In this research, Milling combined Laser Sintering System (MLSS) is used to make a sintered material. MLSS is a rapid tooling system using a fine metallic powder integrated with machining process whereby it can do laser sintering of fine metallic powder and also high-speed milling. This paper deals with the investigation of sintered material machinability by measuring its specific cutting energy and tool flank temperature. Carbon steel (JIS S55C) is selected as a standard steel. The effects of cutting conditions, laser consolidation energy density, powder consolidation mechanisms and unsintered powder on its machinability are measured. It is demonstrated that tool flank temperatures for all sintered materials are higher than JIS S55C. Low energy density for consolidation of metal powder increases the machinability of sintered materials. Cutting at the partially molten powder decreases the machinability of sintered material. Cutting with the existence of unsintered metallic powder surrounding the sintered material diminishes its machinability.

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In this paper, we address the problem of lens aberration adjustment for lenses of semiconductor lithography equipment. The objective of aberration adjustment is to minimize the maximum value of aberration in any part of the images that are projected on the wafer. Formerly, an approximate solution method has been used, which is based on a brute force search for a subset of all cases. However, using that method, computational times are often long and a faster solution method is necessary. Nowadays, owing to significant progress in mathematical programming research, MIP (Mixed Integer Programming) solvers can reach an optimal solution quite fast. That is why, in this paper, we propose an exact solution method based on 0-1 MIP, which addresses the same “lens aberration” problem with the same objective of minimizing maximum absolute value of lens aberration. In real-world 9 instances, our solution method improves maximum aberration values by 18% to 56% over similar results from conventional solution methods.

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The windage of a head gimbal assembly (HGA) is the flow-induced vibration affecting head slider positioning in the off-track direction. Reducing the windage is important for increasing the track density of hard disk drives (HDDs). To develop HGAs with a windage smaller than that of conventional HGAs, we examined the characteristics of HGA windage. We used a 12-mm (from the swage hole center to the dimple) HGA that had a maximum windage peak at 11 kHz. We put it in a spin stand and in a HDD and measured its windage with a laser Doppler vibrometer. The windage amplitude correlated well with the mean airflow velocity in the HDD (measured with a laser Doppler anemometer). Windage amplitude was also affected by fluctuation of the airflow velocity. Our results show that HGA windage can be reduced by increasing the distances between the rotating disk and the cover and the base.

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We are developing an optical three-axis tactile sensor capable of acquiring normal and shearing force to mount on a robotic finger. The tactile sensor is based on the principle of an optical waveguide-type tactile sensor, which is composed of an acrylic hemispherical dome, a light source, an array of rubber sensing elements, and a CCD camera. The sensing element of the silicone rubber comprises one columnar feeler and eight conical feelers. The contact areas of the conical feelers, which maintain contact with the acrylic dome, detect the three-axis force applied to the tip of the sensing element. Normal and shearing forces are then calculated from integration and centroid displacement of the grayscale value derived from the conical feeler's contacts. To evaluate the present tactile sensor, we conducted a series of experiments using an x-z stage, a rotational stage, and a force gauge. Although we discovered that the relationship between the integrated grayscale value and normal force depends on the sensor's latitude on the hemispherical surface, it is easy to modify the sensitivity based on the latitude to make the centroid displacement of the grayscale value proportional to the shearing force. When we examined the repeatability of the present tactile sensor with 1,000 load/unload cycles, the error was 2%.

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Kinematic design of a lower-dof parallel mechanism, a 3-URU pure rotational parallel mechanism, is presented that takes into account the “uncompensatable error”. The uncompensatable error is defined as the position error of the rotation center of the platform caused by errors in the kinematic constants, such as a joint axis error, that cannot be compensated for by control or calibration. Sensitivity matrices for four error sources were derived, introducing virtual revolute joints. An index for evaluating the magnitude of the uncompensatable error was developed and used to numerically investigate the effect of kinematic constants on the uncompensatable error. Finally, an optimal design for an application of the 3-URU parallel mechanism to a tool-orientating device was done in consideration of the uncompensatable error. In this design, the redundant orientation parameter was optimized together with the values of the kinematic constants to minimize the uncompensatable error. Two mechanisms optimal for different workspace specifications were derived.

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Nonrepetitive runout (NRRO) is mainly caused by the diameter differences of balls contained in a bearing and the form errors of the raceway and balls. This paper deals with the effect of grease lubrication on NRRO. The results can be summarized as follows. (1) NRRO in the case of grease lubrication was larger than that in the case of oil lubrication. (2) The rotational frequency of cage increased with the increment of unbalance or rotational speed. In the rotational accuracy on the level of one nanometer, it was clarified that the lubricant was a very important factor in a ball bearing.

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The clamping force of a bolt/nut assembly greatly influences its strength. However it is well-known that the clamping force of a bolt/nut assembly tightened by the torque control method varies widely. In this study, a new tightening method of a bolt/nut assembly that controls the clamping force more accurately has been proposed. In the proposed method, a bolt/nut assembly is tightened by pulling the bolt thread portion protruding through the nut with a force corresponding to the target clamping force. Experiments to verify the usefulness of the proposed method have been performed. The results show that the proposed method can accurately tighten a bolt/nut assembly with an error of approximately ±10% in relation to the target.

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This work formulates and demonstrates a motion generation method for the synthesis of a multi-loop planar six-bar mechanism comparable to the Belgrade/USC robotic hand ^(13)(14). The method presented in this work can accommodate numbers of prescribed rigid-body poses beyond the maximum number of poses allowable using conventional planar six-bar mechanism synthesis models ⁽¹⁰⁾. The example included demonstrates the design of a mechanical hand to achieve twice the maximum number of displacements allowable with conventional synthesis models.

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Logistics has been acknowledged increasingly as a key issue of supply chain management to improve business efficiency under global competition and diversified customer demands. This study aims at improving a quality of strategic decision making associated with dynamic natures in logistics network optimization. Especially, noticing an importance to concern with a multimodal logistics under multiterms, we have extended a previous approach termed hybrid tabu search (HybTS). The attempt intends to deploy a strategic planning more concretely so that the strategic plan can link to an operational decision making. The idea refers to a smart extension of the HybTS to solve a dynamic mixed integer programming problem. It is a two-level iterative method composed of a sophisticated tabu search for the location problem at the upper level and a graph algorithm for the route selection at the lower level. To keep efficiency while coping with the resulting extremely large-scale problem, we invented a systematic procedure to transform the original linear program at the lower-level into a minimum cost flow problem solvable by the graph algorithm. Through numerical experiments, we verified the proposed method outperformed the commercial software. The results indicate the proposed approach can make the conventional strategic decision much more practical and is promising for real world applications.

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A planar four-bar path generation model that also includes mechanism static structural conditions is formulated and demonstrated in this work. Using this model, planar four-bar path generators are also synthesized with respect to static torque, deflection constraints and buckling constraints for a given rigid-body load.

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The steady state performance characteristics of centrally loaded 60 degree single pad externally adjustable partial arc bearing is studied theoretically. Principal feature of the bearing is the facility to control its radial clearance and circumferential film thickness gradient, during operation. The bearing has aspect ratios of 1.0, 0.5 and 0.25 and operates over a wide range of eccentricity ratios and adjustments. Steady state performance characteristics of the bearing are presented in terms of attitude angle, load carrying capacity, oil flow and friction variable. The steady state form of Reynolds equation in two dimensions is solved numerically using the finite difference method. The effect of tilt and the radial adjustments on the steady state performance characteristics are presented in the form of plots. A comparative study predicts that negative radial and negative tilt adjustment results in better load carrying capacity with reduced oil flow and friction.

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A novel Chebyshev functional recurrent neuro-fuzzy (CFRNF) network is developed from a combination of the Takagi-Sugeno-Kang (TSK) fuzzy model and the Chebyshev recurrent neural network (CRNN). The CFRNF network can emulate the nonlinear dynamics of a servomechanism system. The system nonlinearity is addressed by enhancing the input dimensions of the consequent parts in the fuzzy rules due to functional expansion of a Chebyshev polynomial. The back propagation algorithm is used to adjust the parameters of the antecedent membership functions as well as those of consequent functions. To verify the performance of the proposed CFRNF, the experiment of the belt servomechanism is presented in this paper. Both of identification methods of adaptive neural fuzzy inference system (ANFIS) and recurrent neural network (RNN) are also studied for modeling of the belt servomechanism. The analysis and comparison results indicate that CFRNF makes identification of complex nonlinear dynamic systems easier. It is verified that the accuracy and convergence of the CFRNF are superior to those of ANFIS and RNN by the identification results of a belt servomechanism.

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