Mid-range and long-range laser scanners are capture dense point-clouds from engineering facilities. The captured point-clouds can be converted to smooth mesh models by using streaming operations. In this paper, we discuss a solid modeling system based on large-scale mesh models. When an engineering facility is measured by a laser scanner, components are scanned only from the limited directions, and they may be partially occluded by other components. To construct solid models using such incomplete mesh models, we introduce modeling and editing operations based on the reflectance images, which can be generated from point-clouds. We also show how to generate 3D models of standard parts.

View full abstract

For the development of high-functional and complex mechatronics products, it is becoming necessary to manage the design process considering multi-domains such as electrical, mechanical and software specialties. However, at present, in the process of embedded software development, the software developers often have to spend their time and efforts by wasteful and unnecessary design iterations because that they don't understand the original requirements and previous designing intentions exactly. The authors predict that the mechanical designers in previous processes, don't describe the reasons, how to analyze and why to adoption technologies insufficiently. In this paper, the authors propose that the requirement model should be introduced in development process, because all designers can understand "what to make" precisely. In reference of the studies of various requirement definitions, especially object-oriented approach, the authors studied that the procedure of description in the requirement model, which is suitable for the development of high-functional and complex mechatronics products. An intelligent crane system is designed as an example to examine the possibilities of description using SysML. In conclusion, proposed requirement model is confirmed that it can surely describe the product requirement of the mechatronics product.

View full abstract

For the cooperative design activities by a design team, a designer needs design object information not only about geometrical data and these attributes but also the design rationale such as the reason of decision making to understand ideas of the design proposes by other designers. This paper focused on influential relations between parts of design object, and proposed descriptions and management methods of these relations. The management support system was developed, and case studies are done by using the system. As a result, the proposed method can support to manage the influential relations, and this also shows the proposed method have an applicable possibility to transmit design rationale to other designer.

View full abstract

This paper proposes a method of impact analysis of the design change from the initial design stage. In author's previous work, a hierarchical requirement model is proposed in order to define the requirement of the complex mechatronics product. The product requirement is decomposed into three aspects: mechanical, electrical, and software. A hierarchical functional structure is proposed to represent the functional component in each design layer. The states and actions is designed as an activity diagram, and decomposed into the activity diagram in the next design stage. A constraint diagram is proposed to assign behavior elements and technical specifications. A decomposition process of the states, actions, and values is visualized using dependency structure matrix. The design change propagation analysis is proposed based on matrix between components, object flows, states, actions, and values. The proposed method is developed as a proto-type system based on SysML specifications and using Rhapsody. An intelligent crane system is designed as an example. A design change of the required behavior and actions is tested. The design result indicated that the proposed method surely can provide an affected components, parameters, and technical specifications with the change of requirement behavior.

View full abstract

In manufacturing, systems that offer physical products in combination with services have been attracting much attention. For such systems, designers need to focus on customer requirements. There are, however, still difficulties in the decision on what part of the requirements should be investigated, especially in a B2B (Business to Business) service. This paper proposes a method to extract customer requirements in a B2B service. In addition, a tool was developed to help service designers extract customer requirements easily and exhaustively. The effectiveness of this method is demonstrated by a case study in which a utility company is the target client of a service.

View full abstract

The paper proposes an environmental taxation scheme using LCA, which can provide consumers with an incentive to choose vehicles with lower CO_2 emissions. This taxation scheme has two major measures: life cycle CO_2 emissions, and life cycle cost, considered not only in the utilisation phase but also in the manufacturing phase. The authors figure out the tax rate 28.05yen/kg-CO_2, which makes the hybrid electric vehicle's life cycle cost less than that of conventional gasoline vehicles, and is near the existing gasoline tax rates in Japan and Europe. The LCC of EVs becomes more effective with longer driving distances or a long lifetime, with this taxation. When the life-time distances is short at certain level, LCC of GVs are better than that of CEVs because of high CO_2 emission level in the manufacturing phase. The proposed tax system enables consumers themselves to choose the best option of CEVs, depending on their specific needs such as lifetime driving distance and lifetime use.

View full abstract

This paper discribes a new system for a curved shell plate forming which is usually regarded as a special skilled work in a shipyard. The system has a characteristic to support a workman be engaged in a shell plate forming by indicating the logical way where to perform a press or a gas heating. The system adopts a new method for developing a curved shell plate to its appropriate flat plate by using geometric curvature lines found on the curved shell plate. This method has been translated as a software system, and has been introduced in a production lines by a one of the major Japanese shipyard. The system shows a good performance for an improvement of time consuming and an accuracy of a curved shell plate forming, according to the results of data calculated in the factory. Also, this paper introduces an example of application of the system to other works for a ship construction.

View full abstract

Escalators run by chain drive, and the chain, which is wound up as a polygon inscribed in the sprocket, causes speed pulsation due to its geometric motion on the sprocket. If the number of teeth on the sprocket is fewer, the speed pulsation will be large. It is obvious that the number of teeth decreases in the following two cases, one is the case when we make the diameter of the sprocket smaller to reduce the space, the others is the case when we make the chain link larger to reduce the cost. In these cases, the pulsation in the chain will be large and it will make a rider uncomfortable significantly. This paper explains a new drive mechanism to suppress the speed pulsation, which in the method adding fixed rail which can achieve optimal trajectory against the chain roller. The mechanical design of the new system is investigated by kinematics analysis, and experiment results with prototype shows its validity.

View full abstract

Aerodynamic characteristics of a reusable observation vehicle are computationally investigated under subsonic and supersonic flight conditions as a preliminary study for the concept design using a design exploration method and a light CFD tool. The results show that the simulations with a coarse grid can accurately estimate the aerodynamic characteristics like axial force coefficient and the lift to drag ratio. The results of the aerodynamic shape exploration indicate tradeoff information among objective functions, and the correlation between design variables and objective functions. The preliminary knowledge for the aerodynamic shape design is obtaind.

View full abstract

In this paper, Differential Evolution (DE) is examined through two aspects. Thus, one is the meta-heuristics, and the other is the global optimization technique. It is said that DE is the global optimization technique, and also belongs to the meta-huristics. Indeed, DE can find the global minimum through numerical experiments. However, there are no proofs and useful examinations with respect to such comments. In this paper, DE is compared with the Generalized Random Tunneling Algorithm (GRTA) and the Particle Swarm Optimization (PSO), that are the global optimization techniques. Through the examination, some common characteristics as the global optimization technique are clarified in this paper. In addition, the difference of the neighborhood between DE and PSO is clarified. As the result, DE is possible to belong to the global optimization techniques. Additionally, DE is also examined as the meta-heuristics. Through benchmark test problems, the search ability of DE as the global optimization technique is examined.

View full abstract

This paper proposes a hierarchical optimization-based approach for two-dimensional rectangular layout design problems by combining decomposition-based optimization and evolutionary algorithms toward solving complicated layout design problems. The Pareto optimality of subsystem-level layout against the optimality of system-level one is extracted through two-level hierarchical formulation as a prerequisite. In the approach, the layout topology is represneted with sequence-pair and the shape of each subsystem or component with aspect ratio. They are optimized with genetic algorithms, while the Pareto optimality of sub-levels is handled with multi-objective genetic algorithms. Top-level and sub-level layout problems are coordinated through exchange of preferable ranges of shapes and layout. An implemented approach is applied to an example problem for demonstrating its performance and capability.

View full abstract

This paper proposes a new tooling system for forming end shells of aluminum beverage cans to improve panel wall thinning. Shell forming simulations are then performed to investigate the effective factors on forming quality using the finite element method. The structural optimization technoloygy based on numerical simulations is finally applied to search optimum design points of the new tooling system. Optimization results show that panel wall thinning of end shell can be improved 7.4% by the design optimization of forming processes and tool profiles in the new tooling system, as compared with the base line model of conventional tooling system. It is also confirmed that the end shell formed by the new tooling system has higher buckling strength under internal pressure.

View full abstract

Relaxation, fluctuation and surface irregularities of a famous artist's bowl and other objects were evaluated with an analytical procedure developed by applying "fractal" concepts and the "Richardson effect". Important results of this study can be summarized as follows. (1) An analytical system using a scanning laser microscope system was developed to evaluate the irregular surface of fluctuation quantitatively; an analytical procedure to develop the "mesh method" was established. (2) Irregular surfaces in micro areas of the analyzed objects have a fractal nature: (a) a famous artist's bowl, (b) an original work bowl, (c) an original work cup, and (d) a Japanese teacup. (3) The famous artist's bowl has a fractal nature and relative "self-similarity" over wide analytical ranges. (4) Fractal dimensions and the nature of relaxation were connected as range of D=2.3 to 2.6. This value is widely useful for application to the design of a mechanical structure in later studies.

View full abstract

We proposed optical fibers with antireflective subwavelength-grating (SWG) structures and their fabrication method using a nanoimprinting technique. Antireflective coatings on optical fiber end faces are essential optical components to couple efficiently the light with the optical fiber. Because commercially available nanoimprinting machines are designed to press two plates set parallel to each other, it is difficult to set a flexible and long optical fiber in the nanoimprinting machine, and to press the optical fiber end face to a mold. In this paper, we developed a novel nanoimprinting machine to press an optical fiber end face to a plate of mold. Using the developed machine, antireflective SWGs with the periods of 150nm were fabricated on the end faces of plastic optical fibers. A silicon SWG with 150nm period and 348nm height was used as a mold. Reflectance and transmittance of the SWGs were measured and compared with that of a flat end face of a plastic optical fiber.

View full abstract

This paper proposes a kind of feature extraction based efficient registration algorithm including coarse to fine registrations. During coarse registration, a very fast feature extraction method is present. Then an initial estimate for relative rigid-body transform can be brought to realization, through matching these regions with eigenvectors of covariance matrix of feature-closed point clouds, During coarse registration, a new fine registration method will be present in this paper based Iterative Closest Point (ICP) algorithm which had been used in fine registration to align view pairs after the coarse registration. Experimental results of 3D images taken by laser scanner are carried out to compare the convergence and registration result. The proposed registration approach can realize automatic registration without any assumptions about their initial positions, and can overcome the problems of traditional ICP in low overlapping and bad initial estimate. The proposed feature extraction based ICP algorithm and measure procedure management provides an efficient 3D modeling for computer-aided engineering and computer-aided design.

View full abstract

Spacecraft inside a fairing experiences severe high-level random acoustic loads during its launch. To confirm that the spacecraft structures and equipment withstand the launch environment, ground acoustic test is performed in the process of design. Spacecraft is exposed to a diffuse sound field in a large reverberant room during ground acoustic test. On the other hand, spacecraft, especially that has a narrow clearance between spacecraft exterior panel and fairing wall, is exposed to the standing wave sound field, which is called 'Fill Effect', instde a fairing during launch. Fill effect has been identified for these few decades, but there have been few reports to discuss the vibration response of a spacecraft induced by the fill effect. In this paper, the simplified approach is proposed to compare the vibration response of a spacecraft induced by standing wave sound field with the one by diffuse sound field. This approach can be dedicated to the desigh of a spacecraft which may be exposed to severe fill effect. One analysis example of a plate structure under these two sound fields is shown.

View full abstract

We are surrounded by various sounds like the sound of the car, train, rain and all that in our daily life. It might become feelings very relieved, and come to want to prevent our ear unpleasantly at times. Then, it is thought that it is possible to pursue comfort of the specific sound source like an artificial machine noise by evaluating emotion caused by the sound. There are two methods of evaluating emotion. One is the subjective evaluation like the semantic differential method and the other is the objective evaluation method using biological information, such as electroencephalogram and electrocardiogram. And, a latter method is more certain and quantitative. This study establishes the method for quantitatively evaluating the comfort by measuring electroencephalogram. Then, an objective evaluation to an environmental sound is evaluated by this method.

View full abstract

For the past several years, seismic isolation systems have been focused in the seismic design of industrial facilities. This paper deals with the response reduction effect by friction. Friction is expected to decrease the relative displacement by dissipating the vibration energy. The relative displacement between structure and support becomes larger at long period in the case of linear system. Therefore, the response reduction effect by friction should be utilized positively in the seismic design. However, the response magnification of acceleration is used in the seismic design. The acceleration becomes larger by stick and slip motion. Therefore, the response reduction effect by friction is evaluated. In the past studies, the acceleration of earthquake for horizontal direction was used to obtain the maximum acceleration response. And the response reduction effect was evaluated for horizontal direction. However, the friction force depends on the vertical drag acting on the friction surface. The friction force varies by the vertical acceleration of the earthquake. Therefore, the acceleration response spectrum for seismic design should be proposed considering the vertical acceleration. In this paper, the effect of the vertical acceleration in friction response spectrum is suggested. At first in this study, the characteristics of actual earthquake wave such as maximum acceleration, correlation coefficient and peak frequency is shown. Next, the effect of vertical acceleration of actual earthquake is shown. In the last, the response reduction effect by vertical acceleration of the artificial earthquake wave calculated from the design spectrum is shown.

View full abstract

This paper presents the theoretical method to predict the propagation of structure-borne sound of fluid-loaded structure by using Statistical Energy Analysis (SEA). The effects of fluid on sound transmission are considered as the change of mode number and the increase of internal loss factor of fluid-loaded elements in the specified frequency range of SEA model. The complex-valued added mass is used to describe the fluid loaded effect and the sound pressure propagation to the adjacent plate in the fluid is evaluated as the change of transmission coefficient at L and X-type junction consisting of fluid-loaded plates. These analytical procedures are applied to determine the vibration energy transmission in the plate structure containing the water tank. The calculated results agrees well with the measured one and the availability of this method is confirmed.

View full abstract

A set of new boundary integral equations relating the sensitivity coefficients of sound pressure and its normal derivative is presented for three-dimensional acoustic problems based on the direct differentiation method. A linear combination of the derived boundary integral equations is used to avoid divergent, erroneous numerical results around the fictitious eigenfrequencies which are observed for exterior acoustic fields. The boundary integral equations have strongly-singular and hypersingular boundary integrals, and are evaluated as principal values and finite-parts for trianglular constant element discretization. The present formulation is more efficiently used for the fast multipole boundary element method than the conventional one which is based on the regularization, because multipole expansion formulas and other translation formulas have to be implemented also for the fundamental solution of the Laplace's equation for the conventional formulation. The effectiveness of the method based on the present formulation is demonstrated through a numerical test example for an exterior acoustic field.

View full abstract

We verified through experimentation on five carts connected in series by four springs a control method for always efficiently exciting a multi-degree-of-freedom system at a resonance frequency. When an excitation point corresponds to a vibration detection point in a multi-degree-of-freedom system, a phase lag at a resonance frequency and a phase lead at an anti-resonance frequency alternately appear in the vibration characteristics, and the phase lag is 90° at all resonance frequencies. Therefore, if a controller with a 90° phase lag and a constant gain in a wide frequency range is used, self-excited vibration is generated at all resonance frequencies. The local feedback controller for each actuator consists of a self-excited vibration controller that is the sum of the integral control of the displacement and the positive velocity feedback control, a saturation element that limits excitation force, and a negative velocity feedback controller that provides active damping. We used a four-degree-of-freedom system consisting of five carts and four springs in our experiment. Four voice coil motors controlled by the local feedback were used to generate self-excited vibration at all the resonance frequencies of a four-degree-of-freedom system. The self-excited vibration mode can be freely switched on by changing the frequency of the sine wave that is added as an electric disturbance. A system using many actuators with local feedback control, i.e., decentralized control, driven at a resonance frequency is excellent in its adaptability to the environment, in its extendibility, and in its fault tolerance.

View full abstract

This paper describes a new type of magnetic suspension system using a rotary geared motor and a disk magnet. In this suspension system, the suspension force is provided by a disk-type permanent magnet and is controlled by a magnetic flux path control mechanism, which rotates the disk magnet to change the flux passing through the suspended object. This suspension system may realize zero attractive force to avoid the uncontrollable adhesion, changing the polarity of the stator poles for complex applications, and zero-power levitation with the constant air gap. In this paper, suspension principle and the experimental prototype of this proposed system are introduced, the basic experiments using the prototype are examined, and the modeling and simulation are carried out. Finally, some suspension experiments for verifying the suspension performance are executed.

View full abstract

The accelerometers are widely used as vibration feedback sensors in the fields of large-space structures and semiconductor manufacturing equipments. It is preferable that the velocity and displacement signals can be additionally used in order to apply the direct acceleration, velocity, and displacement feedback called DAVDFB. Then, the absolute displacement sensor, which can simultaneously detect the 3 kinds of signals from its stable closed loops, has been proposed, and expected to use as a vibration sensor instead of the accelerometer. However, the proposed sensor has characteristic's dispersion because of its mechanical system. The dispersion, which disturbs the sensor's mass production and the characteristic's conformance, is improved to verify the pole and zero sensitivities in this paper. The results are compared with the simulation and actual experiment.

View full abstract

In this paper, we describe a thermal control of a thermoelectric cooler/heater with Peltier device which is operated by the Peltier Effect. Generally, it is said that the thermal control with Peltier device is difficult because of its nonlineariry. In order to deal with the nonlinearity, we use nonlinear model predictive control for the thermal control of the device. A nonlinear model of the thermal system with Peltier device is derived. The validity of the model is evaluated by comparison with the experimental results. Nonlinear model predictive control system is designed based on the model. Recursive Kalman filter is designed to estimate the unobservable state variables. The experimental results show the accurate control performance. The robustness against themal load is also verified by the experiments.

View full abstract

This paper describes a theoretical investigation for a traveling mode state of turbine blade with one-ringed blade and grouped blade structures (compound periodic structure) when subjected to engine order excitation. In addition, a series of experiments with a simple blade model is performed by simulating engine order excitation under a non-rotating condition. Ceramic oscillators are attached to all the blades. Each blade is excited by a sinusoidal wave with an inter-blade phase angle corresponding to the traveling mode. As a result, traveling mode of the compound periodic structure was confirmed. All of nodal diameter components in a natural mode behave traveling mode when a natural mode is excited to resonance by engine order excitation. The nodal diameter in which the biggest response is not necessarily correspond to the harmonic excitation order.

View full abstract

In order to apply failure diagnosis of a rotating machine, normal and abnormal vibrations of a rolling-element bearing were formulated by using Hertzian contact theory. In this paper, two dimensional dynamics of a rolling-element bearing were formulated and bearing defects were classified to the three types of impulse train. By using these formulations, some numerical examples were conducted to clarify characteristics of bearing vibrations. In the result, it was found that vibration of vertical force at an outer ring has one eigen frequency and the eigen frequency does not change largely by rotating speed and presence of a defect. Using these characteristics, the new method of failure detection was applied to the rotating machine at low speed.

View full abstract

The magnetic damping force of a typical magnetic damper is caused by magnetic flux densities perpendicular to the relative motion between a magnet and a conducting plate. Also, it is known that a magnetic damper is composed of a columnar magnet and a circular coil instead of a conducting plate, and the magnetic damping force generates when the magnet moves in the axial direction of the coil. In this paper, we created newly the magnetic damper consisting of a circular coil and a columnar magnet, and conducted the experiments and the modeling of the magnetic damping force. As a result, it becomes clear that the spatial variation of the magnetic flux density in the axial direction causes the magnetic damping force. Moreover, using the equation of continuity, the axial magnetic flux can be derived from the radial magnetic flux. Consequently, the analytical results agree well with the experimental results.

View full abstract

Free vibrations of the clamped circular laminated plates containing multiple disk-shaped delaminations with different sizes are analyzed on the basis of the theory of small deflection of plates. Embedded circular delaminations are placed at the plate center and the basic assumption is that the delaminated layers are contacting one another. The equations of motion are solved by neglecting the in-plane displacements of the reference-surface and by modeling the crack part as two lapped discs hinged at the edge. Analyses and experiments are carried out for the effect of size difference of the delaminations on the natural frequencies. Theoretical and experimental results agree well, which validates the analytical model assumed in the present study.

View full abstract

Analytical results are presented on geometrical nonlinear deformation of a simplified load cell with double-layered cantilever beams. The double cantilever beams are clamped at the base ends and are connected to a rigid block at the top ends. The beams have excellent characteristics on the large output of strain to the small deformation by lateral loading. However, increasing the load intensity, output of strain shows nonlinearity due to the coupling between deflection and axial deformation of the beam. It is very important for the load cell to be with less of nonlinearity. Based on the nonlinear governing equation, analytical results are derived under the concentrated load acting on the rigid block of finite lengths. The direction of the load is perpendicular to the beam axis. The characteristics of nonlinear restoring force and deformed configuration of the beams are revealed under concentrated load. The generated strain to the load is also calculated. Furthermore, to inspect characteristics as an accelerometer with double cantilever beams, dynamic responses, under periodic acceleration are calculated with numerical integration on an assumption of a single degree of freedom system. It is found that the restoring force of the load cell shows nonlinear characteristics with the type of a softening spring. When the position of loading is closer to the top end of the beam and the distance between the two beams is larger, characteristic of linear relation is improved. Dynamic characteristics of amplitude-gain to the excitation frequency are constant in wide range under the lowest natural frequency. However, the super harmonic resonant response of the third order is generated at lower small region of frequency.

View full abstract

In this paper, we investigate the parameterization of all robust stabilizing modified repetitive controllers for time-delay plants. The repetitive control system is a type of servo mechanism designed for a periodic reference input. When repetitive control design methods are applied to real plants, the influence of uncertainties in the plant must be considered. In some cases, the uncertainties in the plant make the repetitive control system unstable, even though the controller was designed to stabilize the nominal plant. The stability problem with uncertainty is known as the robust stability problem. Several papers to design robust stabilizing repetitive control systems have been published. However, the parameterization of all robust stabilizing repetitive controllers for time-delay plants has not been considered. In this paper, we propose the parameterization of all robust stabilizing modified repetitive controllers for time-delay plants.

View full abstract

Casting motion, an up-and-down rotation of a rod, is one of the motions using the dynamics of a pendulum under gravity. This report examines the property of the casting motion using a simple system that consists of a rigid rod and a point mass pendulum. The rigid rod rotates around one end by an actuator, while the point mass pendulum can rotate freely around the other end of the rod. The rotational motion of the rigid rod is determined as polynomial function of time. Calculated results demonstrate that there is an optimal landing position of a mass that minimizes the landing velocity. Experimental study is also performed to verify the validity of the analytical model. The experimental results agree with the calculated results.

View full abstract

This paper presents a theoretical study on the directional stability of multi-articulated vehicles with multiple axles. The vehicle dynamics model is derived in the horizontal plane having degrees of freedom of vehicle side-slipping and yawing. For an equal vertical load of each axle as well as a similar cornering coefficient of each tire in each of the multiple axles, the equations of motion can be reduced to ones with a singular axle and additional terms that are functions of the numbers of axles and the distances between them. Two types of tractor and double-trailer combinations with multiple axles are examined with regard to straight running stability as well as steering sensitivity in steady-state turning. Non-oscillatory stability incorporating steering sensitivity is analyzed using the stability factor of multiple-axle vehicle combinations. A parameter study of oscillatory stability and steering sensitivity is conducted, and the following conclusions are drawn. (1) The terms on multiple axles are added in the tractor yawing moment and part of the trailer yawing moment. (2) Multiple-axle vehicles vary in non-oscillatory stability and steering sensitivity from single-axle vehicles. (3) A multiple-axle dolly improves oscillatory stability.

View full abstract

A pressure-sensitive paint (PSP) measurement technique is a non-contact optical method based on the oxygen quenching of its luminescence. By using PSP, we measured the pressure distribution on the disk in a hard disk drive, which is difficult to measure by conventional contact methods such as pressure taps. In the PSP measurement, we have to take the temperature non-uniformity on the rotating disk into consideration because the temperature distribution causes measuring error. We employed pyrene sulfonic acid (PySO_3H) as a luminophore of PSP, which has small temperature dependency at appropriate wavelength of the luminescence, and successfully obtained the pressure distribution on the disk rotated at various speeds (10000-20000rpm). The result showed that the pressure is higher at the disk outside than at the center, and forms a concentric circle distribution. In addition, we found that the pressure difference between the inner and outer region of the disk increases as a square of disk rotation speed and a decrease in the distance between the co-rotating adjacent disks.

View full abstract

A liquid packaging machine produces liquid packaging bags by controlling a vertical seal roll, a horizontal seal roll, a cut roll cooperatively. These rolls are driven by servomotors separately as a multi-axis servo mechanism. In this paper we propose two control methods to enable the high speed production. One is two-steps velocity control of the horizontal seal roll. This method enables continuous production of bags of arbitrary size. Second is a phase control which determines the cut position on a film accurately according to the seal position. The phase control changes the rotary phase difference between the horizontal seal roll and the cut roll by adjusting the high feeding velocity of the cut roll. Experimental results using the liquid packaging machine showed the effectiveness of the proposed control methods.

View full abstract

Recently, microfabrication tools have been utilized to quantify the role of the cellular microenvironment on cell activity and function. Improving tissue regeneration by cell culture on scaffold material will also require tools to control cellular organization in 3-dimentional (3-D) condition. Our objective was to improve cartilage tissue engineering using 3-D cell organization technology. In this study, we developed an anisotropic cartilaginous tissue by cell patterning within hydrogel slabs using dielectrophoretic (DEP) forces. Our data indicate that the embedded chondrocytes remained viable and reconstructed cartilaginous tissue along the patterned cell array. In conclusion, DEP cell patterning may become a useful approach for reconstructing anisotropic structure in cartilage regeneration.

View full abstract

In this paper, we propose a mechanism which is named "gravity canceled flexible joint," since a passive flexible joint attracts attention by its collision safety. Manipulators with a passive flexible joint are expected to work in a human environment. However, manipulators with the passive flexible joint have some problems. One is that there is steady position error because of displacement of flexible joints by self-weight. Moreover, the manipulator power and the back drivable range are reduced by self-weight. Mechanical self-weight compensation become efficient for overcoming this problem. Therefore, this paper proposes the passive flexible joint with self-weight compensation mechanism that equips the features with compactness and durability. In order to satisfy these requirements, this research focuses on a end cam. By using the end cam, nonlinear rotational spring is able to design from determining a pressure angle of end cam. Both the self-weight compensation and the passive flexibility are achieved by end cams. From position control experiments, it is clarified that the proposed mechanism can compensate steady position error and showed utility as a joint mechanism.

View full abstract

In this research, an upper-limb motion restrictive orthosis was developed to prevent nasogastric tube self-withdrawal which happens frequently on nursing field. While these functional orthosis were necessary to ensure the safety of patients, sometimes it causes problems that physical harm and mental harm. One of the factors that cause these negative effects is an excessive restriction of patients. Therefore, this paper proposed a new functional orthosis which prevents fingertip's attainment to the nose with minimum operation limit, by controlling the maximum elbow-bending angle according to the shoulder-bending angle. This effect can be expected to prevent nasogastric tube self-withdrawal without excessive restriction. They are associated with the intermittent stopper with a fabric belt. By measuring myoelectric potentials and the range of motion, achievement of upper-limb motion control around the nose and decrease in restrained area was confirmed. From these results, it was shown that the nasogastric tube self-withdrawal was prevented using the orthosis. Consequently, it was clarified that the developed orthosis enabled the stress-free upper-limb motion control without excessive restriction in comparison of conventional physical restrains.

View full abstract

This paper proposes a polyarticular tendon drive system to simulate variable stiffness of human finger. The stiffness of a human finger contributes to ensure stability of a grasping object and dexterous of human finger and then an exoskeleton assistive hand should have the same property of human finger stiffness for safe and agreeable support. The stiffness of the finger in orthogonal direction to a grasping force increases as the grasping force increases, when human pinches an object with his index finger and thumb. Besides, the stiffness is not sensitive to direction of a fingertip displacement when an external force affects to the fingertip. Through numerical simulations and experiments, it is confirmed that our proposed polyarticular tendon drive system has the similar stiffness properties to the stiffness of human finger.

View full abstract

This paper proposes a novel bending technique with a screw drive mechanism, which enables omni-directional bending motion by rotating two linkages, each consisting of a right-handed screw, a universal joint and a left-handed screw. We call this mechanism as double-screw-drive (DSD) mechanism. The DSD mechanism was applied to a robotic forceps manipulator for laparoscopic surgery. The DSD mechanism has three linkages, and opening and closing motions of a gripper are attained by rotating a third linkage. The developed DSD forceps manipulator realizes bending motion without using wires. Therefore, it has high rigidity, and it can bend 90 degrees in any arbitrary direction. Furthermore, in order to control the DSD forceps as a teleoperation system, joystick type manipulator was built and servo systems were constructed. Tracking control experimrnts as well as a lifting experiment for a pig's liver were executed. Experimental results showed that the required design specifications were fulfilled. Thus, the viability of the DSD forceps was demonstrated.

View full abstract

Wall-climbing robots can be used for various dangerous works such as painting, inspecting and cleaning of vertical walls instead of human workers. The typical wall-climbing robots use a magnet or a vacuum suction device for travelling on the vertical wall. For a reliable and an efficient work, the robots should follow a desired path accurately. However, gravitational effect makes lower the performance of the trajectory control for the case of travelling on the vertical wall. In this paper, a trajectory tracking control law for a skid steer type wall-climbing robot is proposed considering the gravitational effect. The control law is a non-linear feedback one with compensation of gravity and wheels' rolling resistance. It is shown that a tracking error converges to zero using Lyapunov method. A window cleaning robot is used for an experiment of the trajectory tracking control. The experimental results confirm the validity of the proposed control method.

View full abstract

It is difficult to stabilize the three dimensional biped passive walker in various environments because the range of the initial conditions for stable walk is narrow. In this study, a three dimensional biped passive walker was newly designed as a passive walk platform in order to make the success rate of the passive walk high. A new control method that would be able to stabilize the passive walker by using a mechanical oscillator was examined. The target path of the oscillator was generated by utilizing the frequency entrainment in order to synchronize the oscillator movement with the changing motion of the stance leg in the frontal plane. Stability of this passive walker was analytically examined by limit cycle of the frontal movement. A period of the changing motion of the stance leg was synchronized with the period of the swing leg by periodic input generated by the mechanical oscillator. It was demonstrated that the passive walker was stabilized when a frontal motion period was synchronized with a swing leg period in various slope angles. Consequently, it was experimentally examined that the passive walker could be stabilized on various slopes and flat floor.

View full abstract

In order to analyze the behavior of a railway vehicle that is subjected to crosswind in more detail, we constructed a simulation program applying a full-vehicle model as developed based on a half-vehicle model. Further, we examined the effect of yawing moment induced by crosswind and that of static wheel load imbalance on overturning or wheel unloading ratio. First, we verified the validity of the simulation program by comparing the data as acquired through the full scale experiment applying lateral force to the vehicle dynamically or the wind tunnel test using a reduced model. As a result, it has been verified that the simulation program is valid for evaluating the wheel load variation of the vehicle. Secondly, using the full-vehicle simulation program, we examined the effects those not considered in the half-vehicle model on overturning or wheel unloading ratio. As a result, it has been revealed that the wheel unloading ratio takes a maximum value when the yawing moment is zero. It has also been apparent that when we consider the relationship between the wind speed and the wheel unloading ratio or overturning, it is imperative to evaluate the wheel unloading ratio as averaged through the vehicle nevertheless the static wheel load imbalance of each axle. Consequently, by using the full-vehicle simulation program, we can analyze the behavior of the railway vehicle as subjected to crosswind or can evaluate the critical wind speed of overturning more precisely. In addition, we can also evaluate quantitatively the difference between the results by the full-vehicle model and by the former half-vehicle one.

View full abstract

In this investigation, hunting stability of an independently rotating wheelset (IRW) with inverted tread conicity is discussed. To this end, equations of motion of IRW with inverted tread conicity are derived and used for the stability analysis. It is demonstrated that unstable hunting motion occurs in this type of wheelset and the hunting frequency decreases as the speed increases, which is totally different characteristics from those of the conventional wheelset. The cause of such unique vibration characteristics is investigated from an energy point of view, and the effect of coupling terms associated with the wheel/rail creep forces on the stability of the hunting motion is discussed using the equations of motion in a block diagram form. Furthermore, it is presented that the hunting motion can be stabilized by adequate choices of primary suspensions and the absolute stability condition is theoretically derived for a single suspended IRW with inverted tread conicity.

View full abstract

We conducted full scale experiment to verify the function of anti-derailing guard rails to prevent the derailments due to large earthquakes. The experiment was arranged to simulate the vehicle/track conditions of Tokaido Shinkansen by using the bolsterless bogie and the track materials both presently in use for Tokaido Shinkansen. Large excitations enough to derail the test vehicle were given in order to make clear the function and effect of anti-derailing guard rails. We obtained the following results. (1) The guard rails worked effectively to prevent rocking derailment by holding the lateral motion of derailing wheel-set. (2) Effective work of guard rails was verified in total 34 test cases of sine wave excitations of the frequency range from 1.1Hz to 1.5Hz. (3) Also effective work of guard rails was verified by using the excitation of Tokai Earthquake. (4) Compared with horizontal ground motion, vertical ground motion of earthquake had smaller influence on the derailment mechanism.

View full abstract

This paper proposes a representation model of the quality state change in an assembly process that can be used in a computer-aided process design system. In order to formalize the state change of the manufacturing quality in the assembly process, the functions, operations, and quality changes in the assembly process are represented as a network model that can simulate discrete events. This paper also develops a design method for the assembly process. The design method calculates the space of quality state change and outputs a better assembly process (better operations and better sequences) that can be used to obtain the intended quality state of the final product. A computational redesigning algorithm of the assembly process that considers the manufacturing quality is developed. The proposed method can be used to design an improved manufacturing process by simulating the quality state change. A prototype system for planning an assembly process is implemented and applied to the design of an auto-breaker assembly process. The result of the design example indicates that the proposed assembly process planning method outputs a better manufacturing scenario based on the simulation of the quality state change.

View full abstract

Since the coercive force of ferromagnetic materials locally increases with the residual stress due to plastic deformation, we can evaluate the damage to a cutting tool made of cemented carbide, that containing ferromagnetic Co binder, from the distribution of residual magnetization after magnetization and multistage demagnetization. The distributions of coercive force and residual stress on a cemented carbide tool, obtained from the X-ray analysis, are found to be consistent with each other. The sintering stress and cutting resistance of the tool can estimated from its coercive force distribution. Near the cutting edge, the residual stress rapidly change from compression to tension, which indicates the relaxation of sintering stress against the machining force after reaching a stable state. Afterwards rapid change in the stress into compression over again indicates the cracking of the tool. We can detect the failure of the cutting tool from the sudden change in coercive force, before serious damage.

View full abstract

In recent years, complicated shapes have been required to be machined at a shorter time. Machine tools have become highly accurate and had multifunction as well as the development of CAD/CAM systems. However, there exist a lot of things difficult or impossible to create even by multi-axis control CNC machine tools. Most of them are made by skilled persons of ingenuity and device. In the future, it is predicted that consumer needs are getting more various and that consumers require individual goods matching for their feeling. The study presents the first trial of creating an artistic workpiece by use of a multi-tasking machine tool. Such a machining technology may be called "Dexterous Machining". As an example, a chain-shaped workpieces are selected, which cannot usually be machined in the conventional manner. Thus, a special type CAM system is developed, taking account of the interference between a cutting tool and a workpiece, and by use of the second main spindle. As a result, it is found that the developed CAM system has the potential of realizing Dexterous Machining.

View full abstract

In the cutting processes, improvement of anti-adhesive effect and wear resistance of cutting tools are strongly required for increasing the tool life. Then our previous researches proposed and developed cutting tools with nano/micro-textured surfaces to determine the role of the textured surfaces in a) retaining cutting fluid, and b) reducing the actual contact area between the tool and chip. In actual, these effects led to increase lubricity on the tool surface and achieve the high anti-adhesive effect in cutting of aluminum-alloys. In this study, the previously developed tool with nano/micro-textured surface was applied to cutting of steel materials (S53C) in the hopes of improving the wear resistance and it was found that the serious problem relating to the wear remains. Therefore, the TiAIN-coated cutting tool with periodical stripe grooves was newly developed to overcome the above-mentioned problem. And it was revealed that the new texture and the coating on the tool surface reduce the tool wear significantly from a series of face milling experiments for steel material.

View full abstract

A truing technique for an electroformed diamond tool with a mesh size of #1000 that can fabricate a flat and smooth tip of diamond grains on a hemispherical wheel working surface was developed to adapt the tool to the nanometer grinding of a cemented carbide. A truing test using a polycrystalline diamond disk with a primary diamond grain size of 1μm as a truer was conducted by varying the contact load between the tool and the truer, the setting depth of cut, the grain size in the diamond slurry used as a grinding fluid and the number of traverses in no-cut grinding carried out after reaching the total wheel depth of cut. It was verified through the truing test that 51% of diamond grains on a hemispherical wheel working surface could be made flat and smooth, and that 76% of grains could be made flat by adding flattened grains with tiny cracks when the contact load, the setting depth of cut, the grain size in the diamond slurry and the number of traverses in no-cut grinding were set at 5.2N, 9μm, 0-1, and 10 times, respectively.

View full abstract