This paper describes a new linear switched reluctance motor (LSRM) with a light and easily replaceable mover. The proposed LSRM has coils at both ends of the stator so as to have a thin shape, which is important for systems with a limited work space. The mover has a simple and thin shape, leading to easy fabrication and space savings. It is made from common materials and is easily recyclable. The flat areas on the surfaces of the mover and stator are used as a slide guide. The prototype LSRM has a thickness of 2.4 mm, and the thickness of the mover is 0.27 mm. The suitable driving signal for the proposed LSRM is determined from the numerical magnetic analysis results. The prototype LSRM shows a velocity higher than 285 mm/s and an acceleration higher than 3 m/s2.
Through dynamic simulation of the cross-hinge four-bar mechanism, it is found the primary reason for unbalance of the mechanism results from the unequal swing angle of driving link and driven link. To simplify analysis and calculation, a spatial switching approach was proposed to switch nonlinear problem into linear problem, by switching the problem of unequal swing angle of driving link and driven link into the problem of length variation of connecting link. Therefore, the length of driving link, the degree of its angle of intersection, and the amplitude of swing are three important parameters that influence the dynamic balance of the mechanism. An optimal design software was designed on the basis of establishment of target function and constraint conditions. Finally, through optimal calculation of the design software and Adams simulation, a case was employed to test the efficiency of the optimal design approach.
The present paper describes the sensitivity coefficient of measurement in the three-dimensional circular interpolation movement that is equivalent to cone-frustum cutting in five-axis machining centers with a tilting rotary table. The sensitive direction of a ball bar having a one-dimensional displacement sensor is parallel to its telescopic bar. In the present paper, the ratio of the measurement value to the actual error is defined as the sensitivity coefficient of measurement. The sensitivity coefficient of each axis is calculated by changing the apex angle and location of the cone-frustum. Different trajectories are obtained according to the attitude of the ball bar. This is due to the resulting variation in the sensitivity coefficient of the ball bar. If the ball bar is set parallel to the base circle of the cone-frustum, and if the center of the cone-frustum is positioned away from the centerline of the rotary table (in the positive direction of the linear axis that is perpendicular to the tilting axis of the table), the trajectory can be obtained appropriately.
This paper describes a general theory for the characteristics of voltage-induction-type electrostatic motors (VITEMs). VITEMs are one of macro-scale electrostatic film motors with multi-phase electrodes on both the sliders and the stators. The motor drives synchronously without voltage feeding wires to its slider due to the indirect power supply using electrostatic induction. Although the numbers of electrode phases can be chosen arbitrary to realize the motor, the characteristics of the motors were analyzed only for two specific cases in the previous studies. This work extends the previously proposed theories so that they can handle a general case, in which the slider and the stator have m- and n-phase electrodes with arbitrary numbers for m and n. The theory can estimate the optimized thrust force performance for any electrode configurations, when given fundamental parameters regarding the capacitance coefficients of the motor, which can be obtained either experimentally or numerically. Using the proposed theory, several different configurations of VITEMs are analyzed and compared, in terms of thrust force performance. The results indicate that electrode thickness considerably affects the thrust force performance of VITEMs, which is not the case for other synchronous electrostatic film motors, and thus suggest that the design of VITEMs should more carefully consider the three-dimensional structure of the electrodes.
We developed a new diagnostic method by using a laser beam. A tooth surface is irradiated by the zonal laser beam from an oblique direction, and then the irradiated laser beam line is shifted along the height of the tooth according to gear rotation. The variation of the voltage proportional to laser reflection between initial and present conditions are compared, and the condition of the tooth surface can be diagnosed for things such as initial or abnormal abrasion, pitting, etc. Furthermore, we developed a method of automatic and remote damage diagnosis on a gear tooth surface according to various gear specifications by using the angle-distance relation map which made from pre-measured data of same material and heat treatment, and taking into account the influence of adjacent teeth. The measured data agreed well with the predicted data made with this method, therefore we can diagnosis the condition of various products automatically.
A method for reconstructing a complete three-dimensional (3D) voxel model from multiple images captured during two circular motions of an object is proposed. The two circular motions include the object with a regular orientation and the corresponding reversed orientation. The shape-from-silhouette method, which constructs a voxel-based 3D model from the silhouettes of two-dimensional (2D) images, is used for the reconstruction. In general, a single camera focused on an object's circular motion cannot capture the entire object using a single fixed orientation. Thus, it is required to invert the orientation of the object at least once to capture the entire object. In this paper, a novel method for integrating two incomplete reconstructed voxel models to produce a single complete voxel model is discussed. Complex examples are provided to demonstrate the effectiveness of the proposed algorithms.
One of the major problems of the push Repetitive Manufacturing Systems (RMS) is the Work In Process (WIP) buildups between the stations due to the push nature of the flow of material. Card-based pull or push-pull production control systems offered smooth production flow with reduced WIP. But, applying these systems to push production environment requires huge cost for major cultural and operational changes. We propose a solution to WIP buildups, without altering the basic structure of operation of the push production system. We propose a bottleneck oriented card-based production control system for push RMS. In our system parts release on the shop floor according to the customer demand whereas the material flow is constrained with the Production Authorization Cards (PAC). The PAC circulates between the first station and the bottleneck station in the form of a loop, reducing WIP buildups between the stations. We have conducted simulation based case studies to demonstrate the efficacy of our approach.
A photomask for semiconductor device production faces serious problems related to the thermal displacement of the mask pattern during exposure. During mask exposure, pattern placement error occurs in the mask. The minimization of thermal in-plane displacement is needed. To estimate thermal displacement, a model based on the three-dimensional steady-state thermal theory and two-dimensional in-plane stress theory was proposed by the finite difference method. Three types of boundary condition, that is, a free edge, a fixed edge, and a combination of a free edge and a fixed edge were investigated to minimize mask pattern placement error. Quantitative relations of the boundary condition and thermal displacement were clarified. It was found that the fixed edge minimizes pattern placement error caused by thermal expansion. Moreover, the combination of the free and fixed edges indicated the directionality of the placement error distribution.
This paper describes the driving voltage reduction of an optical switch that has an S-shaped deformable thin-film mirror driven by an electrostatic force. The prototype optical switch has high-dielectric-constant layers made from Ta2O5 for a low applied voltage to generate a sufficiently large attractive force. Although the dielectric layers are effective at increasing the attractive force, they often cause a charging problem. Thus, suitable driving procedures for solving the charging problem were experimentally examined. In the two driving procedures, AC or DC voltage inputs were used. The experimental results indicate that the driving procedures are effective at reducing the driving voltage to 30 V. However, the results also show that the AC components induce a residual vibration of the spot position. Consequently, the driving procedure with the DC voltage input is proven to be more suitable.
In Japan, since the Great Hanshin-Awaji Earthquake, attention has surrounded the development of disaster victim relief activity using robots. Development of a robot that can adapt to various environments in irregular places, rubble, and confined areas is necessary. A wheel movement type robot, a robot in the shape of a snake and a multi-leg robot are all described in the relevant literature as rescue robots that are currently studied. Among them, the tracked crawler robot can travel by traversing uneven ground flexibly with a crawler belt attached firmly to the ground surface. Although conventional crawler robots have high efficiency and/or high ground-covering ability, they require a comparatively large space to move. In this study, a cylindrical crawler robot based on worm-rack mechanism, which does not need large space to move and which has high ground-covering ability, is proposed. Experiments have demonstrated smooth operation and a forward movement of the robot by application of voltage to the motor. In addition, performance tests show that it can propel itself in confined spaces and in irregular areas. This paper reports the structure, drive mechanism, prototype, and experimental evaluation.
A simulation of the rolling contact fatigue strength of a traction drive element was proposed. The simulation can account for both the distribution of sizes of inclusions in the element material and the influence of traction forces at the element surface. The shear strength of the matrix structure surrounding an inclusion was estimated with an equation. The hardness distribution and the Weibull distribution of inclusion dimensions, which were necessary parameters to calculate the rolling contact fatigue strength, were determined by observation of an actual test specimen. And the rolling contact fatigue strength was compared with the distribution of shear stresses in a roller affected by traction forces. A simulation assuming the same traction coefficient as that in the experiment predicted a rolling contact fatigue strength of 810 MPa with a standard deviation of 39.2 MPa, which differed from the experimental value by only 2.5%. Simulations of the rolling contact fatigue strength were then carried out while varying the traction coefficient. The contact force resulting in failure was observed to fall as the traction coefficient increased and the torque capacity increased. Thus, the torque capacity increases with the traction coefficient, regardless of changes in the rolling contact fatigue strength.
Laser beam cutting (LBC) is a non-contact machining method that is widely used in industry. In order to improve cutting speed and reduce the consumption of assist gas, it is necessary to employ a machining method that applies a suitable eccentricity between the laser beam axis and the assist gas nozzle axis. This paper describes the development of a high-speed, high-precision, magnetic drive actuator, which can be attached to a conventional LBC machine to control the relative displacement between the laser beam axis and the assist gas nozzle axis in two orthogonal directions. First, a magnetic drive actuator is designed and fabricated. In the actuator, the motions of the lens in the radial directions are controlled by electromagnets, and the motions in the other directions are constrained by elastic hinges. Second, a compensation method for the zero point of the displacement sensors that are used to measure the displacements of the lens in the radial direction and an adaptive control method for the actuator are presented. Finally, the effectiveness of the presented control method is verified, and the positioning performance of the actuator is evaluated through experiments. The experimental results showed that the vibration of the lens was reduced using the presented control method, and the actuator had a positioning resolution of 0.75 µm, a bandwidth greater than 133 Hz, and a positioning stroke of 1 mm.
This paper describes a new proposed strategy for Adaptive Plan System of Swarm Intelligent — Particle Swarm Optimization (PSO) using Differential Evolution (DE) with Genetic Algorithm (GA) called DE/PSOGA to solve large scale optimization problems, to reduce calculation cost, and to improve convergence towards the optimal solution. This is an approach that combines the global search ability of DE, GA and the local search ability of Adaptive plan (AP). The proposed strategy incorporates concepts from DE and PSO, updating particles not only by DE operators but also by mechanism of PSO for Adaptive System (AS) with GA. To evaluate its performance, the DE/PSOGA is applied to various benchmark tests with multi-dimensions. It is shown to be statistically significantly superior to other Evolutionary Algorithms (EAs), and Memetic Algorithms (MAs). We confirmed satisfactory performance through various benchmark tests.
This study examined the wear characteristics of ceramic tools when turning BN free-machining steel based on AISI 1045. An experiment was conducted to investigate why the alumina TiC-based ceramic tool showed remarkably better cutting performance than a pure alumina ceramic tool. The tool flank temperature, cutting force, and element distribution on the wear part were investigated. The cutting force and tool flank temperature of the BN free-machining steel were lower than those of standard steel, and the alumina TiC-based ceramic tool allowed for a lower cutting force and tool flank temperature than the pure alumina ceramic tool. After cutting of the BN free-machining steel, on the rake face, a deposited layer containing Al and N was detected, and the amount of the deposited layer on the alumina TiC-based ceramic tool was more than that on the pure alumina ceramic tool. Therefore, using an alumina TiC-based ceramic tool suppresses the tool flank temperature and makes it easier for a protective nitride layer to stick on the wear part; as a result, it has a clearly superior tool wear resistance than an alumina ceramic tool.
Under recent global competition and short product life cycle, we need to undertake agile decision making in every manufacturing process. With this point of view, this study provides a practical hybrid meta-heuristic method for a three echelon logistic network optimization. It supports decision making at a tactical and operational level associated with inventory management for daily planning. That includes a new idea to solve practical multi-depot VRP efficiently. Its solution procedure is developed by means of two modified heuristic methods known as the saving method and tabu search togather with the graph algorithm of minimum cost flow problem. The resulting procedure is expected to play a role of optimization engine in the total system incorporated with information system for inventory management. Moreover, to enhance usability of the method, visualization of result is also realized by virtue of Google map API. Numerical experiments are carried out to validate effectiveness of the proposed approach.