The objective of this research was to establish and realize a streamlined process from product design to manufacturing. Studies showed that this may be effectively accomplished by synchronizing the product and tooling design processes and incorporating manufacturing specifications during this product design phase. The proposed method entails a detailed tabulation of skills and judgments made by experienced manufacturing engineers onto a check list. These elements are quantified and simplified so that a non-skilled worker may perform the tasks. The parameters were then used to construct 3D CAD models forming collection of 3D data that is referred to as the “check module”. Implementing manufacturing specification check sheets and the check modules for a cell phone design resulted in 33% reduction in man-hour compared to existing approach, while the number of tasks requiring judgments and decisions was reduced by 78%. These measures decreased product defects stemming from human error and allowed a streamlined product and mold design.

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A rational method of dimensional reduction is developed in order to analyze accurately a nonlinear vibration generated in a large-scale structure with locally strong nonlinearity. In the proposed method, the state variables of linear nodes are transformed into the modal coordinates by using the real constrained modes that is obtained by fixing the nonlinear nodes, and a small number of modal coordinates that have a significant effect on the computational accuracy of the solution are selected and utilized in the analysis by combining them with the state variables of nonlinear nodes that are expressed in the physical coordinates. The remaining modes that have little effect on the computational accuracy are appropriately approximated and are eliminated from the system. From the reduced model constructed by these procedures, the steady state periodic solution and the stability, the transient solution and the quasi-periodic solution can be computed with a very high degree of computational accuracy and at a high computational speed. The effectiveness of the proposed method is verified by the computational results obtained for a straight-line beam structure with nonlinear supports.

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The occurrence of subharmonic tones in a beam supported by springs and dampers at both ends, and subjected to a nonsymmetric excitation having two components, one independent of, and the other harmonically varying with, time is considered. The beam can form a system with internal resonance due to the size of spring constants of support ends. To analyze the problem, the method of multiple scales is used. The analysis shows that in the system with internal resonance considered here, subharmonic tones of orders 1/2 and 1/3 can occur in a multi mode. The validity of the theoretical analysis is confirmed by numerical simulation.

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This paper describes vibration analysis using finite element method for two viscoelastic blocks connected by a nonlinear concentrated spring. One of the blocks is supported by another linear concentrated spring. The restoring force of the nonlinear concentrated spring has cubic nonlinearity and linear hysteresis damping. Finite element for the nonlinear spring is expressed and is connected to the viscoelastic blocks modeled by linear solid finite elements in consideration with complex modulus of elasticity. Further, the discretized equations in physical coordinate are transformed into the nonlinear ordinary coupled equations using normal coordinate corresponding to linear natural modes. This transformation yields computation efficiency. Influences of share of dissipated energy on nonlinear frequency responses for the viscoelastic blocks are clarified.

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This paper deals with analysis for layout of sound absorbing materials in three-dimensional rooms using damping contributions with eigenvectors as weight coefficients. Elements of absorbing materials are modeled by 3D finite element, which having complex density and complex volume elasticity. By expanding the solution of complex eigenvalue problem with small parameter, equations of motion are derived using first order of asymptotic components. From the equations, contribution of damping elements on modal damping is derived in consideration of multiple modes. The sound absorbing materials are arranged in three-dimensional rooms according to this contribution and the components of eigenvectors at the evaluation points. The availability of this method is verified using an expansion type chamber.

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This paper presents a method by using FEM for estimating SEA coupling loss factors, which is called “FEM-SEA”. The FEM-SEA is a tool for designing structure in detail although analytical SEA can not reach the detail design. The FEM-SEA requires a FEM model which is corresponded to a part of structures including the junction and the neighbor subsystems. The FEM calculation in carried out to entimate internal and coupling loss factors. The nature of the FEM-SEA is dependent on the boundary conditions of the FEM model which are connected with the other subsystems in the whole system. Two kinds of the boundary conditions are discussed to show that the estimating loss factors are not dependent on the conditions at least in the same applicapability as the analytical SEA. Further, it is also shown that the FEM-SEA can be applied more widely than the analytical SEA in case that the boundary condition set is similar to the actual conditions with the other subsystems. As a result, the FEM-SEA supplies the capability to design structure in detail and to apply widely than the analytical SEA does.

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This paper deals with modeling of a semi-active shock absorber using magnetorheological fluid that is a material responds to an applied magnetic field and changes its apparent viscosity. We suggested a dynamic system in which a friction of an impacting body is taken into consideration, and a model in which a shearing resisting force depends on the velocity of flow. The validity of this model and Bingham model was inspected by comparison of experiment with simulation. As a result of this study, it is clarified that resisting forces obtained by the simulation corresponded to those obtained by the experiment, and the present model was effective in order to predict behavior of the MR shock absorber.

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The objective of this study is the loosening detection of bolted joints without human involvement by applying the concept of structural health monitoring. The smart washer consists of a cantilevered plate bonded to a piezoelectric material, which provides self-sensing and actuation functions. The basic principle of how to detect bolt loosening is that the dynamics of a smart washer system vary depending on bolt tightening axial tension. The natural frequency of the smart washer was identified by using the sub-space state space identification algorithm in previous papers. However, the previous method has the problems that the fault detection accuracy deteriorates due to the influence of identification error and modeling error. This paper propose to apply the supervisor based on the model-based Fault Detection and Isolation technique for the detection of bolt loosening by using multiple observer. The numerical simulations and the experimentations were performed to verify the possibility of the observer-based loosening detection by using the smart washer. Improvement of bolt loosening detection accuracy was confirmed by comparing the proposed method with the previous method.

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The automatic inference of depth/distance information is a primary aim of computer vision systems. Though the stereovision method is often used for computer vision, finding matching pairs between frames can often be problematic, particularly when there are several possible choices of matching points. To address these problems, we have developed a depth measurement system that uses a single CCD camera. By setting the optical device in front of the camera lens, the image of a target recorded on the image plane is displaced by an amount related to the distance between the camera and the target. When the optical device is rotated physically at high speed during the exposure of the camera, the image of a moving target traces a spiral streak. Since the size of the streak is inversely proportional to the depth and the pitch and size variation of the spiral relates to the velocity of the moving target, the 3-D information of the target can be obtained by analyzing the streak. In order to make image processing easier, the spiral streaks and their corresponding center line are recorded on the same image. The center line helps in analyzing the streaks. This method has been applied to the measurement of moving tracer particles in flow and satisfactory results were obtained.

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By the change in one's eating habits, the biting force and it's number of times of the mastication function decrease. As a result, the decline of the muscle of mastication has appeared remarkably and young people with the temporomandibular arthrosis are the increasing tendencies. Therefore, mastication is paid to attention, and the establishment of the method of diagnosing is hoped for. In this paper, we developed the less-invasive type measurement system for mastication function. Sensor used the condenser microphone that was able to be measured to the low frequency band (10-100 Hz). The sound generated while masticating was measured with this sensor. First, the muscle sound generated by the opening and closing motion of the mouth was measured with the microphone, and the frequency was analyzed. It has been found that the bandwidth of the muscle sound is different according to existence or nonexistence of the joint sound. Next, the muscle sound when tuinggam was masticated was measured, and the cycle of one stroke was compared by 20's examinee with 30's examinee. It has been found that the cycle of 20's examinee is faster than that of 30's examinee.

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This paper proposes a multi time scale behavior control method for autonomous omni-directional mobile robot. As for motion planning, there are many problems to solve such as pass planning for a goal, moving by obstacle avoidance, keeping away from danger, and so on. The method is based on virtual potential field method. For each problem having a time scale, the corresponding module is constructed and virtual potential field is generated. Virtual force calculated from each potential field is used for generating the velocity command. The numerical simulations were carried out to verify the usefulness of the proposed method. From the results, it was confirmed that the robot can reach the destination without colliding with the static and moving obstacles by using the proposed method.

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Control Moment Gyros (CMGs) has been expected to be applied to an earth observing satellite in recent years. However it is not easy to control it because CMGs has a singularity condition and a major source of disturbance. Although there are many singularity avoidance logics, these optimal methods from the viewpoint of singularity avoidance may cause inner disturbance by fast and furious motion of gimbals in avoiding singularity. From the previous background, this paper presents a new but simple CMGs steering law using preferred initial gimbal angles and null motion for high accurate attitude control system on an agile satellite. Preferred initial gimbal angles are decided by evaluating function considering inner state of CMGs.

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A wheeled mobile robot is one of the nonholonomic constrained systems and has been studied intensively. An unmanned ground vehicle is a kind of wheeled mobile robots and is strongly needed in Japan because of decrease and aging of agricultural workers. In this paper, inverse optimal control with path regeneration is applied to the path following problem of a nonholonomic mobile robot and an unmanned ground vehicle. The designed controller has a stability margin which guarantees robustness to uncertainties on the input. The robustness has a possibility of superior performance on rough terrain where disturbances to the wheels affect the control accuracy. The efficiency of the proposed control system is confirmed by some simulations and experiments, in which a camera and a three-axial angle sensor are used to obtain the position and attitude.

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This paper studies a spherical motor driven by electro-magnetic force. The spherical motor is composed of a rotor and a stator. The rotor has 32 permanent magnets positioned at the vertices of a geometric configuration combined with a regular dodecahedron and a regular icosahedron. There are 84 electro-magnets in the stator. The electro-magnets are excited to make the rotor rotate in omnidirection by the pattern such that the electro-magnets near the rotation goal positions of permanent magnets in the rotor after a small time step are excited to the attractive pole and the electro-magnets apart from the permanent magnets to the repulsive pole. A simulation program is developed for the purpose of designing the structure and excitation method of electro-magnets and evaluating rotation performance. A prototype spherical motor is developed and the motor is confirmed to rotate is omnidirection by the experiments and simulations for rotation performance evaluation.

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When a grasped object is in contact with external environment, it is required to identify contact conditions prior to performing assembly tasks. The contact conditions include contact position, contact force, contact type, direction of contact normal, and direction of contact line between a grasped object and external environment. In order to achieve the assembly tasks, the contact type must be measured and controlled, for example, when changing from point contact type to line or planar contact type. This paper discusses parameter identification and transition detection of the contact conditions by active force sensing. The contact type is assumed to be point, soft-finger, line, or planar contact type with friction. To detect transition of contact type quickly, the limited number of measurement data is utilized, and weight of the latest data are enlarged. To eliminate offset of measurement data, deviated force and moment are derived. To correct and reduce an error of judged contact type, continuity of time series of the judged type is checked and revised. The effectiveness of this method is demonstrated by using numerical examples.

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In this paper, we present the performance of a novel accelerometer for the position estimation of a mobile object. The advantages of the accelerometer-based method are the easiness of installation and the wide adaptation : the accelerometer can be attached to various objects and it is possible to estimate position on uneven ground and indoors. The detector “Inductcoder” installed to our accelerometer is resistant to the noise because it provides digital data. The accelerometer in this paper is free from the friction that is created on the previous version because the new version consists of a cantilever and weight. Some experimental results show that the estimated distance using this accelerometer is more accurate than that using a capacitance-type accelerometer and is comparable to that using a servo-type accelerometer after corrections.

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In this paper, we describe a model based formation flight control of multiple small-scale unmanned helicopters. We design the autonomous formation flight control system as leader-following configuration. In order to achieve good control performance under the system constraint, “model predictive control” is used for the translational position control of follower helicopters. Position constraints such as moving range and collision avoidance problem are considered in the real time optimal control calculation. To achieve a robustness against disturbance, a minimal order disturbance observer is used to estimate the unobsevable state variables and disturbance. The simulation results are presented to show the feasibility of the control strategy. The designed controller is implemented in a laptop on the ground station by C ++ without any other optimizing software. The formation flight control experiment is carried out using two helicopters. The experimental result shows the accurate control performance. The position constraint capability is confirmed through the experiment with the single helicopter. Finally, the robustness against wind is verified by the windy condition experiment.

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The paper proposes an extended method for improving robustness of reinforcement learning called BRL. BRL has a novel character that the continuous state space and the continuous action space are segmented autonomously and simultaneously in the online-learning process. We have presented elsewhere that BRL is an effective technique not only for single robot problems but also for multi-robot problems. In BRL, the continuous state space is segmented by the Bayesian discrimination function method based on the instances perceived from each episode. On the other hand, the continuous action space is segmented by the same method based on randomly generated actions. This seems reasonable when a perceived state is apparently different from the states in the acquired rules. But it seems inappropriate when a perceived state is somewhat similar to the states in the acquired rules. Therefore, in the latter case, we propose an extension of BRL such that an action is calculated as the weighted linear interpolation of the actions in the similar rules. After showing the formalization of the proposed extension, the navigation problem of an autonomous mobile robot is demonstrated to verify the improvement by the proposed method through computer simulation as well as physical experiments.

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In our previous paper, we proposed a method for reducing adhesion forces by oscillation. If the oscillated endeffector gets close to the object on the substrate, contacts with it, and lower mode frequencies are excited, then the adhesion force between the endeffector and the object decreases. However, the following problems have not still been resolved : (1) Since adhesion state was checked by analyzing the data obtained by laser displacement meter, this method is available in only limited situations. Then, it is hard to apply the checking method to the automatic manipulation. (2) Automatic checking system for adhesion state was not developed. (3) Automatic micro manipulation system was not developed. Considering the above, in this paper, we propose a method to automatically check adhesion state by vision. Firstly, we develop a method to estimate the amplitude of the oscillation using the blur in the image resulted from the oscillation. We call the corresponding value to the amplitude AIV (amplitude indicating value).Then, we develop a method for checking adhesion state by AIV. Based on the checking method, we develop an automatic micro manipulation system for pick and place operation. The validity of our method is shown by experiments.

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Research has recently been conducted on active steering using steer-by-wire technology in order to improve vehicle maneuverability and stability. A driver is generally conscious of the vehicle's yaw rate during normal driving and of its lateral acceleration when avoiding an accident. A system that compensates for these drivers' characteristics by active steering is proposed. However, methods of inferring a driver's behavior to avoid an accident have not been established, so switching over to control appropriate for each individual driver has not been possible. Thus, this study proposes a driving behavior-inferring hybrid control system to infer a driver's behavior to avoid an accident and switch to appropriate control using a driving behavior inference model that uses Bayesian networks. Model reference adaptive nonlinear control, expected to be highly robust even in the nonlinear domain, was used for control. A simulation was performed for closed-loop evaluation of the proposed system using first-order prediction of a driver model. Results indicated that the system improved lateral movement about 3.4-fold over when control was not performed while avoiding an accident, and the system was able to safely avoid obstacles.

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This paper proposes an operational assistance system for a telerobotic system which is useful to carry out comfortable nursing care for the elderly and disabled persons. This assistance system provides a movement directive to the human operator such as a family member at a remote location. In this paper, the movement directive is understood through the approximate gaze direction of the user who is a crippled person or a serious disabled person. The human operator receives the details of the movement directive through visual information displayed on the display screen. The effectiveness of the proposed operational assistance system is verified by experiments.

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We have been proposed the tailor-made multilayer piezoelectric actuator (TAMPA) with large displacement and large force. TAMPA has the layered structure of two bimorph-type piezoelectric elements combined by both ends supported. Therefore, the performance of TAMPA is affected by the shape and the stiffness of support. It is necessary to design the optimum structure of support of TAMPA. This paper proposes four-point supported structure because of the plate shape of bimorphtype piezoelectric elements. The effect of the shape of supports is estimated through finite element analysis of TAMPA constructed by four-point support of varied sizes. The TAMPA having the optimum structure determined from estimation result is produced and its performance is evaluated. For production, the mold made by rapid prototyping is utilized. It is possible to produce the support which had arbitrary shape by using this mold.

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In recent years, vacuum chucks have been applied to various devices to hold and carry manufactured products. Especially, the usage of vacuum chucks is very effective for handling a LCD glass panel and a silicon wafer for semiconductors in order to reduce the deformation of them and keep their flatness. It is said that a vacuum chuck utilizing porous material has an advantage that the flatness of an object held by this kind of chuck is superior to that by other types of vacuum chucks with vaccum holes and circumference vacuum grooves. However, there are few published papers that the detailed holiding characteristics of a porous vacuum chuck are clarified. In this paper, the holding characteristics of the porous vacuum chuck are investigated numerically and experimentally.

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It was investigated that tribological properties of CN_x coating slid against a Si₃N₄ ball in ambient air with 5 different temperatures of CN_x as 23, 75, 100, 125, and 150°C and 4 different humidity conditions as <5, 20-30, 40-50, and 60-70%RH during sliding tests. These friction tests result indicated that friction coefficient was lower than 0.05 when CN_x temperature was higher than 125°C at 60-70%RH, 100°C at 20-50%RH, and 75°C at < 5%RH. The specific wear rate was within a range of 10^-7mm³/Nm in several humidity conditions. It could be within a range of 10^-8mm³/Nm when the CN_x temperature was higher than 125°C at 60-70%RH, 100°C at 20-50%RH, and 23°C at <5%RH. It was observed that the CN_x structure and composition of wear tracks were not changed before and after sliding tests with a Raman spectroscopy and an AES. To show a controllability of CN_x coating's friction coefficient against a Si₃N₄ ball with temperature of substrate, we performed friction test between CN_x and a Si₃N₄ ball with rising temperature of CN_x surface from room temperature to 100°C and then cooling to room temperature. Friction coefficient was 0.18 at room temperature, which decreased to 0.01-0.02 at 100°C after rising temperature. After cooling the CN_x substrate to room temperature, friction coefficient returned to 0.18 that was the same as the initial value. These results indicated the friction of CN_x against a Si₃N₄ ball can be controlled with the temperature of CN_x in air.

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Recently titanium alloys and nickel alloys have become eminent for making aeronautic and astronautic parts. Since both nickel alloys and titanium alloys have a very small thermal conductivity, the being used tool will suffer from a huge damage by heat generated during grinding process. Therefore, there is a requirement for a durable tool with excellent cooling capacity. In this research, a new electro-deposited diamond tool for high speed grinding of nickel alloys and titanium alloys was developed and evaluated. The new tool is a cup shaped end mill, its body is made from copper (due to its superior heat conduction characteristics) and the platting layer for bonding the diamond grains # 120 is nickel. The cooling system is an advancement of the former used heat pipe. Water is supplied from outside through a thin tube, that is integrated in the tool body. Thereby the effect of water evaporation, featuring a very large cooling capacity, could be applied. The assayed materials were Ti 6 A 14 V and Inconel 718. The grinding conditions were investigated by some preexperiments. It is concluded from the results that ; (1) The cooling capacity of the new tool using water evaporation is very effective to maintain the grinding potential of electro-deposited diamond tools, (2) The new tool is effective for high speed grinding of nickel alloys and titanium alloys, (3) The new tool and compulsory cooling system are economical and eco-friendly.

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In loose-abrasive machining, a new polishing technique is required to be developed in order to finish a fragile workpiece such as thin silicon wafer or Low-k material and a hard material such as single-crystal SiC or sapphire. Namely, it is very difficult that high finishing efficiency is obtained in the above finishing using the conventional polishing technique. Then this paper deals with the achievement of high efficient finishing by using a structure-controlled polishing pad, which consists of a soft layer and a hard layer. The structure is thought to make the contact area between pad and workpiece expand with high polishing pressure. So it is expected to increase the number of the effective abrasives and the removal volume by a single abrasive. As a result of introducing it for finishing optical glass, high efficient finishing with lower load on workpiece was achieved, as compared with the conventional pads.

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Our group has developed a new free-surface microstereolithography apparatus with high laminate resolution and accuracy for hybrid microstereolithography. We applied a feedback control system to adjust the surface level of the UV curable resin constantly and precisely. Moreover, by modifying the design of the squeegee used to laminate the UV curable resin in the apparatus, we reduced the height of the meniscus just behind the squeegee. Through this modification, the laminateresolution of the apparatus was refined to 10μm. Using the apparatus thus developed, we successfully miniaturized a biochemical IC chip, a microfluidic device which has three-dimensional hybrid microstructure. Compared with earlier microstructures, this advanced apparatus for free-surface microstereolithography can fabricate much smaller microstructures with much smoother surfaces. Henceforth we expect that this achievement will be a key technology to innovate polymer MEMS (MicroElectroMechanical Systems), microfluidic devices and other fields.

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In this paper, we derive the closed-loop equations of the MacPherson strut mechanism as the spatial six-link mechanism of two degrees of freedom. With given values of steering and strut displacements, the formulas for analyzing the attitude of the strut are established. The results of analysis are verified experimentally. The static analysis is done under the several conditions, for example, the angle of the lower arm and the position of the steering rack are varied. By this analysis, it can be shown how the force transmitted through the rod is needed to steer the tires. From the results of analysis, we can know how the force preventing the smooth sliding of the strut occurs. We analyzed the sensitivities to show how the error of the assembling and processing had an effect on the kinematics of this mechanism. The sensitivities can be derived from partially differentiating the closed-loop equations with respect to the kinematic constants. A few of them are verified experimentally. Comparing with result of static analysis, we investigate if the cause of error involve in transmissibility.

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