There is a big need for estimating internal properties of eyeball, since they shoud be closely related to eye diseases, such as detached retina. Based on this background, this paper discusses a new bio-marker expressing the mechanical characteristics of internal eyeball. For this purpose, we focus on subjects having vitreum surgery in which vitreum of subject is replaced with succedaneum. With the assistance of high speed camera, the eye deformations before and after operation are captured during air-puff impartment. Through the analysis, we found the difference between the behaviors before and after operation, especially the shape of eye ball immediately after the tip of cornea recovers. We discuss why such different behaviors happen and how we can explain the physics.
Imparting a local high pressure to cornea with a damage by various accidents should be definitely avoided from the viewpoint of protecting eyes. For such eyes, medical doctors purposely utilize a contact lens for protecting eyes during internal pressure measurement. While attaching contact lens increases the total stiffness due to additional equivalent stiffness coming from contact lens, the tonometer provides us with a smaller pressure under near-sighted contact lens than that without any contact lens. Furthermore, the displacement of cornea under far-sighted contact lens is more than that without any contact lens. We discuss why such unexprected behaviors happen and how we can explain the physics. We also discuss how to convert the internal pressure with contact lens to that without contact lens.
This paper presents a new warning method for the Human-Machine-Interactive operation environment such as a driver assistance system. If the warning information is accurate, providing it to a driver can be expected to have some effect in assisting driving operations. However, if the information presented contains uncertainties, the provision of uncertain warning information to a driver could cause confusion and lose confidence for the warning. Against this structural problem, this study focuses on a method of improving prediction in relation to factors of an uncertain nature that might occur at any time. For discussing this problem, very simple experiments are performed. Authors pay an attention to human's operation under hearing some beat sounds. Relationship between beat sounds and subjects' operations are analyzed. In his experiments, easy to express the human operation, Uchida-Kraepelin test are applied. The results of many experiments performed with a different beat sound show that performance of Uchida-Kraepelin test will be changed unconsciously shortly after beat frequency changed. This result is the sort of key to develop the warning method with ambiguous information because the beat sound affects the performance of the operator unconsciously without decreasing confidence between human and machine. This paper also discusses a probability for implementing this method in real vehicles.
Recently, a variety of baseball bats are sold. The materials used in baseball bat are made from the wood, the aluminum or the FRP. The percussion performance is one of the keys to its selling well. The character called sweet spot is used to evaluate the percussion performance. But the relations between the sweet spot position and mechanical characteristics are unclear. First, sweet spot position is theoretically pinpointed by the modal analysis and the energy theory. The closer collision is to the node of mode, the more rebound. And the closer collision is to the center of gravity, the more rebound. Next, the theory is tested by experiments. The first node and second node are pinpointed by the experimental modal analysis. The most reflective position is pinpointed by the collision experiment. In conclusion, the first node should be used for the sweet spot position. The center of purcussion is poor markers of the sweet spot.
This paper presents a method for comparing the input powers and contribution rates from a power source to a structure in machine operation determined by statistical energy analysis (SEA) and transfer path analysis (TPA). Identifying external forces and contribution rates from input power sources during machine operation is important for analyzing machine and equipment, and dynamic designs. SEA is used for systems with many resonant modes, and predicted results are based on spatial averages. In contrast, TPA is based on estimation of a frequency response function between an excitation point and a response point. In this study, a method is proposed for comparing SEA evaluated by the power injection method and TPA evaluated by the matrix inversion method. The proposed method is validated through numerical analyses, using a finite element method of a simple structure consisting of two flat plates connected in an L-shaped configuration and a partial car model consisting of four subsystems. As a result, the SEA input power is spatial averaged over each subsystem quantitatively agrees with the TPA input power expressed as the product of the force and velocity at the excitation point. Contribution rates from a power source, the SEA and TPA results are qualitatively similar without having to consider the phase.
Fundamental experiments on a test stand to examine the characteristics of magnetically levitated (maglev) vehicle dynamics were conducted. In the prototype test stand, an actual bogie with weights, which correspond to a car body, is magnetically suspended and vibrated by surrounding magnetic exciting coils. This paper proposes a bench test system and a magnetic vibration method which can suspend the bogie and simulate irregular external forces originated by four types of alignment irregularities of ground coils, using a concept of equivalent irregularities. The results of the slowly swept sine excitation experiments confirmed that the bogie in the test stand is magnetically suspended in the same way as the actual bogie running at a high speed. Furthermore, vertical accelerations of the bogie and weights vibrated in the proposed way were compared with those of the moving vehicles to find similarities in a range of frequencies sensitive to ride quality. The experiments technically enhanced the prospect of the test stand to analyze the characteristics of maglev vehicle dynamics for the future.
We developed an SEA (Statistical Energy Analysis) model of a whole railway carbody shell by using CLFs (Coupling Loss Factors) calculated from partial FEM model of it. By comparing with the hammering test results of the actual carbody shell, it was revealed that under 160Hz band all the CLFs between each subsystem should be incorporated in the SEA model, and the modified analysis results matched the experimental ones by less than 5 dB difference. Then, in order to simulate the vibration distribution of the rolling stock with an engine under the floor body, input power of the operational engine was calculated from measured acceleration data of both sides of the engine rubber mount. Calculated input power was applied to the SEA model of the carbody shell to which upper floor subsystems were added, and it was confirmed that the analysis results matched the experimental ones within 5 to 10dB difference.
We theoretically investigate the driving mechanism of a travelling wave ultrasonic motor that consists of a rotor and a stator, in consideration of the rotor vibration. As a result, we can make clear the inverse rotation phenomenon of the ultrasonic motor that could not be analyzed out of consideration of its vibration. And also, it is found that the driving characteristics are classified into six patterns due to the rotor vibration and that, in the case that the phase of the rotor vibration is opposite to that of the stator, the driving force becomes generally greater than in the case of the same phase. Furthermore, it is experimentally confirmed that, in the case of same phase, the rotating direction is normal ( opposite to a travelling wave direction ) if the amplitude of the rotor vibration is smaller than that of the stator.
A flexible string such as a cable or a wire is used everywhere. There are various uses such as a cable for sending electricity, a wire for tension and a mowing machine turning a nylon string. In the past study, the authors investigated the behavior in casting of a fly-fishing line by experiment and analysis. In the case of fly-fishing, casting is the element which anglers must master in order to cast a fly. Anglers have to cast a light weight fly by using the weight of a line. In the past study, an analysis model of a fly line and a rod, arms was made with rigid body and link. Numerical simulation was carried out and a better casting method was examined. In this study, a method to cut off an object by a turning string is examined based on the conventional study results. In the past study about a cable and a line, appropriateness of the modeling has not been numerically verified by comparing an analysis result with an experiment result. However, appropriateness of the modeling has to be verified numerically by an error of analysis and experiment. Therefore, this study pays attention to the basic movement of the line pendulum as the first grade to a cutting method with a string and makes an analysis model, and clarifies the behavior of line pendulum by experiment and numerical analysis.
This paper investigates the influences of the coupling element placed between nonlinear self-excited oscillators on synchronization. A simple model is newly developed by modifying the model treated in our previous report. The model consists of two oscillators subjected to Coulomb friction and a block installed in the coupling element. These elements are connected in series by coil springs and dashpots. In this model, stick-slip motions frequently occur due to the Coulomb friction. The synchronized solutions and the stability are analyzed accurately by the improved shooting method. The new model is validated by comparing the calculated results and the experimental results, and the features of the synchronized solutions are investigated. The results show that the frequencies and vibration patterns of the synchronized solutions closely correspond to the natural frequencies and natural modes of the three-degree-of-freedom system without the Coulomb friction, and that the existence regions of the synchronized solutions depend on the block mass as a parameter of coupling element. When the parameter is appropriately set, the existence regions expand. The mechanism is examined from the viewpoint of the energy transition between the oscillators.
This paper develops an analytical method of the vibration of the finite element rotating shaft model with an open crack which was developed in our previous study. Particularly, the vibration of the rotating shaft with an open crack under the harmonic excitation is investigated, and the fundamental equations governing the vibration of the cracked shaft are derived in that case. By comparing the obtained their theoretical results with the experimental results quantitatively, the validity of the analytical methods and the derived fundamental equations are verified. This result contributes to detect a crack of a rotor in its early stage.
The non-Gaussian response characteristics of an asymmetric nonlinear system subjected to nonwhite random excitation are investigated. The stationary responses are calculated by employing a combination of the Non-Gaussian equivalent linearization technique and the use of the moment equations approach. Skewness, kurtosis, and equivalent linear coefficients are illustrated as the maps of the non-Gaussianity. Numerical results show the effects of the dominant frequencies of the excitation upon the non-Gaussian response characteristics. The relationship between the resonance of the system and the transition properties of the non-Gaussian response is also discussed by considering the equivalent natural frequencies and the potential of the system.
Response distribution of an asymmetric nonlinear stiffness system to non-Gaussian random excitation is investigated. The excitation is a stationary stochastic process characterized by the non-Gaussian probability density and the power spectrum with a wide range of bandwidth. Both bimodal and Laplace distributions are considered as the non-Gaussianity of the excitation. A non-Gaussian stochastic process is generated by calculating an Ito stochastic differential equation in which the drift and diffusion coefficients are determined according to the given probability density and spectral density of the process. Monte Carlo simulations are carried out to obtain the stationary response distributions of linear system, Duffing system, and asymmetric stiffness system subjected to the non-Gaussian excitation. It is shown that the response distribution varies markedly depending on the bandwidth and non-Gaussianity of the excitation, and furthermore, the effect of the asymmetry of the system appears clearly in the response distribution.
In this paper, we propose and demonstrate a system by which a global order is emerged by local interactions among distributed agents. To control a group of distributed agents, we need providing motion commands to the agents. However, employing a global communication system is not feasible for simple and anonymous agents. Thus, we propose a system inspired by slime molds. We utilize phase gradients emerged by oscillators programmed in the agents. We propose and implement a novel interaction method that incorporates relative orientation among agents in order to emerge asymmetric phase gradient. By analysis and experiments we verify the effectiveness of the proposed method.
Arguably, noise suppression via active noise control is effective only within a fraction of the noise wavelength from an error sensor location. To expand the controllable region, it is a common practice to introduce the multi-channelization of a control system or sound power control of a noise source per se. It is also true, however, that they entail the following disadvantages: the multi-channelization causes complication, destabilization and increment of the computational burden; control sound sources need placing close enough to the noise source to achieve sound power control, hence impracticable. To overcome the disadvantages mentioned above, this paper presents a global active noise control method using a parametric array loudspeaker (PAL). Driving the ultrasonic transducers comprising PAL with a proper time delay enables one to produce the wavefront of control sound similar to that of noise, thereby suppressing a noise propagation in the vicinity of the noise source, resulting in the generation of a global zone of quite. The validity of the method presented is then clarified numerically as well as experimentally.
In order for mobile robots to coexist with humans, both safety and efficiency should be satisfied. We propose a method to predict pedestrian movement for collision avoidance of mobile robots and pedestrians. In the proposed method, the pedestrian trajectories are measured and a database of human movement tendencies is generated. The database is applied to the prediction of future pedestrian movement. To decrease the initial time cost for database generation, environmental geometric configuration is considered in the form of virtual forces. To verify the usefulness of the proposed method, we generated the database based on five-hour observation and conducted three types of experiments based on the generated database. The first experiment showed the prediction performance of the proposed method and proved the method guaranteed the safety. The second experiment showed that the proposed method satisfied both the safety and efficiency through the comparative simulations. The third experiment showed the method could apply to the real mobile robot.
The direct yaw-moment control (DYC) poses an optimization problem of determining the traction/braking forces distribution that is to be solved online to minimize the risk of tire force saturation to avoid instable vehicle behaviors. One of the authors has derived an algebraic solution to a similar minimax optimization problem of minimizing the maximum value of the tire workload where the direct yaw moment is explicitly specified. In this study, this algebraic solution is applied to the solution procedure for the extended minimax optimization problem where the total value of the traction/braking forces, that of the lateral force by the steering of the front and rear wheels, that of the yaw moment by the direct yaw moment and by the lateral forces of the front and rear wheels are specified. The proposed numerical approach that uses the golden section method rapidly converges to the exact solution of the essential decision variables as the traction/braking forces of the four wheels. The effects of problem relaxation are demonstrated through numerical examples.
In this paper, to improve operability of the operator, we developed the 3D visual feedback system for Cybernic master system. This Cybernic master system is a master-slave system for manipulations and consists of master-slave robot arm and visual feedback system. To reap full advantage of the system, not only feedback to somatosensory system such as force and impedance control but also optimal visual feedback is an important factor in transmitting information to an operator. To achieve visual feedback, it is installed stereoscopic vision and operation assist system using Augmented Reality. The stereoscopic vision is controlled by our active control method of a convergence angle depending on the distance to objects. The operation assist system can show stereoscopic images that is overlaid the virtual objects. We conducted experiments to verify that the operator can view parallax image stereoscopically at the leaching range that is near to an arm. Our system in short distance was effective compared with normal parallax method. Then, we conducted operation test to ensure that it is possible to perform the area protection with the virtual object. At the result, protection areas were formed, and we ensured that slave arm could not invade those areas. In addition, the operation assists such as not only protection of crash but also the tracing movement and operation instruction by the virtual objects is possible. To achieve the interaction between the object of the virtual space and an object of the reality space has improved the operability of the master-slave system.
Generally, many types of medical equipments, especially heavy equipments, have casters for their easy treatment or movement. However, in the case of earthquakes, if casters are free, large movement is happened and causes a disconnection of the connecting point or collision to the other equipments. On the contrary, if casters are locked, displacement of the equipment becomes small but large response acceleration causes turnover or falling of the installed equipments. In this paper, seismic response mitigation strategies of the wagon with casters were investigated. Instantaneous Optimal Control with ER brake was proposed for controller design. And the effectiveness was confirmed in simulation and shaking experiment. Torque limiting control and gain scheduling were investigated to keep response displacement short under the condition that response acceleration was also restricted.
The floating roofs are used in large cylindrical storage tanks to prevent evaporation of oil. The single-deck floating roof, considered herein, consists of a thin circular plate called “deck” attached to a buoyant ring of box-shaped cross section called “pontoon”. The deck plates are deformed to creat waves and they are subjected to cyclic bending due to wind load. This may lead to initiate fatigue cracks at the welded joints. It is important to know the characteristics of waves in the deck plate. The authors have reported the CFD analysis of a cylindrical storage tank due to uniform wind in another paper. This paper presents the axisymmetric finite element analysis for the sloshing response of the single-deck floating roofs in a cylindrical storage tank using the CFD results as the load condition. It is assumed that the liquid is incompressible and inviscid, and the roof is linear elastic while the sidewall and the bottom are rigid. The basic wave characteristics of the deck plate, such as frequency and amplitude, is investigated.
We have proposed a navigation method using magnetic information that occurs in the environment. This paper proposes a improve navigation method that combines a localization using magnetic information and a lateral error compensation based on external geometric information. In our previous method, it is required to adjust parameters used for the robot navigation. This adjustment is needed excluding unreliable magnetic information. On the other hand, our proposed method enables a robot to travel long distance without adjustment parameters even if the unreliable magnetic information is included. The robot is able to identify its position with the particle filter on a topological map using magnetic information. Furthermore, the robot uses external geometric information for only compensate the lateral error. As a result, the localization accuracy is increased and is not depend on geometric information. In addition, these methods are applicable to the robot using simple algorithm, computational and memory costs are low. Through the navigation experiments, we show that the robot achieved over 2 km navigation in real world. Moreover, the proposed method is compared to other two methods. Finally, the usefulness and advantage of the proposed method are presented.
In this study, a dynamics simulator for Gas Circuit Breaker (GCB) with spring operating mechanism was developed. In the operating mechanism, the spring stores mechanical energy. When opening and closing instructions are entered in the GCB, the solenoid opens the trigger, and mechanisms move releasing the compression force of the spring at a high speed. A compact and light-weight mechanism is required for highspeed operation of the GCB. The highspeed operation, thus, must be analytically investigated. We made a mechanical dynamics model for the whole GCB by including FEM modal analysis. And the dynamics simulator is developed by combining the solenoid electromagnetic field analysis and the gas pressure analysis in puffer room into the mechanical dynamics model. The operating characteristics of the GCB were analyzed with the simulator and were measured in an operating experiment. The analytical results showed good agreement with the experimental results. Therefore, the dynamics simulator can be used to estimate the operating characteristics and appraise the stability of operation. A compact and light-weight GCB can be designed in short time by using the dynamics simulator.
Power assist systems have been introduced to reduce physical burdens of workers in industrial production lines. The authors have studied on control systems for power assisted conveyance of flexible structures. The previous paper proposed a control system design consisting of an impedance controller, a disturbance accommodating suboptimal controller, a disturbance observer and a reaction force controller in order to achieve the robust assist against structured uncertainties. However, the experimental and simulation consideration in the paper adopted single operational force profile which was reserved a priori and compared control characteristics of plural control system designs. Therefore, responses by actual human operational forces have not been fully evaluated yet. Then, a subjective evaluation experiment is conducted in this paper. As an experimental task, participants push the cart about 10 m distance and position the tip of a flexible plate within 100 mm. The participants answer some questions about the operability of the cart. By using Dunnett's test as a statistical method, the effectiveness of the proposed control system is verified. Moreover, especially at the point of the effectiveness of the disturbance observer, another experiment based on the reserved operational force is conducted on moving on a flat and slope track. By the experiments in this paper in addition to the previous paper results, the control characteristics of the proposed control system design is evaluated comprehensively and multilaterally.
Prototype remotely-operated vehicle equipped with high resolution TV monitor and underwater radiation measuring instrument was developed and actual condition of contaminated soil in the regulation pond in Fukushima was investigated. Remarkable contaminated point was observed beneath rainwater outfall of impounding reservoir(Length×Width×Depth; 112m×30m×3.5m) in the order of 3.3~5.24μSv/h. It is found that contaminated small particles in the order of 1-3mm are deposited in the polluted mud at the bottom of the reservoir and suspended by disturbance of water flow, and the contaminated zones in the order of 0.75-3.5μSv/h are distributed in a patchy fashion caused by confluent of outfall in the demarcated region(10m×10m×10m).
Several former top players sent a letter to the International Tennis Federation (ITF) encouraging the governing body to revisit the question of rackets. In the letter, the players wrote that racket technology has led to major changes in how the game is played at the top level. This paper investigated the physical properties of a new type of racket with active piezoelectric fibers appeared recently in the market, and predicted the various factors associated with the frontal impact, such as impact force, contact time, deformation of ball and strings, and also estimated the racket performance such as the coefficient of restitution, the rebound power coefficient, the post-impact ball velocity and the sweet areas relevant to the power in tennis. It is based on the experimental identification of the dynamics of the ball-racket-arm system and the approximate nonlinear impact analysis with a simple swing model. The predicted results with forehand stroke model can explain the difference in mechanism of performance between the new type racket with active piezoelectric fibers and the conventional passive representative rackets. It showed that this new type racket provides higher coefficient of restitution on the whole area of string face and also gives larger rebound power coefficients particularly at the topside and bigger powers on the whole area of string face but the difference was not so large. It seems that the racket-related improvements in play are relatively small and the players themselves continue to improve, accordingly there is a gap between a perception and reality.
In the field of pneumatic actuator for positioning control, there are several causes that bring slow response. In particular, the flow disturbance caused by the air pipe sending compressed air, and the mechanical disturbance generated by rolling bearings prevent high speed and high precision positioning. Therefore, in this study, we propose to apply both the mechanical disturbance observer and the flow disturbance observer as a method of removing two disturbances separately. We call the control structure of this flow and mechanical disturbance observer as “Dual disturbance observer”, and intended to make high speed and high precision positioning with dual disturbance observer. Considering industrial scene, this paper tries to tune parameters of observer through actual experiments.
In this study, we develop a small pressure-sensor-driven round bar grip measurement device called DataGrip and construct the prototype system for infants, who have small fingers. DataGrip is made up of a round bar wrapped with a silicone tube that consists of up-and-down grip shafts. Two small pressure sensors between the grip shafts can measure perpendicularly oriented loads. We display the quantitative load applied to the system. On the basis of the measurement results, the effectiveness of the system in terms of load measurement is evaluated. Further, we examine the results of longitudinal measurement of an infant's grip by using the system. We find that grip strength increases with physical growth, i.e., increase in height and weight.
In the 21st century, as it is important to produce products with care for protecting the earth, a producer must be careful to conserve energy, save resources and reduce waste which pollutes environment. On the other hand, in case of a drilling, much cutting oil was also used for lubrication and cooling. This is large problem for protecting the earth. Therefore drilling technology using strong alkali water with micro-bubble was developed. A drill with through hole was used for this technology. Cooling effect of strong alkali water with micro-bubble was firstly investigated on the experiment. Then heat transfer coefficient of the drill with through hole was evaluted for cooling capacity. Tool life of the drill using strong alkali water with micro-bubble was also evaluated in the experiment of drilling using Ti6Al4V which has small thermal conductivity and is a material with difficult machining. It is concluded from the results that; (1) Cooling of strong alkali water with micro-bubble was very effectuive, (2) Heat transfer coefficient of the drill using strong alkali water with micro-bubble was 3.5 times of that of dry drilling, (3) Tool life of the drill using strong alkali water with micro-bubble was 6.5 times of that of dry drilling and 2 times of that of ordinary wet drilling respectively, (4) The drilling using strong alkali water with micro-bubble was economical and eco-friendly.
The present paper describes the correction of the squareness deviations of three orthogonal axes for identifying the geometric deviations inherent to five-axis machining centers with an inclined A-axis. The center offsets of the circular trajectory of simultaneous three-axis or four-axis control movement including one axis of rotation were calculated using a simulation model consisting of the homogeneous transformation matrix by changing the geometric deviations individually, and the offsets were made connection with geometric deviations. The geometric deviations which were influenced by the squareness of three orthogonal axes were identified. The relational expressions between the center offset and the geometric deviations were formulated. In order to confirm the influence of the squareness deviations, a five-axis machining center with a tilting rotary table, which is perpendicular to the axis of rotation, was tested. As a result, it was found that the squareness of the orthogonal axes affect the parallelism deviations between the A-axis and the X-axis and the squareness of the C-axis to the A-axis as well as the linear offset of the C-axis of rotation from the A-axis of rotation. The correction of the squareness deviations of three orthogonal axes is indispensable in order to actually apply the proposed identification method.
In this paper, we analyzed the mechanical loss factor of a geared motor, which is composed of a 90W induction motor and a parallel gear reducer with total reduction ratio 9 and 18. Gear mesh was lubricated with the grease of NLGI consistency number 2. The loss factor was evaluated as the sum of load independent part, or at no loading, and load dependent part. The loss of oil seal and grease was examined by the measurement of the geared motor at no loading. The friction loss of bearing was evaluated in terms of the coefficient of friction of bearing, which was measured by the unit testing of bearings. Change by a temperature of the loss of grease was measured by the experiment. And the friction loss of tooth flank was decided as the residual value after subtracting other losses obtained value from the experiments. The result shows that the loss at no loading holds the higher proportion of loss, due to the oil seal and the grease. When load was applied, the portion of the loss of tooth flank increased. The mean friction coefficient of a tooth flank by grease lubrication proved to be a representative value of 0.12, which was verified the gear reducer of the difference dimension.
Sound level and vibration of a rolling bearing increase and a ridge mark appears in the bearing surface when the electrical pitting occurs in the bearing. The frequency in which the sound and vibration increase is attributable to the wave undulation of the formed ridge mark on the surface. However, it was clarified that there was electrical pitting phenomenon without ridge mark. Therefore, in this research, the vibration acceleration was measured in occurrence and non-occurrence conditions of ridge mark. Then, the frequency of increased acceleration was clarified experimentally. The conclusions are as follows. (1) In non-occurrence condition of ridge mark, integral multiple components on rotation speed increased. (2) In occurrence condition of ridge mark, the acceleration increased in frequency caused by the wave undulation of ridge mark. (3) The wave undulation of ridge mark varied and the frequency in which the acceleration increased varied even if the experiments were done in the same condition.
This paper proposes a formulation method of ergonomic design problem so as to support the decision making of designers. The optimization problem for each participant is formulated as a multi-objective optimization problem. In addition, the optimization problem for all participants is formulated based on different ergonomic design strategy for considering individual difference: a) design for average participants (Strategy A), b) design for weak participants (Strategy B), and c) design for divided clusters (Strategy C). The regret is defined as the difference from the objective function value of optimum solution for each participant. Then, the ergonomic design problems for three different strategies are formulated as follows; a) strategy A is formulated as the minimization of the average regret, b) strategy B is formulated as the minimization of the maximum regret, and c) strategy C is formulated as the minimization of average regret for divided clusters. The proposed method is applied to the design problem of cylindrical diameter for power grip. The cylindrical diameter is the only design variable, and the average pressure and the coefficient of variance are objective functions. From the result of optimization, it is found that the average regret based on the strategy C is significantly lower than the other strategies. In addition, the average regret based on the strategy A is significantly lower than that of the strategy B; while the maximum regret of the strategy A is higher than that of the strategy B.
Since a technician usually watches the work point while confirming his hand-tip's movement and the state of the tool and the equipment, it leads us to wonder if there exists the relationship between the gaze point movement of the technician and his skill proficiency. If the relationship is clarified, it would be effectively used in the skill education and the evaluation. In order to find out the relationship between the gaze point movement and the skill proficiency, in this research an eye camera and analysis software were used in the size measurement with a micrometer. The analysis of the gaze point movement was observed, and the relationship of the gaze point movement and the skill proficiency was discussed based on the experimental results. It was found out that the technician's gaze point movement relates with his skill proficiency. The result and discussion also showed that it is effective to put emphasis on the contact between the micrometer and the measured object, in the technical training for the size measurement with a micrometer.
We have already developed a speech-driven embodied group entrained communication system called “SAKURA” for activating group interaction and communication in which speech-driven CG characters called InterActors with both functions of speaker and listener by generating communicative actions and motions are entrained to one another as a teacher and some students in the same virtual classroom. In this paper, the eyeball movement of lecturer in virtual group communication is analyzed by using an embodied communication system with a line-of-sight measurement device. On the basis of the analysis, we propose an eyeball movement model, which consists of a saccade model and a model of lecturer's gazing to audiences called “group gaze model.” Then, an advanced communication system in which the proposed model is applied to SAKURA is developed for enhancing group interaction and communication. This system generates lecturer's eyeball movement based on the proposed model by using only speech input. By using the system, we perform experiments for the effects of the proposed model by sensory evaluation. The results demonstrate that the system with the model is effective in group interaction and communication.
This paper proposes the methodology of analyzing the team working process using the information of factory and each worker's location. Analyzing the team working process is done through the following processes:(1) get the data of operation and each worker's location by using active RFID sensor, (2) evaluate the team working process by comparing with the representative sensor data, and (3) extract the error process automatically by using the result of evaluating team working process. The proposed methodology was applied to changing ladle operation in continuous casting. Results show that the methodology can evaluate the team working process normally and extract the unusual process which should be reported to factory manager. In addition, this method can get the new knowledge about changing ladle operation. For example, the quality of production would be poor if no worker does monitoring on pulpit.
In the life cycle engineering, describing scenarios is considered a good approach to sustainability in manufacturing in terms of clarifying visions of future manufacturing industry. When envisioning sustainable futures, describing “backcasting” scenarios is especially hopeful, because in a backcasting scenario, ideal future visions are firstly developed apart from the present situation. Although many scenario development methods have been proposed, these methods are too abstract, especially have no specific procedure for designing backcasting scenarios. This paper proposes a method for supporting design of backcasting scenarios using logic trees. In this method, logic trees support determining the structure of a backcasting scenario and creating storylines, which are outlines of sub scenarios. The logic tree and the storylines support describing the scenario text. As a case study, we described a backcasting scenario on “breakdown” of Japanese manufacturing in 2050. The result of the case study revealed that the logic tree systematically supports determining the structure of this scenario and generating its storylines. And composing scenario text is successfully supported by detailing the logic tree and the storylines.
In this work, we tried to clarify the peeling-off mechanism of diamond-like carbon (DLC) during heating/cooling process. DLC film was deposited on a stainless-steel substrate (SUS 304, JIS) by ion beam sputtering of carbon target. Then, the DLC film was heated up to 250 °C, and then kept at the temperature for 60 min, and finally cooled down to the room temperature. The optical microscope observation revealed that the DLC started to peel off at around 70 °C during cooling process. The residual stress measurement with Storney's method revealed that the residual stress of DLC changes with increasing and decreasing temperature; however, the residual stresses at the same temperature during heating and cooling are almost the same, indicating the there was no irreversible change in the residual stress during heating/cooling process but carry out reversible change caused by the change of thermal stress. The scratching test revealed that the critical shear stress of DLC films decreased during heating/cooling process. It can be concluded that the peeling-off of the DLC is caused mainly by the decrease of the interface strength, or critical shear stress between DLC and substrate, which was estimated to decrease monotonically with time during heating/cooling process.
As the need for product platform and product family has increased over the last 20 years, research within the area has led to the development of various methods that aim at evaluating a candidate of design. Although their differences are considered a strong point of the theoretical field, the large variety can end up complicating the selection process, which will result in choosing less optimal methods for a specific design case. This paper surveys prior works of design methods for product platform and product family, and proposes Design Method Selection Matrix (DMSM) that can help designers choose appropriate design methods. The underlying basis for the proposed DMSM is to determine methods appropriateness based on the availability of information, which is defined by the situation in which the product development project takes place, as well as the importance of information, which is determined by the goal of the project. The output of DMSM is a score for each of the identified methods that represent the appropriateness of the given method, based on the situation and goal(s) chosen by the designer. Suggestions are based on parameters that can easily be determined by designers without extensive experience within platform based product design. The case study demonstrates the effectiveness of DMSM.
This paper describes the influence of the length and thickness of the uncut chip on roughness of the finished surface using TiN- and (Al,Ti)N-coated tools, for dry and minimal quantity lubrication (MQL) systems in hobbing at different cutting speeds. Experiments were carried out to simulate hobbing by fly tool cutting on a milling machine. The following results were obtained: (1) For dry cutting at a cutting speed of 117m/min, low surface roughness was obtained for chip lengths of 15 to 25mm and thickness of 0.10 to 0.25mm, irrespective of the type of coatings. When the MQL system was used, low surface roughness could also be obtained with longer chip length. (2) When dry cutting was carried out at 159m/min, low surface roughness was obtained with the (Al,Ti)N-coated tool for chip lengths of 13 to 20mm and thickness of 0.09 to 0.18mm; these ranges were wider than those for the TiN-coated tool. For both types of tool, much narrower ranges were obtained with the MQL system. (3) Chatter vibration sometimes occurred under the cutting conditions used, and this is thought to be associated with regenerative chatter. The chatter vibration was found to be more severe in the case of the MQL system.
This paper presents the results of practical dry hobbing experiments performed on a traditional productive type of hobbing machine. The HSS (high speed steel) hobs with different combination of coat materials and coating states display significant variations in tool life. A TiN coating hob demonstrates the best cutting performance although the coating cost is the lowest. From these experimental results, two meaningful conclusions are obtained. One is some coat materials proper to HSS milling cutters are not always suitable for a HSS hob applied in dry hobbing. The other is that for a coated HSS hob, a cutting performance and tool life satisfactory to practical application is possible when using the hob to carry out dry hobbing on a general type of hobbing machine, if the coat film on the hob teeth is proper both in material and coating form.