This paper describes the autonomous behavior of block shaped agents existing in a spatially constrained environment. The difficulty of this problem is the determination of the behavior of a block agent under a complex environment dynamically produced mutual actions of many block agents. Moving obstacle avoidance problem causes this difficulty resulting from the autonomous motion of block agents. The objective of this research is to build an adaptive decision mechanism of the behavior for the autonomous block agents when they have their own tasks. Specifically, this paper shows one case study of the proposed mechanism for the problem of removing blocks from a container. It is assumed that the agents are block shaped, and the positions and dimensions of each block are different. Our approach adopted is the Classifier System based architecture. The results of simulation experiments are presented which indicate the possibility of this architecture in allowing block agents to adapt to dynamic environments.
Fiber reinforced plastics (FRP) has become one of the important structural materials in the various fields. Therefore, it is important to evaluate the fracture modes and the fatigue damage of FRP laminates. Acoustic emission (AE) monitoring is useful to study its damage and the modes. However, it is difficult to evaluate the damage and the modes during the fatigue testing. Recently, Wavelet Transform (WT) are the center of attention at the analysis of the signals. The resultant mapping of wavelet coefficients in the time-frequency coordinate plane provides more informative characterization of the signals than the power-density spectra from Fourier Transform (FT). In this report, the AE signals of CFRP and GFRP laminates (i.e. [0°], [0°/90°] and [±45°]) subjecting to cyclic bending loads were recorded at each cycle during the fatigue testing, and were analyzed with WT for evaluating its damage and the modes. By observing the resultant mapping at each cycle, it is possible to develop a methodology for evaluating the damage and the modes by using the characteristic features of the mapping. This system consists of an AE measuring device and a neural network. The network has learned the pattern sets dealing with the interaction between the features of the mapping and the fatigue damage. The character of the mapping was expressed by fractal dimensions that were led by the box-counting method. The effectiveness of this system is demonstrated by comparing results of the neural network with experimental data obtained from the fatigue tests.
Molds and dies are usually fabricated using 3-axis NC milling machines with a spherical cutter. In order to avoid gouging problems in the milling process, a tool reference surface representing the offset shape of the designed surface is computed prior to the cutter path generation. Inverse offset method is used in practice which approximates the tool reference surface as a set of dense points. These points are usually derived as an elevation map of uniform grid points on the xy-plane, therefore distance between the points on the near vertical surface often becomes larger than the acceptable value. Such grid based computation causes stair-case errors on the wall shape, which also deteriorate the surface quality. In this paper, the authors propose an improvement of the inverse offset method. Our method computes the points on the tool reference surface by using additional two grids on the yz-plane and zx-plane. Different from the conventional method, proposed method can control the distance between the points on the tool reference surface being smaller than a certain constant value. Most part of the computation in our method can be accelerated by using the hardware power of the polygon rendering LSI, which is already equipped in most PCs. An experimental program is implemented and some computations of the tool reference surfaces are demonstrated.
To support a cutting tool management system in distributed manufacturing industries, a cutting tool database is necessary to provide required information for the management system. This paper deals with the methodology to construct a cutting tool database and to manage cutting tool information for distributed cutting tool management system using internet. In the past study, by introducing STEP technology and using EXPRESS and EXPRESS-G, we designed an information model of cutting tools, thereby representing models of such basic tool database as parts structure, assembly, nominal size and real size. We proposed an EXPRESS early binding XML for capturing the nature of tool data model, and for generating the serialization format of an EXPRESS data model, and evaluating its usefulness. The conversion of translators to any database systems is done according to mapping model represented by EXPRESS-X using to describe the conditions for conversion.
We propose a new method which can measure large changing deformation phases with a speckle interferometry. In a large object deformation, modulations of light intensity change in speckle interferometry often fluctuate, then the modulations can not be assumed, even-roughly, constant over the deformation. In the proposed changing-phase measurement method, large number of changing speckle images during the deformation are continuously captured A few-tens continuing frames are extracted from all the captured frames, and modulations are estimated over the extracted frames. The estimated modulations and light intensity changes are used to calculate deformation phases and also the final phases in the extracted frame. These calculating process are repeated over all the captured frames. With this method we can measure deformation more than 200μm.
Anti-vibration units have been developed to realize micro-vibration circumstance. Recently, the anti-vibration units using the piezo-elements have been widely developed. In these units, acceleration sensors were ordinarily used. However, in the literature 3), velocity sensors were attached to detect the vibration of structure. Then, the state-feedback theory was naturally applicable to the anti-vibration unit because both the velocity and displacement signals derived by integral action for the velocity could be used. While, the acceleration signal was not utilized as a feedback signal because its signal was not the state variable under the state feedback theory. However, more advanced performance concerning the transmissibility from the vibration of floor to that of isolated table has been expected by using the acceleration signal. In this paper, we propose to utilize the acceleration signal based on the state-feedback theory so as to improve the frequency response of the transmissibility. First, the acceleration signal is passed through a first-order lag filter with small time constant and its filter's output is inserted into the equation of motion. Next, the state-feedback theory is applied to this equation of motion. Finally, the derived controller becomes PID compensator for the velocity signal and it is shown that the feedback coefficients of the PID can be determined by using the optimal regulator design theory.
We have been developed a laser light scattering detector system for the observation of a fine defect on a bare silicon wafer surface. The argon ion laser beam with a single wavelength of 488 nm is turned into a scanning beam through a x-y deflection mechanism, and focused to a small spot by a long focus lens onto the wafer surface at oblique incidence angle of 76 degrees. The system combines a cooled CCD detector and ultramicroscopic technique. The light scattering by the defects on the wafer surface is detected by the high power optical microscope equipped with a 12-bit cooled CCD camera at the surface-normal direction of the wafer. The long exposure and high dynamic range capability of the system allows images with both high sensitivity and high signal to noise ratio to be produced. The light scattering intensity from Si wafer surface depends on the Si wafer samples supplied by corporation. The entire surface of mirror-polished wafer contains micro-roughness and micro-scratches. Micro-roughness constructs a speckle pattern, and the average intensity depends on the magnitude of micro-roughness. The image of the micro-scratch strongly changes with the angle between the incident laser beam and the micro-scratch. The most sharp image is constructed at the angle of 90 degrees. The theoretical estimation of averaged width and depth of the micro-scratches are the order of nanometer, respectively.
As ULSI feature dimensions continue to shrink, and the number of interconnect layers increases from 4 to 8, the resulting surface topography causes serious problems in device patterning. CMP has become a standard technology used in semiconductor manufacturing to planarize the surface topography. We have developed an oscillation-speed-control-type sequential grinding and polishing machine and have proceeded to simulate the polishing process. A previous paper showed theoretically that it is possible to polish within±1% uniformity with the optimum oscillation speed control. This paper presents removal rates measured under high relative velocity and high pressure, and a comparison between experiment and simulation for polishing profiles. It is shown that the removal rate begins to saturate gradually from low relative velocity and that Preston's equation can be used under high pressure caused when the tool overhangs from the wafer. In addition, the experimental result of profiles polished at normal and reverse rotations with disc and ring tools agreed well with the simulation result calculated with a modified equation of relative velocity under high velocity. However, it did not agree when the tool overhung the wafer by a significant amount.
New fabrication methods referred to elastic emission machining (EEM) and plasma chemical vaporization machining (CVM) together with a new figure testing method based on stitching interferometry were applied to prepare the ultraprecise hard x-ray mirror optics. A steeply aspheric ellipsoid mirror for micro-focusing was fabricated and found to achieve nearly diffraction-limited performances. The focusing properties were predicted wave-optically from the measured surface profiles and compared to the observed results. They were in so good agreement that all factors such as incident beam coherency, beam profile measurement, mirror shape metrology and fabrication technology were concluded to be all in the advanced levels.
This paper reports results of machining tests under high hydrostatic pressure, 400MPa, done on four kinds of hard brittle materials; soda glass, quarts glass, quarts, silicon. They were examined by a newly developed machining device that consists of a pressure vessel in which a turntable and a tool stage mechanisms are installed. In the machining tests, end surface of the specimens were machined with a single point diamond tool, and tangential cutting force was measured. The examined specimens were observed with a laser microscope, and profiles of machined grooves and the crack ratio were measured. Results show that external hydrostatic pressure is effective to decrease machining defects and to increase the critical groove section area, which indicates limit of machining volume where no machining fracture arises. Tested materials were separated into two groups based on characteristics of the machining fracture; one is soda glass and quartz glass, the other is quartz and silicon. The former group of materials show steep increase of crack ratio by the increase of groove cross section area, but show small increase of the critical groove section area with the increase of external hydrostatic pressure. Besides the latter material group shows gradual increase of the crack ratio, but large increase of the critical groove section area. The difference of these characteristics depends on difference of crystalline structure. Variation of tangential cutting force was also studied, and results show that cutting force increases with hydrostatic pressure. Magnitude of the effect differs with material.
A precise analysis has been made for the polygonal error of the screw rotor which is cut by using a hob. Firstly, in case that the cutting edge profile of the hob is given as a series of dispersive points, theoretical equations are derived to represent the profile of the screw rotor which is cut by using the hob. Secondly, a theoretical analysis is made to obtain the polygonal error of the screw rotor by using these equations. Thirdly, a numerical analysis method is proposed to obtain the polygonal error of the screw rotor. Finally, theories in this analysis are verified by applying the numerical analysis method to dimensions of the screw rotor hob.
Cutting performances of CVD (Chemical Vapor Deposition) diamond coated drills for brittle materials such as single-crystal Si or silicon carbide ceramics were investigated. For drilling of single-crystal Si, only a mere wear of CVD diamond film around the cutting edges was observed, but damage of cutting edges was dominated by chipping. Chipping performances were affected by shape of drill, the chipping of the cutting edges were repressed for the drills with large web thickness and long tool life were obtained. On the other hand, for drilling of silicon carbide, severe wear of CVD diamond film was observed. Major cutting edge showed "knife edge shape". These phenomena are very characteristic as compared with conventional carbide drills.