This paper describes a successful application of Magnetorheological (MR) grease to a shear type controllable damper. MR fluid is known as a kind of functional fluid which changes rheological property when external magnetic field is applied. However, there is a problem with the sedimentation of the dispersed particles. To prevent the sedimentation, MR grease has been developed. In this study, a shear type controllable damper using MR grease has been developed. Performance test has shown that the proposed damper has wide dynamic range of damping force despite its simple structure. The ratio of maximum damping force in on-state to that in off-state is approximately 30. In addition, the proposed damper is installed between first floor and second floor of a 3-story model structure. The excitation test has shown that the dynamic characteristic of the model structure can be dramatically changed by the proposed damper. This indicates that the response to forced displacement can be controlled by external current.

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The dynamic vibration absorber is well known as a kind of passive-type vibration control device, where the mass and the stiffness elements basically comprise 1-dof system. Despite the reliability and the simplicity in constitution, the absorber does not work effectively for unexpected disturbances. The use of the absorber with fixed property is usually limited to a harmonically excited case, where the damper is only effective for pre-determined narrow frequency range. The damper design following well-known optimal tuning theory can extend the effective range, whereas the damping performance remains at a certain amount and yet the vibration caused by transient disturbances cannot be reduced sufficiently. A frequency-tunable dynamic absorber incorporating element with variable stiffness property can be a measure for placing adaptability to the structure against non-stationary disturbances. The Magneto-rheological elastomer (MRE) is known as a class of smart materials whose elastic property can be varied by the applied external magnetic field. In this paper, the MRE is adopted as the stiffness element in the dynamic absorber whose natural frequency is tunable by the external magnetic field. Both numerical and experimental investigations show that the vibration of 1-dof structure can be fully reduced by the proposed dynamic absorber with variable stiffness functionality.

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This paper describes the effectiveness of an active vibration isolation system that uses an active dynamic absorber as a servo accelerometer in a low-frequency range and a vibration control device in a high-frequency range. Complimentarily, it uses an air actuator as a control device in a low-frequency range and a low-cost accelerometer as a sensing device in a high-frequency range. The main aim of this research is to develop a high performance active vibration isolation system that is lower in cost than conventional active vibration system. It was experimentally demonstrated that the acceleration in a low frequency range can be detected from the control input of the absorber. In addition, by feeding back the estimated acceleration, the vibration was actually attenuated.

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This paper reports new results for developing absolute displacement sensor in order to measure a long period and large magnitude. Measuring of the absolute displacement of vibration objects, the natural frequency of sensor must be lower than the dominant frequency of the object. Therefore, it is difficult to measure a low frequency vibration below 1 Hz using conventional displacement sensors. In order to be lower the natural frequency, the sensor with the low natural frequency is realized by using feedback control. It has been demonstrated that a developed sensor has a detecting range from about 0.2 Hz to 10Hz for absolute displacement. In addition, the measurement displacement amplitude has been expanded to about 700 times. Moreover, by using the second order lag compensator measuring lower frequency range is expanded to 0.1 Hz.

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Robots are expected to be introduced into welfare fields. However, most of the robots are currently used for production in industrial fields, and therefore were designed specifically for use in an environment without the presence of human. These robots have end-effectors with specially designed shapes and capabilities replaced suited for specific tasks. Thus, they could not be used for general purpose because their end-effectors have to be replaced by human in order to accomplish various tasks and adapt to a new one. Therefore, we focused on multifingered manipulators which are versatile end-effectors. In this research, we propose the grasping model of a couple of 2-link manipulators driven by pneumatic actuators, in which manipulators are face to face. Both manipulators are set up horizontally, and the movement direction of the joints is limited to the same direction. The concept of this control law involves virtual springs to simulate the grasping force against the object. It also calculates the torques of each joint corresponding to the grasping forces. We conduct sets of examination to move the object's center position from a starting position to another. As a result, the current object's center converges on the target object's center. Therefore, the efficiency of the proposed grasping model is verified.

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Rheumatoid arthritis, a disease of unknown cause, leads to deformation and dysfunction at the joints of the body. Deformation of the fingers is particularly common, and supposedly more than 500,000 people suffer from progressive dysfunction of the fingers. The patients with rheumatoid arthritis(RA) often have the MP joint volar subluxation figer. In the early stage of subluxation, it is necessary to choose conservative therapy (drug therapy, equipments and hand therapy) or surgical therapy, depending on the stage of the disease progression. Under existing conditions, patients use hand therapy for functional improvement. However, it is difficult for patients to receive enough rehab by ambulatory care. The earlier study prompted the development of a therapeutic use equipment with a membrane pneumatic actuator. A membrane pneumatic actuator produces more power and requires less installation space than a conventional low pressure pneumatic actuator. The therapeutic use equipment was made by referring to rehab by hand therapy. 4 out of 5 patients succeeded in reducing MP joint subluxation thumbs by using a prototype of a therapeutic use equipment. But it is necessary to improve the prototype because it wasn't made by reproducing hand therapy after enough analysis.

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Now, a bipedal robot is developed for the various purposes such as an analysis of the walking mechanism and the entertainment and then they are operated in the human society. Mostly the actuator used for these bipedal robots is an electric motor. We have developed a bipedal robot with compact pneumatic cylinders and with the high levels of structural flexibilities. The degree of freedom is 12. It is difficult that the robot with motor driving is operated quickly and flexibly, but it is possible that our robot does it by the advantage of the pneumatic system. In this research, we report result of carried out frequency response experiment for bipedal robot and estimate and consider about nominal model which used for control system design made by system identification.

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We have developed a bipedal robot with compact pneumatic cylinders and with the high levels of structural flexibilities. In the 1st report, we have described the overview of a bipedal robot which we have actually designed and manufactured and then estimated nominal models and the plant uncertainty for control system design from a closed loop system experiment data. In next efforts, we have simulated the behavior of bipedal robot systems with various controllers and evaluated the controllability of the positional and walking motion. We report these results and also refer to possible applications of the developed bipedal robot.

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The demand for ultra precise positioning of nanometer-order is increasing with the progress of nanotechnology in semiconductor industry. Previously we developed the one axis stage driven by pneumatic bellows for such a demand, and realized ultra precise positioning and long stroke. However, not only a one axis stage, but also a stage with multiple degrees of freedom is often demanded in semiconductor industry. In this paper, we proposed the actuator unit composed a bellows and elastic hinge guide, and show the fine movement stage with 3 degree of freedom applying proposed actuator units. The characteristics of the pneumatic bellows actuator unit are also evaluated and the positioning accuracy of the actuator unit is 50 [nm] or less, which is same level with the accuracy of one axis stage. It is found that the actuator unit can also realizes ultra precise positioning and long stroke though we must improve the control of the stage to eliminate the small vibration in the transient response.

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For the benefit of air pressure, it is used for servo control of pneumatic cylinder. It is necessary to determine quickly the control gain in order to apply the servo control. In previous research, it was known that the dynamics of the servo valve to determine the response of the entire system in the control of the pneumatic system. Therefore, we propose a method for performing position control system design of the cylinder in consideration of the dynamic characteristics of the servo valve, and confirmed the effectiveness. However, this design method is to apply only to the servo valve with a feedback of the valve displacement is not possible. In this paper, we have proposed a design method of a control system based on the stability index for the case of realizing the position control of a pneumatic cylinder with a nozzle flapper type servo valve which does not have the sensors of the valve displacement. When we identified the position control system which is a controlled object and applied the design method of the proposed controller, appropriate response was obtained in the full range of position control, validity of the proposed method was confirmed.

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Manifold blocks are recently used to connect hydraulic components in a hydraulic system that has flow channel inside. They are useful in reducing the size and weight of hydraulic systems. This paper deals with solid manifold block and laminated manifold block as trip equipment with which the turbine of a thermal power or a nuclear power plant is equipped. They are different from machining. We investigate pressure drops of their pipe flow with computational fluid dynamics (CFD) and compare the two types. We devised the new technique of having included CFD in pipeline network calculation. The final purpose is to design a laminated manifold block as trip equipment with which reduction in size and weight or reduction in pressure drops is realized. The conclusions from the aforementioned results are as follows. First, Branch/junction model can be calculated by the new technique of having included CFD in pipeline network calculation. Second, we achieved designing of a laminated manifold block as trip equipment with which reduction in size and weight or reduction in pressure drops is realized.

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The temperature distributions of the cam-ring and the side-plates of a hydraulic vane pump were examined under real operating conditions. Seven thermocouples were embedded in the side-plate and seven were implanted in the cam-ring. Mineral oil type hydraulic oil with ISO VG32 was used as the test fluid. The maximum discharge pressure was up to 20 MPa and the rotational speed was between 15 and 25 rps. The inlet oil temperature was specified at 30 to 50℃. At pressures ranging from the atmospheric pressure to the maximum discharge pressure, the torque and the flow rate were measured and the changes in the temperatures were monitored. The salient conclusions are as follows: The temperature of the cam-ring was maximized at the suction port. The cam-ring's temperature was markedly increased as the discharge pressure increased. The rise in the temperature was decreased as the inlet oil temperature was lower. The circumferential temperature distributions of the side-plate were nearly uniform. Compared with the cam-ring's temperature, the effect of the rotational speed on the side-plate's temperature was greater, but the effect of the discharge pressure was smaller.

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Rotating machineries have problems at bearings to support a rotor such as seismic ACROSS (Accurately Controlled Routinely Operated Signal System) transmitters. The rotor is supported by rolling contact bearings. The bearings in the transmitters, large heat generation occur caused by the high friction loss. In order to solve this problem, externally pressurized gas journal bearings with asymmetrically arranged inherent orifices has been developed for large load rotors. Numerical calculation of this bearing was carried out to obtain the characteristics using Divergence Formulation Method. Three types of bearing models have different placement of feed holes, respectively, i.e., Type A is the conventional symmetric type, which has eight feed holes in the bearing surface with equal distance. Type B is the proposed asymmetrical type, which has six feed holes at loading side of bearing surface and two feed holes at that of counter-loading side. Type C is also the proposed asymmetrical type, which has seven feed holes and one feed hole. The results showed that the proposed asymmetrical bearings have large load capacity and small flow rate compared with the conventional symmetric bearing.

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This paper describes a hydroinertia gas bearing with inclined feed holes, which may achieve higher speed of operation than conventional model. Our purpose is increasing to the maximum rotational speed by inclining feed holes. This study analyzes its pressure distribution by STAR-CCM+ to make clear its characteristic and makes a device of measuring pressure distribution. It'll useful for design bearing of Solid State NMR and improve its performance.

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Shift shock may occur due to engine speed change during shift operation of automatic transmission. In this study, a simulation model of up-shift operation was built, and the model was used as a controlled object. In the shift operation, output torque and shift time are important controlled variables. Engine torque and clutch pressure are control inputs. The relation between the input variables and the controlled variables are interfered with each other, or coupled. By applying decoupling control theory to the shift operation, the relation becomes decoupled. Combining the internal model control as a feedback controller, a decoupling control system of output shaft torque and slip velocity was designed. As a result of simulation study, the output shaft torque and the slip velocity were controlled precisely, and the interference between the input and the output variables was reduced by the proposed controller.

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Air bubbles in hydraulic oil lower the efficiency of hydraulic systems and contribute to instrument malfunctions. To mitigate these problems, it is possible to use an active "bubble eliminator" that uses swirl flow to remove air bubbles. The device shape affects the efficiency of bubble removal; hence, the selection of geometry is the most important parameter for optimizing the device performance. This study investigates the effect of the shape parameters of the device on bubble behavior in the oil, using experimental flow visualization and numerical simulations of the device. In this paper, we conducted the experimental flow visualization and numerical simulation involving various diameters of an outlet port and vent port. The simulation results are analyzed using considering the relationship between axial flow and swirl flow in the bubble eliminator. We conclude that the diameters of the outlet port and vent port, and the length of the tapered tube of the bubble eliminator can be determined.

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An Electro-Conjugate Fluid (ECF) is one of functional fluids. A strong jet flow is generated between two electrodes when a high voltage is applied to ECF through the electrodes. By the use of this strong jet flow, a pump with simple structure, no noise and no vibration can be developed. In this view point, authors had developed an ECF-pump using two metallic meshes. This ECF-pump is compact and no noise. In addition, its structure is very simple and it has remarkable properties. Therefore, it seems suitable to adopt this ECF-pump as the power source of a CPU cooling system. On the other hand, recently, the radiation cooling technique tends to be noticed in releasing much quantities of heat generated from LED lamp to surroundings of the lamp. This cooling technique is no noise. From these view points, by combing the ECF-pump with two metallic meshes and the radiation cooling technique, it seems possible to develop CPU cooling system with no noise. In this study, the above mentioned system is fabricated and the basic characteristics of the system are investigated experimentally.

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Earthquake occurred on March 11, 2011. Many victims were forced to live in shelters. Thus, there are problems such as sleep disorders of the victims because the living in a shelter is poor. In addition, when bedridden elderly people are evacuated, there are sleeping environmental problems because they can't use high performance electric bed in the case. Therefore, in this study, we propose a air mat system that is able to be used in a shelter. This system uses a cloth actuator as a pneumatic mat. In other words, the mat element has cloth actuator. Therefore, the stiffness of each actuator can be controlled by inner pressure. The inner pressure was controlled some valves or decompression system. In this paper, we make basic experiments with using cloth actuator. Through some experiments, we clarify the utility of the system.

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Mountains rescue and a firefighter's rescue operation in the disaster site of an earth-flow disaster have much difficulty. Their activity place has much rubble with a sloping ground or an irregular ground, and cannot perform prompt movement. In the irregular ground or a sloping ground, the assistant suit needs to have the free motion which does not bar activity, and the motion which assists a joint. In order to work continuously by the irregular ground and sloping grounds, such as mountains rescue and the time of an earth-flow disaster, the leg power assistant suit aiming at mitigation of a physical load, extension of activity time, and injury prevention of the rescuer itself is developed.

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Ageing population around the world is increasing the demand of caregiver. The caregiver job itself is already physically challenging and has high rate of work injury. This increase in demand will further increase more work load on this profession. Therefore robotic assistance for caregiver is needed to reduce their work burden especially in physically challenged task. In this paper, a new stand-up supporting system using Big-hand is proposed. The robot system is able to assist patient in standing up motion. The whole system is designed using pneumatic system making it light weight and usable in normal household. Besides, pneumatic power does not cause any interference with any electronics device that the patient is using. Pneumatic actuator weight to power ratio is higher compare to conventional electrical motor as well. The actuator used in this stand-up supporting system is made from different arrangement of flat tube which will produce different motion when pressure is being applied. The working principle for each of the actuator is being explain in this paper as well. A smaller version of the stand-up supporting system has been fabricated and it is tested on a mannequin which proves to be able to support the stand-up motion. Finally, the future development for this stand-up supporting system is mentioned as well.

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The attitude of a spacecraft is usually controlled by more than 3 reaction wheels. However, it is important to consider the attitude control by only 2 wheels for a fail safe. When the angular momentum of the body is not 0, it is known that the attitude cannot be controlled arbitrarily. Therefore, the purpose of this research is to control the direction of spacecraft's communication antenna. We separate the control law into two cases by the configuration of wheels; (1) One of the the wheel is set along the antenna, and (2) Both wheels are not set along the antenna. In the case (1), by using partial linearization and idea of equal ratio divergence, it can control the direction of antenna and stop rotation of the body. In the case (2), by using the output zeroing control, it can control the direction of the antenna and keep rotation around the antenna.

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This paper deals with an approximate linearization control for the Acrobot using a novel linearization coordinate. The linearization coordinate is systematically determined by solving two first order linear partial differential equations and obtained in analytical form, as an infinite series of the state variables. The resulting system with the approximate linearization control posseses a larger basin of attraction comparing with that of the conventional linear control based on linearly approximated model. The advantage of the proposed control is clearly shown in numerical simulations but experimental results also shows their difference.

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This paper reports series of experimental studies for Acrobot System by applying modified Linearization Method, which is an extension of the previous study conducted by Saito who used Exact Linearization by Time Scale Transformation. Saito derived the algorithm formation for a system without viscous damping factor, while author reports simulation data that indicate the aforementioned method is applicable to highly nonlinear system with arbitrary damping factor.

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The back-stepping control (BSC) which should made effective in non-holonomic system such as the electronic throttle for the automotive engines was investigated. As for the strong points of our works, the D-BSC that adds the derivative term in the first step of BSC was proposed, and the linear model of the 2^<nd> order delay element was handled in the second step of it. D-BSC was smoothly shifted to former B as the control deviation becomes small further. A lagged dead zone, here, acted effectively. The values of various control parameters were tried by the Matlab/Simulink simulation, and a handy adjustment was clarified. In the simulation results compared with the PID control, D-BSC had an excellent control of achieving both a quick response and detailed resolution.

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This paper present a new control strategy of an electric power steering system with variable-gear-ratio mechanism, sometime referred to as active steering. Since this system has two functions, i. e. power-assist and variable-gear-ratio, the control input should be carefully designed taking account of those functions simultaneously. A model following sliding mode controller with a disturbance observer is proposed, where the reference model is designed based on a physical system with a desired fixed gear-ratio. The proposed strategy makes it easy to design a controller corresponding to the desired performances.

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This report considers the stabilization problem for nonlinear retarded systems. The author has already proposed a finite spectrum assignment method for nonlinear retarded systems by extending the finite spectrum assignment for linear systems over commutative rings. In this report, introducing a state predictor based on anticipating synchronization, we propose a new stabilization technique for nonlinear retarded systems. The effectiveness of the proposed control scheme is illustrated by a numerical simulation.

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This paper deals with a study on a vibration control system using propellers for crane load. Vibration suppression of crane load suspended by hoisting rope is an important issue to speed-up crane operation. In this study, a novel vibration control system using propeller thrust as control forces is presented. The variable-pitch propeller device is attached crane load, and control vibration suppression of crane load by add forces to crane load directly. The pitch of the propeller can be varied so that the attack angle of the propeller blade possess negative or positive. The normal propeller must switch on or off of the device repeatedly, so that rising properties of the force of propeller is bad. Variable-pitch propeller solved this problem. Changing the attack angle, the direction of thrust can be altered smoothly without changing on-off of the device. Based on previous conceptual design, a large scale experimental device was designed precisely

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The purposes of controlling the crane are to transfer the cargo to the target point as quickly as possible with suppressing the swaying and to quickly minimize the residual sway at the target point. At present, the development of the anti-sway control system for a rotary crane is desired, because the operation of a rotary crane which achieved by cargo windup, boom derricking and boom slewing is very difficult. So, variety sensors to measure the condition of a cargo and controlled methods to reduce the sway are proposed. In this paper, we show to be able to obtain the position of a cargo on three dimensions space by using the IMU, even if the attitude direction of cargo is unstable. And we tried to suppress the sway a cargo by experimental device.

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In recent years, due to the increase of the height of the high-rise buildings, the elevator becomes an indispensable facilities. Consequently, during earthquake, as natural periods of a building and an elevator system get close, the movement of the elevator ropes, the compensating ropes and the control cables become important. Moreover, when the ground motion becomes longer, the ropes may hit the wall of the shaft and cause damage to the equipment. In such case, the elevators have emergency stops. However, during the time required for the restoration of the elevators, the building's functions become unavailable. In this research, numerical analysis is used to compute the motion of the elevator's rope. Several manufacturers have used this kind of program in order to evaluate the response of their own elevator systems, but comparisons between all these results are difficult. For this research, the aim is to make the analysis program usable by each manufacturer. In this paper, the displacement of the elevator's rope is computied by the response of the top of the high-rise building, then evaluating the time for elevator to recover to its stable position will be carried out.

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This paper investigates vibration suppression effect of novel Tuned Mass Damper, namely Wired Tuned Mass Damper (WTMD). WTMD is a tuned mass damper made of an auxiliary mass connected with two small masses with wires. The weights of t small weights give the main auxiliary mass restoring force, while the wires allow the main mass to move over longer stroke than ordinary springs allow. In this study, an experimental structure and WTMD is built, and WTMD's property is investigated.

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This paper describes development of a new control system for active dynamic absorbers using a neural oscillator and position controller. The neural oscillator, which is a nonlinear oscillator, has been studied over the last few decades in the field of biology. The oscillator can be synchronized with an external sinusoidal input whose frequency is within a frequency band determined by the natural frequency of oscillator. In an effort to alleviate the problems associated with the stroke limitation and flexibility, the authors have recently proposed a new control system which is capable of confining the movable region of the mass and following the change of stiffness of the structure. However the proposed system is still coarse, and we are trying to further improve the system. In this paper, we analyze the phase relation between the mass of dynamic absorber and structure to evaluate the performance of energy dissipation. Form viewpoint of effective energy dissipation, the relative velocity of the auxiliary mass and the absolute displacement of the structures should be in-phase. The phase relation of the system including the oscillator synchronized with a structure and position controller was investigated by numerical simulation. As a result of the simulation, it is clear that the proposed system had an appropriate phase relation for vibration control.

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This paper propose the mechanism using lever and attached weight at point of action of lever, installed horizontally in the space between two floor slabs for the purpose of seismic response control of a high-rise building. This mechanism produces the dynamic mass related to the relative displacement between two slabs. The generated dynamic mass is shown to be effectiveness for the seismic response control of building from the point of view of the enlarged mass ratio of tuned mass damper to mass of high-rise building.

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This study is a basic research for the design of active mass dampers' controller using neural oscillators. The neural cells called neural oscillator consist the CPGs (Central Pattern Generator) and have characteristics of no-liner oscillators, and have significant roles for animal walking. One of the most important characteristic is synchronization with sinusoidal external forces. Thus, the CPGs can adapt to the environment changes and make the walking system fulfill the potential. Our recent study, properties of the CPGs are tried to install to the active controller for mass dampers, and the mitigation performance, the evaluation method and the design method of proposed controller have been studied. Especially, on the evaluation method, our prier research shows that proposed controller's performance depends on the synchronization property of CPG constituting the controller. However, there is no study how to select the neural network for the vibration mitigation controller. On this paper, we discuss a synchronization property of connected neural network constituted by twin-oscillators, and disclose its synchronization region and phase locking points which work as important role for proposed controller.

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The active seismic isolation system and the active seismic vibration control system have now been getting attention because of the recent big earthquake disasters. In conventional active isolation devices, the actuators are usually controlled by commands which are generated by the computer based on sensor input. Although these systems have such advantages that a control program can be designed freely, the maintenance of the computer itself and software leaves serious problems to be solved when they are outdated. In this study, a novel seismic control apparatus, in which hydraulic spool valves are controlled by mechanical links directly driven by earthquake motion, is proposed to solve this problem.

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Active control shows superior performance compared with passive control or semi-active control, however, safety concern about active control in case of an electricity shortage is one of the disincentives to install it. In addition, it is required that amount of energy used for control is as small as possible with required performances in terms of energy saving and downsizing of vibration control device. In this study, focusing on an energy optimal control that considers consumption energy directly in cost function, its effectiveness of energy saving and performance are verified. The control method is applied to vibration control for a seismic floor isolation which is actively controlled. Most of the duration time power added to an actuator shows minus value, which means energy regeneration, using the energy optimal control. As a results, superiority of the energy optimal control in energy saving is confirmed by being compared with Linear Quadratic Regulator. Additionally it is shown that the energy optimal control is able to reduce responses as effectively as Linear Quadratic Regulator.

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In earthquakes, it becomes more important to maintain a normal function of equipment placed in a building. One of the most effective ways to reduce vibration is to place some control devices, such as on a building and on equipment. Although centralized control system can control effectively, it is vulnerable to failure. Therefore, to achieve better performance in distributed control system is needed. It is expected to improve performance by giving controller some information about noise. In this paper, we apply the Disturbance-Accommodating control to the equipment controller. The concept of the proposed method is to consider the characteristics of building and control system in frequency domain. From the result of simulations, the effectiveness is verified in distributed control system.

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It is known that a base-isolated building exhibits a large response to a long-duration, long-period wave. Additional dampers installed into main frame and isolation story of a base-isolated building may improve seismic performance of the building. In this paper, a design region in stiffness of isolator k_I- damping coefficient of isolation story c_I space is defined such that conditions on seismic interstory drift of isolation story, seismic acceleration of top story of building, and damping factor of isolation story are satisfied, and the region is called as "SC design region." The objectives of this paper are to propose a method of finding SC design region for base-isolated building with additional dampers and disclose basic characteristics of SC design region via total amount and distribution of damping coefficients of additional dampers in main frame.

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This paper demonstrates effects of harmonically varying damping on a structure with an isolation layer. We applied the method of harmonically varying damping to vibration mitigation of a single-degree-of-freedom structure with sinusoidal base excitation having two frequencies. In the study, an ideal variable damper was used in conjunction with the secondary sinusoidal base excitation to reduce the response due to the primary base excitation. When the primary sinusoidal base excitation contains a natural frequency of the system, a resonance is induced. However, another resonance can be generated by the modulated component caused by the variable damping device and the secondary base excitation. The additional resonance was adjusted to be out of phase with the primary response, and the response of the structure was effectively reduced as a result of the damping. However, no such study considering multi-degree-of-freedom systems have been conducted. This paper presents the effect of harmonically varying damping on the multi-degree-of-freedom systems, especially; the influence on a structure with an isolation layer is discussed. The new proposed semi-active control laws require the phase information of the structural vibrations. However, obtaining the phases of the vibrations would be difficult if the vibrations were complex. Therefore, in this study, the Stuart-Landau Oscillator filter is used for estimation of the phase information from the response of structure. The filter is taken advantage of the synchronization properties of a nonlinear oscillator, and the output of the oscillator has the characteristic frequency designated by the oscillator. The validity of the proposed system is shown by numerical simulation.

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As a method for semi-active control of structural systems, the active-control-based method that emulates the control force of a targeted active control law by semi-active control devices has been studied. In the active-control-based method, the semi-active control devices are not necessarily able to generate the targeted active control force because of the dissipative nature of those devices. In such a situation, the meaning of the targeted active control law becomes unclear in the sense of the control performance achieved by the resulting semi-active control system. In this study, a new semi-active control strategy that approximates the control output (not the control force) of the targeted active control is proposed. The variable parameter of the semi-active control device is selected at every time instant so that the predicted control output of the semi-active control system becomes close to the corresponding predicted control output of the targeted active control as much as possible. Parameters of the targeted active control law are optimized in the premise of the above "output emulation" strategy so that the control performance of the semi-active control becomes good and the "error" of the achieved control performance between the targeted active control and the semi-active control becomes small.

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In Japan, after Hyogo-ken Nambu Earthquake in 1995, base isolated structures have been spread rapidly. Now, there are about 2800 base isolated buildings (apartment complex is 45%, hospital is 12% of all) and about 4300 base isolated houses in Japan. Base isolation technology was effect in The 2011 off the Pacific coast of Tohoku Earthquake. This paper presents the method of semi-active control design for base isolated structure with oil dampers whose damping coefficient can be available to set in two levels, which is to apply two different damping coefficients based on the proposed control design. The damping coefficients of the oil dampers are different each other. The control objective is reduction of both displacement of a base isolated layer and absolute acceleration of a base isolated building which are trade off relations each other. The layered neural network with Genetic Algorithm (GA) is applied to the semi-active control design. Absolute acceleration of the building and displacement of the isolated layer are the input signals of the neural network, and switching parameter for the damping coefficient is the output signal of the neural network. Genetic Algorithm is used to adjust the neural network parameters which decide the control performance. The target of control design is specified to permit the displacement of base isolated layer to the upper limit and to restrain the increase of building acceleration. We study the control performance of the proposed control method using several kinds of earthquake motions in the computer simulation.

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This paper describes characteristics of the FitzHugh oscillator that represents dynamic properties of nerve cells and is applied to a filter, which can extract the designated frequency, for semi-active control of structures. The FitzHugh oscillator is one of the nonlinear oscillator who has a property and which is synchronized with a sinusoidal input. To detect the synchronization region, the phase reduction method is applied. As a result of the application, a phase coupling function to drive the region and phase difference between the output and input of the oscillator, which are important when using the oscillator as a filter, were obtained. In addition, a response of the oscillator to dual frequency input, whose frequencies were the natural frequency of oscillator and another, was investigated by numerical simulation. In the simulation, it was clear that a specified frequency filtered by the oscillator could be extracted. Additionally, in the case of single frequency input, it was unveiled that the completion time of synchronization depended on the initial phase difference between input and output by the simulation.

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This paper deals with a control system design problem for a quadrotor with unknown parameters. An adaptive trajectory tracking control of quadrotor will be proposed based on the backstepping strategy. The stability of the obtained adaptive tracking system will also be analyzed and the effectiveness of the proposed method will be confirmed through numerical simulations.

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This paper considers the problem of controlling both the position and the attitude of a four-rotor mini helicopter. The four-rotor mini helicopter is described by a set of nonlinear equations and some parameters of the dynamics are subjected to uncertainties. This paper presents a new adaptive tracking controller based on backstepping technique, exact feedback linearization and optimal control for position tracking. This controller can make to converge to zero the tracking error of the position and the yaw angle exponentially. A numerical simulation is performed to evaluate the effectiveness of the proposed controller.

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This paper deals with new tracking control problems for moving vehicle robots in three-dimensional space such as single/multi-rotor helicopter, airship, airplane and submarine. The robots are nonholonomic systems described by a set of nonlinear equations and some parameters of the dynamics are subjected to uncertainies. This paper presents new practical tracking controllers to reduce the tracking error less than or equal to any specified positive value for a given desired trajectory asymptotically. By introducing this allowable tracking error, the tracking control problem of the robot system can be reduced to that of a simple linear system. This approach makes the well-known linear control theory applicable in the control design. Moreover, a new adaptive practical tracking controller with online parameter estimation is proposed. A numerical simulation is performed to evaluate the effectiveness of the proposed controller.

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The ability of Reusable Launch Vehicles (RLVs) to carry out multiple missions would significantly reduce the operational expenses for space exploration. However, the control and coordination of RLVs during flight operations present many design challenges. For instance, RLVs travel from earth's surface to space in uncertain environments causing the values of the parameters for the RLVs' dynamic equations not constant. Therefore, various researchers have proposed several adaptive control methods as well as digital control systems for RLVs. We have proposed a digital adaptive feedback linearization control method with time-scale separation using Dynamic Inversion method and Kalman Filter for the control system of a winged rocket. Furthermore, Euler angles are commonly used in calculations related to kinematics of rigid body dynamics. Quaternion is often being used in attitude control system of a spacecraft compared to Euler angles due to the relation between the Quaternion and its angular rate is linear and it has no singular point. In this paper, we propose a digital adaptive feedback linearization control method for the winged rocket using Quaternion. Simulation results show the effectiveness of the proposed method.

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This paper deals with a new repetitive control problem for the cases where both the multiple periods of periodic disturbance to be rejected are uncertainty and the plant has a norm bounded uncertainty. A new period estimator is proposed to estimate on-line both the periods and the plant parameters, and a new adaptive repetitive control system is presented to reject any multiple periodic disturbances even if both the periods and the plant parameters are uncertain. The stabilization problem of the overall adaptive system is reduced to a simple and feasible l_I-norm minimization problem. The controller can be obtained easily by solving a simple linear programming problem. Simulations show the effectiveness of the proposed controller for rejection of multiple periodic disturbances.

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When simple adaptive control (SAC) is applied to the vibration system which includes antiresonance modes, there is the problem that undesirable vibration input is generated. A solution is to use parallel feedforward compensator (PFC) which makes expansion system by plant and PFC into desirable frequency response. On the other hand, PFC is required of attaining ASPR property for the expansion system. We show a new method to solve these problems. Effectiveness of the proposed method is verified by experiments.

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In this paper, we study the data-driven parameter tuning of lumped type controller to one-dimensional heat conduction system, which is one of the distributed parameter systems. Particularly, we focus on one of the applications of the canonical controller, which was proposed by A.J. van der Schaft, as the ideal controller that achieves a given specification. And we derive a tuning method to achieve the desired tracking of one point of the heat conduction system which is actuated at the another point, which corresponds to the feedback interconnection of a distributed parameter plant and a lumped parameter controller.

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In this paper, we propose an adaptive lane keeping controller using the front and rear wheel steering. The developed controller does not require any accurate knowledge of all vehicle parameters, the road curvatures and the measurements of the lateral velocity. At first, a new dynamic expression for the vehicle dynamics is proposed. The dynamic expression is suitable to design a stable adaptive lane keeping controller without using the lateral velocity of vehicles. Next, an estimator is shown for unknown curvatures of target lanes, and then, we propose a method to design ideal transient trajectories for the relative lateral distance and the relative yaw angle between vehicles and target lanes. Finally, an adaptive lane keeping controller is developed. In the adaptive steering system using the developed controller, is proved theoretically that good robust performance can be achieved by setting only one design parameter.

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In this paper, we propose an adaptive rollover prevention controller. At first, using a evaluation function, we propose a design method for an ideal vehicle model achieving good rollover control performance even if driver's steering characteristics vary. Next, an adaptive tracking controller is developed so that the behavior of the actual heavy vehicle can track that of the ideal vehicle model.

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