Designing low-noise air conditioners has recently become one of the most important themes. In particular, the 100 to 450-Hz noise that radiates from resin fans due to the excitation force of the fan motor is a major problem because the radiation characteristic changes depending on the rotational speed and resin temperature. To solve this problem, we propose a noise evaluation index of material characteristics from material and excitation tests and a numerical analysis of the resin fans used for domestic air conditioners. We tested the material characteristics by changing the resin temperature and the direction of resin fiber. Results demonstrate that the Young's modulus changes greatly depending on temperature and direction. We also conducted an excitation test with an excitation machine; results show the vibration mode and noise radiation characteristics of each fan vibration mode. Next, we designed a numerical model on the basis of the two test results and calculated the noise radiation of the fan at low and high temperatures. Results demonstrate that the first vibration mode radiates noise easily, the resonance frequency of the fan changes greatly with temperature change, and the resin fan radiates noise easily at lower temperatures because the change of the A-weighting relative response level of 100 to 450Hz is large. We also show that the A-weighting influence should be considered in a noise evaluation index.

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Positioning control of vibration systems such as flexible structures is one of the most fundamental technologies for mechanical structures. Different from feedforward control based methods, the use of LQ optimal regulator realizes the feedback control of vibrating parts of a controlled object. However, if the standard LQ optimal regulator is applied to long distance positioning problems, it requires much control energy in motion starting and the positioning error becomes large in settling. Therefore, its use is suitable for positioning settling and residual vibration reduction control in short distance problems. Taking such a background into account, this study proposes a control method switching from a simple feedforward access control technique to the LQ optimal regulator. Especially, this paper mentions a proper switching method of the two control modes. The proposed method does not require much computational load in comparison with the author's conventional methods and is practical for many industry applications. The effectiveness of the proposed method is verified by numerical calculations and experiments.

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The Kagawa Satellite KUKAI was developed in Kagawa University and launched by the H-IIA rocket on January 23, 2009. The primary objective of KUKAI is technical verification of a tethered space robot, which is connected to a mother spacecraft through a tether. The tethered space robot is a new type of space robot system different significantly from the Tethered Satellite System (TSS). The tether is to be extended at a relatively short distance, and we do not envision either gravity force or centrifugal force to be an influence on the tether extension. This paper especially focuses on the tether deployment system of KUKAI, which deploys the tether for short distance. Orbital experiment verified and evaluated the developed system.

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This paper presents theoretical research in the fundamentals on the directional stability and controllability of multi-articulated vehicles. The analyses and numerical calculations are conducted by using models incorporating vehicle side-slipping and yawing. Two vehicle combinations are examined with regard to straight running stability, as well as steering sensitivity and off-tracking in steady-state turning. Type I consists of a tractor and two semitrailers; type II is composed of a tractor, semitrailer and full-trailer. The following conclusions are drawn. (1) The criterion of non-oscillatory stability of types I and II is a function of the stability factor as well as that of tractor and semitrailer combinations. (2) Type I is more stable than type II in oscillatory modes. (3) Type I is slightly different from type II regarding non-oscillatory stability, steering sensitivity and off-tracking in steady-state turning.

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This paper proposes a vibration testing system based on an impulse response excited by a laser ablation. In conventional vibration testing using an impulse hammer, high frequency elements of over tens of kilohertz are barely present in the excitation force. A high-power YAG pulse laser is used in this system for producing an ideal impulse force on a structural surface. By illuminating a point on a metal with a well-focused (2μm) YAG laser, atoms, electrons and ions etc. are emitted from the metal. As a result, an ideal impulse excitation force generated by laser ablation is applied to a point on the structure. Therefore, it is possible to measure high frequency FRFs (Frequency Response Functions) in this system. Additionally, a water droplet overlay on the metal is used to adjust the force magnitude of laser excitation. An aluminum block that has nine natural frequencies below 40kHz is employed as a test piece. The system is validated by comparing the FRFs of the block obtained using laser excitation, an impulse hammer, and FEM. In addition, the relationship between accuracy of FRF measurements and sensitivity of sensors is investigated.

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Evaluation of seismic resistant performance for severe earthquakes is required, because of occurrence of earthquakes which exceed the design criteria. Additionally, quantitative evaluation of cumulative damage by earthquakes is also required. In this study, the energy balance equation is applied to the evaluation. The energy balance equation expresses integral information of response, so that the energy balance equation is adequate for the evaluation of the influence of cumulative load such as seismic response. At first, vibration experiment that leads experimental model to fatigue failure by continuous vibration disturbance is conducted. As a result of the experiment, relation between fatigue failure and energy balance equation is confirmed. Then the relation is proved from the viewpoint of hysteresis energy, and consistency between energy balance equation and hysteresis energy is confirmed. Finally, we adopted cumulative damage rule to energy balance equation in order to expect the fatigue life under random waves that have various input acceleration.

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For the characteristics of an anti-vibration apparatus, the static stiffness must be high enough to support the loaded body's mass, and the dynamic stiffness should be as low as possible to curb vibration transmission. For vibration around the resonant frequency, sufficient damping is especially needed to swiftly suppress the motion. An air suspension system is an excellent anti-vibration device. Various types of air spring are readily available in the market, and the characteristics have a particular feature: high static loading capacity and relatively low dynamic stiffness. The remaining issue is low damping and how to increase it. This paper proposes a new air suspension mound that basically consists of two subsystems linked in parallel. The first sybsystem is an air spring itself that supports the pay load. The second subsystem is comprised of a rubber block, a ball screw, and an inertia disc connected in a series to attain low dynamic stiffness or high damping performance. The dynamic stiffness of the proposed mount plunges at certain frequency and rebounds sharply, approaching constant value as frequency increases. The loss stiffness indicates sharp peak at little bit higher frequency than that of dynamic stiffness. It has been proved theoretically that the phenomena are caused by the resonance of the inertia disc. In comparisons of theoretical calculations with actual measurements, the theory fairy agrees with the measured values.

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Recently, high-resolution measurement instruments such as probe microscopes have been used widely, since their price is getting lower, and their size is becoming smaller. Therefore, these measurement instruments have been used in various environments. However, to use these instruments effectively, it is important to isolate the environmental vibration transmitted to the instruments. For this reason, we are developing new built-in type multi-axis vibration isolation devices equipped with inertia force generators (IFG). In designing this vibration isolation device, modal analysis and "direct inertia force control (DIFC)" are used. DIFC is the newly developed design method for the vibration control systems proposed by authors. Combination of modal analysis and DIFC can make the complex control system design process simple and clear. In this paper, we show how the controller is designed, and also discuss the effectiveness of the method by experiment.

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This paper deals with a new topology optimization method based on the level set method that incorporates the augmented Lagrangian method. In previously proposed level set based structural optimization methods, dealing with multiple constraints has been problematic yet this is typically required for real-world design problems. Incorporating the augmented Lagrangian method in the structural optimization method proposed here enables the handling of multiple constraints. The level set function is discretized using finite elements and updated based on the design sensitivity of the augmented Lagrangian with respect to the discretized level set function. In this paper, the newly proposed structural optimization method is applied to the minimum compliance problem and a compliant mechanism design problem. In the formulations of these problems, a perimeter constraint is imposed to overcome the ill-posedness of the level set method-based structural optimization. Some numerical examples that include multiple constraints are provided to confirm the validity of the method, and we show that appropriate optimal structures are obtained.

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In the field of vibration control, accelerometers have been widely used. In stead of this kind of sensors, the velocity and displacement sensors are convenient for vibration control, because the former can detect the velocity and acceleration signals simultaneously. For the latter, the displacement, velocity, and acceleration signals are simultaneously detectable. We previously proposed both sensors characterized by using calibration coil as a back electromotive detector. However, servo parameters for both sensors were tuned by trial and error. Namely, there are no criteria in frequency shaping. Then, in this paper, we propose a design method based on the state feedback. First, it is shown that the velocity sensor can be realized by applying the type-1 servo system and that a special weight setting is required for frequency shaping. Next, for the subject of the displacement sensor, the type-1 servo system is constructed by using an equivalent transformation of pseudo-differentiator. Through the weight matrix tuning for optimal control, it becomes clear that specialized weight is also required.

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For linear time-invariant discrete-time systems subject to unmeasurable and inaccessible disturbances and sensor noises, numerically optimal and efficient method for designing disturbance observers, which estimate unknown disturbances in real time from measurable inputs and outputs, is presented. Using a priori information on upper bounds of increment rate of disturbances and magnitude of sensor noises, the disturbance observer is designed so that the supremums of estimation errors are minimized in the sense of Pareto optimality. The multi-objective genetic algorithm is used to search for Pareto optimal observer gains. The designed observer achieves a good balance between estimation accuracy and sensitivity to sensor noises. Especially, the proposed method provides an efficient design when spectrums of disturbances and sensor noises are partially overlapped or there is a trade-off relationship among estimation accuracies of disturbances.

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In this paper, we consider the control of systems with time-delay and constraints on states and control inputs. It is well-known that the presence of time-delay and physical constraints in dynamical systems causes the instability and performance degradation. In designing control laws for such systems, we apply the following approach. We design a predictive controller to stabilize the system with time-delay. The predictive controller guarantees the stability of the system and achieves the good tracking performance. Then we implement a reference governor to the stabilized system with considering the constraints. The reference governor modifies reference signals given to the system so as not to violate constraints. We apply the proposed method to an RC (Radio Controlled) helicopter control system. The effectiveness of our approach is evaluated through simulations and experiments of the yaw angle control of RC helicopter.

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The porous material with continuous pore is useful for the sound absorbing material. In this research work, rice straw, rice husks, and buckwheat husks were dealt as a porous sound absorbing material that applied the biomass. About rice straw, geometrical condition of that was reproduced in the narrow tube of the simple structure, and the effect of absorbing sound of the tubule in the composite structure was verified. In the experiment, for the various thickness and the back air space were tested by using two microphone impedance tube, and the normal incidence sound absorption coefficient was measured. Moreover, the absorption coefficient was calculated from the acoustical constant obtained from the result of a measurement in a specific condition. And, these calculation values were compared with experiment values. As a result, it was shown to be able to estimate the absorption coefficient of the condition of the unmeasurement. As for rice straw, rice husks, and buckwheat husks, it has been understood it has a useful characteristic of absorbing sound. It leads to the fixation of the carbon, and even if the incineration processing is done, it is a carbon neutral.

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We propose a new training system for high speed motions basing on a variable mechanical impedance display device. In the proposed training system, a relatively small inertia is added to viscous load in order to increase load torque without decreasing maximum speed. Moreover, in order to increase energy consumption, the additional inertia becomes zero during motions. Consequently, the additional inertia is optimized to increase load torque and energy consumption and to keep maximum speed. In this paper, the proposed training system is applied for elbow flexion, and the effectiveness of the proposed system is verified by comparison among these experimental results.

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This paper presents a system for evaluating dynamic sitting balance in elderly people to prevent their falls and hip fractures. The proposed system comprises a three-dimensional position and orientation sensor for measuring the upper body joint angle, a stabilometer for measuring the center of pressure (COP) trajectory and the seat reaction force, and a six-degree-of-freedom platform for producing seat perturbation. The seat reaction force and joint angle of the upper body were used to calculate the joint torque of lumbar and thoracic vertebra. In the experiments, 11 young and 14 older healthy adults tried to maintain a sitting posture relative to the seat perturbation (0.25 and 0.5Hz, 5deg amplitude). Results of experiments show that the COP trajectory and the joint torque were significantly higher in elderly subjects.

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Recently, the number of senior citizens who live alone is increasing tremendously in Japan. The senior citizens who live alone have less support compared with the one who lives as a couple or with family. In this paper, we propose senior citizen monitoring system that detects emergency status by using ubiquitous sensors. The proposed system is composed of behavior recognition sub-system, life pattern generation sub-system, and emergency detection sub-system. The behavior recognition sub-system recognizes the human behaviors by using rule-based system. The life pattern generation sub-system extracts typical life patterns of a user. The emergency detection sub-system finds the emergency statuses by using fuzzy inference system. We developed the proposed system by using ubiquitous sensors and confirmed its efficiency by experiments.

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On the purpose of achieving a human-like high energy efficient walking robot, many research projects use actuators attached on the waist or ankle joints of passive dynamic walking mechanisms. While on the other hand, we developed another type of semi-passive walking robot that is driven by the harmonic oscillation of a spring-mass system. In the mechanism, spring forces are generated at both sides of the robot by the simple harmonic motion of a spring-mass system which is oscillated by a small sized servo motor. The spring forces control the ZMP (Zero Moment Point) in the lateral direction, in sync with the swing leg, which is generated by the same forces as well. Choosing the gait cycle at the resonance frequency, significant decrease of the motor power and energy consumption is possible. Gyros, micro switches and wire displacement sensors are attached to the robot for measuring the angle of the legs, foot contact and spring extension. Gait cycle, spring forces, ZMP in the lateral direction are analyzed based on the measurements.

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In this paper, we propose a semi-closed microchip which can realize the probe type manipulation in the microchip. The semi-closed microchip has,a bath in the middle of microchannel to allow the insertion of micropipettes into the microchip. The bath is sealed off by thin oil film to prevent the evaporation of the solution in the bath. The seal by the oil film can maintain even if micropipettes are inserted into the bath and pulled out from the bath. The seal by the oil film was evaluated by measuring the weight of the bath after 12/24 hours. To use the semi-closed microchip for cell culture and cell analysis, the exchange of the solution in the semi-closed microchip was demonstrated. The cell fixation with the thermo sensitive gel was also demonstrated by fabricating the ITO electrodes as heaters in the bath. Cell culture and the target cell harvesting were conducted by the semi-closed microchip. The proposed semi-closed microchip can be used for cell culture, cell analysis and cell harvesting under a microscope as the biological applications for single cell analysis.

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Femtosecond laser technology has the ability to form stable minute grating structures on various materials, including silicon and stainless steel. By forming a periodic structure on a surface where contacts parts, the tribology characteristics can be improved, because the effect of adhesion decreases as the contact area reduces. Application of a double-pulsed femtosecond laser irradiation can generate periodic structures with asymmetric profiles. We previously showed that microparts, such as ceramic chip capacitors and resistors, can be fed along asymmetric surfaces using simple planar symmetric vibrations. Microparts move in one direction because they adhere to these surfaces asymmetrically. In this study, we tested the ability of an asymmetric surface microfabricated by the double-pulsed femtosecond laser irradiation to feed 0402 capacitors (size, 0.4×0.2×0.2mm; weight, 0.1mg). Among the characteristics evaluated were the differences in profiles of the two inclined surfaces, the effect of decreased adhesion, the coefficient of friction in both the forward and the backward directions, and the friction angle of the 0402 capacitors in both directions. Using the results of feeding experiments of these capacitors, we assessed the feeding velocity and the feeding stability. Simulating microparts feeding using dynamics including adhesion based on measurements, we studied validity of the dynamics derived.

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Double decker storage racks are established in communal facilities for efficient bicycles storage. However, an upper rack of the rack is rarely utilized, because its workload to users in parking operation is large. This paper discusses a design method of a double decker bicycle storage rack equipped with an original load reduction mechanism. First, questionnaire and electromyogram measurement are conducted, and it becomes clear that the physical load is the largest when users lift the upper rack with bicycle. Next, a load reduction mechanism that consists of a compression spring and a slider is developed, and the mechanism is installed in a double decker bicycle storage rack on market. Finally, it is clarified that the mechanism can reduce the physical load of users effectively, from the results of questionnaire and several evaluation experiments.

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Arrangement of steering wheel switches is vital for safe and easy maneuverability of the vehicle. In our previous study, considering the number of steering wheel switches is expected to be increased, maneuverability of various kinds of 8 switches was studied. In this study, to get steering wheel switches easy to handle with less glances for safer driving, maneuverability of 5 kinds of 8 (left 4 & right 4) stepped switches was studied. 6 obverse regular stair steps switches with 2 reverse flat ones were found to be better than 8 obverse regular stair steps switches because of with less glances and less errors. Maneuverability of concavo-convex stepped ones was found not easy to handle without glances because of its complexity contrary to expectation.

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Lateral forces between wheels and rails must be reduced in order that rolling stock runs safely and smoothly on curved tracks. Excessive lateral forces will cause not only derailment of rolling stocks but also destruction of tracks, rail corrugation, track irregularity, squeal noise and wear of wheel and rail. In this paper the authors study 3 methods to reduce lateral forces and improve running performance on curved tracks without development of new wheel profiles and bogies. According to results of numerical simulation, the authors conclude that "expansion of gauge widening" and "increase of tie plate angle of inner rail" or "unsymmetrical grinding of inner rail head" can get sufficient rolling radius difference and are effective for increase of running performance on curved tracks.

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This paper proposes a synthesizing methodology of developing a robotic skill for task execution. Specifically, the paper addresses how to improve reusability of the skill to use it on various robotic systems. First, a skill acquisition system based on human demonstration as well as a skill acquisition method are described. Second, how to improve the reusability of the skill is discussed to obtain a robotic task skill with high reusability. Third, a reusable skill execution system is designed and implemented. Finally, a task skill is developed for a practical task by using the proposed method to experimentally validate the reusability of the skill.

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Multiple robot system with decentralized control attracts attention and is expected to play an important role in transportation systems in factories and warehouses. In transportation systems, it is necessary to plan a route that minimizes the transportation time with less collision and deadlock. The goal of this study is to calculate appropriate routes with reducing communication load and computational load. In this paper, we proposed to combine prior route planning and local avoidance. In order to reduce computational load, each robot predict probability of collision with other robots by comparing present and destination position. A route with less collision is calculated by reflecting the overlap of route which has probability of collision into dijkstra method. The proposed method is evaluated through the computer simulation and the experiment using real robots.

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This paper describes a 3D SOKUIKI sensor module by roundly swinging mechanism and SCIP (Sensor Communication Interface Protocol)-3D command system for taking 3D reflecting points information in real space. We developed a 3D SOKUIKI sensor module, in which the body of the two-dimensional SOKUIKI sensor is moved by roundly swinging mechanism. The sensor module has the communication interface based on SCIP-3D, which is a command language for 3D SOKUIKI sensor defined by the authors' group. We desighed and implemented a minimal set of commands which is named "SCIP-3D mini" for our sensor module. We studied system architecture of the sensor module to implement SCIP-3D interface. We designed and made up hardware and software of the system to control the sensor. We took actual reflecting points in real space experimentally in various environment by using the developed sensor module. The results have shown the usefulness on the real-time environmental measurements.

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This study discusses the position estimation method of two dimensional position of a magnetically levitated body. Two Hall elements are installed in order to estimate both the horizontal and the vertical positions. Both the Hall voltages and the electric current signal are measured and the relationships among the levitation gaps, Hall voltages and the electric current are investigated. As the result, it is observed graphically that these relationships indicate the curved surfaces which are single-valued functions to the levitation gaps, and these curved surface are represented by explicit nonlinear functions of Hall voltages and the electric current. The estimation of both the horizontal and the vertical positions are performed by using these obtained explicit nonlinear functions, and its accuracy are validated experimentally.

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This paper considers the high-precision positioning control problem of a dual-stage feed drive. An equivalent-input-disturbance-based approach is employed to construct a control system to improve the disturbance rejection performance. A numerical example is used to illustrate a design procedure presented in Reference [16], and to demonstrate the validity of the method. A comparison between the presented method and a disturbance-observer-based method is also presented to demonstrate the advantages of the method.

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In the laser scribing of a glass sheet, a crack propagates across as the surface is locally quenched down immediately following CO_2, laser beam irradiation. In this process, the crack depth and scribable conditions are influenced by various parameters such as the laser power, the scribing velocity, and the distance between the heating area and the cooling area. Therefore it is important to examine the laser scribing phenomena by analysis of these parameters. We analyzed crack propagation phenomena by a finite element method, using a two-dimensional model with a pre-crack. The crack depth was evaluated by calculating the stress intensity factor. The obtained conclusions are as follows: The depth of the crack caused by the laser scribing can be estimated by giving a dynamic threshold of the stress intensity factor, K_<Dth> in the two-dimensional crack propagation analysis. The scribable maximum velocity for each laser power can be estimated by giving a static threshold of the stress intensity factor, K_<Sth>. As a result, the suitable scribing conditions in the laser scribing for the practical use can be selected.

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This paper proposes an optimum design method of cooling channels layout in a plastic injection molding die based on the simultaneous evaluation of warpage to produce precise plastic products and molding cycle time to improve productivity. The numerical simulations, such as injection process analysis, cooling process analysis and ejection process analysis, are implemented to calculate the warpage induced by residual stresses and the molding cycle time. A multi-objective optimum design problem is formulated to achieve the warpage reduction and the short molding cycle time, simultaneously. In this formulation, the warpage and the molding cycle time are adopted as objective functions, and the cooling channel arrangement as design variables. The basis vector method is used to change the cooling channel arrangement. The response surface method is applied to reduce the number of numerical simulations in the optimization process. Through two-dimensional numerical examples, it is found the availability of the optimum design method by discussing on the effect of the cross sectional shape of cooling channel for the minimization of warpage.

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At an early stage of design process, it is required to discuss many ideas derived from design requirements using designer's knowledge and experiences. Especially, at conceptual design stage, many designers often discuss together about new product and discuss design ideas considering its effectiveness. However, according to increasing the complexity of the functions of products and variety of consumer's needs in recent years, it becomes difficult for designers to discuss about ideas by only conversations and figures. Then, in the conceptual design process, it is required to derive many ideas that meet the design requirement considering the complicated requirements. The derivation process of ideas often wastes the time because of the inertia of designer's thinking process. In this study, we will propose the method to support derivation process from the visualized relation using Data Envelopment Analysis. Through the experiment, we will confirm the effectiveness of our study.

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