We describe our approach to the robot's Hanetsuki task (Japanese badminton), that is, to return the incoming shuttlecock to the human's side with a racket. A learning method using a novel database is proposed to compensate for the insufficiency in a model-based approach. Experimental results obtained by using the developed Hanetsuki robot are also shown.

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In-situ forces in knee ligaments during anterior and posterior drawer tests were determined under the priciple of superposition. Sequential section of ligaments of two amputated knees was performed, while the three-dimensional path of intact knee motion was reproduced using a robotic system. Under 100N of anterior force, the in-situ force in the anterior cruciate ligament (ACL) was 88N at 0° of flexion and decreased to 54N at 90° of flexion ; however the in-situ force in the medial collateral ligament increased with increasing flexion angle. The posterior quarter of the anteromedial portion of the ACL and posterolateral portion of the ACL were loaded under unterior force. Under 100N of posterior force, the in-situ force in the posterior cruciate ligament (PCL) was 30N at 0° of flexion, and increased to 105N at 90° of flexion. The anterolateral portion of the PCL was loaded under posterior force. All data were important for a better understanding of the mechanism of the knee instability test and for improvement of the diagnosis of the ligament injury.

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Sliding accuracy characteristics such as the variation of floating height and the pitching-mode angular fluctuation of an externally pressurized gas-lubricated pad bearing travelling on a linear guide way are investigated theoretically with special attention paid to the relationship between the sliding accuracy and the machining error of the guide-way rail, where sinusoidal undulation of the guide-way surface is assumed. The effects of pitch length of the undulation of the rail surface on the sliding accuracy characteristics are discussed. The experimental results verify the validity of the theoretical analysis of the sliding accuracy of the bearing pad.

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This paper shows the lubrication characteristics considering the surface roughness of piston-ring surface and cylinder wall for a refrigeration compressor. In this first report, the effects of piston-ring face profile and boundary conditions on the oil film thickness, power losses and flow rate are analyzed theoretically. The power loss of the piston-ring accounts for a large percentage in all power consumption wasted by the refrigeration compressor. Therefore, decreasing the power loss of the piston-ring contributes to reducing overall compressor power consumption. It is found that the surface roughness effect causes a small change in the film thickness and a significant change in the friction loss of the piston-ring. Numerical results are presented in graphic form for some roughness heights.

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In this paper, we examined the accuracy and efficiency of the time marching scheme for the nonlinear-unsteady-direct analysis of coupled differential equations of the motion equation and the Reynolds equation. Examination of some schemes gave the following results : accuracy is influenced by the method of time marching and the coupling of the motion equation and Reynolds equation ; the scheme of integrating coupled differential equation by Runge-Kutta method is most accurate ; the stable scheme for spatial difference improves the accuracy of time integration. The method wherein a time marching step is controlled automatically improves the efficiency of calculation.

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A flexible pad bearing was developed as a highly stable bearing. This bearing has a monolithic construction with a pad and a web which supports the pad. Therefore, manufacturing the bearing is easy, and the flexible pad bearing is superior in durability. However, the static and dynamic characteristics, which indicate characteristics of load capacity, the coefficient of friction and stability, in the flexible pad bearing have not been completely obtained because the bearing has no time from development. In this paper, the static characteristics of the flexible pad bearing were studied theoretically. Consequently, the flexible pad bearing was found to be suited for use with light loads and at high speeds. Furthermore, at lower eccentricity ratio, it was found that the load capacity of a flexible pad bearing with a thinner web is larger than that with a thicker web, and that the coefficient of friction in a flexible pad bearing with a larger preload factor is smaller than that with a smaller preload factor.

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The tribological properties of alumina ceramics in unlubricated sliding contact were investigated using a pin on disk test machine under controlled temperature and normal load. The tribological behaviour can be classifled into two groups as follows : (1) At low and high temperature, T<300°C and 800°C<T, wear surface becomes smooth by formation of tribo-film. Friction coefficient or specific wear amounts is less than 0.7 or 10^-6mm³/Nm, respectively. (2) At middle temperatures, 300°C<T<800°C, wear surface becomes relatively rough due to brittle fracture. Friction coefficient and specific wear amount show high values. These behaviours are summarized as wear diagram with temperature and normal loadaxes. Furthermore, it is analysed experimentally that formation and preservation of smooth tribo-film on wear surface reduce the wear volume.

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The optimization method of profile-shift coefficients for the design of conventional mechanical paradox planetary gear drives of maximum efficiency is proposed and described. The objective function of all of the four profile-shift coefficients is converted to a function of only two profile-shift coefficients. Drawing the objective function on a plane with the coordinates of the two profile-shift coefficients and connecting the points with the same value gives a map of contour lines ; the ridge which gives the maximum efficiency becomes almost a straight line on the plane. Also, the constraint domains, which are determined from the constraint conditions such as contact ratio and undercut, are located on the straight ridge ; the lower limit of the constraint domains also becomes a straight line. The optimum profile-shift coefficients are investigated by increasing one of the profile-shift coefficients step by step from the value determined by the intersection of the two straight lines. Thus the optimum profile-shift coefficients have been determined for various conventional mechanical paradox planetary gears ; the obtained maximum efficiencies are almost 78% for those gear drives.

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Unlike a cylindrical gear, crossing of two gear shafts occurs in a bevel gear, so its tooth bearing changes sensitively with assembly error, shaft angle error and deviation of apex, and the tooth end contact is easily caused. To prevent the tooth and contact, crowning of a tooth flank is performed by means of a coniflex gear. The practicality of a crowning gears is well recognized and they has been used in many industrial applications. It is important for strength design to know the load distribution on a line of contact and the tooth root stress of the bevel gear where crowning was performed. In this paper, the load distribution and the tooth root stress distribution of coniflex gears are calculated. These calculated values were compared with measured values, and validity of this calculation method was examined.

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The purpose of this study is to develop a gear-cutting method of hypoid gears to achieve a good tooth bearing and good performance for practical use. In the first report, the authors proposed a new cutting method of parallel depth hypoid gears which mesh with each other at one point at a constant angular velocity ratio, and precisely stated the theory for the gear-cutting method. One of the features of this method is that the designer can control the trace of the point contact mark on the tooth surface as desired. In this report, the theory of the trace of the point contact mark is shown precisely. In order to confirm the validity of the method, some hypoid gears were designed and manufactured, and the traces of the point contact mark on red lead corresponded to those of the theory.

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This paper reports a study on the grinding performance of various wheels with different types of bond materials and diamond grains. Both moderate and aggressive grinding conditions are adopted in this study. Under the moderate grinding condition, grain rotation motion is observed in resinoid-bonded diamond wheels during the grinding process. This motion contributes to a reduction in the grinding force. Based on this finding, grain rotation motion is introduced as a new self-sharpening mechanism of resinoid-bonded diamond wheels. Also, attritious wear is found to dominate the wear process of all kinds of diamond wheels. Under the aggressive grinding condition, four typical wear types are found, with each corresponding to a specific combination of bond materials and diamond grains. It appears that the tearing off or macro-cracking of grains dominates the wheel wear process when the wheel grades are low ; but micro-chipping or attritious wear plays a decisive role when the wheel grades are high.

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An investigation of the relationship between the grinding force ratio and the residual stress of a ground surface was carried out to obtain basic information on the improvement of the surface integrity of the ground surface. The grinding method of this study is the horizontal-shaft surface grinding with a WA wheel or CBN wheel. The residual stress of the ground surface is measured by the X-ray diffraction method. The distribution pattern of residual stress of the ground surface is determined by the grinding force ratio. A sufficiently small grinding force ratio results in a compressive-stress-type distribution pattern. The surface generated by the CBN wheel grinding represents a compressive-stress-pattern, which leads to a better surface integrity in general. This is a result of very small force ratio that we found particularly with the CBN wheel grinding.

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A system is proposed to recognize cutting state in end milling by comparing dynamic cutting force predicted by a mathematical model with the measured cutting force. In order to realize the recognition system, a precise cutting force model is constructed, and a method to identify the most probable parameters in the model is developed by applying the steepest descent method. The actual cutting force is measured with a piezoelectric-type dynamometer, and it is confirmed that the cutting force predicted by the model agrees with the measured one. Monitoring of tool wear is also tried by comparing the predicted force with the measured one.

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Determination of parting direction is the prerequisite for all subsequent processes in mold design. The parting direction is directly related to the location of parting lines and affects the side-core mechanism and the location of gates, ejector pins and cooling pipes. In this paper, a method of obtaining the feasible solutions for parting direction from the 3-dimensional CSG (constructive solid geometry) model is proposed. A genetic algorithm is applied to search for a solution. Some experiments conducted using a computer indicate that the genetic algorithm allows us to obtain the feasible solutions for parting direction.

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The finishing pressure distribution over the finishing area is clarified in the case of magnetic abrasive machining of an internal surface of a tube. This paper shows that the finishing pressure distribution of the magnetic abrasives is affected by the magnetic field distribution over the finishing area, which controls the finishing characteristics. It is found that increases in excitation current and amount of magnetic abrasives supplied increase the finishing pressure by increasing the magnetic field strength. It is also found that both the magnetic field strength and its gradient are minimum at the center of the magnetic pole and maximum around the edge of the magnetic pole, a phenomenon called the "edge effect". Magnetic abrasives converge sequentially around the pole edge, generating high finishing pressure. The results of the finishing experiments indicate that the higher finishing pressure due to the edge effect increases the finishing efficiency.

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The opposed dies shearing process proposed by one of the authors is based on the idea of smooth sheared surface formation utilizing a cutting mechanism and has excellent features not found in other shearing processes. This process involves two stages ; after sufficient shearing between die and protruding die, a product part is separated successively by a knock-out punch, where knock-out timing is important to prevent fracture of the surface and burr formation. Therefore, this process requires use of a precise hydraulic press which facilitates this complicated action and exact knock-out timing. This requirement seems to prevent wide practical application of this process. Therefore, we propose a simplification of the opposed dies shearing process utilizing differential pressure. First, this idea was tested using a coli spring substituted for hydraulic pressure and its feasibility was confirmed. Secondly, a differential pressure mechanism was realized with a hydraulic press and straight shearing of mild steel was achieved. Basic phenomena of this method were studied and it was found that knock-out timing is controllable by varying the pressure difference. Furthermore, a die set unit utilizing this mechanism was developed and disk blanking of aluminium with a mechanical press was demonstrated.

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An approximation method is proposed to estimate the system production rate for an automatic merge machining-assembly production system in which L parts are machined in multi-stage series lines and are assembled. In this method, the system is decomposed into L series machining lines, each of which considers the parts delay occurring in other series machining lines. From the comparison between approximation and simulation results, it is found that the estimation error is very small. Furthermore, we study the effects of system parameters on the system production rate. The main results are as follows. (1) As the number of machining lines feeding assembly parts increases, the production rate decreases but the decrease becomes slight. (2) When the number of stages in machining lines is greater than two, the number of stages has little effect on the production rate.

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In this paper, we present a complete soft model for a plant piping CAD, which takes into consideration not only the piping elements but also the spaces among piping lines. Using this model, we can recognize the volume of the space among pipe lines digitally, instead of the intuitive view of the figure on the screen. A plant space is divided into many sub-spaces called "ragion space" by piping line segments. This region space is defined by the shape of the rectangular solid and can be handled on the same level as the piping element data in piping CAD system. As the specific design works used this space model in CAD system, we can achieve computerized checking of the total interference of piping lines as well as maintenance space checking of valve parts. We also report the concept of region space, the procedure for data base construction and the application program in the piping CAD system.

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In order to develop a micro manipulator system for micro-bonding by adhesive, the characteristics of super elastic hinges made of super elastic materials, for example, made of shape memory alloy, have been analyzed and represented in the form of charts which enable rational design of the mechanisms as micromanipulators. Making use of the characteristic charts ; shapes and size of hinges can be directly considered in the determination of kinematic parameters of the pantograph mechanism with super elastic hinges. The effective performance of the design system is demonstrated with an example of the manipulator for micro-bonding by adhesive.

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First, new constraints on the manipulating force/moment and the translatory/angular velocity at the end effector of robots are proposed, in which the values with different dimensions such as force and moment and such as translatory velocity and angular velocity can be treated as numerically equivalent. Under those constraints, the maximum output power at the end effector can be calculated. And the power transmission index which is defined as the ratio of the maximum output power at the end effector mentioned just above to the sum of the maximum power of all actuators in the mechanism is proposed as a new quantitative measure of spatial isotropy of output of robotic mechanisms. The main characteristics of the power transmission index is summerized as follows : (1) it is a nondimensional quantity that varies between zero and one, (2) its value equals zero at a singular point which is commonly observed in both in-parallel actuated mechanisms and serial mechanisms and is also peculiarly observed in in-parallel actuated mechanisms. Illustrative examples on a planar in-parallel actuated mechanism and a serial mechanism with three degrees of freedom are shown and relationships between the power transmission index and conventional evaluation values for robotic mechanisms such as transmission index and manipulability are discussed.

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