A tensile test system for isolated cytoskeletal filaments, which enables to control strain rate, was newly designed. A pair of piezo-driven cantilevers were used to manipulate the specimen and to measure tensile load from the deflection of one of the cantilevers. The displacements of the cantilevers were optically and electrically detected. The specimen strain, determined from the cantilever displacements, was used as a feedback signal. We proposed a servo-system for strain rate control in which a desired path for the strain transition was designated. The path was chosen as a triangular-shape waveform against time, along which the strain rate is kept constant. We measured tensile properties of a single stress fiber isolated from a smooth muscle cell with this system to obtain a stretching stiffness of 45nN per strain. Performance evaluation and the tensile test demonstrated that the system enabled to carry out strain rate-controlled tensile test.

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Prestin is a motor protein responsible for the outer hair cell (OHC) electromotility which amplifies the vibration of the organ of Corti in the inner ear. Identification of the functional significance of particular amino acids is necessary to characterize prestin. In this study, an attempt was made to clarify the role of the GTSRH sequence at positions 127-131 in prestin conserved in six proteins of the solute carrier (SLC) 26 family of which prestin is a member. To elucidate what role that sequence plays in the characteristics of prestin, mutations were introduced into the sequence and the characteristics of the constructed point mutants were investigated by Western blotting, immunofluorescence experiments and the whole-cell patch-clamp technique. The localization of T128A was altered, the anion transport function of H131A and that of S129T were lost and such functions of G127A, T128A, S129A and R130A declined. These results suggest that the GTSRH sequence plays an important role in the localization of prestin, as well as in its anion transport function.

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We observed cell shortening and dynamic changes of actin filaments during detachment from the substrate by using a thermoresponsive-gelatin. The thermoresponsive-gelatin, a mixture of the poly(N-isopropylacrylamide) grafted gelatin (PNIPAAm-grafted-gelatin) and PNIPAAm, was coated on the glass bottom culture dishes. Rat aortic smooth muscle cells (SMC) expressed GFP-actin were cultured on the thermoresponsive-gelatin-coated dishes filled with serum free Dulbecco’s Modified Eagle’s medium (DMEM) or Ca^{2 +} -Mg^{2 +} -free Hank’s balanced salt solution (HBSS(-)). They adhered normally at 37°C, and became shortened and detached from the dishes when the ambient temperature was dropped below 34°C due to melting of the gelatin substrate. The shortening of SMCs was larger in DMEM (51.0 ±3.0%, mean ± SEM, n=14) than in HBSS(-) (35.8 ±3.6%, n=14). Actin filaments remained straight during detachment in HBSS(-), while in DMEM, they locally concentrated and disappeared at cell periphery. The shortening of SMCs upon detachment from ordinary plastic culture dishes by trypsinization was more than for both media. No significant difference was observed between the two, indicating detrimental effects of the trypsin. The present method was useful to study the cell contraction and the actin filament behavior during cell detachment for this causes minimal damage to cells.

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Endothelial cells lining the inner surface of blood vessels regulate the exchange of molecules between the blood and the vessel wall. This study investigates the effect of long-term shear stress on macromolecule permeability across endothelial monolayers. In vitro system to measure transendothelial permeability to tetramethylrhodamine conjugated albumin under shear stress was developed. The temporal variation in albumin permeability under 1Pa and 4Pa over 48h was quantified using a fluorescence spectrophotometer. At 4Pa, albumin permeability did not show a statistical significant change over 48h. Under shear stress of 1Pa, the average albumin permeability between 12 and 30h was 2.5-fold higher than the average between 0 and 6h. Under shear stress of 1Pa, the average albumin permeability between 36 and 48h was 1.8-fold higher than the average between 12 and 30h. These results show that both the magnitude of, and the length of exposure to, shear stress regulate transendothelial permeability.

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We report successful design, fabrication and testing of a novel lamination micro mixer to be integrated in the micro-scale immunomagnetic cell sorter (µ-IMCS), which should be a key device for clinical applications of regenerative medicine. This paper covers, (i) the concept of µ-IMCS, (ii) design and fabrication of lamination mixer using MEMS technologies, (iii) numerical analysis for the evaluation of the mixer performance, and (iv) experimental evaluation of target cell capturing with the present micro mixer. In order to reduce the sedimentation loss of the cells and the magnetic beads, the conduits in the mixer are designed in such a way that the stream is turned over 180degree. It is found in the CFD analysis that the present lamination mixer realizes better mixing and lower sedimentation loss than the one without rotation in the previous study. Experiments reveal that the cell capture rate is (i) increased by up to 8.6 times compared with that in a straight channel, and (ii) decreased with decreasing the residence time. It is also demonstrated in a preliminary experiment that CD31 expressions of HUVEC and hMSC obtained with the present micro mixer are in good agreement with the data obtained with a conventional cell sorting system. Therefore, the present mixer should be a viable component in a µ-IMCS.

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The effects of a shear flow on the uptake of fluorescence-labeled low-density lipoprotein (DiI-LDL), acetylated LDL (DiI-Ac-LDL), and lucifer yellow (LY; a tracer of fluid-phase endocytosis) by cultured bovine aortic ECs were studied using a rotating-disk shearing apparatus. It was found that 2hours’ exposure of ECs to a laminar shear flow that imposed ECs an area-mean shear stress of 10dynes/cm² caused an increase in the uptake of DiI-LDL and LY. By contrast, the uptake of DiI-Ac-LDL was decreased by exposure of the ECs to a shear flow. Addition of dextran sulfate (DS), a competitive inhibitor of scavenger receptors, reversed the effect of a shear flow on the uptake of DiI-Ac-LDL, resulting in an increase by the imposition of a shear flow, while the uptake of DiI-LDL and LY remained unaffected. It was concluded that a shear flow promotes the endocytosis of DiI-LDL and LY by ECs, but suppresses the uptake of DiI-Ac-LDL by ECs by inhibiting scavenger receptor-mediated endocytosis.

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Blood flow velocity profile in microvessels is essential for in vivo studies of substance exchange between blood and tissue. This paper was aimed to investigate the temporal and spatial variations in the velocity profile of red blood cell (RBC) flow in arterioles with both bifurcation and confluence in the rat mesentery, using a particle image velocimetry (PIV). The microcirculation in rat mesentery was observed under a microscopic system with a high-speed digital camera. The images of RBCs flow in microvessels were recorded simultaneously with the arterial blood pressure. Based on the high-speed video images, instantaneous velocity vectors of RBCs in arterioles with bifurcation and confluence were evaluated using a high spatial-resolution PIV algorithm. Then, the time-averaged and ensemble-averaged velocity profiles over the cross-section were calculated from the proximal through the bifurcation to the distal to the confluence. The velocity profile of RBCs showed two peaks at bifurcation and confluence, respectively. The double peaks were most marked at the apex of bifurcation, but not so much marked at the confluence. The variation of centerline velocity showed that the length of vessel under the influence of bifurcation or confluence, was approximately 1.5 times the diameter at the proximal to the apex of bifurcation, but its length was reduced significantly at the distal of confluence.

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The present paper describes the experimental work on the flow through the tapered right-angle branch model with the taper angle of 1°, in which the side branch bifurcates at 90° from the trunk. The results show that in laminar steady flow the wall shear stress reaches the maximum at the upstream corner of the side branch making significantly variation along the proximal wall in the form of a damped sinusoidal wave. Furthermore, it is suggested that the wall shear stress in the tapered right-angle branch varies more moderately than that in the straight right-angle branch. Therefore, the result of the present study distinctly explains that the tapered right-angle branch is more reasonable for human artery than the straight right-angle branch.

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The flow in the human ascending aorta was quantified using two-dimensional (2D) cine phase-contrast magnetic resonance imaging (MRI). The quality and reliability of the method were demonstrated with a specially designed phantom model; the flow rate determined with the MRI agreed well with that obtained with a measuring cylinder. The method was then used to measure the aortic blood flow of three healthy human volunteers. The velocity profiles at the supra-aortic valvular plane and ascending aortic plane (approximately 2 and 5cm distal to the aortic valve, respectively) were significantly different. At the peak of systole, the profile was almost axisymmetric at the supra-aortic valvular plane, while it was skewed towards the anterior side of the vessel at the ascending aorta. The Reynolds number, volume flow rate, and stroke volume were all within the normal physiological range. This study demonstrated that the 2D cine phase-contrast MRI technique can be used to provide detailed information on the flow velocity and configuration of a blood vessel, making it a promising tool for analyzing complex hemodynamics in the aorta.

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The distribution of wall shear stress and velocity in laminar steady flow has been experimentally studied in a model right-angle branch, in which the side branch bifurcates at a right-angle from the trunk. The branch model has a radius of curvature at the upstream corner and a square edge at the downstream corner. The wall shear stress was measured with an electrochemical method, and the velocity profile was measured by using laser Doppler anemometry (LDA). Near the upstream corner, along the proximal wall the wall shear stress has the form of a large-amplitude, damped sine wave. At the upstream corner, the amplitude of the wall shear stress increases markedly with decreasing the radius of curvature. The damped sinusoidal variation of wall shear stress along the proximal wall is one of the characteristic flow structures in right-angle branches. Also, the wall shear stress measured with the electrochemical method is compared with that estimated from the velocity profile measured by using LDA.

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Flow-induced changes in dimensions and mechanical properties of blood vessel wall were studied in the rabbit left common carotid arteries connected directly to the left external jugular vein via an arteriovenous fistula (AVF) to increase its blood flow by >10-fold for 4 weeks. Contralateral artery was used as control. We found significant increase not only in diameter, but also in thickness and length of unloaded artery exposed to increased flow, indicating the increase in wall volume. The increase in diameter and thickness but not in longitudinal length correlated significantly with the volumetric increase of the wall. Pressure-imposed test showed that the wall became less distensible in response to flow increase. Fluid shear stress estimated for physiological condition was significantly higher in AVF side than control, indicating that 10-fold increase in flow was not compensated in 4 weeks. Circumferential strain in a physiological pressure range was significantly lower in AVF side, while hoop stress was similar in both sides. These results may indicate that circumferential stress but not strain is maintained constant, and longitudinal change is not regulated in flow-imposed arteries.

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For purpose of a better understanding of the behavior of the global hemodynamic interactions, a closed-loop lumped parameter computational model was developed for the human cardiovascular system with a detailed compartmental description of the heart and the main vascular circulations. Construction of the model was implemented based on a phenomenological characterization of hemodynamics using an electrical analog method and solution of the governing differential equations of the model was carried out by use of a fourth-order Runge-Kutta method. Most of the hemodynamic parameters predicted by the present model were either consonant with the clinical measurements or within reasonable physiological ranges. Furthermore, the present model was applied to predict the clinical cardiac hemodynamic characteristics observed in patients with heart abnormalities. Reasonable agreements between predictions and measurements indicate that the present computational model can serve as a useful assistant tool for computer-aided diagnosis and surgical treatment, as well as posttreatment prediction.

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Model experiments of blood flow are very important in the study of mechanical aspects in cardiovascular research and the development of artificial organs. Several blood analog fluids, such as non-Newtonian fluids have been developed and used in model experiments. However, little is known about blood substitutes with biocompatible properties. We have developed novel procedures for preparing human hair protein films, and have fabricated protein particle suspensions from the films, by mechanical stimulation, for use as blood analog fluid. The average diameter of the protein particles was controlled and microscopic observations were done using a confocal microscope. The Casson’s plot patterns of the suspension containing the protein particles were similar to those of human blood. The protein particles also worked well as ultrasound contrast agents in the ultrasound Doppler flow velocity measurements in the model experiments. Therefore, the protein particle system is a promising alternative for blood cells in artificial blood.

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A mathematical model of rigid multibody dynamics with one three bodies was built firstly, based on which, the contribution of inertial torques during the steering maneuvers of a hovering Drosophilawas analyzed systematically. To eliminate the contribution of aerodynamics, the flying maneuvers were simulated within vacuum. The wings’ kinematics schemes and morphological parameters were idealized in concordance with those of real Drosophila. Several kinds of wing kinematics were analyzed, and the simulation results imply that inertial torques may play a role in the steering maneuvers of insect free flight. For the symmetrical flapping motion of bilateral wings, the inertial pitch torque conducts the rotation tendency of nose-up climbing or nose-down falling. And for the asymmetrical flapping cases, all inertial torques can influence synthetically the attitude of whole insect and finally result in the corresponding steering maneuvers. The simulation also suggests that the inertial torques due to wings supination may effectively contribute to insect steering maneuvers.

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In the present investigation, we constructed formulation to analyze the deformation of flagellar filament combining the evolution equations for space curves with the Kirchhoff rod model as well as the detailed structure of the filament of Salmonella. In the analytical results of the present study, experimental results of the large elongation of close-coiled filament (Hoshikawa and Kamiya, 1985) and the small deformation of normal filament rotating in water (Kudo et al.) are reproduced. Comparing the results of deformation of flagellar filament between the analyses and the experiments, the torsional and the flexural rigidity of the flagellar filament are estimated to be GJ=4.6pNµm² and EI=6.1pNµm².

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The size of the tympanic membrane and ossicles and the stiffness of the middle-ear ligaments and joint are different between individuals, and the effects of these differences on middle-ear transfer function have not been clarified. In this study, using finite-element middle-ear models, the effects of individual differences in the size and mobility of the middle ear on its transmission characteristics were analyzed. The individual differences in the size of the normal middle ear were found to affect the transfer function by up to 10dB. The effects of the Young’s moduli of the stapedial annular ligaments and the incudostapedial joint on the transfer function were large compared to the effects of the Young’s moduli of the other parts of the middle ear.

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To circumvent some of the problems inherent in conventional hearing aids such as low gain at high frequencies due to acoustic feedback, discomfort in occlusion of the external ear canal and so on, implantable hearing aids have been developed over the past two decades. The most prominent feature of implantable hearing aids is that a transducer is directly coupled to the one of the middle-ear ossicles. However, since invasive surgery is necessary for implantation of these hearing aids, they have not as yet been widely employed. We therefore constructed a prototype of a non-implantable hearing aid which is mainly composed of a microphone amplifier system and an electromagnetic transducer developed in our previous study. It can generate an excitation force to vibrate the ossicles by a coil adhered to the tympanic membrane. In this study, the excitation force generated by this hearing aid was evaluated using human temporal bones. The best result of experiments using three bones indicates that the newly developed hearing aid can generate an excitation force of more than 80dB SPL in terms of sound pressure at frequencies between 0.8 and 3.2kHz.

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Despite the importance of sliding contact in diarthrodial joints, the contact analysis algorithms presented over the past decade have been limited to cases of infinitesimal deformation and thus cannot reflect the real mechanical behavior of articular cartilage in daily life. In this study, a new finite element contact analysis approach allowing a large amount of sliding between articular cartilages is presented based on the biphasic theory, which is an effective model for articular cartilage. The geometric constraint condition and the continuity condition of the fluid phase on the contact surfaces are introduced by applying Lagrange multipliers. The formulation is carried out by transmitting the contact traction of the tissue and the hydrostatic pressure of the fluid phase equivalently between the contact surfaces by means of integrating virtual work due to contact over the contact area. The effectiveness of the proposed algorithm is verified by two numerical examples.

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Recently, many types of methodologies have been developed to regenerate articular cartilage. It is important to assess whether the reconstructed cartilaginous tissue has the appropriate mechanical functions to qualify as hyaline (articular) cartilage. In some cases, the reconstructed tissue may become fibrocartilage and not hyaline cartilage. In this study, we determined the dynamic viscoelastic properties of these two types of cartilage by using compression and shear tests, respectively. Hyaline cartilage specimens were harvested from the articular surface of bovine knee joints and fibrocartilage specimens were harvested from the meniscus tissue of the same. The results of this study revealed that the compressive energy dissipation of hyaline cartilage showed a strong dependence on testing frequency at low frequencies, while that of fibrocartilage did not. Therefore, the compressive energy dissipation that is indicated by the loss tangent could become the criterion for the in vitro assessment of the mechanical function of regenerated cartilage.

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Poly(vinyl alcohol) (PVA) hydrogel is one of the anticipated materials for artificial cartilage. PVA hydrogel has high water content and a low elastic modulus similar to natural cartilage, but its major disadvantage is its lower strength. PVA hydrogel experienced rapid wear under severe conditions such as mixed or boundary lubrication. Therefore, the existence of a protective surface film with low friction becomes important to prevent surface failure. In this study, the reciprocating frictional tests for a sliding pair of PVA hydrogel and glass plate were carried out, and fluorescent observations were performed to identify the roles of adsorbed protein film. Albumin and γ-globulin, which are contained in natural synovial fluid, were used by mixing into the lubricant. It appears that groups of albumin molecules adsorb on the smooth γ-globulin adsorbed layer at content of 2.1wt% of proteins with an appropriate ratio. But in the case of a lubricant which has excessive protein at 2.8wt%, albumin and γ-globulin adsorbed separately. Considering the wear reduction at 2.1wt% content of protein, albumin and γ-globulin constituted synergistic adsorbed film for wear reduction. It is indicated that albumin constructs a low shear layer and γ-globulin forms a layer protecting PVA hydrogel from wear. It is considered that wear and friction of PVA hydrogel were reduced due to slip of the boundary of adsorbed albumin and γ-globulin layer. Content of protein and ratio of albumin to γ-globulin (AG ratio) are important to constitute the appropriate protein film.

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Digital Image-based Elasto-Tomography (DIET) is a novel surface-based elasticity reconstruction method for determining the elastic property distribution within the breast. Following on from proof of concept simulation studies, this research considers the motion evaluation and stiffness reconstruction of a soft tissue approximating gelatine phantom. This initial phantom work provides an intermediate stage between prior simulation studies more detailed phantom studies to follow. Reference points on the surface of a cylindrical phantom were successfully tracked and converted into a steady-state motion description. Motion error based mechanical property reconstruction allowed an estimation of the stiffness of the gelatine when actuated at 50Hz. The reconstructed stiffness compared favorably with independently measured stiffness properties of the gelatine material when experimental assumptions were considered. An experimental noise estimate of 50% was confirmed accurate by comparing experimental motions to simulated motion data with added noise.

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We have developed a technique for estimating 3D motion of knee prosthesis from its 2D perspective projections. As Fourier descriptors were used for compact representation of library templates and contours extracted from the prosthetic X-ray images, the entire silhouette contour of each prosthetic component was required. This caused such a problem as our algorithm did not function when the silhouettes of tibio and femoral components overlapped with each other. Here we planned a novel method to overcome it; which was processed in two steps. First, the missing part of silhouette contour due to overlap was interpolated using a free-formed curvature such as Bezier. Then the first step position/orientation estimation was performed. In the next step, a clipping window was set in the projective coordinate so as to separate the overlapped silhouette drawn using the first step estimates. After that the localized library whose templates were clipped in shape was prepared and the second step estimation was performed. Computer model simulation demonstrated sufficient accuracies of position/orientation estimation even for overlapped silhouettes; equivalent to those without overlap.

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In segmental pedicle screw instrumentation, the relationship between the combinations of pedicle screw placements and the degree of deformity correction was investigated with a three-dimensional rigid body and spring model. The virtual thoracolumbar scoliosis (Cobb’s angle of 47 deg.) was corrected using six different combinations of pedicle-screw placements. As a result, better correction in the axial rotation was obtained with the pedicle screws placed at or close to the apical vertebra than with the screws placed close to the end vertebrae, while the correction in the frontal plane was better with the screws close to the end vertebrae than with those close to the apical vertebra. Additionally, two screws placed in the convex side above and below the apical vertebra provided better correction than two screws placed in the concave side. Effective deformity corrections of scoliosis were obtained with the proper combinations of pedicle screw placements.

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Finite element contact analyses of dysplastic hip joints were performed based on CT and MR images as a surgical planning tool of the shelf operation. The 3-D cartilage thickness was approximated using MRI, and the joint contact force was calculated from a 3-D expansion of the Ninomiya’s method. After surgical planning, the anatomical parameters including the CE angle, the AC angle, the sharp angle and the spheric sector angle were improved to normal hips. The mechanical parameters including the maximum contact pressure, the contact area and the quality of contact pressure distribution also were improved. The present models and the results can be used as a computer simulation tool for optimal pre-operative planning of the shelf operation in hip dysplasia.

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The purpose of this study is to develop a measuring device (SWELL) for lower leg swelling of the human during standing work tasks. The device consists of a flexible wire, a coil spring, and a flat spring with a strain gauge. It is demonstrated to be accurate enough for practically from the results of calibration test and heat test. The wire of the device is to be wound around the lower leg with proper tension and the strain that the flat spring produces is measured as the leg swelling develops. For a verification test, experiments were carried out to measure the swelling of the lower leg for thirteen subjects during prolonged standing. The results showed that the magnitude of the swelling increased almost linearly for 30 min and the relationship between the magnitude of the swelling and the subjective complaint of the leg was significant.

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Whiplash injuries are most common disorders in rear-end car accidents, while the injury mechanism is yet unknown. Many numerical and experimental approaches have conducted to investigate the cervical behaviors with solely two-dimensional analyses in the sagittal plane. In real accidents, however, as impacts may affect several directions, the cervical behaviors should be evaluated three-dimensionally. Therefore, we evaluated the cervical behaviors under assumption of the posterior-oblique impacts depending on the impact angles with 3-D FE analysis. In addition, we analyzed the stresses occurred in the facet joints considering the relationship with a whiplash disorders. The cervical behaviors showed complex motion combined with axial torsion and lateral bending. The bending angle peaked in the impact at the angle of 15°, and the peak compressive and shear stress on the facet cartilage at C6-C7 increased by 11% and 14%. In the impact at the angle of 30°, the torsion angle peaked at C2-C3, the peak shear stress in the facet cartilage increased by 27%. It showed that the torsion and lateral bending affected the cervical behaviors, and caused the increase of peak stresses on the soft tissues. It is assumed as one of important causes of whiplash injury.

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This study presents an assessment of walking stability in elderly people, focusing on local dynamic stability of walking. Its main objectives were to propose a technique to quantify local dynamic stability using nonlinear time-series analyses and a portable instrument, and to investigate their reliability in revealing the efficacy of an exercise training intervention for elderly people for improvement of walking stability. The method measured three-dimensional acceleration of the upper body, and computation of Lyapunov exponents, thereby directly quantifying the local stability of the dynamic system. Straight level walking of young and elderly subjects was investigated in the experimental study. We compared Lyapunov exponents of young and the elderly subjects, and of groups before and after the exercise intervention. Experimental results demonstrated that the exercise intervention improved local dynamic stability of walking. The proposed method was useful in revealing effects and efficacies of the exercise intervention for elderly people.

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In this paper, we propose a decentralized motion control algorithm of multiple mobile manipulators for handling a single object in cooperation with a human. In the proposed control algorithm, the grasping point of the mobile manipulator is controlled as if it has a caster-like dynamics referred to as virtual 3-D caster, and each mobile manipulator could handle the object based on an intentional force/moment applied by a human. In addition, the coordinated motion control algorithm between the manipulator and the mobile base for each mobile manipulator is designed. By using these motion control algorithms, the coordination among multiple mobile manipulators is realized without using the geometric relations among robots. The proposed control algorithms are experimentally applied to two mobile manipulators and experimental results illustrate the validity of the proposed control algorithms.

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This paper aims at constructing an efficient interface being similar to those widely used in human daily life, to fulfill the need of many volunteer rescuers operating rescue robots at large-scale disaster sites. The developed system includes a force feedback steering wheel interface and an artificial neural network (ANN) based mouse-screen interface. The former consists of a force feedback steering control and a six monitors’ wall. It provides a manual operation like driving cars to navigate a rescue robot. The latter consists of a mouse and a camera’s view displayed in a monitor. It provides a semi-autonomous operation by mouse clicking to navigate a rescue robot. Results of experiments show that a novice volunteer can skillfully navigate a tank rescue robot through both interfaces after 20 to 30 minutes of learning their operation respectively. The steering wheel interface has high navigating speed in open areas, without restriction of terrains and surface conditions of a disaster site. The mouse-screen interface is good at exact navigation in complex structures, while bringing little tension to operators. The two interfaces are designed to switch into each other at any time to provide a combined efficient navigation method.

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This paper presents an adaptive decentralized coordinated control method for multiple robot arms grasping a common object. In the proposed controller, the dynamic parameters of both object and robot arms are estimated adaptively. The desired motions of the robot arms are generated by an estimated object reference model and each robot controller works independently as hybrid adaptive controller. The asymptotic stability of position and internal force of the object is proven by the Lyapunov-Like Lemma. Experimental comparisons between adaptive control with force sensor and one without force sensor for the two robot arms grasping a common object are shown.

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This research on a 2-link pneumatic manipulator develops from the occurrence of chaos phenomena and it’s stabilizing control in following a circular trajectory by considering a dead time in the system. In generally it is difficult for this manipulator to follow a desired trajectory, because chaos is often caused in the manipulator with a dead time of the pneumatic signal transmitted through the long air tube. In order to solve this kind of problem, the chaos behavior is made clear by recording the Lyapunov exponent of the trajectory, and a new stabilizing method with a neural network is proposed. Through simulations and the experiment, the occurrence of chaos and the possibility of stabilization are verified by using the proposed method.

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In this paper, the posture stabilization and longitudinal motion control of a unicycle robot is presented. This unicycle robot has two gyroscopes acting as an actuator for the lateral stabilization and a wheel as an actuator for the longitudinal stabilization. The system is modeled based on Lagrangian Dynamics and system identification method. A gain-scheduled robust control method is applied to enhance its disturbance attenuation ability so as to achieve better performance in posture stabilization and longitudinal motion control. Satisfactory experimental results are obtained.

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Problems with the control, oscillatory motion and compliance of pneumatic systems have prevented their widespread use in advanced robotics. However, their compactness, power/weight ratio, ease of maintenance and inherent safety are the factors that could potentially be exploited in sophisticated dexterous manipulator designs. These advantages have led to the development of novel actuators such as the McKibben Muscle, Rubber Actuator and Pneumatic Artificial Muscle Manipulators. However, some limitations still exist, such as deterioration of the performance of transient response due to the change of the external inertia load in the pneumatic artificial muscle manipulator. To overcome this problem, switching algorithm of control parameter using learning vector quantization neural network (LVQNN) is newly proposed, which estimates the external inertia load of the pneumatic artificial muscle manipulator. The effectiveness of the proposed control algorithm is demonstrated through experiments with different external inertia loads.

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This paper presents a technique for synthesizing adjustable RSSR-SC mechanisms to achieve phases of prescribed rigid body positions. The benefit of this method is that RSSR-SC mechanisms can be synthesized to achieve multiple phases of prescribed rigid-body positions using the same hardware. By specifying the joint axes of the C-S and R-S links and establishing perpendicularity between these links and their corresponding joint axes, the constant length condition becomes the only design constraint for these links. The prescribed rigid-body positions are then incorporated in the link constraint Equations with respect to the prescribed coordinate frame for each link and the RSSR-SC mechanism joint variables calculated. The example problem in this work considers a two-phase moving pivot adjustment problem with fixed and adjustable crank and follower lengths.

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A two-axis reciprocating machine, termed Complementary Scotch Yoke (CSY), is regulated via a novel control algorithm. Containing two independent driving motors, it is capable of converting two-axis rotary movements into double-mode linear harmonic motions. The axes are subject to periodic disturbances of quadruple characteristic frequencies when the machine undergoes harmonic motions. A feedback law emulating multi-mode vibration absorbers is designed to compensate for the periodic disturbances so that the driving axes are regulated at the set angular speeds. The virtual passive controller ensures stability of the unforced system, and it is shown that the periodic disturbances can be canceled out if the virtual vibration absorber has all of the characteristic frequencies of the disturbance. Experimental results on a CSY prototype confirm the effectiveness of the proposed method.

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In our previous work, a frequency-domain method for estimating the mass, stiffness and damping matrices of a structure was presented. In that method, the accuracy of identified system matrices for different data point configurations are addressed and shown that a more accurate damping matrix can be identified and the present method is insensitive to the data point configurations used in the identification procedure even for cases with only few data points. In this paper, a system matrices reduction method for a damped system is proposed. In this reduction method, a mapping matrix is formulated based on the original complex mode shapes and utilized to transform the original system matrices to reduced ones, which possess the selected modes of original system. The selection of active degrees of freedom is also addressed in this paper. The simulated and experimental results indicate that the reduction method is effective and accurate.

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It is well known that the natural frequencies of a pipe become lower as uniform internal fluid velocity increases. The pipe becomes unstable if the fluid is faster than the critical velocity. But in the case of a pipe conveying harmonically pulsating fluid, resonances will occur even though the mean velocity of the fluid is below the critical velocity. Therefore, for improved analysis, the effects of pulsating fluid in the pipe should also be taken into consideration. In this study, a finite element formulation for the pipe was carried out while taking into consideration the effects of the fluid pulsating harmonically in the pipe. The damping and stiffness matrices in the finite element equation vary with time. A stability analysis based on the Bolotin method was carried out. And, a method to directly estimate the forced response of the pipe that does not need to solve a time data from time-variant system is presented. Several numerical examples are given in this paper that validate of this method.

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This paper proposes a new impedance controller that is to be applied to bilateral teleoperation under a time delay. The controller has a variable damping designed to achieve a good tacking performance and contact stability concurrently. The damping of the slave impedance is modulated based on the distance between the slave and its environment. The stability of the teleoperation system including the human operator and the environment is analyzed using the absolute stability. The validity of the proposed control scheme is demonstrated in experiments with a 1-DOF teleoperation system. The experimental results show that the system performs better with a damping modulation than with a constant damping or with a variable damping, which changes based on contact signals.

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Tooth surface undulation is one of the important sources of gear noise and vibration. The vibration caused by this source is observed as the occurrence of non-meshing vibration component or ghost noise on a vibration spectrum. Frequently ghost noise occurs at the same frequency with natural frequency of a gear pair, consequently its amplitude is amplified to the considerable level and lead to unexpected and severe noise and vibration problems. In this paper a method for inspecting tooth surface undulation is proposed and applied to a helical gear pair. Vibration characteristics of individual gear are extracted from the vibration signal of a gear by synchronous averaging technique, then a frequency response function that can be determined experimentally is applied to the individual averaged signal to assess the tooth surface undulation. The undulations are evaluated by applying this method to the measured vibration signals of the gear pair operated at various speeds and various torques, and show good agreement with each other regardless of operating conditions and also with the expectation by precise tooth surface measurement, even though the undulation is very small in the level of 0.1µm. These results suggest the ability of this method to assess the tooth surface geometry relevant to vibration.

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In this paper, the characteristics of disk-type hydrostatic thrust bearings supporting concentric loads; simulating the major bearing/seal parts of axial piston pumps and motors were investigated. An experimental setup was designed to determine the performance of slippers, which are capable of increasing the efficiency of axial piston pumps and motors, for different conditions. The working parameters and the slipper geometry causing the minimum frictional power loss and leakage oil loss were determined. Since slippers affect the performance of the system considerably, the effects of surface roughnesses on lubrication were studied in slippers with varying hydrostatic bearing areas and surface roughness. The results of the study suggest that the frictional power loss and leakage oil loss were caused by the surface roughness, the relative velocity, the size of the hydrostatic bearing area, supply pressure and capillary tube diameter.

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A new nozzle system which consists of a discharge nozzle and supply equipment has developed for environmental friendly metalworking fluid, called oil-on-water droplet metalworking fluid. This system provides excellent cutting performances in terms of roughness on finished surfaces, burr dimensions and cutting force in both aluminum alloy and stainless steel milling. As its application to practical use, the system has been employed for grooving process in the production line of engine main bearings which was conventionally machined under dry condition. It has been shown that the developed system can improved the machining performances in terms of machining error and tool life. The improvement for the machining error leads to significant reduction in the rejection of defective parts in the production line and more than twofold increase in tool life is obtained.

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A global optimization approach named “Modal Trimming Method” has been proposed to derive suboptimal solutions for equality constrained nonlinear programming problems. To obtain a tentative suboptimal solution, a local optimal one is searched by a conventional gradient method. To improve the tentative suboptimal solution, a feasible one is searched by an extended Newton-Raphson method. In this paper, it is shown that the capability of global search for feasible solutions is obtained by the behavior of solutions with the chaos, and the mechanism for its occurrence is clarified. The method is revised to prevent the trap into local optimal solutions because of the behavior of solutions with the cyclic vibration. The method is also extended to consider inequality constraints including upper and lower limits for variables as well as discontinuous feasible regions. The method is applied to various test problems, and it turns out that the method has a high possibility of deriving the global optimal solutions as the suboptimal ones for a wide range of problems.

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A step-by-step time integration method is presented for dynamic response analysis based on Benthien-Gurtin’s principle of minimum transformed energy in linear elastodynamics. First of all, a single convolution-type (Gurtin-type) functional in the real space is obtained from the functional in Laplace space. Then the concrete functional, that can be used to construct time integration methods by adopting some interpolation functions, is established after successively spatial and temporal discretization. The cubic Hermite interpolation functions in temporal domain are adopted to show the procedure of constructing time integration method and the new numerical method is developed finally. The specific stability characteristics about the unconditional and conditional stabilities of the numerical method are investigated in detail. The numerical examples show that the algorithm is of satisfying accuracy and is an effective method for the numerical calculations of dynamic response problems in engineering.

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This research proposes a model-based planning system for planning multi-axis 3D surface scanning machine. Firstly we describe a simulation system for performing collision avoidance, occlusion detection, and evaluating the measured portions of the surface. Then based on this simulation system, as our initial trial, we propose a simple path planning method to increase surface coverage and reduce measuring time by iterations. This research aims at measurement of complicated automotive parts, such as sheet metal parts and press dies. The implementation result shows the efficiency and automation of our approach.

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In this paper we propose methodologies and algorithms of NC cutter path generation for subdivision surfaces. We select Loop surface as the subdivision surfaces. A path plan including rough cut and finish-cut is developed based on the LoD (Level of Detail) property of subdivision surface. We generate a coarse mesh that covers the limit surface to implement the rough cut. For finish-cut we use ball-end mills and offset cutter contact data to generate cutter location data. In these two steps we use a Z-map model and a collision detection/correction method is presented for the interference-free of these two steps. We implement our methods and present machining results. All of these two kinds of cutter paths are computed rapidly and automatically.

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The performance of manufacturing systems can be adjusted by allocation buffer into the manufacturing system. Buffer will improve the performance of manufacturing systems by improving the utilization of the constraints; yet buffer will also increase the makespan and the work in progress. Due to the complex nature of the systems, buffer allocation is usually difficult to optimize. This paper presents a prediction model of the effect of buffer based on the shifting bottleneck detection and a blocking and starving analysis. The prediction model is used to optimize the buffer allocation using only a single simulation.

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A system and procedures are developed to optimize the cutting speed for CNC turning. The current amount of tool wear is estimated based on the in-process cutting force measurement by applying the method developed and reported previously. Once the tool wear is estimated for the different cutting speeds, the coefficients of the Taylor’s tool life equation are determined or successively modified based on the estimated tool wear data. The optimum cutting speed is obtained by referring to the criteria of either the minimum production cost or the maximum production rate. The system developed is applied to actual turning of carbon steel with coated carbide tools, and it has been proved that the system runs satisfactory. The method developed here can be readily applied to unknown combinations of the work material and the tool, as it searches the optimum cutting conditions automatically while the process is going on.

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High speed, high quality and short delivery are the development trend of the manufacturing industry. In this paper, the Taguchi dynamic characteristic theory was used coupled with proposed ideal function models under a two-phase optimization strategy. The main objective of this work is to develop optimized machining parameters in the high-speed milling process with the characteristics of high machining efficiency and geometrical accuracy, and wide applications. The experimental results showed that the machining time can be effectively reduced using the designed optimal parameters obtained from the first phase of the strategy. The process variance was only 63.96% of the initial conditions, and the robustness of the process was increased 1.56 times. The control factors having the most influences on the machining time and the robustness of the CNC milling process in order of importance were identified as cutting speed, number of teeth, and feed per tooth. The dimensional relationship between the input and output of the milling process under the first-phase optimized conditions was derived as Y=1.001090M. Therefore, according to this model, final adjustment to the input programmed dimension can be made in phase two to obtain the ideal machining accuracy.

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A buffered digital differential analyzer (DDA) algorithm in a computerized numerical controller (CNC), interpolating more than one segment in a sampling interval, maintains the speed of motion, according to the programmed feed. The DDA interpolates sequential position data, where the gaps between pairs of data are variable, using a fixed increment of a parameter constrained by the required accuracy of the chord of the motion. Without considering the time function of the parameter specified by two terms of a Taylor expansion, the algorithm determines the suitable position from the interpolated position data, to ensure the accuracy of the both speed and contour of motion. A parametric curve, determined by the non-uniform rational B-spline (NURBS), is employed to verify the improvements in curve motion.

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We describe a looper controller design for a hot strip finishing mill in steel plants. The main function of the looper system is to balance the mass flow of the strip by accumulating material in the middle of the stands. Another function is to control the strip tension which influences the width of the strip. To ensure strip quality, it is very important to control the tension of the hot strip finishing mill. However, because there is a mutual interaction between the looper angle and the strip tension, it is difficult to control the looper system. Previous researches examined only the operation of a single stand. But it is not sufficient to examine the operation and effect of whole stands because the operation is wholly interdependent. In this paper, we present a full model of the hot strip finishing mill in order to more effectively control strip tension. We propose several control methods for the full-stand hot strip finishing mill, denoted as conventional PI, PI with cross gain, and coefficient diagram method (CDM) PID control. In the real plants, there are some problems by using higher order controllers such as LQ, LQG and H_∞. By comparison, the PID controller is very simple and easy to apply to all real plants. To that end, we present our findings on PID controls and their potential use in the hot strip finishing mill.

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