Showing papers in "Jsme International Journal Series C-mechanical Systems Machine Elements and Manufacturing in 2004"

Influence of Carrier and Gear Manufacturing Errors on the Static Load Sharing Behavior of Planetary Gear Sets

Abstract: In this paper, a state-of-the-art contact mechanics model of a planetary gear set is employed to study the effect of a number of manufacturing and assembly related carrier and gear errors on the load sharing amongst the planets Three different groups of errors are considered: (i) time-invariant, assembly-independent errors such as carrier planet pinhole position errors, (ii) time-invariant, assembly-dependent errors such as planet tooth thickness errors, and (iii) time-varying, assembly-dependent errors such as gear run-out errors With such errors present, planet load sharing characteristics of an n-planet system (n=3 to 6) is investigated for different piloting configurations under quasi-static conditions Load sharing behavior as a function of key manufacturing errors is quantified and design guidelines are proposed for better planet load sharing behavior

A Study upon Durability of the Artificial Knee Joint with PVA Hydrogel Cartilage

Abstract: An experimental investigation upon the durability of the artificial knee joints with PVA hydrogel articular cartilage is presented. PVA hydrogel is manufactured by the cyclic freezing/thawing and annealing methods; femoral component is a disc made in stainless steel. This work is original in the meaning that: a weighting method to differentiate the worn mass from the mass of exuded water for PVA hydrogel is suggested; an original wear test rig, which simulates the anterior-posterior displacement of the knee motion during walking is proposed; wear factor variation against the number of walking cycles (durability curve) for PVA hydrogel is reported. The lowest wear factor obtained is on order of 10-6-10-5mm3/Nm. PVA hydrogel with reduced water content (45-50%) produces the smallest wear factor, for the same polymerization degree. Reduction of the wear factor is on order of 104 when the PVA polymerization degree increases from 1800 to 12300. PVA hydrogel manufactured on a hydrophobic substrate (PTFE) presents a 16-27% lower wear factor than that prepared on a hydrophilic substrate (glass). When layer thickness increases from 2 to 3.6mm, the wear factor reduction is 18%. Influence of the standing interval in start-up conditions on the wear factor is also investigated.

The Design of a Controller for the Steer-by-Wire System

Abstract: Drive-by-Wire (DBW) technologies improve conventional vehicle performance and a Steer-by-Wire (SBW) system is one of the DBW technologies. The control algorithm of the SBW system was designed in this paper. To verify the control algorithm, the SBW system is modeled using the bond graph method. The first aim of the control algorithm is controlling the steering wheel assist motor to make the real vehicle's steering feel and for a vehicle designer to adjust the steering feel as he finds necessary. Therefore, torque map is designed to determine the steering wheel reactive torque. The second aim is controlling the front wheel assist motor to improve vehicle's maneuverability and stability by using understeer and oversteer propensity of a vehicle. Furthermore, high performance control algorithm is proposed in this paper and Active Roll Stability Control (ARSC) method is designed as one of the high performance control algorithm.

Effect of Debris Distribution on Wall Concavity in Deep-Hole EDM

Abstract: In deep-hole electrical discharge machining, the electrode jump height and hence the movement of the machining debris inside the side gap affect the wall concavity of the machined holes. In this study, the dielectric fluid flow and the debris distribution in the machining gap caused by electrode jump is analyzed to understand the wall concavity phenomenon of the holes using a computational fluid dynamics (CFD) simulation program. Fluid flow and debris-fluid interaction under low and high electrode jumps are examined and compared. The accuracy of the predictions obtained by the numerical calculation is assessed through comparisons with experimental data.

Temperature Distribution Measurement in EDM Arc Plasma Using Spectroscopy

Abstract: This paper describes the measurement of temperature distribution in EDM arc plasma using spectroscopic analysis. The temperature distribution measurement was achieved by using a lens system to magnify the image of the plasma and a mask to limit the plasma region to be observed. The fluxes of two different wavelength spectra radiated from the arc plasma were measured simultaneously with optical fibers and photomultipliers, after which the temperature distribution was computed from the radiant fluxes using the line pair method and Ablel's inversion. Also, the influences of machining conditions, such as electrode shape, gap distance and discharge current, on the temperature distribution were investigated.

Fast Response MR-Fluid Actuator

Abstract: Magnetorheological (MR) fluids are materials that change their rheological behavior upon applying a magnetic field. They have been promising as functional fluids that can improve the properties of mechanical systems. We have developed an actuator using MR fluid. In the previous paper, a method of designing MR-fluid actuators was proposed on the basis of magnetic circuit theory. The basic experiments were carried out and static properties that agreed well with the design were obtained. However, the transient response, which was not considered in the design phase, was not very fast. In this study, we investigate the dynamics of the MR-fluid actuator and aim to improve the response. The transient magnetic analysis is examined in consideration of the eddy current. Two approaches to improving the response are proposed. Finally, we realize a much faster MR-fluid actuator.

Stability Analysis of High Speed Railway Vehicles

Abstract: The lateral mathematical model of a high speed vehicle system with 17 degrees of freedom is set up and the nonlinearities arising duo to suspension parameters and wheel/rail interactions are considered. The coupler traction force in tension and compression cases which is the function of vehicle speed and position in the trainset is also taken into account in the model. The critical speed at the Hopf bifurcation point on straight and circular curved tracks are studied by utilizing efficient numerical methods. The influence of track curve radius and superelevation on the critical speed is investigated.

Experimental Study on the Ultraprecision Ductile Machinability of Single-Crystal Germanium

Abstract: Single-crystal germanium is an important infrared optical material. In the present work, single-point diamond turning experiments on single-crystal germanium (100), (110) and (111) planes were conducted in order to examine their ultraprecision machining characteristics. Three kinds of surface textures and chip morphologies were observed during the brittle-ductile transition of the machining mode. The brittle-ductile boundary changed significantly with the crystal orientations of the workpieces. Due to the crystallographic anisotropy, micro-fractures were generated on the workpiece surface in a radial pattern from the rotation center. However, it was possible to produce completely ductile-cut surfaces on all crystal orientations by using undeformed chip thicknesses smaller than a critical value, namely, the minimum critical undeformed chip thickness, which was approximately 60nm under the present conditions. Compared to wet cutting, dry cutting was beneficial for ductile machining on a few specific crystal orientations. The findings in this study provide criterions for determining process parameters for the fabrication of aspherical and diffraction infrared optics using single-crystal germanium.

Digital image based elasto-tomography; proof of concept studies for surface based mechanical property reconstruction

Abstract: Digital Image-based Elasto-Tomography (DIET) is a novel method of determining the distribution of elastic properties within the breast. Using an array of calibrated digital cameras and an inverse reconstruction algorithm, DIET allows reconstruction of the internal elastic stiffness distribution of the breast using only motions at the breast surface. This reconstructed stiffness should clearly show carcinoma based on their high elastic property contrast with healthy tissue. Proof of concept studies are presented for both the calibration of the digital imaging system and the inverse reconstruction algorithm. The reconstruction algorithm identified high stiffness tumors in the majority of test cases, even with the addition of random noise based on expected calibration accuracy.

A Study of Adhesion Force Model for Wheel Slip Prevention Control

Abstract: In order to enhance the speed of wheel slip prevention control for railway vehicles, modeling of adhesion characteristics after saturation of adhesion force, which had hitherto not been performed with trains, was performed via a beam model. The behavior of adhesive force between the wheel and rail in a wet condition was examined with a brake performance test stand for an actual vehicle. Results of comparing the model and test values indicated that the beam model represented test values well.

Design of Fracture Fixation Plate for Necessary and Sufficient Bone Stress Shielding

Abstract: The objective of treating the fractured bone is to achieve painless functioning of the bone and undisturbed healing at the fracture. Internal fixation by stiff bone-plate is one of the standard methods to achieve these objectives. Recently, there is considerable interest in the usage of compliant plates to enhance bone healing with reduced stress shielding. Herein, first an analytical solution is developed to determine screw forces in the bone-plate assembly that conforms the plate and the bone under bending load. Based on the analytical calculations, an optimal fixator plate selection criterion for necessary and sufficient stress shielding is proposed. Second, effectiveness of employing a non-homogeneous stiffness graded (SG) plate rather than a homogeneous stainless steel (SS) plate for stress shielding is investigated using a finite element method. It is found that stress shielding on bone by SG plate is less compared to SS plate.

Generation of an Optimal Gait Trajectory for Biped Robots Using a Genetic Algorithm

Abstract: This paper proposes a method that minimizes the energy consumption in the locomotion of a biped robot. A real-coded genetic algorithm is employed in order to search for the optimal locomotion pattern, and at the same time the optimal locations of the mass centers of the links that compose the biped robot. Since many of the essential characteristics of the human walking motion can be captured with a seven-link planar biped walking in the saggital plane, a 6-DOF biped robot that consists of seven links is used as the model used in the work. For trajectories of the robot in a single stride, fourth-order polynomials are used as their basis functions to approximate the locomotion gait. The coefficients of the polynomials are defined as design variables. For the optimal locations of the mass centers of the links, three variables are added to the design variables under the assumption that the left and right legs are identical. Simulations were performed to compare locomotion trajectories obtained with the genetic algorithm and the one obtained with the gravity-compensated inverted pendulum mode (GCIPM). They show that the proposed trajectory with the optimized mass centers significantly reduces the energy consumption, indicating that the proposed optimized method is a valuable tool in the design of biped robots.

Optimal Cross-Coupled Synchronizing Control of Dual-Drive Gantry System for a SMD Assembly Machine

Abstract: The present paper deals with the development of synchronizing controller for dual-drive servo system that is often used for SMD (Surface Mount Device) assembly machine. Instead of coordinating the commands to the individual feed drives and implementing closed position loop control for each axis, this work is achieved by the evaluation of an optimal cross-coupled compensator aimed specifically at improving synchronous accuracy in dual feed drives. The optimal control formulation explicitly includes the synchronous error in the performance index to be minimized. In this paper, surface chip mounter is used for experiment. It demands to synchronize the positions of its two primary driving axes. The system is modeled as the first order approximation and cross-coupled optimal synchronizing controller is designed. The synchronizing control is simulated and experimented with actual system for various velocity profiles. The results show that the proposed controller reduces the synchronous error considerably, compared to the conventional uncoupled control for the dual-drive system.

Mechanical Anisotropy of Rat Aortic Smooth Muscle Cells Decreases with Their Contraction

Abstract: Tensile properties of smooth muscle cells freshly isolated from rat thoracic aortas (FSMCs) in their major and minor axes were measured using a laboratory-made micro tensile tester. The relationship between the tension applied to a cell and its elongation was obtained in untreated cells and those treated with 10-5M serotonin to induce contraction. An initial stiffness of untreated FSMCs, normalized by their initial cross-sectional area perpendicular to the stretch direction, was significantly higher in the major axis (14.8±4.3kPa, mean±SEM, n=5) than the minor axis (2.8±1.0kPa, n=5). The stiffness increased significantly in response to the contraction, but the increase was much higher in the minor axis (59.0±9.4kPa, n=4) than in the major (88.1±13.3kPa, n=4). The difference between the two directions was insignificant in the contracted state. Observations of the morphology of actin filaments with a confocal laser scanning microscope in untreated FSMCs revealed that they were long fibers running almost parallel to the major axis, while those in contracted cells showed an aggregated structure without a preferential direction. These results may indicate that anisotropy in untreated FSMCs is caused by the anisotropic alignment of their actin filaments, and that such anisotropy disappears in response to actin filament reorganization caused by the contraction.

Development of Interactive Industrial Design Support System Considering Customer's Evaluation

Abstract: To respond to rapidly changing and diversifying customers’ requirements, an industrial design support system for eyeglass frames which allows the customer to participate in the industrial design process was developed. This system is based on the Interactive Evolutionary Computing (IEC) technique so that a customer can interact with the system to express his or her Kansei requirements through images. The design of an eyeglass frame cannot be determined in isolation but rather must be determined by considering its appearance on the customer. In the developed system, the user evaluates each sample suggested by the system and narrows down the candidate gradually. Its usefulness was demonstrated by operational experiments and questionnaires.

High Speed Machining of Bio-Titanium Alloy with a Binder-Less PcBN Tool

Abstract: Using a binder-less PcBN tool, improvement of processing efficiency was tried in machining of a vanadium-free titanium alloy, Ti-6Al-2Nb-1Ta which was recently applied for a surgical implant material. The tool which is prepared through the direct conversion sintering of h-BN under both high pressure and temperature, exhibits an improved high thermal durability. It was confirmed that a binder-less PcBN tool exhibited lower flank wear and kept sharper cutting edge compared to the tools made of materials such as sintered carbide, conventional PcBN and polycrystalline diamond with Co-based binder, after turning in cutting speed of 4.2m/s, feed rate of 0.15mm/rev, depth of cut of 0.5mm under an application of a high pressure coolant. Also, milling tests were conducted with a radius end mill tool whose tip was made of the binder-less PcBN material. As a result, the possibility of high speed milling at cutting speed of 8.3m/s was found.

Evaluation of Grinding Wheel Surface by Means of Grinding Sound Discrimination

Abstract: In this study, a new technique of in-process evaluation of a grinding wheel surface is proposed. Some specific wheel surfaces are prepared as references by the appropriate truing and/or dressing procedure, and grinding sounds generated by these wheels are discriminated by analyzing the dynamic frequency spectrum by a neural network technique. In the case of a conventional vitrified-bonded alumina wheel, the grinding sound can be identified in the optimum network configuration. Therefore, this system can instantaneously recognize differences in the wheel surface with a good degree of accuracy insofar as the wheel conditions are relatively widely changed. In addition, the network can perceive wheel wear because the grain tips are flattened as grinding proceeds and the grinding sound becomes similar to that of a wheel generated with lower dressing feed. The resinoid-bonded cubic boron nitride (CBN) wheel is also discriminable when a grinding sound in a higher frequency range is analyzed.

Compensation of Gravity-Induced Errors on a Hexapod-Type Parallel Kinematic Machine Tool

Abstract: This paper presents a methodology to compensate contouring errors introduced by the gravity on a Hexapod-type parallel kinematic machine tool with the Stewart platform. Unlike conventional serial kinematic feed drives, the gravity imposes a critical effect on the positioning accuracy of a parallel kinematic feed drive, and its effect significantly varies depending on the position and the orientation of the spindle. We first present a kinematic model to predict the elastic deformation of struts caused by the gravity. The positioning error at the tool tip is given as the superposition of the deformation of each strut. It is experimentally verified for a commercial parallel kinematic machine tool that the machine's contouring error is significantly reduced by compensating gravity-induced errors on a reference trajectory.

Sensorless Plunger Position Control for a Switching Solenoid

Abstract: In this study, the sensorless control algorithm is applied to improve the position control accuracy of the output plunger of a switching solenoid. The main purpose of this study is the attempt to develop a fluid-technical proportional valve with simplest construction and lowest cost. Since the switching solenoid is not equipped with a position sensor and consequently no closed-loop control theory can be applied, the accuracy of the position control of the output plunger becomes a most critical question. Therefore, a modified open-loop controller using the sensorless control algorithm is proposed. The basic idea is the utilization of the sensorless control algorithm to estimate the steady-state position of the plunger. Then, this estimated position is fedback to the controller and the input current during the steady-state response is real-time adjusted according to the error signal. Finally, a series of experiments are carried out and the results show that the proposed modified open-loop controller improves significantly the steady-state accuracy of the plunger position and provides an alternative approach to design unconventional proportional valves.

Vibration Suppression of Railway Car Body with Piezoelectric Elements

Abstract: A new method for improving riding comfort by reducing vertical flexural vibrations in railway car bodies using piezoelectric elements is studied in this paper. Piezoelectric elements are attached on the car body in order to convert vibration energy to electrical energy, which can be dissipated in a shunt circuit. Assuming the car body as an elastically supported Bernoulli-Euler beam, theoretical analysis and numerical simulations are carried out. The numerical results are supplemented by experiments on a 1:5 scale model of a Shinkansen vehicle. Both numerical and experimental results indicate that the method yields significant vibration suppression with only a small amount of added weight. Two types of shunt circuits; a single-mode circuit and a multi-mode circuit are studied.

Boundary Control of an Axially Moving Steel Strip under a Spatiotemporally Varying Tension

Abstract: In this paper, a vibration suppression scheme of an axially moving steel strip in the zinc galvanizing line is investigated. The moving steel strip is modeled as a moving beam, in which the tension applied to the strip is a spatiotemporally varying function. The transverse vibration of the strip is controlled by a hydraulic touch-roll actuator at the right boundary. The mathematical model of the system, which consists of a hyperbolic partial differential equation describing the dynamics of the moving beam and an ordinary differential equation describing the actuator dynamics, is derived by using the Hamilton's principle for the systems of changing mass. The Lyapunov method is employed to design a boundary control law for ensuring the vibration reduction of the system in the presence of a spatiotemporally varying tension. The exponential stability of the closed loop system under the boundary control is proved through the use of invariance principle and semigroup theory. Simulation results verify the effectiveness of the boundary control law proposed.

PID-Type Fuzzy Control for Anti-Lock Brake Systems with Parameter Adaptation

Abstract: In this research, a platform is built to accomplish a series of experiments to control the Antilock Brake System (ABS). A commercial ABS module controlled by a controller is installed and tested on the platform. The vehicle and tire models are deduced and simulated by a personal computer for real time control. An adaptive PID-type fuzzy control scheme is used. Two on-off conversion methods: pulse width modulation (PWM) and conditional on-off, are used to control the solenoid valves in the ABS module. With the pressure signal feedbacks in the caliper, vehicle dynamics and wheel speeds are computed during braking. Road surface conditions, vehicle weight and control schemes are varied in the experiments to study braking properties.

Novel Principle of Mechanical Energy Dissipation

Abstract: A novel application of Nano-Technology in the field of Mechanical Engineering, called Colloidal Damper (CD), is investigated. This device is complementary to the Hydraulic Damper (HD), having a cylinder-piston construction. Particularly for CD, the hydraulic oil is replaced by a colloidal suspension, which is consisted of a mesoporous matrix and a lyophobic fluid. In this work, the porous matrix is from hydrophobized silica gel and aqueous solutions (water and antifreeze agents) are considered as associated working liquids. A design solution from a practical point of view of the CD static test rig and the measuring technique of the static hysteresis are described. A synthesis of the CD static performances is presented, i. e., the influence of the mean pore diameter, mean particle diameter, particle architecture, liquid surface tension, working pressure, silica gel quantity, water evacuation and relaxation time is illustrated. Our findings agree with the previously published data.

Suppression of Transient Vibration for Geared Mechanical System with Backlash Using Model-Based Control

Abstract: This paper deals with a control technique of eliminating the transient vibration of a geared mechanical system with backlash. This technique is based on a model-based control in order to establish the damping effect at the driven machine part. The control model of dynamical compensator is composed of a linear reduced-order model related to the velocity control loop and the delay element related to the backlash. The control model estimates a load speed converted to the motor shaft. The difference between the estimated load speed and the motor speed is calculated dynamically, and it is added to the velocity command to suppress the transient vibration of the load. This control model is easily obtained from design or experimental data and its algorithm can be easily installed in a DSP. This control technique is applied to a mechanical system composed of spur gears. Simulations and experiments show satisfactory control results.

Effect of Shear Stress on Permeability of Vascular Endothelial Monolayer Cocultured with Smooth Muscle Cells

Abstract: Effect of fluid shear stress on permeability of endothelial monolayer was investigated using an endothelial cell (EC)-smooth muscle cell (SMC) cocultured model (CM). Permeability of ECs to bovine serum albumin was measured after exposure to shear stress of 1.5Pa for 48 hours. Morphology and VE-cadherin expression of ECs in CM was almost same as of ECs cultured alone (monocultured model, MM). Under static condition, EC permeability was 5.1±3.0 × 10-6cm/sec (mean±SD) in MM and 6.5±3.4 × 10-6cm/sec in CM. After exposure to shear stress, EC permeability in CM (2.2±1.9 × 10-6cm/sec, p < 0.05) significantly decreased compared with the static model. However, EC permeability in MM (3.9±3.2 × 10-6cm/sec) did not significantly change compared with static cultured condition. These results suggested that cellular interactions between ECs and SMCs have important influences on EC permeability.

Micro V-Groove Grinding Technique of Large Germanium Immersion Grating Element for Mid-Infrared Spectrograph

Abstract: The 8.2m SUBARU large space telescope in Hawaii requires a mid-infrared high dispersion spectrograph with a resolution of 200000 at 10µm which employs a Germanium Immersion Grating (GIG) element. For this, the GIG element with a large number of sharp and smooth micro V-grooves must be fabricated. Previous studies were focused on the fabrication of a prototype GIG element. The grinding system developed however was not applicable for the fabrication of practical larger GIG element due to insufficient machining space and fast wear of the small grinding wheel used. The ultimate goal of this project was therefore to develop a new grinding system capable of fabricating larger GIG elements for practical use. This paper discusses the results achieved in the first phase of the research, which focused on the principle of the grinding process and grinding system, as well as describes results of micro-truing and micro-grinding experiments using a #4000 metal bonded diamond grinding wheel. Wear variation of the grinding wheel and its effects on the corner radius of micro V-grooves are also discussed. The minimum wheel tip radius of 8.2µm was achieved using this #4000 grinding wheel by micro-truing, and V-groove corner radiuses ranging from 15µm to 25.8µm were also achieved using the same grinding wheel.

Vector Liapunov Function Approach to Longitudinal Control of Vehicles in a Platoon

Abstract: An important aspect of an automated highway system design is the synthesis of an automated vehicle following system. Associated with automated vehicle following system is the problem of the stability of a string of vehicle, i.e., the problem of spacing error propagation, and in some cases, amplification upstream from one vehicle to another, due to some disturbance at the head of the string. In this paper, the novel method to determine the stability of a string of vehicle is established based on the vector Liapunov method. Based on the new results for the stability of string of vehicle, the controller is constructed by sliding mode control method. The stability domain of the controller parameters of the string of vehicles is enlarged.

Time Optimal Path-Tracking Control of Kinematically Redundant Manipulators

Abstract: In this study, we propose a time optimal control scheme for kinematically redundant manipulators to track a predefined geometric path, subject to joint torque limits. The scheme can make full use of redundancy to increase the path-tracking velocity, and the time optimal trajectory planning problem is solved by using the phase-plane analysis and the linear programming technique. Computer simulation is also executed on a three-link planar rotary manipulator to show that, 1) the redundancy of the manipulator is fully used to increase the path-tracking velocity, and 2) redundant joints plus one more joint use their bound values of torque all the time while the time optimal path-tracking task is performed.

Robust Stability Analysis of TS-Fuzzy-Model-Based Control Systems with Both Elemental Parametric Uncertainties and Norm-Bounded Approximation Error

Abstract: This paper discusses the robust stability of Takagi-Sugeno (TS) fuzzy model based control systems. First, it is pointed out that the complex nonlinear control systems with uncertain parameters can be represented as the TS-fuzzy-model-based control systems with both elemental parametric uncertainties and norm-bounded approximation error. Next, a sufficient condition is proposed in terms of linear matrix inequalities (LMIs) for ensuring that the TS-fuzzy-model-based control systems with both elemental parametric uncertainties and norm-bounded approximation error are robustly stable. Some examples are given to show that the proposed sufficient LMI condition may obtain less conservative results than the existing ones reported recently, owing to the proposed sufficient condition taking the elemental information of the parametric uncertain matrices into consideration.