The Vibration Database (v_BASE) Committee under the Dynamics, Measurement and Control Division of the Japan Society of Mechanical Engineers (JSME) has been gathering vibration and noise troubleshooting case studies which were encountered and successfully solved in machine systems and plants, and has been building up a vibration database from them. This committee started in 1991, and is now celebrating its 20th anniversary. In commemoration, an event was held last September 5th 2011 in the Dynamics and Design Conference (D&D, Division Conference) at Kochi University of Technology, and the new research database (3rd edition, in CD-ROM) was released last March 2011. The number of collected data in the database now amounts to 817 cases. This long term continuing committee is JSME-unique and incomparable in the world. For this reason, we reported the conducted activities to date of the committee and the vision for the future looking back to the past 20 years.

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In this paper, a number of artificial earthquake ground motions compatible with time-frequency characteristics of recorded actual earthquake ground motion as well as the given target response spectrum are generated using wavelet transform. The variation of maximum displacement, velocity and acceleration responses of SDOF elasto-plastic systems by excited these artificial earthquake ground motions are evaluated numerically and theoretically. The coefficients of variation of maximum displacement, velocity and acceleration responses are shown in the case of the ground motion using the time-frequency characteristics of recently actual occurred large earthquake motions. Under the given design response spectrum, a selection manner of generated artificial earthquake ground motion which causes larger maximum displacement response of elasto-plastic structure are suggested.

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This paper presents a new structural design concept for reducing sounds radiation from a plate structure. On this concept, structural intensity technique is used. The concept is based on a modal expansion of structural intensity on a plate. Using modal form of intensity, a desired power flow (distribution of intensity) can be obtained. Structural intensity in modal form can be expressed by superposition of weight coefficients and “cross-modal functions”. The weight coefficients depend on an excitation point location. The cross-modal function is determined by products of two natural mode shapes with spatial derivatives and is expressed in a vector field. The cross-modal functions can be classified into two types of power flow: non energy transmission type and energy transmission type distributions. In the case of the cross-modal function having non energy transmission type distribution, the power through over the plate is zero because the integral of power flow is zero. Therefore, modal form of intensity suggests that enhancement of a non energy transmission type cross-modal function leads to less energy transmission. First, this paper presents the basic theories of proposal concept. Next, in order to describe the concept, relation between transmitted powers and cross-modal functions is obtained. Then this paper proposes the concept for reducing sounds radiation from a plate structure. Finally, numerical simulations and experiments on a three-plate structure (J-shaped structure) are carried out to demonstrate the interruption of the energy transmission as a result of generating non energy transmission type intensity.

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This paper presents a design procedure of robust H_∞ controller for bending-torsional vibration of three dimensional two link flexible robot arm. As the posture of the arm and the payload varies according to tasks, it possesses uncertain vibration modes. The controller must be designed to be robust to such posture fluctuation. In this research, H_∞ robust control design with structured uncertainties is utilized to describe the model error in bending-torsional vibration. An experimental system is set up, and two physical models are identified by utilizing Seto's modeling method. A H_∞ controller is designed by using these models and an integrator to realize servo control for positioning. Control simulations and experiments are performed. According to these results, the presented modeling and controller design method is certified to be effective.

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A nonlinear controller for accelerating a mobile inverted pendulum (MIP) with interconnection and damping assignment passivity-based control (IDA-PBC) is proposed. For underactuated systems, nonlinear partial differential equations (PDEs) must be solved to derive the IDA-PBC and it is a difficult task in general. However, this study shows that the MIP can be properly described as a full actuated port-Hamiltonian system focusing only on the pendulum dynamics. The controller is derived without solving the PDEs. Although our controller is for only the pendulum part of the system, the translational acceleration can be indirectly controlled utilizing the relation between the inclination of the pendulum and the acceleration arising from instability of the system. The controller can achieve various properties through energy shaping procedure of the IDA-PBC. Especially an energy function which will lead to safe operation of the MIP is proposed in this study. The function ensures that motion of the pendulum is restricted in a predefined region and converges to a desired pendulum angle. The controller also gets the pendulum back to the desired angle with a large state-dependent gain when the pendulum comes close to fall over. Effectiveness of the controller is verified through simulations.

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Planetary surfaces are covered with soft soil. So the wheels for exploration rovers easily slip and lose the traction force. Understanding the interaction between wheel and soft soil is important for traction control to make rovers travel long distances efficiently. The interaction between wheel and soft soil has been studied in the field of terramechanics. Since terramechanics-based wheel model considers only the static state of wheel sinkage, the wheel model is not applicable to the dynamic sinkage. Therefore the authors deal with the problems of wheel sinkage and slip. The traction mechanics in the dynamic sinkage is important in order to predict the wheel motion when the sinkage becomes to be the static state. This paper presents a terramechanics-based wheel dynamics model with consideration of the dynamic sinkage. This paper also proposes dynamic wheel models for solving the problem of wheel sinkage and a shear deformation model for solving the problem of wheel slip. This paper evaluates the proposed models by simulation study. The simulation results show that the proposed models are able to solve these problems and they are applicable to the dynamic wheel sinkage.

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This paper describes vibration analysis using finite element method for box structures consisting of elastic flat plates and damping layers on their bottom plates. The box structures are supported by nonlinear concentrated springs on the bottom plate. The restoring force of the springs have cubic nonlinearity and linear hysteresis damping. Finite element for the nonlinear springs are expressed and are connected to the elastic plates modeled by linear solid finite elements in consideration of 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. Using material damping and shares of strain energy for the parts (i.e. the plates, the damping layer and the springs), we evaluate damping couplings among the parts. Further, we clarify influences of the damping couplings on nonlinear impact responses.

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Domino is a popular entertainment to enjoy the pleasing wave propagation in a row of solid pieces. This play game may be, however, a tough research subject of dynamic contact mechanics, because finite rotation, contact and friction are included in toy mechanics and these nonlinear effects are all of scientific interest. The major concern of this paper is to develop a computational model to study the domino wave propagation in a long straight row. More specifically, a total of N dominoes are modeled to rectangular rigid-body solids in shape of D (width) x H (height) x B (breadth). Equally spaced dominoes in a long straight row (L=492cm) are assumed to simply rotate around the front bottom edge. To trigger the wave propagation, the first domino is slowly inclined till its side diagonal slightly goes beyond the plumb line. The successive collision mechanism between individual toppling dominoes is investigated as a 2D problem in contact mechanics and we obtain an excellent agreement between the model prediction and experimental result.

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In this paper, we propose a novel concept for the real-time target tracking of vibrating objects to extract vibration image regions using band-pass digital filters at all the pixels in an image, assuming that significant periodic changes in image intensities exist at pixels around vibrating objects. By combining vibration-based image processing with color feature extraction as a masking process, our algorithm can prevent the latency effect on a digital filter, which may degrade its tracking performance. Band-pass digital filters at a pixel level are actually implemented on a 1000-fps real-time vision system that can measure vibration distribution over a wide range of frequencies. By using our target tracking system, we can continuosly track a vibrating object at the center of the camera view by controlling a 2-axis active vision system with vibration-based image features.

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This paper describes an approach for high-performance image retrieval method named interlaced fast sequential matching and its application to mechanical drawing processing. Conventional image retrieval methods for a huge image such as Correlation Matching and SSDA have a shortcoming with their performance.Thus, we use the interlaced fast sequential matching with rotation process in order to avoid the difficulties in the conventional methods. If we can find an efficient method to retrieve any drawing objects without OCR process, the more efficient management of old mechanical drawings can be performed. We first discuss some essential issues to be considered in mechanical drawing processing. Experimental results by using the proposed method are also described. The good performance of the proposed method is shown.

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In this paper, a component restricting pressure change caused by oil temperature change is proposed. One of the merits of an oil-hydraulic system is to keep the value of oil pressure when pressurized oil is enclosed in a container. However, it is impossible to keep the value when the temperature of the oil is changed. Using a pressure control sub-system to prevent it, the whole system becomes complicated. In addition to it, the energy is consumed when the pressure is adjusted by the quantity of the oil flowing into or out the container. From these view points, it is effective to develop the component which prevents the pressure change according to the oil temperature change without the control of the quantity of the oil. Therefore, in this paper, a component to prevent the pressure change based on the oil temperature change is proposed to make the merit of oil-hydraulic system certain when the temperature of the oil is changed. And, in the cases where the temperature of the oil is increased and where the temperature of the oil is decreased after it is increased, the basic characteristics of the component investigate experimentally.

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This paper proposes the concept of networked JIT control based on a client-server architecture via the Internet, which is an expanded version of the Just-In-Time (JIT) control. In the proposed concept, the server machine has the database for the JIT control and the client machine has a plant to be controlled. The server machine performs the computation of an inverse model of the plant utilizing data stored in the database. The client machine executes a feedback control algorithm, communicates the plant data to the server through the Internet, and sends control commands to the plant. In addition to the general advantages of the JIT control, this concept allows for sharing the database on the server with the clients and reduces the costs of the addition of more clients. A control system of a robot manipulator driven by pneumatic muscle actuators, which are elastic and safe for humans but nonlinear and difficult to model, is constructed based on the proposed concept. Experimental results show that the proposed networked JIT control is realizable and leads to an improvement in the performance of the manipulator.

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We developed an arm model by first creating bone models (humerus, ulna, and radius) based on CT images of human arms; muscle spring models (brachialis, biceps brachii, and brachioradialis) based on magnetic resonance (MR) images; and ligament wire models (17 ligaments that connect bones) based on literature and MR images, and then integrating these models. MR images of a human arm with the elbow flexed at arbitrary angles were obtained. Furthermore, these image data and the simulation results were compared to determine the simulation accuracy. The arm model was also used to analyze the behavior of each bone at ligament rupture. Comparison of the simulation results with MR images of a human arm during elbow flexion revealed a deviation of up to 16.7 mm at the midpoint of the ulnar notch of the radius (distal portion). This could be explained by the following: (1) the slice interval (3 mm) used to obtain MR images of a human arm; (2) influence of the articular capsule; and (3) influence of ligaments around the wrist. When medial collateral ligament rupture and ligament rupture around the lateral collateral ligament were simulated with the model, both bones extroverted and introverted, respectively. The deviation of both bones during medial collateral ligament rupture was greater than that during ligament rupture around the lateral collateral ligament, indicating that the medial collateral ligament was a major contributor to elbow stability. The above results demonstrated that the arm model created in this study simulated human arm movement well.

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The objective of this study is to investigate the effect of the tensile force ratio between the two extensor muscles for the hip joint on the forces acting on the knee joint. We have created a 2D model of lower limbs and have performed some simulations to introduce the forces acting on the knee joint for various daily activities. Our simulation results demonstrated good agreements with the in vivo data available in the literature except that the tangential components of knee joint force became pretty larger than those from the in vivo data at high knee flexion angle. We considered that the discrepancy was attributed to the fact that we had assumed the hamstrings force is equal to the gluteus maximus force in order to solve an indeterminate problem, thereby introducing too large values of the hamstrings force. Then we expected that the above discrepancy could be eliminated if we change the tensile force ratio between the hamstrings and the gluteus maximus basing upon a certain biomechanical criterion. Thus we changed our model so that we could introduce the knee joint forces as a function of the above mentioned tensile force ratio. Simulation was performed for the various tensile ratio values and it was found that the knee joint force was sensitively affected by the tensile ratio and the above discrepancy could be eliminated if the ratio value was appropriately chosen. The subject of our future study is to find out the way how to determine the value of the synergetic muscles' force ratio to best fit the calculated joint force to the in vivo data with reflecting a biological rationality.

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In this paper, we propose a method to synthesize subject-specific three dimensional finger models including skin and bones from geometric database and representative dimensions that can be measured by a caliper. The geometric database necessary for our method was developed by analyzing principal feature of the individual differences by using principal component analysis. The proposed method synthesizes subject-specific models by blending these principal features. The weight for each feature was determined by numerical optimization so that the synthesized subject-specific model reproduces the representative dimensions of the actual subject. We applied our method to fifty fingers. The average of the maximum error was 1.0mm, while the average error was 0.2mm. For more than 70% of the subjects, the bone as well as skin geometry were synthesized with acceptable error range from the representative dimensions of surface geometry. As for the remaining 30%, there was significant error in bone length. This method has distinct advantage over the conventional method in which time consuming manual segmentation for medical images is necessary, since we can generate subject-specific finger models in 5 to 10 minutes automatic computation.

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Quadrant glitches are one of the causes of deteriorating the machining accuracy in NC machine tools because those leave streaky marks on the machined surfaces. The quadrant glitch is caused by friction of the ball screw and linear guides of feed drive systems. In this study, when the circular trajectories are precisely investigated by conducting the circular motions under various conditions, it is found that the preload in the ball screw affects the height and shape quadrant glitches at low feed speed. It is caused by the difference of contact points between balls and grooves of ball screws. It is also found that the quadrant glitch becomes one peak in case of oversize preload in ball screw, and two peaks in case of offset preload. In this study, a method for compensating two peaks observed in quadrant glitches due to the change of contact points between balls and grooves of a ball screw is proposed. A proposed compensating method can cancel the friction torque changes generated in the ball screws with a new mathematical model. It is confirmed that the proposed method can decrease the quadrant glitches in a wide feed speed range through simulation and experiment, and the proposed method can correct two peaks of the quadrant glitches in high accuracy. In addition, from circular motions with mass, it is confirmed that the proposed method can correct the quadrant glitches without deteriorating effect of mass.

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When people walk, there appear paths. When there are paths, people walk there. In this study, we introduce a simple vision-based system that traces a walking people and running vehicles, identifies the paths and determines the anomalies (outliers, abnormal motions) departing from the paths. The system obtains video data at the location above some meters or ten and some meters above the ground. An optical flow method is used to trace the moving object. Initially, the system knows no road. By cumulating trajectories of moving objects, the system assumes the set of the trajectories as a path. Once paths are assumed, a motion not following the roads is detected as an abnormal motion. When the motions similar to the abnormal motion continue, the system reconsider that there appears a new path. Appling to the real outdoor environment, we have verified the validity of the present method.

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We developed a technique for searching for useful information suitable for the user's work from a database consisting of the past projects and delivering it to the user with the aim of improving operational efficiency. Previously, information sharing systems have been developed, but there was the problem that information was not used if the user oneself did not retrieve it. Useful information suitable for the user's work can be delivered automatically by using our original technique, which are keywords extraction and relevancy evaluation by TF·IDF·ITF between search results and the user's work. The developed system was applied to information equipment design and was confirmed that it was able to deliver useful information with 80% accuracy.

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In a non-magnetic single-component development system in electrophotography, formation of a thin and uniform toner layer on the development roller is important for obtaining high image quality. We conducted experimental and numerical investigations to clarify the dynamics of toner particles in this process. Two approaches were adopted for the investigation. One is experimental and the other is numerical simulation using the distinct element method. We manufactured a mock-up apparatus consisting of a supply roller, a development roller, and a doctor blade for forming a thin toner layer on the development roller. The thickness, surface roughness, and charge density of the formed toner layer were measured after the doctoring process. It was clarified that the thickness of the toner layer was increased, but the charge density was decreased, by increasing the applied voltage and rotational speed. These findings were confirmed by direct observation of the toner motion in the doctoring area with a high-speed microscope camera. Numerical calculations performed using an improved distinct element method revealed that the elastic energy applied to the toner particles, which is an index of toner degradation, was increased by increasing the stiffness and pressing force of the doctor blade, but decreased when the curvature of the blade tip was large. The present experimental and numerical results can be used to improve non-magnetic single-component development system in electrophotography.

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This study deals with an ultrasonic oscillation method for friction reduction and lubricity improvement in meshed gears. In recent years, the gear is used in critical environments such as in a vacuum chamber or space environment. Thus, instead of using a conventional method, i.e., lubricant oil, a new method of the friction reduction and lubricity improvement is rather demanding. This paper describes frictional experiments for meshed gears oscillated by an ultrasonic actuator which is fixed on the end surface of the gear shaft. Strain gauges are attached on the fillet between the dedendum flank and the bottomland to measure stress conditions during forward and reverse rotations when a constant torque was applied about the gear axis. The friction on the tooth flank is evaluated from the averaged stress difference between the forward and reverse rotations. The study showed that when no lubricant was applied, the ultrasonic oscillation has reduced the friction between tooth flanks by approximately 40% compared to non-oscillation results.

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For the purpose of improving the efficiency of automotive transmission, there is a greater need to modify even the gear dimensions and tooth surface for reducing gear mesh power loss. In our study, we developed the prediction program and examined some reduction methods of the mesh power loss. To predict the mesh power loss of transmission gears accurately, it is necessary to estimate the friction coefficient at tooth meshing surface. But there was no formula with high accuracy for useful estimation of friction coefficient under mixed lubrication condition such as gear meshing condition. The one of authors proposed the new estimation formula of friction coefficient. In this paper, the usefulness of proposed estimation formula is confirmed and the prediction program of mesh power loss applying the proposed estimation formula of friction coefficient is also validated by several gear pair tests. From this prediction program and some experiments, the influence of gear dimensions, tooth surface modification, tooth surface roughness and driving condition on mesh power loss is discussed.

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In roughing of large module gears, high efficient gear cutting with a formed milling cutter is noticed. In this case, the milling cutter is an insert type with both negative top rake and side rake angles. It is well known that negative rake angles increase cutting force and produce undesirable cutting surfaces. In this paper, a design method of insert-type gear formed milling cutters with both positive top rake and side rake angles is proposed. Firstly, the profile of cutting edge is calculated from the axial profile of the cutter by giving the design parameters such as the top rake angle, side rake angle and cutting edge angle, and the shape of insert pocket for the cutter body is designed by giving the thickness, length and width of the insert. However, these obtained design parameters are not always available because interference between the flank face and the work may occur. Therefore, a simulator that can interactively decide these design parameters was developed. Finally, the formed milling cutter were designed and made using the proposed method. Cutting tests using the trial-made milling cutter were carried out. As the results, the sufficient accuracy as the cutter in roughing of large module gears was obtained.

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Relief grinding for involute helical pinion cutters with no profile error is realized by through grinding with a trapezoid-like grinding wheel. As a calculation example, an involute helical pinion cutter with semi-topping and protuberance cutting edges is used. First, a method for calculating the grinding wheel profile to finish the tooth flanks of the pinion cutter with the exact cutting edges is proposed. Next, the profile errors of cutting edges after regrinding are calculated and evaluated by means of the tooth profile of the work gear being shaped by the reground pinion cutter. As the results, it was found that the profile errors and the changes in shapes of the semi-topping and protuberance cutting edges after regrinding are very small. Finally, the usefulness of the proposed methods was confirmed through the grinding tests of the pinion cutter.

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There have been few reports dealing with the drilling in Printed Wiring Boards (PWBs) with micro-drills, smaller than 0.2 mmin diameterand, super-high-speed spindles, higher than 160,000rpm. In these cases, problems that it is impossible to prevent the breakage of the micro-drill and keep the position accuracy of the drilled hole have occurred. We therefore focus on the step-drilling method with high speed and short stroke as a novel technique to resolve these problems. On the other hand, there is a problem to determine the complicate combination of feed speed, rapid feed speed and stroke length in this method. Thus, we attempt to apply the response surface method to optimize these parameters. As a result, a proposed method is found to be effective to improve the drilled hole quality and drilling efficiencyin such kinds of micro-drilling in the PWBs.

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This paper deals with the thermal stress cleaving of the thick glass with multiple laser beams. A continuous CO₂ laser with a wavelength of 10.6 μm is used to generate the thermal gradients which cause the compressive stress at laser irradiated area and the tensile stress outside of the irradiated area in the specimen. A pulsed Er:YAG laser with a wavelength of 2.94 μm is used as a heat source to raise the temperature inside of the specimen. As a specimen, the soda lime glass with a thickness from 1.3 to 8.0 mm is used. The absorption coefficient at the wavelength of CO₂ laser is 18.42 mm^-1 and that of Er:YAG laser is 0.58 mm^-1. The effect of internal heating with Er:YAG laser on cleaving characteristics, such as a laser power per unit length, thermal damage of the laser irradiated surface and surface roughness and straightness of the cleaved surface, are investigated experimentally. As a result, the application of multiple laser beams to the thermal stress cleaving made it possible to fabricate the thick glass without any damage such as a tipping and a sub-crack on the laser irradiated surface. The surface roughness and straightness at the cleaved surface is quite improved by the internal heating with Er:YAG laser irradiation.

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