This paper introduces a vertical ladder climbing of humanoid robot only by a posture control without any external sensors. The humanoid robot does not have any special structure for fixing the body to the ladder. The robot maintains the body on the ladder by its grippers like human does. As a problem of this locomotion, a free gripper position of the climbing robot is not controllable because a yawing of the robot body around the axis connecting a supporting gripper and foot on the ladder is not fixed. To solve this problem, the momentum around the axis caused by the gravity is used to control the yaw motion of the body so that the various gait such as pace gait and trot gait could be realized in a ladder climbing maneuver. The algorithm of ladder climbing with recovery motion is experimentally verified by using "Multi-Locomotion Robot (MLR)" which is developed to achieve various types of locomotion such as biped, quadruped walking and brachiation.

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This paper deals with a contact optimization problem from some methodologies which have been reported up to now in order to reduce brake squeal noise and fundamentally investigates how to make the contact region or contact shape between pads and a disk rotor. At first, a finite element model is built up for the assembled brake system and a complex eigenvalue analysis is conducted. The contact surfaces between the pads and a rotor are divided into eight regions. Each region is used as a parameter to find out the better contact condition. In the case of parametric studies, however, multiple squeals can not be controlled because of the size or shape of divided region. Therefore, a new approach is proposed by using a simple model simulation. It adopts a distributed spring model as a property of contact stiffness, and calculates the sensitivity of each spring for a squeal. If the sensitivity is positive and at a high level, the corresponding spring is removed. The proposed method is applied to automobile disk brakes. As a result of several simulations, it is confirmed that the proposed method is practical.

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The tube bank is used in a boiler, a heat exchanger and a steam generator. These tubes sometimes vibrate violently and come to the fatigue failure due to the flow induced vibrations which are caused by the cross flow. This phenomenon is that the large vibration arises at the critical velocity and it is called fluid elastic instability. However the influence of tube arrays on fluid elastic instability has not been clarified yet. In this paper, the influence of tube arrays on fluid elastic instability is examined by experiments. As a result, it is clarified that the tube vibrations become large as T/D increases and LD decreases, and the tube vibrations strongly depend on the dynamic characteristics of tubes their selves such as natural frequencies and damping.

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In the Hot-Rolling process, when a thin strip runs on the Run-Out-Table (ROT) at high speed in the state of non-tension (a head or a tail of a strip), the defects resulting from the running instability pose a chronic problem. Moreover, for the running unstable phenomenon, the maximum line speed has been restrained, and has also become a prevention factor of productivity. In order to solve and improve this problem, various methods have been proposed from the former, but it has not eradicated completely. In this paper, we propose two types of the experimental method to simulate the ROT running phenomenon in a laboratory. The ROT strip running unstability theorem was proven by using them experimentally. By utilizing them, the improvement cost and term become cheaper and shorter.

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Active magnetic bearing (AMB) becomes to be widely used in various kinds of rotating machinery. However, as the magnetic force is nonlinear, nonlinear phenomena may occur when the rotating speed becomes higher and the delay of control force relatively increases. In this paper, the magnetic force is modeled by considering both the second order delay of the electric current and the first order delay of the magnetic flux. The AMB force is represented by a power series function of the electric current and shaft displacement. The nonlinear theoretical analysis of the vertical rigid rotor supported by AMB with PID control theory is demonstrated. The effect of the coefficient of the integral feedback on the nonlinear phenomena are clarified theoretically and experimentally.

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In a traditional turbine-generator set, rotor shaft designers and blade designers have their own models and process of design by neglecting the coupled torsional effect. Recent longer blades system for higher output and efficiency, torsional coupled umbrella mode of blade system tends to be nearby the double frequency electric disturbance. (i.e. 100Hz or 120Hz) For estimating the rotor-blade coupled vibration of rotating shafts in high accuracy, the analysis must include the identification process of mathematical model's parameters by real model. In this paper we propose to use a quasimodal technique based on the similar concept of modal synthesis method, but it is a unique method to provide a visual reduced model. An equivalent mass-spring system is produced for uncoupled umbrella mode and modal parameters are measured in one turbine rotor real system. These parameters are used to estimate the rotor-blade coupled torsional frequencies of a 700MW turbinegenerator set and the accuracy of the estimation is verified through a field test.

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In nuclear power stations, the storage of a lot of spent fuels is becoming a serious problem because of the shortage of the residual space of the spent fuel pool. It is planned to construct an another plant where the spent fuels are temporarily stored. In that plant, the spent fuels will be installed in a container called canister. The canister, in turn, will be stored in an outer cylindrical container called cask, which will be a free-standing structure. Thus, the cask-canister system is seen as a two-degree-of-freedom coupled system. Therefore, it is very important to evaluate the sliding motion of the cask-canister system subjected to seismic excitations. In an analytical model, the canister and the cask are treated as rigid bodies that are connected by a spring and a dashpot. The equations of motion are derived for the sliding motion when the floor is subjected to a horizontal earthquake excitation. The sliding displacement of the cask and the relative displacement of the canister against the cask are evaluated by numerical simulations, and the effects of the canister vibration on the sliding motion of the cask are discussed.

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New optimum design methods for dynamic vibration absorbers are proposed for the cases when the primary system has some uncertainty in dynamic characteristics and excitation frequency fluctuates in small range. In the previous paper, we derived analytical and very simple design equations which give the optimum natural frequency and damping ratio of the absorber for given excitation frequency range in the special case that the excitation force amplitude is proportional to the square of the frequency and the objective function is velocity amplitude. In this paper, approximate design method of the dynamic vibration absorbers for general excitation force and general objective function is discussed. Two different types of the approximate design equation are proposed and calculation results by using the proposed design methods are compared with the exact solution by using numerical method. Through the discussion it can be seen that the proposed design methods are very useful.

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In the field of precision positioning, an air type anti-vibration apparatus has been widely used. To realize the low vibration circumstance, some fundamental developments that decrease the natural frequency of isolated table are still executed. In addition to such development, many time-consuming jobs are necessary to eliminate the high frequency dynamics of isolated table. For example, the local mechanical vibrations are symptomatically attenuated using viscous damping materials. When the high frequency vibration due to the contact of electrical wirings is excited, it is necessary to rewire the electrical wires. Though these troublesome jobs are indispensable, it is not recognized that the nozzle flapper type servo valves used in the anti-vibration apparatus are the mechanical vibration source. To suppress the vibration levels, in this paper firstly, it is clearly shown that these servo valves are the vibration source. Next, it becomes clear that the vibration level of servo valve body icreases by adjusting the pressure feedback gain. Finally, the mechanical methods using the viscoelastic material are applied to reduce the vibration level and remarkable results are experimentally shown.

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This paper describes the experimental results of dynamic tests used a 1-storey steel building model with pipe-type-damper. The building model was designed to have the same first natural frequency as the detached houses, which is the external size, 1.4m×0.9m×2.35m and the total mass, 760kg. The first natural frequency of building model is 3.92Hz, and the damping ratio is 0.25%. The two tests used the building model were performed; (1) is free vibration test, (2) is traffic-induced vibration test. The results of free vibration tests showed that the pipe-type-damper could give building model the damping. Also, the damping ratio of the building model are almost the same as the design value; the experimental value is 7.53%, and the design value is 8.19%. The results of traffic-induced vibration tests showed that the pipe-type-damper was able to reduce the acceleration and displacement of building model against minute vibration.

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In this investigation, the on-line and off-line hybrid contact algorithm for modeling wheel/rail contact problems is developed based on the elastic contact formulation. In the tabular contact search used in existing specialized railroad vehicle dynamics codes, contact points are predicted using an assumption of rigid contacts. For this reason, the contact points can be different from those predicted by the on-line based contact search used in elastic contact formulation. The difference in the contact point becomes significant when flange contacts that have large contact angles are considered. In the hybrid algorithm developed in this investigation, the off-line search that can be effectively used for the tread contact is switched to the on-line search when the contact point is jumped to the flange region. By so doing, a computationally efficient procedure is achieved while keeping accurate predictions of contact points on the wheel flange. Furthermore, the use of the proposed hybrid algorithm can eliminate the use of time-consuming on-line search for the second point of contact as well. Since the location of the second point of contact is pre-computed in the contact geometry analysis, the occurrence of two-point contact can be predicted using the look-up table in a straight-forward manner. It is demonstrated by several numerical examples that the proposed hybrid contact search algorithm can be effectively used for modeling wheel/rail contacts in the analysis of general multibody railroad vehicle systems.

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It has been shown in our previous report that DYC is not compatible with the tire force usage equalization and it is important to consider total tire force F_x and F_y as feedback signals for DYC being compatible with the tire force usage equalization. Also, the control logic devised then has been found very effective in the electric vehicle run test. However, the vehicle dynamics control of a general car is controlled by the hydraulic brake system. In this report, our control logic is applied the hydraulic brake system of the electric vehicle, and an attempt has been made to clarify whether our control logic is effective or not for real vehicle by conducting real electric vehicle braking turn tests. According to the electric vehicle braking turn tests, the tire force usage rate has been not saturated by our control logic, and our control logic has improved the driving stability more than ABS of special condition and other DYC. It has been found that our control logic is very effective for braking turn of the independent wheel-in motor electric vehicle. Also, handling has become neutral steering by using our control logic at braking turn.

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The calibration for the traceability of acceleration has long been based on the measurement shown in the ISO standards using a one-axis accelerometer, a one-axis vibration table and a laser interferometer. However there has been no description on multi-axis accelerometers in the ISO standards. On the other hand, the application of multi-axis MEMS accelerometers and gyros has become remarkable these days. This paper discusses the mathematical derivation of the matrix sensitivity very precisely. Three kinds of acceleration vector spaces are introduced. The relationship between the number of axis of the sensors and the dimension of the calibration acceleration vector space is discussed. New classification of cross sensitivity is introduced. The concept of the matrix sensitivity derived by sinusoidal inputs is expanded to the shock input where every component of the sensitivity matrix is expressed by a transfer function. The simple numerical example shows how large the influence of cross sensitivity is in the multi-axis accelerometers. New classification of accelerometers is proposed in terms of the sensitivity. The limit of the conventional calibration technique is shown.

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A control system design for two-inertia resonant systems where a shaft is subjected to torsion is proposed. On the basis of elementary knowledge in strength of materials, we derive an inequality condition for avoiding metal fatigue of the shaft. To satisfy the derived condition as well as other design specifications, a feedback controller is designed using the LMI-based H_2 synthesis on the basis of the critical control concept. An illustrative design example shows that the amount of torsion in the shaft remains within the acceptable level at which fatigue could be negligible.

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In this paper, we propose a new approach to dynamical modeling of the spherical multi-d.o.f. ultrasonic motor based on nonholonomic mechanics, and a practical motion control method using periodic signals with variable phase. We point out that this system is analogous to the so-called rolling sphere manipulation system as far as the kinematics is concerned, although there is also an indispensable influence of the drift term which stems from its momentum dynamics. For this system, we propose the multi-cycle phase switching (MCPS) method to suppress this influence by periodically changing the phase shift, of the piezoelectric vibration. The proposed method is free from redundancy because it uses only two vibration modes, while the conventional methods required three modes.

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An animal has a characteristic ratio of forefoot and rear legs so that its morphology can adapt to the living environment. Likewise, the structure of robot should be better fitted the locomotion in the working environment. This paper derives an optimul structure of the quadruped robot, which minimizes the sum of joint torques of the robot. Minimization of the joint torque allows to reduce the joint acceleration in walking motion, and hence to reduce energy consumption. Numerical simulation analyzed joint torques in each limb length and slope angle under walking on a slope. The optimal Ratio of the Rear leg Length (RRL) is derived by the simulation as the physical structure. Our analysis suggests that the joint torque will increase as the slope angle becomes steeper in the case that the rear legs are shorter than forelegs. On the other hand, the joint torque will decrease as the slope angle is declined in the case that the forelegs are shorter than the rear legs. Experimental results validated the simulation analysis.

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This paper describes a bio-mimetic water strider robot with microfabricated hydrophobic legs. Various kinds of supporting legs with hydrophobic microstructures on their surfaces were developed using MEMS (Microelectromechanical Systems) techniques. The lift and pull-off forces of these supporting legs were analyzed theoretically and then measured. The experimental results were in good agreement with the calculations. Water strider robot with twelve micro-fabricated legs driven by a vibration motor successfully moved on a water surface and also made left/right turns by exploiting differences in the resonant frequencies of the legs.

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For autonomous mobile robot, ultrasonic Time-of-flight (TOF) ranging systems are widely used to measure distance. However, ultrasonic TOF ranging systems tend to neglect minute reflected waves below the threshold level. Therefore, we have proposed the integration-type ultrasonic wave sensor which utilizes the integration value of sonar's reflected wave to recognize travelable area for autonomous mobile robot. The proposed method determines the pass and desired velocity simultaneously, but the calculated desired velocity changes significantly because of noise or error of the ultrasonic wave sensor. This paper presents the novel way to filter the velocity with considering the acceleration. By considering the acceleration, we can take the limitation of driving force of robot into consideration. The validity of the proposed method is investigated by applying the method to autonomous mobile robot in various environment.

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The purpose of this study was to develop simulation models for the planning of the stimulation timing and to evaluate the possibility of detecting swing-though gait cycle using an accelerometer and a machine learning technique (Neural Network). Two non-disabled adult males volunteered for this study. One 2-axis accelerometer, heel sensor and infrared rays sensor were used for the sensors. For Neural Network training, acceleration data was processed with input data, and the infrared rays data and heel data were processed with the target data. The microcomputer produced output signals using the Neural Network program. The accuracy of the microcomputer output data was compared with the motion analysis data. The Neural Network detector could correspondingly detect predict the beginning of gait cycles. The present system has a potential to access the reconstruction of FES assisted swing-through gait with free-knees in paraplegic patient.

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We compared the energy consumption in upper limb muscles during the swing-through gait using axillary and elbow crutches to consider the selection of a suitable crutch for the swing-through gait by FES. We also analyzed the joint moments of lower extremities during swing-through axillary crutch gait to produce a functional electrical stimulation pattern. This study showed that swing-through gait with C-posture was effective to reduce muscle fatigue of lower extremities. Knee buckling can be prevent using FES, because it could generate sufficient knee extensor torque to keep extended knee position during body stance phase. The data obtained from this study has the potential to be applied in simulation models for the swing-through gait in complete paraplegics. Our future plans include the development of simulation models and a stimulation program for the reconstruction of swing-through gait in complete paraplegics.

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It is important for non-invasive measurement of arterial stiffness to set a pressure sensor on the center of artery. In previous our study, moving the reflection optical sensor on an inner side of wrist, we observed inversion phenomena that a dicrotic wave and a percussion wave of reflection photoplethysmography (incident wavelength of 530, 650 and 810nm) were turned over. If the relationship between inversion phenomena and a location of artery is clarified, we expect that inversion phenomena will be applied to use an artery detection system. The purpose of this study is to clarify the mechanism of inversion phenomena, and to suggest the artery searching method by using inversion phenomena. In this study, we investigate the mechanism of inversion phenomena by a measurement of pulse wave using the reflection optical sensor and a numerical analysis of light propagation in a wrist, and examined this method to estimate a artery position by this measurement. Numerical analysis results indicated the cause of inversion phenomena is influence of scattering. In the results of measurement, inversion phenomena occur under the optical sensor setting on the center of artery. In conclusion, it is available for an artery searching method to use reflection photoplethysmography of incident wavelength 530nm and 810nm.

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Determining muscle forces of the finger during heavy work is important for an understanding and prevention of tenosynovitis. Electromyography is one index of muscle activity. Measurements by surface electromyography (sEMG) are noninvasive and simple to apply to obtain signals of muscle action potentials. The sEMG potentials of muscles near the electrode are superimposed. To identify the muscle activities from sEMG measurements, it is necessary first to analyze the characteristics of sEMG conduction in the forearm. This paper develops a conduction model of the forearm that incorporates the muscles and the radius and ulna bones. sEMG distributions were analyzed using the finite element method. The root mean square (RMS) values of sEMG values and the power exponent of attenuation in relation to the length between the electrode and the source of muscle action potential were estimated in this work. Further, the positions of the muscle action potential were reverse-estimated using the RMS values and the power exponent of attenuation. As a result, the peak potential position of the sEMG distributions was distorted at a circumferential angle around the longitudinal axis of the model up to a maximum of 48゜. The power exponent of attenuation was found to increase monotonically with increases in the inter-electrode distance (IED) of the surface electrode pair. The errors in the estimated positions of muscle action potential increased with decreases in the distance between the source of muscle action potential and the radius and ulna bones.

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Severely handicapped often uses respiratory pressure for an input device to control various instruments such as TV, motored bed, curtain, air conditioner in everyday life. The input device is typically ON/OFF type for the control of the equipments. Considering the application of motored wheelchair, the ON/OFF type interface is not desirable. The control of motored wheelchair needs preciseness and quickness for safe operation. A new input device using respiratory pressures is proposed for such purposes. The paper examines basic performances of human respiratory pressure regulation as an analogue input method. Then possibility of two-dimensional input device is discussed. Basic experiments to check the performance of two-dimensional analogue input device by respiratory pressure for the control of motored wheelchair are shown.

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The main objective called as the population-based optimization techniques is to find a global minimum. However, it is sometimes preferable to find multiple optima in the engineering design. The Adaptive Range Particle Swarm Optimization (ARPSO) to find multiple optima is proposed in this paper. The active search domain range of the ARPSO is only one, however, many active search domain ranges to find multiple optima are generated in the proposed appoach. At first, the many active search domain ranges are generated by the paired particles, and the procedure of the ARPSO is applied. Then, the paired particles find local or global minimum separetely. Many active search domain ranges are sometimes integrated through the search process. The detail procedure to integrate the active search domain ranges is also explained in this paper. It is possible to find multiple optima with high accuracy by the proposed approach. The validity of proposed method is examined through numerical examples.

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This research applies SLSV (Single-Loop-Single-Variable) method to reliability-based topology optimization (RBTO) for frame structures to improve computational efficiency. The design problem is formulated to minimize the structural volume of frame structure in terms of crosssectional area of each frame element under the two reliability constraints. The two mode reliability criteria consist of the mean compliance and mean eifenfrequency criterion under variations on applied loads and nonstructural mass. Through numerical examples, higher computational efficiency and accuracy of reliability approximation by the SLSV method are demonstrated in comparison with those by the conventional double loop method that mode reliabilities are evaluated by the first order reliability method (FORM). Additionally, the importance of normalization of the limit state functions that are directly applied as constraint conditions in the SLSV method is also demonstrated.

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Tapered seal is widely applied to hold lubricating oil inside the clearance at the ends of fluid film bearing utilized in precise machines such as a spindle motor of HDD system. This study aims to analyze theoretically the fundamental working mechanism of tapered seal. Applying the analysis on meniscus of fluid surface due to the surface tension cooperating with the results of computational fluid dynamics for velocities and pressure fields under the axisymmetric and steady-state condition, the mechanism of the sealing ability of the tapered seal is clarified, and an index value which represents the sealing capacity of a tapered seal is introduced. The effects of some design and working parameters, such as the taper angle of the sleeve and the initial fluid volume, on the sealing capacity are discussed through the index value. The role of the barrier film coating on the sleeve surface to the sealing capacity is also studied theoretically.

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This paper proposes a new compensation method for lost-motion characteristics in the NC machine tools employing slide-way. Lost-motion is a major disturbance to motion accuracy of the NC machine tools. In order to solve such problems, many compensation methods for lost-motion have been developed to improve them. However, these conventional methods have not been able to compensate some behaviors. In this paper, lost-motion characteristics are measured under various sliding speed and various approach distance. Table lift caused by dynamic pressure of lubricant oil is measured at the same conditions. From these results, experimental model as a function of decrement of lost-motion and table lift is proposed. A new compensation method based on experimental model is applied to circular motion. It is confirmed that a new compensation method improves circularity.

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The objective or this investigation is to clarify a new and high efficient mirror machining, that can be named superposition superfinishing (SSF process) using a fine abrasive stone. In this machining, at first process (SVC process: superposition vibration cutting) high efficient cutting is achieved with simultaneously providing (20〜50Hz) low frequent vibration and ultrasonic vibration above 20kHz on fine abrasive stone, and at next process (SF process: superfinishing) mirror surface can be obtained in a short time with only low frequent vibration. In this report, it is shown that basic machining characteristics and possibility of high efficient mirror machining on this new process are practically confirmed by several experiments.

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Planning of a design process that includes creative and concurrent activities has become more important for successful product development in a competitive market. Because of this creativeness and concurrency of design process, required time and cost of a design task is vague. Therefore, in planning a design process, it is more essential to manage a target of design attainment, and to predict whether or not a planned design process can achieve the target, than to predict time and cost required in whole design process. This paper proposes a new method of design process planning that focuses on quantitative prediction of design attainment in a creative and concurrent design process. A growth curve model using fuzzy numbers is introduced to predict the progressive attainment of each task and progressive attainment of consistency between tasks after running a planned design process. A design structure matrix (DSM) is used to represent task dependency and communication efficiency. A design process plan is evaluated by the probability that the task attainment achieves the target level. A prototype system that supports design process planning based on the proposed method is developed. This paper demonstrates its application to a student formula car project.

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The purpose of this study is to investigate the influence of mechanical vibration upon the blood circulation of the human body. Ten healthy persons were employed as subjects in the experiment. The subjects were laid in a state of the face up position and mechanical vibrations with lower frequency and energy were added for 20 minutes. Dynamics of the blood circulation were measured using an ultrasonograph and a sphygmomanometer before, during, and after the vibration. The results showed that the pulsative index representing resistance to the peripheral circulation significantly increased during the vibration. Mechanical vibration with even lower frequency and energy influenced the peripheral circulation. However, its physiological mechanism has still been unclear.

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