The purpose of the study described in this paper is to analyze and predict the vibration responses of an internal combustion engine (ICE). Firstly, all substructures of the ICE are modelled by the finite-element method, and their dynamic characteristics obtained by a component mode synthesis method (CMS) or by a multiple component mode synthesis method (MCMS) are checked by comparison with experimental results. Secondly, the dynamic characteristics of the whole system synthesized by MCMS are compared with experimental results to verify the accuracy of analytical results and the proprieties of the adopted connecting conditions. Thirdly, a computational prediction of the vibration characteristics, when the supplementary parts for reducing the vibration response level are added to the bottom of the cylinder block of the original engine, is carried out and also compared with experimental results. In addition, the overall level of the force at intake/outtake valve setting points is experimentally estimated in the frequency domain for the purpose of application as a factor of excitation forces in the engine during operation. Then, by using the FE model and the estimated valve-driving forces, the forced vibration analysis is carried out with MCMS. It is shown that the result corresponds well with the experimentally obtained results.

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In order to suppress structure-borne sound radiated from a vibrating plate, vibration control of the plate is of primary importance. Instead of conventional vibration control methods which aim to merely eliminate the vibration, in this paper, utilization of the vibration to accelerate the cancellation mechanism of structure-borne sound is considered. First, with a view to clarifying the generation mechanism of structure-borne sound, acoustic intensity is considered at each vibration modal resonance frequency. From these distribution patterns of acoustic intensity the cancellation mechanism of the sound due to the existence of negative acoustic intensity is discussed, and an attempt to interpret the meaning of the negative acoustic intensity is made. In addition, it is shown that radiation patterns often taken for granted do not necessarily hold true for some vibration modes. Furthermore, the relationship between the radiation efficiency, radiated power and active control effect for suppressing the vibration is discussed. Finally, it is shown that the inherent cancellation mechanism is achieved not only spatially but also temporally in the acoustic field.

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A repetitive control scheme which is applicable to a class of nonlinear systems with periodic reference signals is proposed. The nonlinear terms in the systems are assumed to be polynomially bounded. Sliding mode control is applied to an augmented system in which an integrator and a repetitive controller are combined in order to obtain a linear input-output relation. The stability condition for the repetitive control system realized by the proposed method is derived. It is shown that this system satisfies the internal model principle for a given frequency bandwidth. The frequency bandwidth is given by the stability condition. An illustrative example is given.

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This paper describes the autotuning of feedback gains for a small tunneling robot. We have already proposed the directional control method wherein the head angle of the control input is the sum of the deviation multiplied by feedback gain K_p and the angular deviation multiplied by feedback gain K_a. In this paper, we used a neural network to obtain feedback gains K_p and K_a. The input of the neural network is an initial deviation and an initial angular deviation. The output of the neural network is the feedback gains K_p and K_a. This neural network learns from the deviation errors. The neural network which can be applied to any initial deviation was formed by using plural initial deviations in learning. Moreover this method can tune optimum gains to any design line. These results showed the validity of the proposed autotuning method.

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The 2-wheel mobile robot features the ability to easily perform spin turns and transverse motion. The problem, however, is that the robot is prone to slow damping vibration in the turning direction. Usually, a guiding algorithm controls the position and heading only. Without considering dynamics, it is difficult to suppress vibration. We propose a method to prevent vibration by taking the dynamics of the robot into consideration. A mathematical model of the robot demonstrates that the turning accelerative and elastic torques act reactively on the motors of the left and right drive wheels. Although these two torques act on each motor with equal magnitude, they have different signs. A difference in the reactive torques occurs, and this is thought to be the main cause of vibration. Our proposed method is to suppress vibration by imposing feedback of the difference of the reactive torques. Experiments have shown significant results in suppressing vibration by means of this technique.

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For the purpose of 3-dimensional (3-D) shape inference from image brightness, it is necessary to establish the direction of light. In this paper, we propose an iterative algorithm for estimating the direction of light from the brightness and the surface normal on the occluding boundary. From the numerical results, it is found that the algorithm yields a reasonable solution in a small number of iterations. Furthermore, we consider the convergence of the 3-D shape inference algorithm, and show that the smaller the difference between the viewing direction and the direction of light, the faster the algorithm converges.

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The small sliding at contact points of fingertips is investigated in this paper. The grasp stabilization method with internal stiffness is proposed and its stabilizing effect is demonstrated for the planar three-fingered hand. The grasp stabilizing conditions for the internal stiffness are determined and the optimal grasp in contrast to the conventional point of view is discussed. Finally, the stabilizing effects using the internal stiffness are illustrated by numerical examples.

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In this paper, we describe an alternative method based on a new idea for measuring the circular movement of machining centers. ISO has employed three methods for the acceptance tests of machine tools : the first is a rotating one-dimenional probe method, the second utilizes a two-dimensional probe and a master circular ring, and the third utilizes a kinematic ball bar. At present, it is necessary to develop an alternative method with no relation to the latter two methods because their patents are pending. We have developed an alternative method by improving the rotating one-dimensional probe method. The newly developed method is superior to the other two methods ; the rotation angle can be detected and the rotation radius is variable. The effectiveness of the developed method is confirmed experimentally.

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The Ministry of Labor in Japan has established a standard for the mechanical structure of power presses. The standard stipulates that the power press be equipped with an overrun monitor function that enables the slide to be forcibly stopped when the slide fails to stop within a specified allowable range around the top dead center. The operation of the power press is considered to be a man-machine system in which both the operator and the machine may make errors. The overrun monitor function is defined as a requirement for safe operation of the system. A signal processing method is established for fail-safe operation of the overrun monitor function. A fail-safe overrun monitor system based on the signal processing method is presented.

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This paper deals with the mechanism and control method for a man-robot cooperative-work-type manipulator, aiming at application in fields involving structurally changeable tasks, such as the construction field and civil engineering field. Because of the imminent labor shortage in our aging society, robots will be increasingly used in these fields. To support robot operation, this study aims to develop a cooperative-work-type manipulator to be controlled easily by the direct teaching method. The man-robot cooperative-work type manipulator has the following features. ( 1 ) It has an operational sensor to preform tasks in cooperation with a human operator. ( 2 ) It also has an environmental sensor to control contact force between the robot and the environment. ( 3 ) The end-effector of this robot has a vacuum system to carry heavy payloads. ( 4 ) To facilitate position control operations when assembly tasks are performed, the first arm of the manipulator is made flexible, and it has a bending vibration control system. With these features, the robotic system makes it possible to perform man-robot cooperative work.

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Because plastic gears possess sufficient self-lubricating ability, operation without lubrication is feasible. Accordingly, plastic gears seem to be most suitable for use in vacuum, where lubricating oil cannot be used. However, with plastic gears, there are also problems pertaining to heat resistance, the occurrence of dimensional change as the moisture contained in the atmosphere dehydrates in vacuum, and so on. For the purpose of applying plastic gears to practical use in vacuum, in this research, the dimensional change in vacuum of various plastic gears which were used in atmosphere was examined, a few operation tests were performed, and the results were investigated.

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Resin concrete has been widely used in machine tool structures in order to improve the dynamic properties, reduce the lead time of production and reduce thermal deformation. It has been pointed out, however, that Young's modulus of concrete is about one-seventh that of cast iron and thus, that resin concrete is inferior to conventional materials in static stiffness. Therefore, in this paper, a new material referred to as ceramic resin concrete has been developed for use in precision machine tool structures. This material consists of epoxy resin and ceramics, i.e., alumina, silicon carbide, zirconia or a mixture of these. A practical manufacturing method for the ceramic resin concrete was established. It is concluded from the experimental results that the Young's modulus is three times and the compressive strength is two times that of conventional resin concrete.

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To obtain a polyacetal with high strength and rigidity, we should select a composite polyacetal filled with, for example, carbon fibers. However, this may not be true in the case when this kind of composite polyacetal is used in water. That is, it is considered that the sliding Characteristics might decrease because water enters into the bonding space between carbon fibers and polyacetal and between carbon fibers themselves. In this study, operating tests of a polyacetal gear filled with carbon fibers in water and with water drops were performed and the wear of the gear and the change of the tooth profile were determined. By comparing these results with those of an unfilled polyacetal gear, we investigated the usefulness of polyacetal gears filled with carbon fibers in water or humid environments.

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One of the effective ways for reducing the mass of a helical spring is to make a hole in the cross section of the spring wire. In this paper, we discuss the shape of outer and inner boundaries of the wire cross section of a helical spring that has minimum mass. Stress is calculated by means of the finite-element method (FEM) based on the stress function, and the optimization problem is solved by means of the steepest descent method used in the previous paper. In consequence, the converged solutions obtained from various initial shapes greatly differ in shape, but are almost equal in mass. The stress around the outer boundary of the converged cross sections can be made nearly uniform. It is also found that there are many solutions whose mass values are almost equal to those of the converged solutions. In comparison with a helical round wire spring, the weight of the present spring has been reduced by about 50%.

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A method for determining the parameters of the rheological properties which express the model of the limiting shear stress of lubricants is proposed. The relationships between the traction coefficients of the roller tests and the mean film temperature rises of lubricants are calculated. The maximum traction coefficients are revised to those of the isothermal condition by the traction coefficient-temperature relationships and analyzed using an approximate formula which estimates a maximum traction coefficient based on the limiting shear stress. The zero pressure value of limiting shear stress To and slope of the limiting shear stress-pressure relationship m are presented for two traction fluids Santotrac 50 and Daphne 7074 at temperature 313 K. Maximum traction coefficient and limiting shear stress at high temperature are predicted using the traction coefficient-temperature relationships.

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Oil viscosity is an important factor in oil film formation ; its effects on the scoring resistance of gears have been examined. In spite of scoring taking place easily where specific sliding is high, few papers have treated the specific sliding as important. As a basic study to establish gear design procedures for better resistance to scoring, we examined the effects of oil viscosity on antiseizure capacities of mineral base oils. The experiments were carried out using a two-cylinder test rig under various specific sliding conditions. In the higher specific sliding range the antiseizure capacities rise with an increase in oil viscosity. In the lower range, however, the effects are nominal ; thin oils are applicable in severe conditions of heavy load, high sliding velocity, and high bulk temperature where thick EP oils are ordinarily used. A method for applying these results to the scoring design of case-hardened spur gears was proposed.

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Synchronous drive belts are used in driving car engine camshafts and other mechanisms. Load was measured on each tooth root of a cam pulley engaged with a synchronous drive belt with rounded teeth used with a four-cycle gasoline engine, and then was the dimensionless load distribution ratio calculated by dividing the tooth root load distribution by the belt tension load. Thus, the relationship between the distribution ratio with engagement position load and the belt tension load was analyzed. As the result of this study, the following conclusion reached : When material properties, tooth profiles and other specifications are the same, under both dynamic and static loads, the tooth load distribution ratios of pulleys with rounded teeth used to drive engine camshafts are almost the same as the speed range adopted in the operation of production car engines.

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The greatest possibility of the conical involute gear is in the use of straight conical involute gears in place of bevel gears. However, the key for realizing this usage is to establish the method of grinding straight conical involute gears which have a comparatively large cone angle. In this study, three grinding methods to finish such a gear are developed : Niles-type infeed ginding, table sliding infeed grinding, and inclining work-arbor infeed grinding. The principles and the available machines are described, the test results are discussed, and it is concluded that the most practical method is table sliding infeed grinding.

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In hobbing, the hob cutter has many cutting teeth, and moreover each hob tooth has three cutting edges. When a hob cuts a gear, each of the cutting edges of one tooth produces one chip simultaneously. Then the chips resulting from those cutting edges interfere with further cutting, and the specific cutting forces become larger than those in orthogonal cutting. In this paper, the interference of chips is theoretically investigated. A basic and simple model of chip interference is the cutting of full-depth or non-full-depth triangular cuts. Thus, the specific cutting forces in non-full-depth triangular cuts made with a point nose straight tool are theoretically investigated in terms of various included angles. The result shows that the specific cutting forces become large when the included angle of the tool is small. The specific cutting forces with an included angle of 90 degrees are about 1.3∼1.35 times those produced by a flat tool.

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This paper deals with machining tests, regarding oxygen-free copper (OFC) as one of the materials suitable for diamond turning. The machining tests were carried out to study the optimal cutting conditions for OFC, the selection of a suitable high-purity OFC material for mirrors and the mirror-finishing properties of the suitable OFC material over long cutting distances. The test results show the following. ( 1 ) The optimal cutting conditions are 9-17μm/rev for the feed rate and 15-20μm for the depth of cut. ( 2 ) The raw material produced by the processes of hot rolling, cold rolling and heat treatment is the most suitable with respect to the surface integrity. ( 3 ) The surface roughness is stable in the cutting distance range of 500 km. As for tool wear, crater wear, in particular, is remarkably large, while flank wear is negligible.

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This study deals with the automation of polishing work by use of an industrial robot with 6 degrees of freedom. Since polishing work, which takes much time, requires experience, patience and skill, it is manually performed by skilled workers. This study aims at rationalizing such difficult polishing work by introducing a robot and CAD technology. The arm of the robot can be equipped with two kinds of polishing tools, i.e., a rotational tool or an ultrasonic vibrational one, to cope with various cofigurations of the workpiece surface. In addition, the system allows collision-free polishing paths derived from the CAD system to be expressed in the robot coordinate system by use of a touch sensor. The system is found to be effective for obtaining a smooth workpiece surface, based on several experimental results.

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A plant layout design system is proposed using a hybrid approach with a constraint-directed search procedure and a mathematical optimization technique. In layout design, a plant must be arranged to satisfy spatial constraints imposed by its components. In our approach, the whole space of a plant building is divided into finite compartments with a modular size in order to separate the description of the layout into the combinational part and the dimensional part. According to this, the approach consists of two steps. In the first step, a constraint-directed search procedure is applied for fixing the combinational relations among plant components so as to satisfy the spatial layout conditions. In the second step, an optimization technique is applied for determining the actual dimensions of compartments so as to minimize the size of a plant building taking the size of components into consideration. In the optimization, mixed-integer programming and sequential linear programming are combined and the mathematical model is formulated automatically from the result of the first step. The system using this hybrid approach has been applied to the design of a nuclear power plant in order to check its validity and effectiveness.

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