low heat generation cpmpared with a conventional system with electromagnetic coils.

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The giant magnetostrictive materials (GMM) is characterized by high power, large displacement, fast response as well as safety, long lives and flexibility, which are often required by the aerospace structure. As one application of the giant magnetostrictive actuator, the vibration suppression for the aerospace structure has been explored. In this report, results of the several simple vibration control simulations and experiments using developed devise and/or simulation model are reported. They show that vibration suppression in 10 s can be realized. Low voltage drive of GMM in vacuum and inflammable atmosphere may be of vital significance. A novel pressure sensor incorporating with a telecommunication capability has been developed and its performance has also been evaluated.

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This paper aims at presenting the advantage of the separate type of the hybrid piezoelectric damping comparing with the previous series type of the hybrid piezoelectric damping from the viewpoint of active control power requirement. There are three types of the hybrid piezoelectric damping; one is a series type (integrated type, type I) and others are separated types in collocated and non-colocated conditions (types II and III). Simple flexible cantilever beam with surface bonded piezo-elements is used as a test structure. The results indicate that the hybrid piezoelectric damping whose configuration is type II and III are superior to the type I in active control power requirement under the severe vibration suppression performance condition.

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This paper proposes a new type of seismic system sensor based on the principle of servomechanism. The low natural frequency of the sensor is realized by using a positive feedback of relative displacement, relative velocity signal and negative feedback of relative acceleration.signal between the measured object and the inner mass of the sensor. Based on this principle, the sensor of a light mass and hard springs is constructed. It is shown that the sensor with small size and lightweight can have a low frequency measuring range. The results demonstrated by both theoretically and experimentally.

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This paper studies the optimal control profile to move flexible space structures in the rest-to-rest maneuver. A simple model of flexibe space structures treated in this paper is a rigid main body equipped with a flexible appendage. The optimal control profile is obtained by minimizing the bending moment at the root of the flexible appendage and the performance is compared with that of the time-optimal control. The optimal control profile is also studied in this papaer with inequality constraints of the maximum value of the bending moment. The optimal control profile obtained in this study is verified the validity of its performance by both of numerical simulations and experiments.

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The Engineering Test Satellite VIII(ETS-VIII), which will be launched in 2003, has large flexible appendages such as deployable antennas and paddles. On the other hand, high attitude accuracy is required, but it is hard to determine its flexibility parameters correctly under 1G circumstances of ground test facilities. The on-orbit system identification of its dynamics is very beneficial for this case, because it enables the validation of flexibility parameters used in the design phase, and besides the controllers gain tuning. The experiment of this identification is planed now. In this paper, we explain the overview of this experiment system and summarize the results of preliminary case studies for the system identification of the ETS-VIII dynamics model. In the case studies, it is assumed to use 1) attitude and translational responses during longitude station keeping maneuver, 2) step responses in normal operation mode and 3) impulse response in normal operation mode. The identification is feasible if the impulse responses are available. The responses during station keeping maneuver are not efficient for this identification without changing the conditions (e.g. the firing pattern of station keeping thrusters).

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Self-adaptation of structures for discrete connection by between subsystems is discussed in this paper. The system identification and the vibration control of the Large Space Structure (LSS) is described. The trend on study of LSS constructed by connecting subsystems was explained and a concept of the self-adaptation was proposed. Applying the Subspace State Space Identification method (4SID) that one of the system identification, a beam structure patched piezoelectric ceramics has a function of the self-sensing, and more, the structure can achieve to equipped with the adaptability due to system variations by connecting subsystems. The idea of self-sensing and the advantage of the 4SID gives a insight for the connecting problem of the LSS.

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We consider estimation of stability derivatives of aircrafts from flight data. An estimation scheme which utilizes multiple observers is applied. The multiple observers are designed for representative models derived by rewriting the state equation of the system. Under a certain condition, the output signal is described by output estimates generated by the multiple observers. Using this property, the estimates can be computed from input and output data.

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This paper presents a synthetic method that based on both the algorithm of the geometry nonlinear feedback and nonlinear system optimal control of hierarchical differential feedback regulation. This method enables us to solve optimal feedback control problems without solving the Riccati Equations or adjoint vectors. Also, the method takes into consideration the avoidance of conjugate points, which is a important aspect of research in optimal control of nonlinear system. As a simple example, airship optimal feedback tracking control has been studied numerically using the present algorithm.

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This paper is devoted to analysis three dimensional behaviors of wave traveling on tether connecting between a mother satellite and a subsatellite and studies analytically the behavior of flexible tether by modeling tether as continuous material that have density and flexibility. Result of numerical analysis show insight into the three dimensional behavior of flexible continuous material tether in space.

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Most of mechanical sensors and actuators located on the satellite main body induce many disturbances and influence stringent pointing and stability requirements. Momentum and reaction wheels are essential instruments for the satellite attitude control systems, but they are also one of the large disturbance sources. The authors developed a device to detect wheel disturbances precisely. In the test, a ball bearing type reaction wheel is mounted on an air- floating block of this device and the displacement caused by wheel disturbances is measured. The wheel disturbances measured by laser range sensor and force/torque sensor are evaluated and the usefulness of low frequency and level disturbances detection is shown.

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In inter-satellite link with a lot of low-earth-orbit (LEO) satellites, each satellite will communicate with one or more satellites. In such cases a satellite needs to have multiple optical antennas which are required small and light. A communication link between satellites is cut at high latitudes because an antenna drive angle is large due to high relative angular rate. In order to reduce this link-lost time, a wide drive range with high speed is required for an optical antenna. To meet these requirements, we propose an optical antenna of a coude-path type. This paper describes the mechanism and the experimental results of the optical antenna we have developed.

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In this paper, the vibration isolation control of the Centrifuge Rotor (CR) is discussed. CR is the rotating equipment for providing artificial gravity in the International Space Station (ISS). CR is the biggest item of mechanical equipment in ISS; CR has a weight of 2t and the diameter of the rotor is 2.5m. CR is scheduled to be launched in 2006 and NASA plans to utilize it for life science experiments conducted during a 10-year period. In order to provide precise gravity environment, it is required that CR has high vibration isolation performance; for that purpose, CR is equipped with vibration isolation mechanism (VIM). VIM consists of pivot-type springs and active dampers, and it provides 0.1 Hz of cut-off frequency for the vibration isolation.

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Static shape control for deployable membrane space structures using discretized piezoelectric films around creases is proposed. The performance of the shape control on one-dimensional deployable membrane is theoretically investigated. The results show the possibility for controlling the shape distortion with small pieces of piezoelectric films.

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This paper proposes a method for solving BMI problems in simultaneous design of structure and control systems. This method transfers simultaneous design problems with H_∞, H_2, and pole placement constraints described by BMIs into dual-LMI problems by Schur complement, and locally solves the problems through the cone complementary linearization algorithm. A simple numerical example indicates that the method comparatively quickly finds a structured controller which contains structural parameters.

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This paper describes simulation of deployment of a tethered satellite system. The mass and flexibility of the tether are taken into account in the simulation model, which we call a flexible model. In the control design, the mass and flexibility of the tether are neglected, and the controlled system is expressed by a bilinear state equation, which we call a bilinear model. We compare simulation results of the flexible model and the bilinear model under a linear state feedback control, which is designed for the bilinear model. The simulation result of the flexible model is almost the same as the simulation result of the bilinear model, which implies that we can employ the simple bilinear model for the control design.

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This paper studies the attitude control problem of articulated spacecraft. In such a system, it is required to control the spacecraft attitude against disturbances and model variations by appendage rotates at high angular velocity. To this problem, we apply the robust gain scheduled controller synthesis based on H_∞ synthesis of Linear Parameter Varying System. The controller is designed by two type methods of analytical and numerical convex decomposition. The capability of these methods is investigated and compared through a numerical study.

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This paper proposes a method of energy efficient trajectory control for free-flying space manipulators. The proposed method reduces control torque in the manipulation by using redundant degrees of freedom in the manipulator motion. The required torque is reduced by controlling the major axis of the dynamic manipulability ellipsoid (DME) to the direction of the desired end-effector motion as close as possible. A numerical example is given for a model of planer 3-link space manipulator to show the feasibility of the present local control algorithm. This paper also investigates the influence of various mass distribution due to the added mass at the endeffector.

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This study is concerned with proposing and developing the motion and vibration control strategy for the flexible link mechanism in order to achieve the high performance and stability. Reducing vibration and making positioning time faster are simultaneously required in this system. First, a modeling method of the flexible multi-body systems is presented based on modal analysis. In this method, each flexible body modeled by FEM is transformed into the modal space at the 1st stage of the model reduction and then the total system is constructed by transforming the reduced model obtained by synthesizing each modal model into the modal space at the 2nd stage reduction. A smart flexible link mechanism is developed by the piezoelectric film sensors/actuators in order to achieve the required motion and vibration control performance. The control systemdesign is conducted with mixed H_2/H_∞ control problem, resulting in the enhanced performance and stability.

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This paper studies a control problem to maneuver the attitude of free-flying space robot. Model of the free-flying robot is a rigid main body equipped with a one-link flexible manipulator. The control algorithm applied in the present paper is the minimum-time control and thus the bang-bang control. Results of numerical analysis show a fundamental dynamic feature of free-flying space robot equipped with a one-link flexible manipulator.

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When we control a flexible manipulator based on a dynamic model, we need to estimate the state variables with accuracy. In the case of flexible manipulators, the state variables include elastic deformations and their velocities due to flexibility. We focus on visual sensor to measure these distributed state variables of flexible manipulators. First, we discuss a distributed state estimation method which uses discrete position information of markers attached on flexible links. Second, we apply the virtual joint model to flexible manipulators, and transform the real elastic deformations to the virtual joint angles. Third, when we estimate the lumped state variables by the proposed method, it is possible to identify physical parameters of the dynamic model. Finally, some experiments were carried out to verify the effectiveness of the proposed method.

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In this paper, we consider the two-inertia system with the torque/acceleration feedback as the vibration control. The inertia-ratio is a very important factor on two-inertia systems. It is shown that each feedback can change the inertia-ratio. The disturbance responses are compared, and the effectiveness is shown experimentally.

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When the mobile manipulator works on the rough terrain, the mobile manipulator oscillates. In such case, to make the mobile manipulator pursue a task, it is necessary to estimate the oscillation. In this paper, a method for estimating of the oscillation of the mobile manipulator using the stereo camera mounted rigidly on the mobile manipulator is described. When the mobile manipulator oscillates, a point which is fixed at the scene moves in the images obtained by the stereo camera. From the motion of the feature points in the image, the motion of the mobile manipulator can be estimated. A method for controlling the position of the end-effector is also described. Simulation results is shown to confirm the effectiveness of the method described in this paper.

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This paper proposes a inchworm type robot with crawler for rescuing under destroyed constructions. The previous report shows the method of climbing up stairs using the 5-link type robot. Unfortunately, this robot is able to move only straight. For practical use, mobile robots have to change its moving direction. This paper develped a 3rd version of the inchworm robot which has crawlers for three links, a rotational joint for changing of the lateral direction, and the control syatem with dual CPUs. In order to estimate the ability of this robot, the kinematical analysis and the development of the control program are executed. As a result, the effectiveness of this robot is confirmed by the experiment.

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This paper develops an approach for the control of the motion of a multiple-link manipulator possessing unactuated joints. A three-rigid-link arm with its shoulder joint actuated and two elbow joints unactuated is modeled as a nonlinear Affine system. The system is a case of second-order nonholonomy since the constraints at the passive joints contain terms of accelerations. In the proposed method to solve the problem of optimal positioning the control input is expressed as a general function of a Fourier basis parameter acquired by using the Ritz method; then this parameter is optimized through the application of the Newton method. Numerical simulations were carried out and tests with an experimental setting demonstrate the effectiveness of the approach.

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If the artificial muscle which had the characteristic of the skeletal muscle can be created, it thinks that the control system like the movement system of the human being which has applicability flexibly can be realized. This study had the last purpose of the development of the artificial muscle which combined electro-rheological fluid and ultrasonic motor, experimented on the basis in the real time rotation speed control of the ultrasonic motor by RT-Linux.

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ER fluid is a fluid whose rheological characteristics can be controlled by electric field. We developed a clutch-brake device using particle-type ER fluid (ER clutch-brake). In this study, at first, we used it as a clutch for Rehabilitation Training System which is a force display for rehabilitation. And next, we used it as a brake for Isokinetic Training System. The isokinetic exercise is one of the training methods, in which joint velocity is kept constant.

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The purpose of this study is to realize horse-like trot gait by a quadruped robot. In this report we proposed the model of horse-type quadruped robot which has a motor-spring system at each fetlock joint. Next we designed and made a quadruped robot based on the proposed model. Finally steady and periodric trot was done by the robot.

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We propose a method to analyze underwater robots basing on a learning control and a nonlinear time scale translation. In the water, the additional forces and moments called added mass, hydrodynamic damping and buoyancy act on the arm and it is difficult to estimate these forces and moments. At first, the input torque pattern of the learning control is modified by the tracking error without estimating added mass, hydrodynamic damping and buoyancy. Next, the obtained torque pattern is investigated through a nonlinear time scale translation.

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This paper presents our Auto Tuning System which is to tune up the control gains to optimal values for industrial robots. A perfomance index is well defined so that it can represent the dynamical features of real robots aptly. The system is not only practically useful by itself, but also sophisticated when considering the analytically optimal pole assignment of a controlled system. Once a factory worker sets it going, Auto Tuning System tunes the control gains over the all required configurations and joints of a robot arm. While its operating, workers are completely free of observation.

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Recently, visual servoing has gained increasing attention from researchers in the field of both vision and control. In this paper, a novel image-based visual approach for controlling nonholonomic mobile robots to track a moving target is presented. The mobile robot is endowed with a fixed camera, and a visual feedback controller is used to control the mobile robot to track a moving target of interest. A three dimensional state space representation of the camera-target visual interaction model fully defined in the image plane is used. In the case of unknown height of the moving target's symbol traced by camera, global stability is proved using an adaptive backstepping control law. Based on Lyapunov's direct method, the closed-loop stability is guaranteed. Experimental results of a mobile robot with two actuated wheels endowed with a fixed camera are provided for illustrating the tracking ability of the controller.

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A distributed control method for hyper-redundant manipulators of shape adaptation to complicated and unknown environment is proposed. A manipulator consists of serially connected joint units. Each unit is modeled as a translational vector, and it controls the length and direction of this vector. The tip of each unit detects an obstacle using its proximity sensors and autonomously moves along the obstacle with a certain distance away from it; thus the manipulator bends, expands and contracts along the shape of environment. The manipulator can move into/out of long and narrow space only by guiding its end-effector. The adaptability of a planar manipulator with directional sensors to round shape is evaluated.

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This paper presents an approach of realization of compliant motion by a decentralized control in redundant manipulator. Manipulator is divided to several subsystems, and each subsystem has virtual impedance in partial workspace. Each subsystem performs autonomously by using virtual impedance and the information transmitted from adjacent subsystem. The reaction forces are calculated by the reaction torque estimation observer. It becomes possible to realize the compliant motions against environment. The validity of this method was confirmed by the numerical simulation.

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This paper describes a new type of two stage servo head arm for magnetic disk drives. The four PZT actuators are bonded to the stainless steel head arm. The PZT actuators are used for the accurate follow-up of a track and to control some of vibration modes of the head arm. The servo system has a bandwidth of more than 2 kHz. The PID control method was used in the design of controllers for vibration control and tracking motion control of the arm. The characteristics of a prototype of the servo system were measured and its effectiveness was verified by experiment.

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In this paper, we develop a new design method of feedforward control input by using final-state control method. The feedforward input can be obtained so as to reduce the spectrum at the desired frequency. The proposed method is applied to short seek control of hard disk drives. The experimental results show the effectiveness of our method.

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In Hard Disk Drive, a digital control system is usually applied because of the dispersively recorded positioning signal on a disc. Therefore, to improve a head positioning accuracy, it is necessary to make a sampling frequency high in conventional method. However, it is very difficult to increase a sampling frequency, because of the decrease in Hard Disk Drive capacity. So, to solve this problem, the method of improving a head positioning accuracy without making a sampling frequency high is proposed in this paper. In proposed method, a control signal to Voice Coil Motor is changed in sampling period. Furthermore, by setting the changing time allocation and gain of the control signal to the optimum, a phase delay by discretization is recovered and stimulating a resonance mode of Voice Coil Motor over Nyquist frequency is avoided. Proposed method does not require an alteration to hardware at all, and this method is easily applicable to a mass-production only by changing a control program. The validity of the proposed method is confirmed by the numerical and experimental results with a miniature 2.5-inch Hard Disk Drive.

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In the optical head servos of optical units, the restraint of vibration, both from the head itself and from external disturbances has become an important technical issue. In this paper, we introduce a hybrid control method that combines the use of an external disturbance observer with that of a VSS(Variable Structure System) controller for the purpose of restraining vibration, and we show that this method results in reduction of actuator displacement to 75% of that achieved with previous methods.

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