It is well known that libration of a tethered satellite system (TSS) in elliptic orbits behaves chaotic motion. By past studies, it is also known a delayed feedback controller (DFC) has high robustness and is effective in controlling chaotic librational motion of TSS. To investigate chaotic librational motion of TSS, we have developed a ground-based experimental setup that can emulate pitch motion of TSS in elliptic orbits. This setup consists of three parts; rotational stage, sliding device and lifting device. By driving these three parts synchronously, rotation central force field affecting a TSS can be emulated on this setup. We expect that the behavior of TSS can be stabilized by transferring pitch motion toward near periodic orbit. In advance of such stabilization experiments, performance of this setup, that is supposed to be capable of emulating required orbit, must be confirmed. Because appearances of periodic pitch motions in this setup approximately correspond to that in space, we can conclude that this setup has high capability of emulating librational motion of TSS in elliptic orbits.

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In this paper, contrary to the past studies that treated the fixed skew angle for pyramid type CMGs systems, an adaptive skewing pyramid type CMGs (ASCMG) is proposed, in which the skew angle is treated as a variable to obtain larger toques. For this CMG system, a steering control law is proposed, which handles not only gimbal but also the skew angle. The proposed control law consists of pseudo-inverse term and null motion term. Numerical simulations show that the skew angle automatically changes in order to shorten settling time of the maneuver, and to avoid singularities, and returns to the ordinary angle, that is, β = 54.73[deg], at the end of maneuver.

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This paper proposes the synthesis procedure for the motion control system to simultaneously reduce slippage and vibration in a planetary rover. It is confirmed that the slippage generating in early phase of the rover motion is involved with acceleration and deceleration of the driving mechanism. The vibration due to flexibility of the rover is also induced by self-motion, that is acceleration and deceleration. Therefore, in this paper, we focus on the design of the acceleration target for the control system. The acceleration profile is then derived only by solving a regulator problem with an initial velocity and taking account of the maximum value in acceleration.

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While the vehicle equipped with the boom sprayer is operated in the agricultural field, the boom may oscillate due to its flexibility. Although active vibration control by using joint actuators is a method to reduce the vibration, reaction torque may affect attitude of the vehicle. So the objective of this research is to design a control system to suppress the vibration of the boom and keep attitude of the vehicle stable simultaneously. In this paper, flexible booms are modeled as rigid arms and torsional springs connected with the vehicle at joints. In formulation of dynamic model, motion and vibration of the system are limited to 2-dimensional ones. Dynamic properties of ground and wheels of vehicle is considered in lateral and longitudinal directions. Equations of motion of the system are derived by using Lagrange's equation. Optimal type-1 digital servo system is employed to achieve the vibration and stability control of the system. The same dynamic model is configured on numerical simulation software. After examining validity of the simulation model on the software, the performance of the control system is evaluated by using the model on the software. The simulation is performed on various conditions and weighting matrices that characterize the controller.

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Effectiveness is examined experimentally in this paper for vibration suppression on tethered flexible space structures like the tethered space solar power satellites (SSPS) by employing a micro tension actuator. In the experiment, a micro tension actuator is used to generate very small tension and control the structure vibration. The micro tension actuator employs with a very flexible arm connected to tether in order to overcome the penalty of nonlinear behavior of tether. The model employed is a tethered space solar satellite. The control performance of the micro tension actuator is examined in its performance to suppress flexible structure connected through tether. Results of the experiment have verified the validity of this controller and the ability is confirmed on the vibration suppression of the micro tension actuator.

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This presentation explains the present state and the advantages of the Tokaido Shinkansen, which pioneered high speed railways in the world, and gives a brief survey of the Superconducting Maglev, a next generation high speed railway.

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This research aims at establishing an integrated control design method for the full-vehicle active-suspension system which can adapt to driving conditions and improve both ride comfort and driving stability. In order to improve driving stability, the proposed method is considered not only changes in vehicle body attitude but also vehicle motion in horizontal direction, such as yaw rate and lateral acceleration. Additionally, based on findings from a research of the driver's feeling characteristics, new control method for vehicle attitude is proposed. Moreover, the gain-scheduling algorithm that decides the balance of frequency weights with evaluation of driving condition based on several state quantities on vehicle is proposed. The numerical simulations with different road surface and operation conditions are carried out. As a result, it is confirmed that the proposed method has superior controlled performance compared with the passive suspension and skyhook control.

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It is very important to establish appropriate dynamical model of rubber bushing for the suspension vibration reduction, vehicle noise refinement and vehicle maneuverability enhancement. This paper aims to present a novel empirical modeling method of rubber bushing used in double wishbone suspension system. Firstly, the mathematical equations of both Berg and Dzierzek models are derived, and the theoretical methods employed to identify parameters are discussed. Secondly, static and dynamical characteristics of the rubber bushing were tested and the prediction precisions of the both models are analyzed with the parameters identified from the experimental data. Based on the detailed analysis of dynamical stiffness and damping, a novel empirical model is established, taking advantage of both Berg and Dzierzek models. The novel model can gain reasonable compromise between prediction accuracy, identification difficulty and computational effort, and it can be suitable tool for automotive chassis dynamics simulation and analysis.

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In this paper, correlation between surface Electromyogram (EMG) signal and lateral acceleration of the car was studied to examine the possibility of EMG as an indicator of ride comfort. As a physiological signal, recently surface EMG has been used as an objective indicator in some researches. In our study, the EMG measuring experiments are conducted with a normal car and its modified car. Two different cars make a driving slalom in the test course, and a subject sat in a rear seat. Surface EMG signals of Sternocleidomastoid muscles on both sides of the neck are measured. It is found that the values of EMG signals of opposite sides to the direction of car acceleration are growing. In addition, the results show a tendency that root mean square (RMS) value of EMG gets smaller when the acceleration is smaller.

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In this paper, we designed a control system of an electric power steering (EPS) by considering an active stabilizer. A full vehicle simulation model with the active stabilizer is derived and used to design a controller of the EPS. Although controllers of the EPS are designed generally to obtain the steering feeling similar to a hydraulic power steering (HPS), it is difficult to obtain comfortable steering feeling on driving situations such as on a rough road. Therefore, we design a controller of the active stabilizer which can not only reduce the roll motion of a vehicle body but also suppress the self-aligning torque which acts on a steering axis through front tires on the rough road. The controller of the EPS is designed by applying a gain-scheduled control considering the self-aligning torque which acts on a steering axis from the front tires during driver's steering and a sensor torque on the steering axis. The control system of the EPS considering the active stabilizer is tuned according to a design strategy of the control system. It is verified that the proposed control system is effective to obtain the comfortable steering feeling similar to the HPS during the driver's steering and reduce the loads of both the driver's steering and the EPS during the rough road running.

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In recent years, it is reported that passenger's dynamics and sensibility are different from a driver. However, there are few researches about a suspension control which considers the dynamics of human body, and a sitting position. In this paper, new semi-active suspension control logic is developed to reduce passenger's vibration and motion. First, a vehicle and passenger model including the dynamics of human body and the sitting position is constructed. Second, robust control system design method which uses the vertical acceleration of a passenger's head as one of controlled value, is proposed. In order to control the jerk which is generated by changing of a damping coefficient rapidly, the robust controller is designed based on Lissajous figure of damping force. From the result, it was confirmed that in nearly the resonance frequency of vertical direction of the passenger's head, the proposed control method can reduce the passenger's vibration better than general control methods which use a vertical acceleration of the vehicle body as the controlled value.

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The seats for high speed railway vehicle have vibration characteristics which induce high frequency and torsional vibration. That has a possibility to disturb the ride comfort. To analyze the vibration mechanisms and to obtain useful findings for seat design considering ride comfort, the seat model which has nine-degree-of-freedom is proposed. Backrest and seat-base of the seat are modeled in the simulation model, which includes pitch motion components of backrest, vertical, longitudinal, pitch, roll and yaw motions of seat-base. It can describe the vibration characteristics of the seat against the floor acceleration input. In this report, the seat vibration simulation is conducted by using the proposed seat model with the goal of decreasing high frequency vibration. From the result, the relationship between model parameters and vibration characteristics of the seat is investigated.

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New functional seats are continually developed to use the recreational vehicle, and sinking seat is a functional seat that is necessary for sinking space. Stowage of the sinking seat is adjustable by manual operation. But seat is very difficult to manual operate because of the operational resistance to the seat weight. Recently, several vehicle companies are developing the handy automatic sinking seat in order to remedy manual operation's shortcomings. Automatic sinking seat is necessary development of optimization for operation sequence and modularization design of the electric driving system. In this paper, present the structural design method to the transition from manual to automatic operation of sinking seat and verified the validity by computer simulation.

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Active magnetic bearings (AMBs), being inherently nonlinear, are often modeled with linear approximations about the operating point. μ-synthesis control which offers robust stability in the presence of uncertain parameters also provides a method for overcoming the limitations that arise from this linear approximation. In the past, experimental measurements have been taken at the zero deflection point to determine the uncertainty range in the current stiffness and position stiffness parameters. This paper proposes an analytical method for deriving, from the non linear force equation, the nominal (minimum) range of uncertainty for the position stiffness and current stiffness in the μ-synthesis control of AMBs. This is of particular interest in applications where zero deflection is not expected at the bearing location. Stiffness range calculations for a high speed magnetic bearing machining spindle are also presented as a case study.

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A nutating subreflector is a convenient method for switching an antenna's beam between its target and background. Technically, the nutating mechanism introduces potential dynamical instability to an antenna structure A typical nutator system can be roughly separated in two major rotating parts, the rocker and the reflector. Both of them equipped with controller, voice coil motor (VCM) and encoders/sensors. We propose combined dual plant modeling to reduce the couple system and combining the rocker and reflector plant in single transfer function form. Besides, we checked the nutator system's stability, controllability and observability. Laser Doppler Vibrometer (LDV) and Dynamic Signal Analyzer (DSA) were used to experiment on the realistic system to build up system dynamic response to verify the mathematical system. PID (Proportional-Integral Derivative) and PDFF(Pseudo-Derivative Feedback with Feed-forward Gain), were designed for it individually. Moreover, adding a white noise block in front of the VCM plant which can simulate the outside disturbance due to wind torque or other environmental impact. Our target was to proposed better effective control loop which inhibited the disturbance effectively. We present a complete analysis of combined dual plant modeling as well as control loop about the nutator system, and verifying the mathematical plant by LDV and DSA.

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The selection of optimal inputs and outputs from larger candidate sets is an important prerequisite for an effective robust control application. This is especially true for active damping of complex and high-dimensional multi-input multi-output systems (MIMO) with flexible modes. Existing optimal selection strategies are commonly based on a single nominal system model and cannot explicitly consider parameter variations in the system. Consequently, an optimal selection for the nominal plant may perform poorly for a different parameter setting or even render the perturbed closed-loop system unstable. The proposed integrated input-output (I/O) selection strategy overcomes this problem by explicitly considering a set of systems covering the range of parameter variation. It is structured in three consecutive selection steps, where only the subset of accepted candidates is fed into the subsequent selection; thus, it is also computationally efficient. An additional advantage is a quantitative ranking of the final candidates, which enables the control engineer to make an optimal I/O choice. The method is illustrated by a flexible beam example as well as at a blended wing-body passenger aircraft model.

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The purpose of this study is to define design variables of a detection algorithm of the loss of balance (LOB) with a balancing task in the seated posture. The design variables were determined through the sensitivity analysis to attain the highest success rate of the algorithm. The detection algorithm mainly consists of an internal model of the central nervous system and a control error anomaly detector. This study selected five time variables: two variables S1 and h1 were related to the internal model, another two S2 and h2 to the detector, and the other hd to both the model and the detector. S1 and S2 represent data selecting windows; h1 and h2 time shifts; and hd an operating period of the LOB detection algorithm. The success rate was increased by up to 10% comparing with the previously published case when S1 and S2 were set to 2.0〜8.0 sec, h2 to 0.01〜0.10 sec, and hd to 0.1〜0.34 sec. The results also showed that the success rate was insensitive to h1. This study suggested a scheme of improving the algorithm to detect the loss of balance.

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In this paper, a modification method of vibration modes is proposed when dynamic characteristics of vibration system changes by assembly. In case of changing of dynamic characteristics, the component mode synthesis (CMS) is widely used. However, in the aim of vibration control, these CMS technique is not used well. Therefore, vibration modes are modified for reduced-order model. In this method, vibration modes are modified by using static correction modes (attachment modes). By using these modes, orthogonalization is performed by using subspace iteration. First, a concept of the modification method of vibration modes is proposed. Next, this concept is applied to our modeling method "Extended Reduced-Order Physical Modeling Method". Finally, dynamic characteristics by this method are verified by using an elastic vehicle. By using the elastic vehicle, single lane change test and simulation are performed.

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In this paper, a new modeling method of coupled flexible bodies taking the change of coupling angle into consideration is presented. In this method, each flexible bodies are modeled independently first, then the dynamics of few specific coupled systems with specific angles are identified. By interpolating these coupled systems analytically, the general dynamics of coupled system with arbitrary angle could be derived. The presented method is applied to a flexible two-link arm and its property is discussed.

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This paper deals with a problem of modeling and vibration analysis of a high speed rotating flexible manipulator. Conventional method of modeling does not exactly express the bending mechanism of flexible arm. Then a new description of deformation on the flexible shaft and Hamilton's principle are used to derive the dynamic model of the rigid-flexible manipulator. A nonlinear dynamic model is proposed to describe the dynamic behavior of flexible arm and the dynamic equations of the system are also presented. Derived equations consist of some nonlinear forces and geometrical nonlinear stiffness. The present research considers the effect from those nonlinear forces coupling with angular functions (angular position, velocity, acceleration). An external forced vibration method is applied to evaluate the characteristics of flexible vibration. In this research, numerical calculations based on two strategies are applied to analyze the flexible vibration. In the first strategy (AIM, angle independent method), angles of joints are assumed to be independent of the external forces. In the second strategy (ADM, angle dependent method), the effect on the angular functions of joints due to the external forces is considered. Especially, the gravity force affects significantly on the residual deflection of flexible arm and on the angular functions.

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In this paper, structural sound and vibration control using passive and semi-active shunt piezoelectric damping circuits is presented. A piezoelectric patch with an electrical shunt circuit is bonded to a base structure. When the structure vibrates, the piezoelectric patch strains and transforms the mechanical energy of the structure into electrical energy, which can be effectively dissipated by the shunt circuit. Hence, the shunt circuit acts as a means of extracting mechanical energy from the base structure. Different types of shunt circuits (such as an RL series circuit, an RL parallel circuit and an RL-C circuit) employed in the passive damping arrangement, are analyzed and compared. Using the impedance method, the general modelling of different shunt piezoelectric damping techniques is presented. The piezoelectric shunt circuit can be seen as an additional frequency-dependence damping of the system. One of the primary concerns in shunt damping is to choose the optimal parameters for shunt circuits. In past efforts most of the proposed tuning methods were based on modal properties of the structure. These methods are used to minimize the response of a particular structural mode whilst neglecting the contribution of the other modes. In this study, a design method based on minimization of the sound power of the structure is proposed. The optimal parameters for shunt circuits are obtained using linear quadratic optimal control theory. Numerical simulations are performed for each of these shunts techniques focusing on minimizing radiated sound power from a clamped plate. It is found that the RL series, RL parallel and pulse-switching circuits have basically the same control performance. The RL-C parallel circuit allows us to reduce the value of the inductance L due to the insertion of an external capacitance C. However, the control performance will be reduced simultaneously. The pulse-switching circuit is more stable than an RL series circuit with regard to structural stiffness variations. Finally, experimental results are presented using an RL series/parallel shunt circuit, RL-C parallel shunt circuit and pulse-switching circuit. The experimental results have shown that the vibration and noise radiation of a structure can be reduced significantly by using shunt circuits. The theoretical and experimental techniques presented in this study provide a valuable tool for effective shunt piezoelectric damping applied for control of vibration damping and radiated sound.

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It is very important to predict the interior noise of automobile for the assessment and enhancement of NVH performance in the design stage. For the analysis of middle and low frequency noise, the Finite Element Method (FEM) and Boundary Element Method (BEM) are usually employed. In this paper, the interior noise of automobile is predicted based on FEM and BEM, and the panel acoustic contribution is calculated. Firstly, the theories of FEM and BEM are studied comprehensively, the governing equation of the coupled acoustic-structural FEM is derived based on the second kind Lagrangian equation of nonconservative system, and the acoustic boundary integral equation is derived through Green's theorem; then, the finite element and boundary element models of body and acoustic cavity of passenger compartment are built respectively, the acoustic responses are obtained through FEM and BEM simulation; the linear correlation coefficient is introduced to assess the relations between the two results; finally, the Panel Acoustic Contribution Analysis (PACA) is carried out, through which the panels contributing more to the interior noise are identified, and the foundation for the structural optimization to reduce the vibration of panels and interior noise level of automobile is laid.

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This paper deals with a non-contact transportation system using ultrasound wave levitation phenomenon. It is the purpose of this paper to verify a relevancy between the transporting direction of the levitated object and the propagating direction of a travelling wave. First, active wave control is introduced for oscillating the flexible beam at high frequency. Then, HSMAC (Highly Simplified Marker And Cell) method is introduced for calculating two-dimensional surface model with incompressible fluid. Finally, the relevancy is verified by the experiment. As a consequence, it is clarified that the propagating direction of a travelling wave is able to be reversed by operating the frequency lower and higher near a resonant frequency, and by adjusting the phase difference to positive or negative. Furthermore, if the levitated object is situated within a viscous boundary layer, the transporting direction of the levitated object is reversed as compared to the propagating direction of a travelling wave.

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As one of structural health monitoring systems, the authors developed a broadband ultrasonic propagation system using macro fiber composite (MFC) actuators and fiber Bragg grating (FBG) sensors. This system can send and receive broadband Lamb waves efficiently in a specific direction, and the MFCs and FBGs can be integrated into composite laminates because of their flexibility and high fracture strain. In this research, this system was applied to detect an interlaminar delamination in carbon fiber reinforced plastic (CFRP) laminates. One MFC and one FBG were bonded on each surface of the CFRP laminate to generate and receive the symmetric modes and the anti-symmetric modes separately for identification of the multiple modes of Lamb waves in the laminate. Then we investigated the mode conversion of Lamb waves at both tips of a delamination in the middle of the thickness of the lamimate, through an experiment and finite element analysis (FEA). On the basis of the knowledge about the mode conversion, an index to evaluate the delamination length was proposed using velocity changes by the mode conversions. From the results of experiments and FEA for the laminates with an artificial delamination, this new index was found to be effective to evaluate the delamination progress in the laminate quantitatively.

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This paper considers active control of the sound transmission loss of a flexible panel partitioning an open space. Targeting the broadband frequency range, a control strategy presented in the work comprises both active and passive control for the purpose of minimizing the total acoustic power transmitted from a panel excited acoustically from the other side, hence hybrid control. As with a passive control strategy, a double-leaf partition method is employed, thereby enhancing the sound transmission loss in the high frequency range. In the low frequency range, on the other hand, active cluster control is introduced in an effort to suppress the sound transmitted power without causing spillover. Taking advantage of the symmetric properties of the double-leaf structural model, radiation cluster which is an orthogonal contributor with respect to acoustic field can be defined. First, the sound field system produced by a double-leaf wall with air space acoustically excited is described. Cluster control consisting of cluster filtering and cluster actuation is then employed, the system state being expressed. Moreover, the optimal control law for minimizing the total acoustic power radiating from a vibrating panel is derived. A numerical analysis is then conducted, clarifying the control effect for suppressing the transmitted sound power. Finally, an experiment is carried out, demonstrating the capability for enhancing the sound transmission loss using the hybrid control strategy.

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This paper considers an analytical investigation into the active controls of acoustic power mode in double-wall structure coupled to an acoustic enclosure. Harmonic sound plane wave from outward is transmitted into the enclosure. The purpose of this investigation is to control the potential energy caused in the enclosure. In the high frequency range, the acoustic sound transmitted through the double-wall structure is very low. It becomes a broadband control system by applying active control that is more effective in the low frequency range to the double-wall cavity.

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Flexural waves traveling in an elastic wedge (plate whose thickness decreases towards zero following a power law function) are not reflected back and accumulate at the zero thickness edge what results in a very efficient damping. In practice reflection always occurs because manufacturing a zero thickness edge is not possible. To solve that problem Krylov proposed the addition of a small quantity of damping material on the thinner edge of the plate what results in very effective damping. In this paper, the application of elastic wedges to reduce the vibrations of turbine blades is investigated. The objectives of this research are to evaluate the damping effectiveness of elastic wedge theory in blades and second, to evaluate a non-polymeric material as vibration damping material. In this way, the vibration energy of the blade is dissipated by the damping material and, at the same time, high temperature and low strength problems characteristic of polymeric damping materials are prevented. First, a FEM modal analysis of a simplified blade model is performed to understand the effects that the elastic wedge has on the modal shapes and frequencies of the blade. Next, to evaluate the damping levels achieved, a frequency response of the simplified blade model with and without elastic wedge is evaluated with the added damping material. The results show that elastic wedge theory combined non-polymeric damping materials can be an efficient method to reduce vibrations of turbine blades or similar applications.

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Bending vibration of flexible structures can be suppressed by using piezoelectric elements. A plate type of piezoelectric elements is usually used, and they are attached to the target directly with the adhesive bond. Piezoelectric elements can be used as both actuators and sensors, and it is known that they should be attached to the position where the curvature is large. The efficiency of a piezoelectric element as an electromechanical transducer depends on the curvature. A lot of vibration suppression methods using piezoelectric elements have been proposed thus far. These methods are based on various vibration suppression principles; however, all of their performance is limited by the efficiency of the piezoelectric element. The efficiency can also be enhanced by the size of the piezoelectric element. However, the efficiency is usually insufficient even if the size of the piezoelectric element is large. Therefore the performance of vibration suppression using piezoelectric elements is lower than that of mechanical vibration suppression methods generally. It is necessary to solve this problem so that the vibration suppression techniques using piezoelectric elements yield practical applications. In this paper, a new technique, which enhances the efficiency of piezoelectric elements by using spacers, is proposed. This method is based on the idea that the piezoelectric element should be located optimally not only in horizontal direction but also in perpendicular direction. The optimum height of the spacers is formulated theoretically, and the effectiveness of the proposed method and theoretical analysis is validated through simulations and experiments.

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This paper presents a novel transparent smart film actuator based upon a conductive polymer. Almost all conventional smart sensors and actuators based upon PVDF film were first shaped in accordance with desired shaping function, and then attached onto a opaque and rigid substrate. And PVDF film was coated with opaque aluminum to apply a voltage and to acquire an electrical charge from PVDF film surface. Because of structural opacity and rigidity, their applications were restricted to a specific area. To overcome such problems, this paper introduces a transparent conductive polymer Poly (3, 4-ethylendioxythiophen) / poly (4-styrenesulfonate) (PEDOT/PSS) for electrode of PVDF film, with result that the PVDF film becomes a transparent distributed parameter actuator per se, hence transparent smart material fit for optical flexible device is developed. Firstly, this paper overviews conductive property and transparency of conductive polymer. Then two-dimensional modal actuator film for exciting specific structural mode is proposed. Furthermore, a conductive polymer-based cantilever beam entailing the capability of modal actuating is developed, the validity of the proposed transparent smart film actuator based upon a conductive polymer being analytically as well as experimentally verified.

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Backlash occurs in gear drive systems that are used with machine tools and transport mechanism. The problem with backlash is that it reduces positioning accuracy and tends to make vibrations worse, especially when the driving load is large and a large drive system is used. A multi-motor drive can be used to distribute the force when the driving load is large. By using a system with a multi-motor drive, in this paper, a method that compensates for backlash is introduced. In this method, the phase of a slave motor is displaced depending on the phase of the main drive motor at the final position of the system. It is shown that this method is effective in increasing the stiffness of a gear drive system and improves the positioning accuracy of the system.

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This experimental study describes the fabrication process to make an approximate linear contraction type electro-active ionic polymer metal composite (IPMC) for using in the application of linear actuator. IPMC normally is a bending type actuator, but the lack of force and the bending type actuation caused the inconvenience for utilization. The main objective of the research is trying to create a new type of contractile IPMC actuator. The fabrication process, the dynamic characteristics of the specimen, and the actuation of linear contraction type electro-active IPMC are verified.

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This paper examines the past and present state of MOVIC, and points out challenges that will have to be considered so that it remains as a premier international conference in the field of motion and vibration control.

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Toward the development of 5kW micro gas turbine (MGT) fueled by biomass gas, we developed the software for controlling supply fuel gas. The rotational speed of the output shaft of the power turbine is controlled to maintain the target speed. Two fuel flows for the primary combustion zone and secondary combustion zone in the multistage combustor are controlled. The role of fuel flow control for the primary combustion zone is to adjust flow of city gas 13A to stabilize the tubular flame. The other fuel controller adjusts the flow of mock biomass gas to the secondary combustion zone to maintain turbine speed for various load and fuel components. As for the control scheme, two controllers based on the modern control theory (H infinity theory) and classical control theory (two DOF PID theory) for multistage combustor were tested and successful operation was achieved.

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In order to reduce emissions of greenhouse effect gas, the development of all renewable energy is required. Therefore, this paper focused on small-sized hydraulic generator. Because the small scale hydropower has a large amount of potential power generation. Standard mechanical bearings are installed in conventional small-sized hydraulic generator to support the rotating shaft. However, mechanical ball bearings cause rotational loss, noise and limitation of device durability. In order to upgrade performance of hydraulic generator, permanent magnet hybrid type magnetic bearing is proposed in this study. Stator is designed by finite element method magnetic field analysis. According to the analytical result, by making the root of stator salient pole wider and eliminating magnetic saturation, stronger bearing power was obtained. And a simple experimental setup was fabricated based on the analytical result. The bearing force characteristic and the negative spring force characteristic were clarified by static characteristics evaluation. Moreover, in order to confirm dynamic performance in time domain, impulse response was measured and result showed good response performance. In addition, by using measured coefficient of bearing force and negative spring force, numerical simulation was carried out to check dynamic performance in frequency domain. Simulation result of frequency response showed wide enough bandwidth.

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Biomass resources are drawing attention as alternative fuel for combating the energy crisis and for atmospheric environment protection. The small gas engine in a distributed power generation system is an efficient system to use it, because the biomass resource is stored in large area and its energy density is low. The composition of gas fuel generated from biomass is affected by the source type, the gasification method, and the gasifying condition. Then, the gas engine must be operated stably with high thermal efficiency in view of these fuel fluctuations. The authors aim to develop a small gas engine system for biomass gas by modifying the control system of a conventional spark ignition engine to absorb fuel fluctuation. Then, the original gas engine control algorithm was developed, which can define target values of equivalence ratio of premixture and ignition timing realizing high thermal efficiency in fuel combustion property by analyzing in-cylinder pressure data in real time. To develop a control algorithm, combustion experiments with various components fuels assuming component of real biomass gases like as fermentation gas and pyrolysis gas, were carried out. It was clarified that the relationship between dimensionless combustion duration and equivalence ratio is expressed in first order liner function regardless of fuel components. Indicated thermal efficiency can be also expressed by dimensionless combustion duration and volumetric efficiency. In addition, the relationship between combustion duration and MBT can also be expressed in first order function regardless of fuel components. Original engine control algorithm uses these relationships obtained from in-cylinder gas pressure in real time. Thus, biomass fueled gas engine system was developed by applying the algorithm to the automobile gasoline engine with hardware modifications of only fuel supply system and flywheel. The engine system was connected to a gasification plant using wood chip and operation test was carried out. As a result, the engine system could set optimum premixture condition and ignition timing, which realized stable and high thermal efficiency operation automatically.

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Multi-packet blade systems consist of several blades which are attached to a disk and connected through shrouds. The blades of a multi-packet blade system are mostly assumed to be identical. However, there always exists small, random mistuning among the blades due to manufacturing tolerance, in-operation wear, and environmental changes. Such mistuning may cause significant increase in the forced vibration responses of some blades in the multi-packet blade system. Critical fatigue problems often occur in mistuned system since the forced vibration response of a mistuned system is often significantly larger than that of a perfectly tuned system. Therefore, it is very important to predict the maximum blade response. In this study, blades are idealized as cantilever beams and the flexibilities of the disc and the shrouds are idealized as discrete springs. Equations of motion are derived by using the hybrid deformation variable method. To verify the vibration localization with random mistuning, transient analysis are carried out for the multi-packet blade system excited by multiple nozzle jet forces.

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Previous theoretical studies have shown analytically and numerically that a vibrating system can be stabilised and its vibrations can be suppressed by an open-loop control of a stiffness parameter, a stabilisation by parametric stiffness excitation. In this paper this approach is investigated further numerically, analytically and experimentally for a flexible rotor with multiple disks supported by active bearings. A periodic, open-loop control of the stiffness coefficients of a bearing is realised by periodically changing the control parameters of an active magnetic bearing. This periodic variation of control parameters is regulated at fixed frequency and amplitude in such a way that it acts like a parametric excitation on the rotor system. As it was shown for simple vibrating structures (chain mass system, cantilever, Jeffcot rotor), the periodic variation may lead to an effective vibration reduction in a complex rotor system. Since this control is open-loop, it can operate in parallel to existing and well-established controllers already used in active magnetic bearings. In this paper, the method of damping by parametric excitation is realised for the first time experimentally in a rotor system. Both direct numerical simulations and analytical predictions are performed to calculate ranges for control and system parameters where damping by parametric excitation is effective. Results from both methods are compared with first experimental results. Finally, analytical conditions are given under which the damping by parametric stiffness is effective and the damping effect is guaranteed.

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Auxiliary bearings are used in many rotor systems, e.g. those with active magnetic bearings. In a case of a contact with the auxiliary bearing, high impact forces and wear are possible. Therefore the auxiliary bearings have to be replaced after a certain number of contact events. This is very costly and often needs complete dismantling of the rotor system. In this paper a concept for model based condition monitoring of an auxiliary bearing is developed. The rotor system is modeled in a multibody simulation environment, including the contact to the auxiliary bearing and various fault parameters. After contact (drop or bouncing contact) occurs in the real rotor system, an identification algorithm analyses the measuremental data of the contact event and determines the fault which occurred. Based on the results of the identification algorithm, an optimization tool aligns the rotor simulation with the measurement by varying the fault parameters. After the alignment of the simulation, the simulation results are evaluated. The contact forces are evaluated against location on the surface of the auxiliary bearing and are stored. This procedure is performed after each contact event. Hence, a weighting of the load over the surface of the auxiliary bearing is gained. Depending on the material and structure, these data can be used for a life-time estimation of the auxiliary bearing. Using an active magnetic bearing test facility, the monitoring system has been successfully tested.

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This paper presents a vibration isolation system using negative stiffness suspension. The vibration isolation system is developed by combining a positive stiffness suspension in series with a negative stiffness suspension. The developed system could realize zero-compliance to direct disturbance, as well as ground vibration isolation. In the previous system, the ground vibration and, the static and low frequency sinusoidal direct disturbances were efficiently suppressed. However, there was a reverse action in case of impulse or step wise disturbance. Therefore, a peak was appeared which was, sometimes, larger than the displacement caused by the step load. This unpleasant response might hamper the objective function of many advanced systems. In this research, a feedforward controller is added in combination with zero-power control to overcome this problem. Some experimental results are presented to verify the proposed control system in a vibration isolation apparatus.

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This paper deals with the control system design for active isolation table. It aims at controlling vibration of the installed object and isolation table. An experimental isolation table with flexible loaded object is built. Control simulations are carried out by using feedback controller designed according to LQ control theory.

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A three-degree-of-freedom (3-DOF) active vibration isolation system using vibration cancellation technique is presented in this paper. The disturbance cancellation concept is put into action to design the controller as well as to eliminate the displacement of the isolation table respect to the base under static load. The corresponding controller is designed in such way so that it can generate additional opposite force against disturbance. This additional force just makes the movement of the isolation table along the opposite direction of the disturbance to cancel the effect of the middle table movement on the isolation table, which finally leads zero compliance of the isolation table. Voice coil motors (VCMs) are used for getting linear actuating effect of the system's moving parts. The developed system under mode control showed the capability to maintain zero compliance under static disturbance in the 3-DOF motions associated with horizontal translations and a vertical rotation. Moreover experiments have been conducted to measure the dynamic response of the controlled system associated with direct disturbance.

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Dielectric Electro-Active Polymer (DEAP) devices consist of a dielectric polymer sandwiched between two electrodes. This paper describes the use of a tubular DEAP actuator for active vibration isolation. First, the quasi-static and dynamic characteristics of the actuator are discussed. These involve the voltage-strain-force behaviour of the actuator. It is seen that the actuator is inherently non-linear, involving an approximately quadratic relationship between excitation and extension under given loading conditions. In a control context, this can be compensated for either by driving the actuator about some d.c. off-set excitation in a quasi-linear manner, or by including a linearization component within the control. Next, issues concerning the frequency response over a wide range of frequency are considered. Internal resonances exist in the actuator, which limit the bandwidth over which it can be used for active control. The actuator has significant internal damping. The potential for active vibration isolation is then explored. The dynamic performance is limited by the potential bandwidth, the maximum force that can be generated and the maximum range of movement, together with the inherent nonlinearity. Performance for harmonic disturbances is investigated within an adaptive feedforward control scheme. Experimental results are presented. Good attenuation of the excitation frequency is achieved but compensation is required to get good attenuation of higher harmonics introduced by the actuator nonlinearity. Isolation in response to a band-limited random input is then demonstrated, with attenuation of 19dB being achieved over a frequency range from 2-8 Hz.

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The polynomial or algebraic method based on the transfer function can achieve simultaneously pole and zero placement. Since the method has clear physical interpretation, it is easy to introduce many different constraints such as vibration modes and the operation limit of the actuator. However, if the controlled plant is high-order, numerical problems arise in the solution of a Diophantine equation. This paper presents a new polynomial design method on the modified delta δ^^--plane instead of the s-plane and the z-plane for the microprocessor control. As an illustration, active damping of second-order system is considered. The numerical sensitivity of a Diophantine equation becomes about one thousandth of that based on the conventional design. The simulated results show that the proposed method is applicable to the high-order systems.

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In single mode vibration control using the synchronized switch damping (SSD) approach, optimal control performance is obtained when the voltage on the piezoelectric actuator is switched at each extremum of strain. In multimodal control, the switching actions usually do not take place at the extrema of each individual mode. Hence it is important to investigate the influence of the switching phase and switching frequency on the control effect of an individual mode. In the study, the influence of the switching phase delay and switching frequency on converted energy from each individual mode under the condition that the switched voltage is constant is investigated. The theoretical results show that the control performance deteriorates with increasing phase delay and that control effect can only be obtained at some special switching frequencies.

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In this paper, we describe our work on realizing the manipulation of nut and bolt for assembly work using dual arm manipulator. Generally, force sensor is used for estimation of external force. However, the cost of this sensor is expensive and easily damaged by inappropriate contact with object. This has led us to use other sensors instead to estimate the external force. Then, the results are compared with measurement from force sensor to validate for correct estimation. With the application of impedance control for robot hand, our robot could be able to grasp nuts ranges from several sizes down to as small as radius 2 mm. Moreover, we are experimenting on more challenging task such as grasping a bolt and screwing it to a nut using vision and force data. Furthermore, we applied a method called following control to make finger maintains its contact with worktable while making the grasping task. Thus, this could improve grasping nut task at a higher success rate even with some errors from robot position and vision data.

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We present a new type actuator though the swing type arm was as a reference of small form factor optical pickup heads that had already utilized the material of piezoelectricity or slim plate of metal to perform focusing action. The seesaw type actuator is a new driving mechanism used for swiveling the small form devices. The configuration of the seesaw swivel actuator has unique features including a rotary supporting base for coarse and fine tracking, and a seesaw arm swivels along a pivot without a hinge to permit a tilted focus movement. Moreover, to achieve precision positioning of the seesaw actuator, a lateral focusing voice coil motor, which attached the middle seesaw arm, is proposed. In order to adjust the broad air gap between the tracking coil and the base magnet, a horizontal voice coil motor combined a ring type magnet provides uniform and uninterrupted magnetic output and the magnetic component is unlike multi-segmented magnet arrays form. The seesaw actuator was designed on the basis of finite element structural analyses for focus/tracking actuations and the dynamic characteristics were verified by this simulation. An original seesaw actuator with particular magnetic circuit was specifically manufactured and assembled for a micro ODD. Natural frequencies of seesaw swing arm are measured to confirm the results of finite element analyses. Furthermore, the parameters optimization procedure uses as design variables to optimize the initial model and improve the system response. The vital discussion is the New magnets array design

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This paper studies the behavior of the giant swing motions of a two-link horizontal bar gymnastic robot using chaos control. Until now, the generalized method of control on such systems with non-holonomic constraints has still not been established. The delayed feedback control (DFC) of chaos, proposed by Pyragas, is well known as an effective method for stabilizing unstable periodic orbits embedded in chaotic attractors. However, the DFC has a limitation such that it can not stabilize any systems with an odd number of real eigenvalues greater than unity. The stability analysis of continuous systems like gymnastic robot by a modified DFC method called Prediction-based DFC (PDFC) is concentrated in this paper. Firstly, a Poincare section is defined to regard the target system as a discrete-time system so that the system stability can be evaluated easierly. Meanwhile, a way to calculate analytically the error transfer matrix and the input matrix which are necessary for discretization is proposed. Secondly, the stability of the gymnastic robot system controlled by the PDFC is discussed. Finally, some simulation results show that it is effective in the control of the giant swing motions with the proposed method.

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The German Pavilion on the World Exhibition EXPO 2010 in Shanghai shows an interactive 3D-pendulum as one of its main attractions. The pendulum consists of a sphere with 3m diameter which is equipped with several hundred thousand LEDs and used as a projection screen. The sphere is mounted via a long bar at an electrically driven crosstable which is used for the excitation of the pendulum. The crosstable is located in a theater-like building where the visitors can follow the show. Thereby, the sphere performs large circular and pendular motions, while the crosstable can only perform very small motions. Also during some parts of the show the sphere should move in a certain way which is obtained by interpreting the visitors' action as a physical excitation. In this paper the system and control design are discussed and experimental results are presented.

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