Laminated shells made of fiber-reinforced composite materials have been increasingly used in light weight structural applications. Many laminated composite shells among these applications are made by filament-wound forming. In this paper an influence of material anisotropy and geometric parameters on natural frequencies for laminated cylindrical shells for the case of simply supported is studied and discussed. The formulation is based on the Flugge-type and Donnell-type shell theories using the First Order Shear Deformation Theory (FSDT). The results are compared to those of the Classical Shell Theory (CST). The purpose of the present analysis is to show a guideline for the convenience of dynamic design in a wide variety design situations with a view point to selecting shell theory.

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This paper deals with experimental and theoretical analysis with respect to vibration mode characteristics of brake a'ssy of a drum brake at squeal noise generation. Using experimental timehistory mode analysis, the vibration mode of backing plate (B/P) at squeal generation is found to be 3rd circumferential progressive-wave type vibration mode. In the impact vibration testing of the drum brake a'ssy on bench test we find the similar 3rd circumferential vibration modes with 90 degrees phase shift. A theoretical vibration model including B/P modeled as the circular plate is proposed. Complex-eigenvalue analysis of the vibration model shows a 3rd circumferential progressive-wave type mode in the B/P vibration when the friction becomes larger than a critical value.

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This paper presents the numerical simulation of the dynamic response of rarefied gas lubricated slider bearing on a magnetic recording disk. In previous papers, various attempts had been done based on modified reynolds equation such as analysis of dynamic responses by periodic acceleration and experiments. However, the results of experiments have shown that the disk movement is random rather than periodic, so that the acceleration by air lift becomes to have random quality. We have already presented the scheme of the computation and the results without rolling movement. If there is any irregularity on the disk, such as a bump or a grain of dust, the rolling will occur. The object of the present study is to simulate the behavior of the head slider in this case. The present method has an advantage such that only one computation based on a randomized disk movement permit us to obtain resonance region of frequency. Results of the analysis for random acceleration are shown by dynamic response diagrams of a head slider and power spectra of the response.

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The vibration control problem of a single pendulum system has been investigated by the vertical movement of a pivot attached to a cart. Since the dynamic equation of the pendulum mounted on a cart is generally a nonlinear time-variant system including the angular acceleration θ^^·(t) in the system parameter, a VSS control scheme having a 4 type switching logic is presented using the Lyapunov's method. By optimally designing the switching plane (s=0) and by linearly approximating the discontinuous function sgs (s) characterizing the VSS near the plane s=0 (i.e., in the optimal range |s|≤0.3), satisfactory active damping effects can be obtained both from simulating and practical points of view. Furthermore, in addition to the robust damping effect related to the VSS control, there exists the amplitude-dependent damping that is effective even at larger amplitude.

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This paper deals with an optimal placement problem of sensors and actuators for active vibration control of flexible structures. For undamped flexible structures with collocated sensors and actuators, each solution of two generalized algebraic Riccati equations are obtained explicitly. Using these two solutions, it is shown that the stabilizing H_∞ suboptimal controller based on the normalized left coprime factorization approach can be synthesized directly for all candidates of the placement. The sensor/actuator placement problem which optimizes other closed-loop performance can be formulated easily by applying this H_∞ controller. As a design example, a placement problem which minimizes H₂ norm of the closed loop transfer matrix using this H_∞ controller is considered for a cantilevered beam. The experimental results show the effectiveness of the sensor/actuator placement method stated in this paper.

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This paper is concerned with vibration suppression of a flexible concrete distributor arm. The concrete distributor arm with length of over 30 m is modeled as a multi-link flexible arm by using FEM (Finite Element Method) together with a singular value decomposition for reduction of mathematical model. DVFB (Direct Velocity Feedback) is applied to the control of a joint torque for suppressing the vibration. A hardware test model is set up to simulate the actual system. The vibration of the flexible multi-link arm is successfully suppressed in the hardware test. Farther, it is shown that the results by using the mathematical model are in close agreement with those of the hardware model.

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It is found through vehicle dynamics simulation that a carbody hunting motion for arc tread wheel becomes smaller than that for conic tread wheel in new type SHINKANSEN train which is bolsterless and has soft suspension between carbody and bogie. Then we studied about the reason, comparing kinematic hunting wave length of a bogie with the natural frequency of the carbody and also evaluating input energy from rail to vehicle. The analysis shows that vehicle with arc profile treat has high frequency from short kinematic wave length in a high speed (270 km/h) whereas low carbody natural frequency, then the frequency of carbody hunting motion becomes apart from the natural frequency and smaller than that with conic profile. In addition, the energy input from rail to vehicle were calculated from simulation and verified the validity of relation between the carbody natural frequency and hunting characteristics. An arc profile that varies with lateral displacement of wheelset also shows that the energy input from rail is smaller than that in a conic profile.

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Comparison between responses of test train running on track irregularities artificially set on SHINKANSEN and those of vehicle dynamics simulation was made at the speed up to 210 km/h. In comparison between the measurements and simulation using basic parameters, the response to line irregularity of the measurements and simulation for the wave length longer than 40 m is nearly identical, although that of simulation becomes apparently larger than that of measurements for wave length of 20 m. Then the state of track irregularity artificially set was precisely investigated and an enlargement of gauge in the section of 20 m wave length was found. And simulation of the response assuming the gauge enlargement was nearly identical with that of measurements. In this report, the influence of wave length and gauge variation on the response to track irregularity mentioned above due to comparing measurements and simulation is analyzed. Besides, by using same simulation program, the influence of gauge variation on carbody hunting motion of new high speed SHINKANSEN train which has soft suspension between carbody and bogie due to bolsterless bogie is studied.

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In studies of active vibration control of railway vehicles, recently, the preview control which has been designed using the LQ theorem or the H_∞ control has attracted the attention. In this paper, a design method of the preview control action based on the H_∞ control theorem is derived, such that the designed control system provides the desired features of both the preview control and the H_∞ control. A simulation study is done for the vertical vibration problem using a half-vehicle model. As a result of the simulation study, it is shown that the preview control action has some properties as follows. (a) The frequency response gain of the acceleration of car body in higher frequency range is reduced. (b) The variation of the pitch angle of car body is reduced. (c) The robustness against the mass variation of car body is obtained.

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The working fluid of the oil damper is usually treated as an incompressible fluid. However, it becomes clear that the damping coefficient of the oil damper is strongly dependent on the impressed frequency. The primary reason is considered to be the effect of compressibility of oil, including the compressibility of air melting in it. The influence of the inertia force of oil on the frequency characteristics is too small to cause the drastic change of the damping properties. We have already proposed an expression for a viscous oil damper by considering the compressibility of oil. The theoretical expression is still not verified by the experiments. According to our theoretical study, the effects of compressibility appear in the high frequency level (more than a few hundred hertz). In such a frequency level, it is difficult to measure the damping force with a high accuracy. In this paper, we perform an experiment with a new device. It was obvious from the experimental work that the frequency characteristics of the viscous oil damper were well explained by our expression.

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In the previous paper, an elastoplastic damper utilizing continuous plastic bending of thin metal rods was developed. In this paper, an improved damper that is improved a winding mechanism of the metal rods of the elastoplastic damper for a larger resisting force and a compound damper that is added a friction mechanism as a fale-safe mechanism to the elastoplastic damper are proposed. The trial dampers were made and the resisting force characteristics and fatigue strength of the dampers were measured. The seismic responses of an L-shaped pipe supported by the dampers were also measured using an electrohydraulic shaking table.

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In order to investigate problems related to soil and construction machinery, such as a hydraulic excavator, an understanding of the physical interactions between the soil and the machine is essential. The purpose of this study is to empirically examine actual excavation processes by measuring various physical parameters. In this article we present results from the outdoor excavation experiments in which two different soil types, sand and loam, were excavated by using a real-sized bucket equipped with many sensors. Several physical parameters were measured such as excavation load, lateral and longitudinal distributions of pressure and friction exerted on the bucket surface and fracture of soils. Also effects of artificially reduced friction of the bucket surface were tested in two different ways; use of a low friction polymer and use of mechanical vibration.

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This paper is a study on the identification of physical parameters of flexible minute objects by the active sensing using a two-fingered miniature gripper. The gripper is consisting of two flexible fingers actuated by piezoelectric bimorph strips, which ride respectively on translation stages driven by fine ball screws. A semi-conductor strain gauge is bonded on the surface of one finger to measure the vibration of the coupled finger-grasped object system. First, the two fingers are shifted laterally until they come in contact with the object and hold it. Then, one piezo-actuator of gripper is driven by a step input voltage so that the two fingers shake the grasped object. The first natural frequencies of symmetric and antisymmetric modes of the coupled system are read through the spectral density analysis of the strain gauge output, from which the mass and stiffness of the grasped object are determined uniquely. The proposed identification method is studied theoretically and its effectiveness is verified experimentally by using a sponge rubber block and a salmon roe.

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A new pneumatic rubber actuator, named bubbler, realizing linear motion has been designed and developed. The bubbler consists of a silicone rubber slab, and its inside is divided into many chambers. When pressure is applied to successive chambers sequentially, the surface of the rubber slab produces linear traveling waves which drive objects placed on the actuator. This actuator can be used for a mobile robot base or for a conveyor. The mechanism and characteristics of this actuator are discussed in this report. The characteristics of the actuator can be estimated by applying a simple linear analysis for various driving conditions; frequency, length, duty of the generated waves, vertical loads, and horizontal loads. Experimental results are very promising. The walking speed of the prototype, 63 mm×60 mm×9 mm in size, was found to be 4.7 mm/s and the load-to-weight ratio in the order of 40:1.

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Recently computer simulation plays more and more important role in design stage. But it is difficult to make an accurate model of computer simulation represented by finite element method (FEM), because there are some differences in physical parameters from those of real structure. In this paper, the physical parameters of FEM which are not consistent with those of real structure are treated as damage. The detection of damage location, and its physical values are studied based on neural network and computational mechanics. An approach of damage detection is discussed with four types of structure of neural network as digital type, analog type, coordinate type and hybrid type, by holographic neural network. Comparing to the multiple layer neural network (back propagation training scheme), it is shown that holographic neural network is more accurate and faster in training and detection.

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A new discrete deconvolution procedure is developed that uses the wavelet packet based system decompositon. The system is decomposed into subsystems using the wavelet packet transform and the inversion of each subsystem is derived approximately. We show how to select the wavelet packet bases to mitigate the effects of ill-posedness due to the narrow bandwidth of the system. A new wavelet bases family with the optimal transition band performance is generated to surpress the approximation error. Furthermore we introduce the soft thresholding into our procedure to reconstruct temporal inhomogenious signals more efficiently.

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This paper describes a hydraulic servo system of variable compliance used in the environment of frequent machine-human interaction. Sufficient reliability is critical in such a circumstance, so a mechanical adjustment of compliance of the servo system is considered here. In the present system neutral position of the bridge valve circuit is controlled to adjust the compliance. Mathematical model of the system is derived to study the static and dynamic behavior of the system. In the operating condition with large compliance, the present system has a strong nonlinear characteristic, and the nonlinear control technique of feedback linearization was successfully applied. On the other hand, conventional linear control was applicable for the operating condition of small compliance. Validity of the present servo system was confirmed by experiment.

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The variable resonance-mode type of side-branch resonators which can be adjusted freely at the desired resonance modes (i.e., desired resonance frequencies and mode shapes) with a single closed-end tube configuration, unlike a conventional side branch, are newly developed and their attenuation characteristics are investigated theoretically and experimentally. The mechanism of variable-mode is based on the principle that the resonance mode of fluid wave motion in a side-branch tube can be changed arbitrarily with the adjustment of reflection factors at the choke orifices which are inserted in it. The present variable resonance-mode type of side-branch resonators are devised in order to reduce the several harmonics of the fixed discrete-frequency pressure pulsation such as those generated by a fixed speed hydraulic pump. A successful mathematical means (optimum design method) of sizing the desired lengths and diameters of n number of choke orifices and lengths of divided n+1 number of side-branch tube parts so as to coincide resonance frequencies with the desired one is outlined. It has been confirmed in the bench tests that the proposed side-branch resonators yield the satisfactory insertion loss characteristics so far as they are used in a hydraulic circuit with very short length of outlet pipe in which the influence of standing wave is negligible. Further, the present side-branch designed so as to reduce the 1st and 2nd harmonics of pressure pulsation has proven to be very successful also in application to a real hydraulic excavator for reduction of air-borne noise as well as pressure pulsation of these harmonics.

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The main purpose of this study is the numerical evaluation of the stress state in the Flexspline which is the key element in the Strain Wave Gearing. When the Flexspline is deformed into an elliptical shape by repeated load from the Wave generator, the fatigue of Flexspline at the root of the gear becomes a serious problem. The Cup Type Strain Wave Gearing is modelled using brick element, beam element and joint element in the three dimensional field. Based on the three dimensional FEM analysis, the hoop stress at the root of the gear in the Flexspline is evaluated. The effect of the torque, the position of Bearing ball and the contact between Flexspline and the outer ring of Bearing on the stress states are studied.

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An optimal operational planning problem is discussed for a heat pump space cooling system considering characteristics in ice bank during ice making and thawing. This problem is formulated as a mixed-integer nonlinear programming one, in which the operational strategy of heat pumps and ice bank is determined so as to minimize the daily operational cost. An algorithm is proposed to solve this optimization problem on the basis of the log barrier method. Through a numerical study, it is ascertained that the proposed algorithm is a useful tool, and it is investigated how the characteristics in ice bank influences on the operational strategy.

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At the conceptual design stage, design process is not always logical because of the lack of design criterion, procedure and knowledge clearly established. This process is dependent on the individual designer with specific design experience. It is important to consider the designer-dependent subjective aspects, but a limited attention has been devoted to the computerization of design process including such aspects. In this article, we discuss an artificial design assistant for conceptual structural design, and its personalization to individual human designer. In this framework, the rule-based inference is used to generate and to evaluate the design candidates from multiple evaluation criteria to be considered by the human designer, and the genetic operations combined with the genetic case-base are used to suggest the candidate to the human designer with probabilistic fluctuation. The progress of the design process is managed by the human designer through the interaction with the artificial design assistant. Based on the response of the human designer to the suggestion from the artificial design assistant, the preference of the artificial design assistant is adjusted to meet that of the human designer from the multiple evaluation criteria of the design in terms of the parameters for the genetic operations. Proposed idea is implemented and examined for the conceptual design of skeletal bridge structure including the constructive layout, the structural topology and geometry. The case studies demonstrate the effectiveness of the artificial design assistant with the personalization capability proposed in this study.

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In design problems, it is possible to classify design variables into three classes: integer, discrete and continuous variables. It is said that mixed variable optimization is the one of the most daunting problems in design optimization. Genetic algorithms are very effective algorithms especially for large scaled combinatorial optimization problem. Thus, they are also effective in integer and discrete programming. However, as they are not well coded to its tedious expression in converting chromosomes to design variables, we need to do some special efforts to overcome these flaws. In the proposed method, it automatically adapts a searching range according to the situation of the generation. Thus, we do not have to take tedious expression into account. Moreover, we do not have to give too many genes to chromosome, thus not only we can save computational memory but also the convergence becomes more better. In this paper, we combine the proposed integer and discrete adaptive range genetic algorithms and adaptive real range genetic algorithms which we presented in the former studies, and present an extended genetic algorithms method which adapts a searching range for each design variable for mixed integer, discrete and continuous programming. We applied the proposed method to well known test problems in mixed optimization problems, compare the results with the other methods and show the effectiveness of the method.

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The method of analysis of three dimenional sound field coupled between inner and outer space separated at an enclosure is developed by using the three demensional Boundary Element Method (BEM) for the object evaluating the method of reducing the sound noise generated by machines. Though the analysis of two dimensional sound field of it had already been developed and the features had been shown by authers the actual sound field is not two dimensional but three dimensional and the obtained results by two dimensional analysis is only available to estimate the feature of actual sound field qualitatively. Then, the three dimensional analysis is developed to estimate the feature of actual sound field quantitatively and the differences of results of analysis between two dimensional and three dimensional analysis are discussed.

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Data input devices for physically handicapped people have already been developed. One simple device detects the blowing action of the operator as input signals to select desired menu items. Another advanced device detects eye movements as input signals. One problem associated with these advanced data input devices is that a lot of times is required to input items. In this work a pointing device operated by the posture of head is presented. An important feature of our device is that the operator can input items immediately by turning his head toward desired items displayed on CRT monitor.

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In the present paper, we propose an H-slit beam which can be effectively utilized to achieve a highly unidirectional deformable structure, and the outlines and characteristics of a 3-axis force/torque sensor based on the above proposal is also reported. This force/torque sensor can measure very small reaction forces/torques generated by the motions of a robotic manipulator having its degrees of freedom in only one plane. For such application, a sensor structure which accepts no effect of gravitational force influence on the manipulator's structure, is needed. The important points to consider include that the sensor should be sensitive only in the direction of measurement of force/torque, and very stiff in all other directions. To achieve these goals, we propose the H-slit structure as an extension of the parallel beam structure. The idea behind is the formations of a 4-1ink closed structure; the joints between the links are deformable, so the strain guages are fixed at these positions. By changing the dimensions of links, a variation in sensativity and directional stiffness is possible, and by changing the dimensions of H-slit, a mechanical over-load protection is also achieved.

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This paper describes the measurement of vibration intensity in a U-shaped shell which is excited at the center of the curved part. A formulation of vibration intensity was introduced to cylindrical shells. The formula is defined as a summation of flat terms which are similar to vibration intensity in flat plates and curved terms which are related to curvature of the shell. The each of curved terms was estimated by FEM. The vibration intensity on the curved part of a U-shaped shell was measured. To obtain the vibration intensity in shells, it is necessary to measure both out-of-plane and in-plane vibrations. In this study, the out-of-plane and in-plane vibrations at 8 points near the aimed point were measured by accelerometers to obtain one direction component for two dimensional vibration transmission. The experimental results are discussed and compared with numerical results obtained through FEM. It is clarified that the influence of the curvature radius on vibration intensity strongly appears when the wavelength is longer than the radius.

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We investigated mutual relationships between rhythmic motions of plant organs (roots and stems of peas (Pisum sativum)) and environmental informations by stimulating an organ with the LED light and the sound, using the newly developed measuring system. This system can record 3-dimensional motions of two plant organs automatically by image processing, and in this system the overhead crane was equiped with the light stimulating instrument or the sound stimulating instrument, which can locally stimulate the necessary part only. As a result, when the tip of a stem was stimulated with the blue light (470[nm]), it grew toward the light source as the amplitude of the rhythms increased. When stimulating a stem with the white noise for 1[h], the amplitude of rhythms in it grew bigger after stopping the stimulation. In addition, we found some correlations between rhythmic motions of the stimulated organ (stem) and the other organ (main root) when the tip of a stem was irradiated with the blue LED light.

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Approach for modeling and feedback noise control of a one-dimensional duct based on experimental modal analysis and LMI is presented in this paper. The modal parameters of a coupled acoustical-structural system are derived from measured noise and vibration data. The state equation of the duct is described by the identified modal parameters. An active noise controller is designed based on LMI approach in which an optimization problem is defined as a mixed H₂/H_∞ control problem. The performances of the noise reduction and the robust stability are described with H₂ and H_∞ norms of the closed loop system, respectively. Frequency response shaping is performed by the presented approach with weighted modal matrix and frequency weighting functions. Simulations and experiments are carried out and the desired performances are obtained by the presented approach.

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The methodology for designing optimal driving pattern of a moving cylindrical liquid container to reduce residual free surface oscillations after a rapid access process is presented. The control scheme proposed in this paper is based on the optimal control theory and the magnitude of control input is selected as a cost function. The effectiveness of this method is shown through experiments and simulations. In the simulations, free surface oscillations are formulated based on the finite amplitude theory and modeled as a nonlinear system with third order nonlinearity. The effect of liquid depth and the access time on the amplitude of residual surface oscillations is discussed in detail and the comparison between experimental and simulation results is performed.

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An attitude controller for a 50 kg-class micro satellite which could be launched by H-II rocket as a piggyback payload of a main satellite is considered. One of the candidate configurations for such an attitude controller is bias momentum control using a magnetically suspended momentum wheel with gimballing capability. Magnetic bearings can generate internal torques and tilt the axis of the momentum wheel relative to the despun mainbody, and this function can be used for the active stabilization of the attitude motion of the satellite. The disturbance torque acting on the satellite caused by the release of a tethered subsatellite from it is estimated for the controller design. The attitude controller for estimated disturbance is designed based on the linearized equations of motion of it applying the H_∞ control theory. The performance of the controller is evaluated through numerical simulation.

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Future spacecraft such as Orbital Maneuvering Vehicle or "Remover" which tries to capture and remove large space debris objects in orbit are supposed to do large angle and complicated position maneuver in space. The equation of motion of the rigid body which performs attitude and translational motion (six degrees of freedom motion) is a nonlinear equation. This paper applies Sliding Mode Control which can handle a nonlinear plant to the six degrees of freedom control for such a vehicle. Through a numerical simulation of proximity flight around a tumbling target object, its feasibility is investigated.

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Sliding mode control is applied to the attitude control of a spinning vehicle by the combination of one-shot thrusters that generate lateral thrust with a pulse width of less than 1 ms. This thruster system has several advantages such as small control delay and low cost, and can be used in high altitude, low dynamic pressure and hyper sonic enviroments. We adopt the regulator scheme to reject disturbances of precession for the LUNAR-A penetrator of a lunar probe. The Control system is designed for discrete time computer control and thruster consumption has been reduced by using the method of linear quadratic optimal control applied to the design of switching hyperplanes. This reduction results in a lower total weight of the vehicle.

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This paper presents the intelligent control technique using neural network for Man-Machine system. The proposed controller consists of LQ controller and a distributor. The distributor which is composed of neural networks decides the ratio of a control input from LQ controller and a operator's input. This contrtol technique is applied to a industrial vehicle in order to prevent falling-down and suppress vibration. The usefulness and effectiveness of the control technique are verified numerically and experimentally.

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An acquisition technique of autonomous distributed rule for posture control of Variable Geometry Truss (VGT) is suggested by applying the Genetic Programming (GP) method. Each control rule produced by GP consists of hierarchical tree structures. The main tree structure contains condition trees and rule selection trees as function nodes, and control trees as terminal nodes. The acquisition system trains individual rule by the posture control simulation for the randomly given initial postures, and evaluates the rule by the simulation of given test postures. The validity of the acquisition system is confirmed numerically by applying to the stiffness maximization of ten-module VGT.

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When a linear controller is applied to a nonlinear system, it sometimes causes some deterioration of the control performance. Neural control can be useful as a controller for nonlinear system. Its learning architecture can be classified into General Learning, Specialized Learning, Forward and Inverse Modeling and Feedback-error Learning Architectures. However, these architectures have the following defects, that is, the output of plant does not always track the objective value, learning law can not be determined when dynamics of plant are unknown and the structure becomes complicated, etc. In this study, to improve the above defects, a Learning Control system, which has simple structure using only one artificial neural network and has feedback function, is proposed via Input Matching.

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This paper proposes Tactile Display for presenting the moving or shearing direction to the skin of human finger. In many type sense which human finger has, by using vibro-tactile stimulation we aim at the development of tactile feedback system. The vibro-tactile stimulator utilizes vibrating pins to provide ticking sensation to the human operator's skin. We use the micro resonator which is driven by electro-magnetic force for vibrating pin. We make an experiment which present vibro-tactile stimulation using micro resonator and confirm the ability to perceive the vibro-tactile stimulation. Next we array the micro resonator as matrix state and construct the tactile display. We show the tactile feedback experiment using this display in this paper. At the experimental results, it becomes cleared that the tactile display has the ability to present much information to the skin of human being.

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This paper addresses a new concept of constructing stable grasps of arbitrary planar object. We consider the manipulation of arbitrary objects by a multifingered hand, where the contact type is object rolls without finger slipping on the object surface. The synthesis of stable grasps is constructed by virtual springs at the frictional contact point. Each finger has a two directional virtual spring whose stiffness is known but compression is unknown. We explore the positive definiteness of the stiffness matrix of the grasp system from the view point of potential energy. It is shown that the stability is greatly influenced by spring stiffness, position and curvature of fingers, object curvature, and initial grasping forces.

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This paper describes a technique based on the electric-fluid analogy to predict dynamic responses of pressurizing devices drived by Electro Rheological (ER) fluid. In the electric-fluid analogy, flow response is modeled by an electric circuit by the analogy of basic transient equations between flow and electric circuit. This study consitutes a model of the flow inside electrode annuli of the pressuring device. The parameters of resistance and additional electric sources in the model are derived by assuming that the flow can be approximated by Bingham flow. The inertance is derived from a physical consideration of fluid inertia. Because the capacitance is greatly influenced by the amount of tiny air voids in the ER fluid, the capacitance is estimated from the result of a simple experiment. The prediction results of the transient responses of the electrodes show rather well agreement with experimental data.

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This paper is concerned with a control method for trajectory tracking and obstacle avoidance to unknown object by redundant manipulators. When a desired trajectory of a manipulator's hand is on a surface of a object, the object could be an obstacle, and tasks of trajectory tracking and obstacle avoidance should be controlled parallel in the same time. To realize such control to an unknown object, we propose a preview control system, which includes path planning function using GA and potential field around the detected object in the control feedback loop. This system is based on an assumption of real time sensing of the unknown object shape. GA is used to choose the safest configration of the virtual manipulator which is referred by the preview controller. The effects are confirmed by simulation experiments.

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This paper presents a force control strategy for a manipulator/vehicle system floating on the water. The proposed strategy makes it possible to compensate the reaction force/moment by actuator force restricted in a plane fixed to the vehicle. Moreover the poroposed control strategy reduces the number of actuators required for the force control by utilizing the restoring force/moment applied to the vehicle. In this paper, we derive the relation between thruster outputs and the force/moment exerted at the end-effector based on the kinematics of the system taking the restoring force into account. Using this relation, we calculate the realizable force at the end-effector.

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A large class of robotic force control problems, including painting, scraping, and grinding, involve simultaneous force and position control. In many of these aplications, the robot is required to exhibit very high-speed performance while also tolerating unknown or poorly defined constraint specifications. In recent years, some experimental results of robots performing such tasks using hybrid and impedance control strategies have been presented; however, many of these studies neglect the inherent restrictions of actual industrial implementations of force controlled robots. Moreover, evaluation of the performance of the force control algorithms is typically based on data from robot-mounted sensors, rather than workpiece-mounted sensors, the latter being much more important for industrial users of force controlled robots. This paper introduces a high-performance 3 DOF robotic testbed designed specifically to test industrial applications of force control and contour following. The testbed consists of a force sensing table and a 3 DOF manipulator. The manipulator design and control are strongly influenced by practical restrictions arising during application to industrial tasks. Specifications of the developed system, as well as results of preliminary system characterization experiments, are presented in this paper.

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In this study, the design of bilateral controller for the master-slave system is discussed on the basis of the H_∞-optimal control framework. In this paper, a divided design procedure is adopted, the several controllers that achieve given performance specifications are designed in order. The performance variables and the frequency weighting functions are chosen properly, each controller is derived by solving LMI problem. Furthermore, a specified controller is redesigned to compensate instability caused by a time delay exists in the communication channel between the master and the slave. Since it can be considered that the time delay reflects as a perturbation to the system, the compensation of time delay results in the robust stability problem of the system with the perturbation. In order to keep the maneuverability, the impedance parameters are adjusted, such as the apparent decrease of perturbation. The validity of the proposed method is confirmed in control experiments using a direct-drive master-slave system.

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This paper proposes an alternative power-scaling algorithm of a controlled telemanipulator with time delay in the transmission line. In the proposed algorithm the motion and force relation, or the power scale, between the master manipulator and the slave manipulator can be specified freely by using two scaling factors. In this system, a communication part of a telemanipulator, which has the time delay, is stabilized based on the scattering transformation. Besides, in the sense of passivity, the scaling algorithm for realizing the power scaling stably is discussed. Although the power scaling had been considered to violate the passivity condition, in the proposed scaling approach, the total stability of the resultant system is guaranteed for an operator and a passive environment with unknown dynamics in view of passivity. The proposed method is experimentally applied to a telemanipulator and the experimental results illustrate the validity of the system.

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In this paper, derivation of equations for the dynamic analysis of closed loop mechanisms is described. The unified method which is applicable to any types of mechanism is obtained as a result. The condition of non-singular matrix which expresses the equilibrium of forces and moments on links and joints shows that the procedure of the derivation is a kind of conventional loop cut method. However, in this method, the forces and moments at cut points can be described by the explicit functions of the forces and moments acting on the links without introducing extra parameters such as the Lagrange's multiplier. It is also shown that the procedure of the derivation can be expressed by linear functions formed by matrices and vectors which helps to develop a computer program with less cost.

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Cellular Robotic System (CEBOT) is one of the Distributed Autonomous Robotic System (DARS) which consists of heterogeneous robotic units called cells and availability of structure reconfiguration. A robot of CEBOT can change their function through connection or disconnection with another cell. Functional reconfiguration increases the adaptability against the change of environment. But it has specific problem concerned with the cost for changing its cooperative structure. This paper deals with the behavior and the property of system composed of functionally reconfigurable robots. We focus on a system property concerned with collective behavior, especially the trade-off between adaptability and efficiency through computer simulation for a model of load transportation task.

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The influence of the surface modification treatment on the rolling contact fatigue and the scuffing capacity of rollers was examined by two cylinder test under oil lubrication. The surfaces of test rollers were modified by the electroless Ni-P alloy plating and the sulfurizing. The rolling contact fatigue strength and the scuffing capacity of the surface modified rollers were larger than those of the non-coated rollers. In the fatigue test the failure mode of both the surface modified rollers and the non-coated rollers was the spalling caused by subsurface cracking. The friction coefficient of the Ni-P plated rollers was smaller than that of the non-coated rollers, and the surface roughnesses of the modified rollers were decreased with increasing wear of modified layers. The small friction coefficient and the small roughness contribute to the improvement of the scuffing capacity, and moreover they might reduce the surface contact stresses and the rolling contact fatigue strength might be improved.

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A new simultaneous measurement method of temperature and thickness for lubricating oil film was proposed. In this method, two fluorescent dyes with different fluorescent spectrum and temperature characteristics were dissolved in oil and excited by same laser light. The temperature was obtained by the intensity ratio of fluorescence and the oil film thickness was obtained by the intensity of fluorescence. The 488 nm light of Ar Laser was used as a light source. From the experiments, Coumarin 6 and DCM were selected as appropriate fluorescent dye for this method. The fluorescence from Coumarin 6 in PAO increases with temperature and that from DCM in PAO decreases with temperature, and the intensity ratio of each dye changes greatly with temperature. It was confirmed that, by using the combination of Coumarin 6 and DCM with PAO, this method can he applied to measure the temperature and thickness of oil film in the temperature range from 60°C to 140°C.

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A precise analysis has been made for a method to obtain a profile of the thread surface of the screw rotor which is cut by using the given profile of a hob, especially in the case where the basic thread profile of the hob is given as a series of dispersive points. Firstly, it is clarified that under certain circumstances a singular point (a cusp) will occur on the thread profile of the screw rotor corresponding to the basic thread profile of the hob, and that, because of the cusp, the interference phenomenon will occur on the thread surface of the screw rotor. Secondly, numerical analyses are proposed to determine the interference by using a conditional equation of the cusp and to obtain a profile of the thread surface of the screw rotor. Then, the theories in this analysis are verified by applying the above numerical analyses to the dimensions of a pair of screw rotor hobs.

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This paper deals with the torque compensation cam (TCC) mechanism which minimizes the fluctuations of input shaft torque. By virtue of this effect, TCC is good method to reduce the vibration and to increase the operating speed of mechanisms driven by cam. However, it is sometimes difficult to find out the proper size mechanical spring through the market for the huge application. A novel design methodology replacing the coil spring to the air spring may fit this area which requires huge torque. In summary, the energy balance equation and the characteristic of air spring type TCC are derived. The procedure of design optimization is obtained to minimize the total energy of the system. The optimal control with the pressure as the function of operating speed during start cycle and at arbitrary operating speed is analyzed.

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In the preloaded double nuts of lead screw, the nuts displace slightly in the axial direction with the preload change because of the deformations of threads and screw, nut body. To apply this small displacement to the fine feed in ultraprecision positioning, the nut displacement characteristics accompanying preload change are examined against ball and sliding screws. Theoretical displacement is the order of nanometer with preload change of 1N and less displacement is easy to obtain under low spacing part stiffness. The experimental results obtained by the feed units show the step feed of from nanometer to submicron and the range of fine feed comes to several microns. The feed drive equipped with preload control lead screw has the advantage of high resolution positioning over a long traverse path by using it in combination with coarse positioning of screw rotation and fine positioning of preload control.

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