In this study, a new algorithm to search the shortest path of mobile robot between start and goal points in given environment is proposed. In the path search, computation of collision domain of robot and environment is crucial. A domain on which the reference point of robot must not trespass is called collision domain. Collision domain is quickly computed by Inverted Template Method using double-stage fast Fourier transform. Collision and collision-free domains are represented by a tree structure to save memory and to reduce the calculation time. When robot does not rotate, path is searched in a two-dimensional plane and the domains are represented by a quadtree. The path is taken in collision-free domain by Minimum Total Distance Method. Firstly, the L1 distance of each cell in collision free domain is determined successively from the start point, and then from the goal point. Secondly, thetwo values on each cell are summed up to obtain total distance map. Finally, the shortest path is found by tracing the cells which have the minimum total distance in the map. When robot can rotate in xy-plane, the rotation angle is associated with z-axis. The shortest path is searched in three-dimensional collision free domain represented by an octree.

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Flexible machine can be designed by combining the standardized modules. Here, a module is a simple hardware or software unit that performs a simple function and can be easily combined with others. This paper proposes two design principles of such machines from a viewpoint of information. The first design principle is the consideration of the system's entropy. Entropy can be a measure of the uncertainty of the system and used as a criterion for evaluating module combination. The second is the consideration of information flow balance in the system.Interpretive Structural Modeling (ISM) is useful to clarify the inherent hierarchical structure in the information system. After ISM, the information processing load and data transfer rate in the system can be examined. The combination that decreases the entropy with a minimum information processing load is preferable. Experiments to design a sensor system were conducted and a combination of a CCD camera and an ultrasonic sensor demonstrated the usefulness and effectiveness of the principles.

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Designing shapes of products is one of the most primary activity in design process. It is common, especially in the early design stage, that designers have only a vague image of shapes in their mind, and they try hard to extract these image by making sketches or prototypes. At this stage, exhibiting a definitive image of shapes with hard lines to the designers might restrict the bounds of their imagination. Therefore, a new methodology of representing free form shape feature with the aim of making the system capable of holding and exaggerating their features after synthesizing them to support designer in their early design stage is proposed. The key idea in this study is dynamic representation and generation of feature shapes. Developmental biology is applied to devise a computational model of the representation called Cell Model using genetic algorithms (GAs). Finally, a computer program is developed to evaluate the methodology by combining two existing shapes. It is demonstrated that the methodology can show variety of shapes with original, often exaggerated, features.

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In spite of fairly complex contents described in a given part drawing, an experienced engineer produces process planning in short time. By transplanting the experienced engineer's decision making process into computer environment, the flair typed process planning system was developed, utilized and discussed in the case of easy process planning on our previous paper. In the paper, the model to show the engineer's decision making process was called the thought-model. The models for the case of difficult process planning are examined in our recent research so far. During the research, it turns out to be necessary that the way of dealing with special interpretation of the engineers' knowledge in some thought-models should be constructed as thought object in only the case of difficult process planning. This paper is to report on such thought-models for the case of difficult process planning, the special interpretation of the engineer's knowledge and the way to handle it in a computer environment.

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The generalized Hough transform is a method for extracting similar figures to the template figure in an image. The generalized Hough transform needs huge memory for the four dimensional parameter space which represents locations, scales and rotation angles of objective figures and requires processor power for address conversion from an image space into the parameter space. The paper proposes a method using multiple two dimensional parameter spaces for reducing the volume of the parameter space and for performing high speed processing. As the experimental result, the method provided high rate repeatability on the position, the scale and the rotation angle of extracted figures and short processing time.

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This paper facilitates the conception of signal flow graph theory, which makes it possible to determine, the angular velocity of the planetary gear trains. In design of the planetary gear train, the determination of the angular velocity of these is one of the important subjects. In almost the method used for kinematics analysis of planetary gear train are inherent for gearing itself and are tedius. In order to make these analysis of the planetary gear train understandable, the article proposes the representation by algebraic vector equation and graph theory for these problems. Moreover, the article presents examples of the application of this method for the complex type, 2K-H type and 3K type paradox gear trains.

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Laser lithography is an optical forming method which heaps up thin layers solidified by laser beam. Since plastic models which are made by laser lithography process have ledges on their surfaces, reducing ledges is required to use them as master models for jewelry. A diagonal irradiation method for reducing ledges is presented. The diagonal irradiation method improves surface roughness by means of heap up diagonal shape solidified by diagonal laser irradiation. Diagonal solidifying behavior was clarified by theoretical calculation. As the result of an experiment, average surface roughness of 10μm in steep slope area and improvementof out of roundness was obtained by the diagonal irradiation method.

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A method for measuring surface profile of objects with large steps is proposed and verified by some basic experiments. The method uses a pattern of two primary color gratings with different pitches, which is projected on the object surface through a liquid crystal projector controlled by a computer. In the single grating projection, the integer grating order becomes ambiguous and the profile cannot be determined when the height change between any adjacent pixels is larger than a height corresponding to the grating pitch. In the proposed method, two gratings are projected on the object at a time. Two phases of the deformed gratings are calculated by phase-shifting technique. Integer orders can be determined by the phase difference between them. In the experiment made for proving the validity of the proposal, the deformed gratings are observed through color filters sequentially. An object with step height of 20.0mm is measured with standard deviation about 0.3%.

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This paper is concerned with the design and control of high speed spindle suspended by magnetic bearings using the discrete time sliding mode control method. The plant dynamics, consisting of actuator dynamics and flexible rotor dynamics, are described in detail. A new discrete time sliding mode servo controller using linear observer, which can attenuate the chattering phenomenon, is proposed. The usefulness of the proposed controller is demonstrated through the computer simulations and several rotational experiments up to 100 000rpm for a spindlemagnetic bearing system.

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According to the increase of the concern to the ecological problem, the use of agricultural chemicals for weeding in the golf course is made the social problem. Therefore, automatic machine weeding is expected. This study, first, surveys what is the weeding work of golf course. Next, it investigates how to detect the weed in the loan. Sensors of several principles are trially made and examined comparatively at the “fairway” and “green” of golf course. Examined sensors are follows : (1) Detecting from the difference of the color (image processing by CCD camera, color sensor with band pass filter). (2) Detecting from the difference of the water percentage (microwave transmitter and receiver). (3) Detecting from the difference of the tactile feeling (tactile sensor made by urethane rubber with strain gauge). The result shows that any sensor can detect the weed in the loan. Sensor output, however, changes depending on the season, time and weather. Therefore, to realize the automatic weed detecting system, it is very important to develop the “sensor fusion” technique by using the plural sensors of the different methods.

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5-axis control machining has the potentials of producing workpieces with complicated shape efficiently and accurately in comparison with conventional 3-axis control one. NC data for 5-axis control machine tools are in general offered by CAD/CAM systems, which create collision-free CL data from the workpiece and tool shapes. The post-processor plays an important role of providing actual NC data from CL data, taking account of a variety of 5-axis control machine tool structures. The study deals with the proposal of how to construct generalized post-processor, independent of the machine tool structures, by applying a concept of the form shape function, which represents the linkage and kinematics of control axes. As the result, the validity of the proposed generalized post-processor is experimentally confirmed.

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The Cross Grid Encoder is a position detector with a grid which crosses at a right angle, superior to conventional optical linear scales which have not been capable, as the Cross Grid Encoder is, of two-dimensional position detection. When this system is applied in the Circular Motion Test, measurement of behavior on a small radius and high feedrate was conducted with high precision, a capability which the DBB test has not offered. In addition, since it can measure the error of not only the circular interpolation but also the linear interpolation, it is possible to obtain information which is very beneficial for the improvement of machine accuracy. This study investigates the causes of the impediments towards machining accuracy improvements by comparing the accuracy measurement of the double-axis feed motion and actual machining accuracy on the ultra-high precision NC machine tool. Finally, by clearing away the ultimate causes of the impediments the improvement of machining accuracy is confirmed.

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A mating part must have a smooth surface and an accurate form at the fitting area. When a new internal finishing process is utilized by the application of magnetic abrasive machining to internal finishing of hole of mating parts, it is necessary to clarify the effects of this finishing process on the form accuracy, such as the cylindricity and roundness. The effects on the cylindricity have been already reported, so that this paper discusses the effects on the roundness. Theoretical equations describing the roundness curve on the process are presented and experimentally proved. According to the equations, the roundness will be worsened with the finishing process. The rates of changes in the roundness curve before and after finishing are calculated less than 0.1% under the conditions used in the experiments. On the other hand, the changes in the roundness curve are observed in the finishing experiments of neither the clean pipes nor the workpieces with high form accuracy. These result in that the effects on the roundness are considered negligible under the conventional finishing conditions. Consequently, it is clarified that this finishing process has a characteristic to make the surface smooth with hardly changing the initial roundness curve.

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This paper deals with the discrete error analysis of material error calculation in Dynamic Machining Simulator (DMS). DMS can simulate the material removal per tool revolution in a real-time fashion when the tool moves along the path defined by a CNC program. Based on calculated removal rate, the feed rate is optimized so that the loading to the tool can be maintained at the permissive maximum value. In this simulation technique, the accuracy of the material removal calculation which is to be performed in a discrete manner, is very important to achieve the reliable control. In this study, the algorithm for error analysis is developed and optimum values of simulation parameters are determined for three typical end mill operation.

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This paper examines the grinding performances of SiC whisker wheel. The effect of various parameters of wheel on the surface finish are clarified. The selected parameters related to the grinding wheel design are the segment width, additive, whisker diameter and bonding material. The experimental results obtained are as follows : (1) The smaller the diameter of whisker and thenarrower the segment width, the better the surface finish. The resin bonded wheel with Cr₂O₃ additive has shown the best surface finish. (2) The ultra fine grinding chips and the finished surface have been observed. (3) Surface finish with a roughness value of 1.5 nmRa has been successfully obtained.

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In this study diamond turning and Vickers indentation testing on single-crystal silicon, quartz crystal, fused silica, and glass were carried out. Based on the fracture behaviour of these brittle materials, the mechanism of ductile-regime turning was investigated. The material removal mechanism tends to change from ductile to brittle with increasing depth of cut. With the turning of single-crystal silicon, quartz crystal, and glass, cracks, produced by excessive tensile stress around thecutting edge of the tool, propagate upward from the cutting edge to the free surface of the work. However, since these cracks do not remain behind as damage on the turned surface, the turning process proceeds under a ductile regime. At a larger depth of cut, brittle fracture occurs due to elastic recovery (elastic/plastic mismatch stress field) after the cutting tool passes. This is the same mechanism as that found in crack formation occurring during the unloading period of the indentation cycle. On the other hand, the fused silica showed different fracture behaviour. After indentation, Hertzian cone crackswere produced at maximum tensile stress in the elastic stress field. Therefore, it is difficult to realise ductile-regime turning with fused silica, as extensive cracking is generated in front of the cutting edge.

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In cutting and grinding operations, cutting and grinding fluids are generally used for cooling and lubricating workpieces at the point of cutting. These fluids often contain sulfur, phosphorus, chlorine or other such extremepressure additive to improve the lubricating performance. These chemicals present health hazards they are introduced from the running machine into the workplace atmosphere in the form of liquid splash. Furthermore, treatment of the waste liquid costs high, and the treatment itself is a source of air pollution due to the fact that the process involves extremely high temperatures, and particularly so when the waste liquid contains chlorine. This paper describes the results of a study of a new grinding method (Cooling Air Grinding System). It eliminates the need for hazardous conventional grinding fluids, yet provides a better grinding performance than the conventional technology. The method consists of a CBN wheel, well known for its low heat emission during grinding, and a supply of cooling air to the grinding point. The CBN wheel has been treated previously with a solid lubricant or an extremely small amount of vegetable oil was supplied at a rate of 10ml/h in addition to the cooling air supply. The test results indicate that the combination of CBN wheel and air supply maintains a clean workplace and suppress heat emission into the atmosphere.

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The internal abrasive wheel is dressed using a high accuracy external gear with electroplated diamond grains. This dressing can be done with short dressing time and correct transferring of the profile is achieved. If intermeshing gears are selected to have a proper length of path of action, the abrasive wheel has a sufficient gear guiding ability. The guiding ability was clarified by dressing experiments. When the radial feed in dressing is lower than 150mm/min, the corresponding abrasive wheel speed can be increase up to 80rpm. Change in abrasive wheel driving power is very small without producing glazing of abrasive grains, and the dressing time could be reduced by about 40%. The form transferring ability appears in the accuracy of a dressed abrasive wheel. When the radial feed is 2.5μm/traverse, the accuracy of a dressed abrasive wheel was less than 20μm. As the form transferring ability is very high, this dressing will get much better appraisal. These results can be applied for making gears of high accuracy using the gear honing method.

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