This paper describes a motion control for parallel mechanism. A motion control is commonly based on an acceleration controller. High performance acceleration controller is realized by the disturbance observer. In parallel mechanism, high performance acceleration controller is also expected to be improved in workspace. However, it is difficult to calculate its forward kinematics analytically. In a conventional method, it takes more time to compute its forward kinematics compared with serial mechanism, unless passive joint angles are measured directly. Thus, it is possible to reduce sampling rate of controller. In this paper, the conventional acceleration controller based on disturbance observer is extended to parallel mechanism. A new observer is proposed which estimates not only disturbance torque, but also forward kinematics through identity observer. The estimated joint angular velocity is transformed to workspace velocity by jacobian matrix. And forward kinematics is obtained by integrating workspace velocity. Moreover, estimated joint angle which is calculated by inverse kinematics, is used to reduce estimated error. By implementing the feedback of estimated disturbance to input torque, disturbance torque is compensated without inverse dynamics calculation. High performance acceleration controller in parallel mechanism is realized as well as in serial mechanism. A new parallel mechanism is also developed for the biped robot which has light legs. The validity of the proposed method is confirmed by the experimental results.

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To realize a positioning with high accuracy for straight-corner slide system, the internal gear type trochoidal corner curve rack system has been developed. This system consists of a straight trochoidal rack, a corner curve rack with internal gear type trochoidal cam tooth, a roller pinion and a linear-corner slide system. Also the tooth profile is generated using trochoidal curve loci. In this report, the motion principle is analyzed using the polar complex vectors analysis which is similar to the linear motion type cam rack. And to eliminate a backlash on the connecting section of a straight rack and a corner rack, the conditions to modify the teeth profile are shown. It is proved that a reduction ratio and a tooth height are limited to keep the non-backlash meshing for the straight-corner slide system. Also the combination of each profile shifting coefficient of the straight rack and the corner curve rack is limited.

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This article describes a geometric calibration method for a coordinate measuring machine based on a three degree of freedom parallel mechanism. In generally, identifying whole, necessary and sufficient, kinematic parameters included in kinematic models of parallel mechanisms is hard because of the strong correlation between each parameter. In this study, we propose to use some different links on the calibration to improve the mathematical condition of the Jacobian matrix on the least squares method. To use the different links, all kinematic parameters are estimated and the positioning accuracy of the parallel coordinate measuring machine is improved from 100 μm to 5 μm in the experiments. Firstly, the pilot unit of the parallel coordinate measuring machine is introduced. Secondly, necessary and sufficient kinematic parameters of the parallel coordinate machine for calibration are formulated. Finally, kinematic parameters are estimated through the calibration experiment.

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This paper proposes a method to measure the direction of an indicator and to extract the center of a circular analog meter in an objective image. It is difficult to exchange analog meters for digital meters because many meters must be checked by the human visual sense in industrial fields. Then, a method to recognize an analog meter in a captured image is required. In the proposed method, the center of a circular meter is extracted by the combinational Hough transform based on the geometrical feature between a pair of edge pixels on the meter frame and an edge pixel on the indicator. The experimental results show that the centers of analog meters were extracted and the inclinations of indicators were measured successfully by the proposed method.

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Environmental support is one of the effective approaches for robots to do tasks efficiently in office and home environments. In order to accomplish robust and rapid task realization of robots, both the environmental support and robot motion should be designed carefully. Authors have proposed the integrated methodology of designing two factors by using reliability theory. In this paper, we realize environmental support by attaching “artificial marks with memory” to all the objects in the working environments. We take the following steps : (a) preparing four motion primitives for robot motion generation. (b) Classifying “task realization method” into four from the viewpoint of environmental support and robot motion generation. (c) Programming motion sequence for each class by combining the four primitives in (a), after getting task specification. (d) Evaluating four classes by using reliability theory. We show the effectiveness of the proposed methodology through realizing a sliding door-closing task and a faucet-closing task(see video) with a real robot system.

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In this study, a construction of an automatic inspection system of X-ray images was tried. Images used in this study are acquired by a X-ray inspection for internal bonding wires of semiconductor integrated circuits. From a quality control point of view, a nondestructive inspection of complete parts such as solder balls, socket pins, bonding wires and so on, is very important. However, because of improvements of semiconductor integrated circuits, a visual inspection by using X-ray images becomes increasingly harder. In this study, the bonding wire inspection is particularly discussed. The wire is thin compared to a general inspection resolution and overlaps to other elements. In some case, the wire becomes deformed and breaks. Consequently, it is necessary for the automatic inspection system of the bonding wire to propose a specific image processing. As the result of the investigation by experiments using actual X-ray images, it was confirmed that the system constructed was effective to the inspection of the bonding wire.

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This paper describes an optimum designing method of optical system for convex and concave defect detection, which uses patterned illumination. “Reaching Range of the Ray(RRR)”, which is calculated numerically based on the defect shape, is defined. RRR indicates width of effective area on the patterned illumination that contributes to observation of the defect. It is used as guidance for sensitivity of defect detection. Determination method of illumination pattern and optical alignment by using detection sensitivity based on RRR is shown. This paper also described an estimation method of observation images of defects and a selection method of defect detection algorithm for various shapes of defects.

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A vacuum bellows assembly that can follow a twisted displacement around the axis is newly developed. It consists of 36 convolutions with a core whose inner circle is eccentric to the outer one. The deformation of the bellows is analyzed by means of a finite element method (FEM), while a torsional moment is applied to the bellows. From the analytical result, it is explained that the new bellows can be twisted much easier than a traditional bellows. Besides, it is experimentally shown that the newly developed bellows with a total length of 86 mm, an inner diameter of 40 mm and an outer diameter of 70 mm is able to be twisted quite smoothly up to about 5°.

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In YAG laser cutting process of thin plate, it is important to understand the assist gas flow from the tip of a convergent nozzle in order to improve the machining accuracy, since melted material is mostly carried away downward by the gas flow. Besides, it is considered that the nozzle shape influences the assist gas flow. In this paper, the effects of the nozzle shape on assist gas flow and machining results in micro machining by a pulsed YAG laser are experimentally investigated. There is an unstable region where the pressure on a workpiece changes periodically regardless of the internal shape and exit diameter of nozzle. The unstable region starts at low cylinder gas pressure and becomes smaller in range with increasing the exit diameter. Under middle and high cylinder gas pressure conditions over 300kPa, height of dross becomes smaller with the increase of the exit diameter for a nozzle of conical internal shape, since the pressure on workpiece increases. Furthermore, when the conical inner wall of nozzle is changed to a convex inner wall, it is possible to reduce the height of dross. Additionally, the height of dross becomes lower, when the curvature of the inner wall increases under the high pressure condition.

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In contour grinding process with ball-end grinding wheel, successive cutting point spacing and also wheel peripheral speed change continuously on a working wheel surface. And these parameters will have an influence on grinding mechanism. Then, in order to make grinding mechanism clear, undeformed chip shape is theoretically analyzed in this paper. Fundamental relationships about substantial parameters, which represent the undeformed chip shape, such as chip thickness, chip length, interference angle and cross-sectional chip area, are theoretically analyzed. Then, in order to obtain these parameters, numerical simulation method is established. The undeformed chip shape is symmetrical form to rotational angle of cutting edge, and is extremely longer and also thinner than that in ordinary external cylindrical plunge grinding. Effects of tool and grinding conditions on the undeformed chip shape are investigated, and it made clear that an increase of wheel peripheral surface speed should be reduce cutting force affected on a grain. Furthermore, grinding force distribution on a wheel working surface is predicted considering with the chip thickness and the wheel peripheral speed.

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This paper deals with thermal deformation of a base material during laser cutting to avoid interruption in a long processing by the thermal deformation. The thermal deformation of a base material cut by laser beam was clarified experimentally. In experiment, the SUS304 sheets of 1mm in thickness were cut by several conditions, and we measured the residual heat, the flux of heat and the thermal deformation of cut sheets. In low-power and low-speed pulse beam cutting, both the residual heat and thermal deformation was lowest. In high-power and high-speed pulse laser cutting, the thermal deformation was larger than the deformation by CW laser cutting in which the residual heat was largest. It was clarified that the thermal deformation of the base material was influenced by flux of heat.

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In the case of internal oscillation grinding of deep straight hole which is longer than a wheel width, a workpiece is finished in a taper shape because of a larger elastic deformation of wheel spindle in grinding process. In this paper, the controlled internal oscillation grinding technique for optimal form accuracy of a deep straight hole is developed, introducing retraction grinding method in which a grinding wheel head rapidly retracts a small amount against infeed direction at the beginning of spark-out grinding. Main conclusions obtained in this paper are as follows; (1) In internal grinding of a deep straight hole with retraction motion, the setting retraction amount is decided by the wheel spindle recovery which is almost in direct proportion to the retraction amount. (2) At the optimal retraction amount finishing a workpiece to a minimum taper error, the elastic deformation of wheel spindle just after retraction motion is constant decided by the grinding system even if the plunge speed or the speed ratio are different. (3) The optimal retraction amount is decided by subtracting the above own elastic deformation of wheel spindle from the elastic deformation of wheel spindle just before the beginning of spark-out grinding process without retraction motion.

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It is important to reduce the run-out and vibration, at the same time, of the spindle for high speed machining centers due to the unbalance mass in order to get high machining performance. We have confirmed the effectiveness and the problem of a three-plane balancing method for flexible rotor in the previous report. In this paper, we have discussed the effectiveness of a four-plane balancing method. In the experiment, the run-out and vibration of spindle are measured with two displacement sensors and two accelerometers at the spindle nose and end. We have confirmed that after reducing the vibration of the spindle by means of a field balancer at high speed the run-out can be reduced by calculating the force balance.

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Generally, the specifications of the robustness and the disturbance or noise applied to the control system are often provided in frequency domain. The traditional observer design is based on a state space structure in time-domin representation of a linear system. In this paper, a robust observer against disturbances is designed by using a transfer function in frequency domain. This method is composed of a diophantine equation including disturbance characteristics, and only three steps are required for the design. We can directly construct an estimation error dynamics depending on the input/output disturbance or noise frequency characteristics. The proposed method has a disturbance-robustness and its design example is presented through simulation.

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This paper describes degreasing of carbon steel cutting surface using electrolyzed reduced water, which is obtained in cathode compartment by electrolysis of dilute NaCl solution. The electrolysis was carried out using diaphragm type electrolyzer with Pt electrodes. Using the electrolyzed reduced (cathode) and oxidized (anode) water, the effect of corrosion on carbon steel was investigated, and the efficiency of emulsification, decomposition and solubility of oil by electrolyzed reduced water was investigated. Then, the efficiency of electrolyzed reduced water as detergent was studied, and compared to pure water, trichloroethylene and tetrachloroethylene. As result of the study, following could be identified. (1) Electrolyzed oxidized water eats into carbon steel, but electrolyzed reduced water do not eats into cutting surface of carbon steel. (2) The best temperature of electrolyzed reduced water for degreasing is at 60°C efficiently. (3) The efficiency of degreasing with the electrolyzed reduced water is the half of that of trichloroethylene and tetrachloroethylene, but longer treatment of degreasing enables to work in equivalent level.

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The study deals with the tool path generation method for 5-axis control machining in consideration of tool interference with a workpiece. Since 5-axis control cutting tool can take an arbitrary attitude against the workpiece surfaces, it allows us to produce workpieces with a variety of complicated shape. However, a serious problem such as the interference between the cutting tool and the workpiece takes place. Thus, it is strongly required to develop a CAM system to generate the interference-free tool path. A sophisticated interference-free tool path generation method have been already developed by making the most of the concept of configuration space, which expresses the relationship between the tool attitudes and the tool interference. However, since the boundary of the configuration space was formed by a curve interpolation, the operation required much calculation time, and often led to the instability of calculation. In order to solve the above problems, a linear interpolation was employed, instead of the curved one. This results in shortening the formation time of the configuration space and in increasing the robustness in the calculation stability. As a result, it is experimentally found that the CAM system for 5-axis control employing the improved configuration space is capable of producing a closed impeller, which is a typical example of workpieces with complicated overhanging shape.

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Silicon nitride (SiN_x) films were fabricated with extremely high deposition rate using the atmospheric pressure plasma CVD technique. The films were prepared on Si(001) wafers at atmospheric pressure in a very high frequency (150MHz) plasma of gas mixtures containing He, H₂, SiH₄ and N₂ or NH₃. Film properties (structure and composition of SiN_x) were studied as a function of each deposition parameter by Fourier transformation infrared (FTIR) absorption spectroscopy and Auger electron spectroscopy. The maximum deposition rate was 120nm/s, which was 40 times as fast as that achieved by the conventional plasma CVD technique. It was found that SiN_x films with uniform structure could be deposited using NH₃ as the N source gas. When N₂ was used, however, the composition of the film changed in the normal direction of the surface.

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This paper presents analytical and experimental dynamic deformation results of a flexible cantilever that is a main structural element of a space antenna. Piezoceramic actuators and piezoelectric polymer sensors are bonded on the almost whole upper and lower sides of the cantilever for shape and vibration control. The beams correct the surface error of the antenna reflector and suppress vibrations caused by disturbance. Two control systems are studied : (1) a velocity feedback control system to create damping force on the beam, and (2) a positioning control system for shape control. The calculated results, which are in good agreement with the experimental results, show that the beam changes shape as desired without transient vibrations and that these control systems are sufficiently robust against disturbance.

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