The rubber surface of a smoother roll in a paper making machine is deformed into a certain convex polygon at a high nip force and a high operating speed of the rolls rotating in contact with each other viscoelastically. The polygonal deformation occurs gradually, which leads to strong vibration of the machine. This paper describes the model of this system, which treats this vibration phenomenon as instability due to a time lag, and a theoretical analysis of this phenomenon. We also conducted an experiment to identify the parameters for use in the analytical model. From the test results, we found that deformation recovery characteristics of the rubber are time-dependent. The numerical results showed good agreement with actual results from machines.

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A simulation method was developed to calculate the vibrational response of a group of hexagonal bars installed in a restraint immersed in liquid during seismic excitation. The influence of fluid force on structural motion was modeled using an added-mass matrix. This matrix was then transformed into the space composed of the eigenmodes of the hexagonal bars without added mass and used for eigenvalue analysis of the entire bar-group structure. This method reduced the computational time needed for practical added-mass matrix calculation and the eigenvalue analysis. It was shown that the proposed method yielded almost the same eigenvalues as the conventional method conducted in standard physical space. Added-mass models for use in impact-vibration analysis were investigated using the proposed method. Comparing the results calculated using the proposed method with those calculated using concentrated added mass, which is a simplified model, showed that the latter can be used for a rough response calculation, while the precise calculation requires the added-mass matrix method.

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In this paper, the governing equation for a pipe conveying fluid is modified by including the influence of the following factors : (1) differences in pressure within and around the pipe ; (2) boundary conditions of the fluid and the pipe. The solution of the new general basic equation depends on the boundary conditions. Application of the new equation to a cantilever pipe discharging fluid gives a result closer than the previous ones to the experimental value. The critical speed obtained from the new theory for the cantilever pipe aspirating fluid is higher than that obtained from the previous theory.

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The accuracy of a workpiece produced using metal-cutting machine tools is decided by the deviation at the cutting point from the demanded working displacements between the workpiece and tool. Chatter vibration, which is the most important phenomenon among the dynamic characteristics of machine tools, is hard to suppress after machine tools have been constructed. Also, the elimination of chatter vibration is important in order to improve cutting accuracy and productivity of the cutting operation. In this study, the structural dynamics of machine tools are identified by a normal transfer function that determines the necessary design change from simulation by FEA. The predicted local effects of component modification computed by FEA to improve the dynamic performance by reducing chatter were found to coincide with those observed in a practical cutting operation. This study shows that modification of structural units to overcome chatter is an effective and cheap way of improving the cutting performance, and reveals how the stiffness changes with changes in the stability.

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A nonlinear mathematical model representing the load sway dynamics of overhead cranes is developed in which simultaneous trolley and girder motions are allowed during hoisting or lowering of the load. The nonlinear model is linearized about the nominal operating trajectories that are obtained from the desired transport plan. The resulting linear model, however, has time-varying parameters. This complicates the design problem of a feedback controller to suppress the load sway. The stability of the load sway dynamics in the presence of feedback is investigated and a set of sufficient conditions on the feedback parameters is obtained to guarantee the asymptotic stability of the load sway in the sense that sway angle is bounded and tends to zero as time tends to infinity.

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Vibration control is important in mechatronics, aerospace engineering, civil engineering and other engineering fields. Recently, active vibration control rather than passive vibration control is being used, reflecting modern control theory. In this paper, we propose an optimal digital feedback regulator which is based only on the first and second-order information for a system elminating transient disturbance. The Wiener-Hopf criterion is adopted in this control scheme. Since the controller is constructed as a finite-impulse response filter, the computation require to design the optimal filter is reduced to that of solving the finite discrete-time Wiener-Hopf equation. This equation is solved recursively, increasing the order of the system each time, via the fast algorithm proposed here. Furthermore, the solvability condition of the equation is clarified and the stability of the feedback system is proved. The effectiveness of the proposed method is verified experimentally by application of the control system to grab-swing elimination in a moving crane.

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This study deals with the problem of sensing structural vibration to provide an error signal to an adaptive feedforward control system, which aims to globally attenuate both structural and acoustic disturbance. This paper demonstrates the validity of a newly proposed "smart sensor" as a distributed parameter sensor made of PVDF film which is designed to measure an acoustic power mode of the total acoustic power radiated from a vibrating plate. Firstly, with a PVDF distributed parameter sensor attached on the entire surface of the plate, the formulas for sensing the j-th acoustic power mode are derived. Then, by considering the practicability of implementing the smart sensors, alternative formulas for sensing the acoustic power mode are derived for a strip-type smart sensor. The characteristics of the smart sensors optimally shaped for measuring the acoustic power modes are also shown. Moreover, based upon an adaptive feedforward control with the filtered-xLMS algorithm, an experiment was conducted to demonstrate the minimization of the acoustic power radiated from a vibrating plate.

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A new active control method for the attitude angles of wheels is proposed to improve the maneuverability and stability of automobiles. From theoretical analysis and computer simulation, it is clarified that this control yields satisfactory vehicle cornering performances during steering, acceleration and braking. The dynamics of lateral movement and yawing of the vehicle as a result of tire attitude control are investigated using a quasi-steady-state analysis model for the case of tractive or braking force. An extended stability factor related to the characteristics of toe and camber angles of wheels is defined, which is applicable to circular turnings with lateral and longitudinal accelerations. Effects of control are analyzed using this factor. Furthermore, a modified control method is proposed, which makes it possible not only to improve vehicle dynamics but also to decrease actuating values of attitude angles in actual driving.

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In this paper, the problem of stability robustness of the LQG system under noise uncertainty and nonlinear/linear time-varying plant perturbations is investigated. The saddle point inequality of the closed-loop system performance is employed to cope with noise uncertainty, and a new condition for sufficient system stability robustness under nonlinear/linear time-varying plant perturbations is presented. Finally, an illustrating example is given to show numerically the superiority of the proposed sufficiency condition over the one reported recently.

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This work deals with the absolute stability of a control system having a 2-input and 2-output fuzzy controller designed by indirect fuzzy reasoning. The absolute stability of the control system is analyzed treating the fuzzy controller as a nonlinear element using Yakubovich's method. The obtained conditions are described by a formulation similar to the usual Popov's condition and a constraining relation between the gains of two types of controller. An example is shown to confirm the analytical result obtained by a graphical method.

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This paper deals with a continuous recognition method for finger signs used to express some numerals in Japanese sign language by image processing technology. There have been some reports about recognition methods for finger letters; however, these were concerned with the finger letters which could be recognized from only the hand shape. Some finger letters are expressed by both hand shape and motion; therefore, it is necessary to use sequential hand images to recognize such finger letters. We propose a new continuous recognition method for sequential hand images and their contour curves. First, we define some properties of the hand image with its contour curve. Next, we determine a judgement rule for discrimination of the hand shapes based on the above properties. Finally, we describe a recognition rule to apply the judgement rule to some sequential hand images, and show some examples to demonstrate the feasibility of the continuous recognition method.

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In the process of mechanism design and trajectory planning of in-parallel actuated manipulators, it is necessary to know the locations of all singular points in the working space. We propose a new method for numerically locating the singular points of in-parallel actuated manipulators based on the pressure angle. A singular-point curve is defined as a set of singular points. Kinematic and static characteristics at singular points are analyzed by pressure angles and instantaneous screw axes. Singular points of the Stewart Platform are investigated using the proposed method. The neighborhood of singular points is determined from output error, isotropy of output force and driving force, and thus the practical working space is defined.

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This paper describes a new analytical method of simulating the vibration behavior of spatial serial manipulators composed of multiple elastic links. The adjacent link joint method is proposed to calculate the internal forces and moments acting interactively between two adjacent elastic links, which are connected with an offset and a spatial twist angle. The position and posture of the adjacent link joint between the two adjacent links are determined by solving a system of linear equations, namely the equilibrium equations of forces and moments acting on the joint; then the internal forces and moments are calculated. The free and transient vibrations of a spatial 2-link manipulator were analyzed and experimentally examined. The calculated natural frequencies and vibrational accelerations agreed well with the measured values.

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In this paper, an inspection method for detecting machine setting errors such as tool setting and workpiece setting errors in spiral bevel gear cutting in a Klingelnberg cyclo-palloid system is proposed. In this method, the coordinates of many points on the gear tooth surface are measured and a theoretical gear tooth surface expressed as a function of the machine settings is estimated by the method of least squares so that the surface fits the measured data. The deviations of the estimated machine settings from the design settings are considered to be the machine setting errors. The machine setting errors in gear cutting were detected using this method and corrective cutting which compensated for the errors was carried out. As a result, more accurate gears could be obtained.

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This paper deals with the effects of surface treatment on the bending fatigue strength of SCM 415 carburized spur gears. The test gears are hobbed and carburized, then the tooth surfaces are treated by a combination of shot peening, chemical polishing and electropolishing. The residual stress is increased by the surface treatment. The SN curves are obtained from the results of a constant stress amplitude fatigue test, and the enhancement of fatigue strength due to the surface treatment is clarified quantitatively. The fatigue strength is well approximated by an experimental formula which has been proposed to evaluate the strength from the hardness and residual stress. The effect of variations in hardness and residual stress of test gears is eliminated using the formula, and the influence of surface roughness on fatigue strength is evaluated. It is approximately equal to the relative surface condition factor specified in the ISO strength rating formula.

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In order to simulate the wear of the valves and valve seat inserts of automotive engines, impact wear tests were conducted using rings made of a JIS SUH 3 steel valve material and disks made of a sintered alloy valve seat insert material. Test conditions were as follows : impact energy of 0.588 J ; normal air atmosphere ; ambient temperatures of room temperature, 200°C and 400°C ; and sliding speeds of 0 to 0.8 m/sec. Under these conditions, very low wear was observed for both materials subjected to impact without sliding. For impact with sliding speeds over 0.4 m/sec, a bright worn surface was observed and the wear rate was severe at room temperature and 200°C. However, at 400°C, oxidation occurred and no acceleration of the wear rate was observed at any sliding speed. These results can be explained in terms of the occurrence of oxidation and the mechanical properties of the test materials.

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This paper describes the development of a finite element analysis program for the nonlinear and time-dependent Reynolds equation based on an incremental formulation. This program can be utilized to predict the dynamic behavior of gas-lubricated grooved journal bearings. The accuracy of the program is clearly demonstrated through analyses of both non grooved and grooved journal bearings.

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This paper deals with an optimum design method for joint elements in boiler plant structures which are excited by earthquakes. Characteristics of joint elements which connect the boiler and its supporting structure are assumed to be viscoelastic, elastoplastic, or a combination of both. Considering the expansion of this study to an active or semiactive aseismic structural control of joint elements, the structures are modeled with the aid of a block diagram. In order to improve the efficiency of calculation, a substructure synthesis method is introduced. Time-domain optimization is carried out using a nonlinear programming technique. To prevent seismic damage of pipes and ducts, limitations for relative displacements between the boiler and its supporting structure is introduced as inequality constraints. Elastoplasticity and viscoelasticity of joint elements are simulated by a combination of a spring, a Coulomb friction and a dashpot. These joint element characteristics are optimized to minimize seismic time response of the structures. This method is applied to actual boiler plant structures and has been proven effective and practical for aseismic designs of boiler plant structures.

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This paper deals with a modal identification method for large-scale structures such as boiler plants in thermal power stations. The proposed method utilizes seismic records which include multidirectional base acceleration data, and multi-I/O identification is carried out. This method is composed of two stages: (1) processing of frequency transfer functions by multi-variate autoregressive (AR) spectral analysis, and (2) curve-fitting to extract modal parameters. This method is examined using time-series data of seismic response simulation, and a comparative study is carried out between multi-input and single-input identification. It is shown that asymmetrical structures excited by earthquakes should be identified using multi-I/O identification. This method has actually been applied to in-situ seismic observation data of a boiler plant in operation. As a result of these investigations, this kind of modal identification has proven to be an effective tool for seismic modeling of large-scale structures.

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An efficient and simple algorithm is developed to classify whether a kinematic chain has total degree of freedom or partial degree of freedom. The developed algorithm uses the sequential removal of binary link strings from the given kinematic chain and can be applied to both planar and nonplanar kinematic chains. The developed algorithm is successfully applied to the enumeration of nonfractionated kinematic chains. Since the algorithm is systematic and efficient, it can be applied to the more complex kinematic chains which have not been reported in the literature yet.

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The temperature of most spindle head units in precision machine tools is controlled by forced circulation of liquid lubricant or coolant in order to minimize its thermal deformation. However, overcooled or thermally unstable coolant may cause an unacceptable temperature distribution in the spindle head unit. Accordingly we propose the incorporation of two concentric heat-exchange jackets into the spindle head unit. The inner jacket allows heat exchange with the overcooled oil, after which, oil at a constant temperature is circulated through the outer jacket so that the temperature distribution of the head unit may become uniformly moderate. As a result of this study we developed a feed-forward temperature control method to adjust the oil temperature prior to heat generation at the spindle bearings. Using a bench-lathe model and our oil temperature regulator, it has been confirmed that the dual cooling jacket structure is practically effective in decreasing the thermal deformation of the spindle as well as the machine tool itself when used in the feed-forward temperature control system.

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A new process of sheet metal forming by which various curved shells are formed without the need for any expensive dies was proposed. In this process, a small area in the sheet metal blank is pressed between a pair of rigid or elastic standard tools which have a simply-shaped head such as a hemispherical or hemicylindrical one. This local forming operation is repeated incrementally over the entire blank. As a result, the blank can be formed into various shapes. To realize the forming process, a computer-controlled forming machine was designed and manufactured. Forming processes for spherical, ellipsoidal and hyperboloidal shapes were examined, and these fundamental shapes were successfully formed with good geometric accuracy and surface appearance. The effects of the forming paths and parameters on the product shape were investigated.

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The micromachining process for very small cutting depth of 1 μm or less is not well understood in spite of the successful development of ultraprecision machining technology. Sliding along the clearance face of the tool due to elastic recovery of the workpiece and plowing due to the tool edge radius may become important in the micromachining range. To obtain a clear understanding of these two factors, an orthogonal cutting model, the round edge cutting model (RECM) was suggested.

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