This paper represents a hand shapes recognition system for the Human Machine Interaction (HMI) with service robot of disable people. This system uses a touchpad to precept the touching of fingers, as well as to provide a background for hand shapes image. Each finger can stay in one of the 4 statuses: stretch- touching on the pad, retracting-touching on the pad, stretch-detaching over the pad and retracting-detaching over the pad. Hand shapes, posed to express HMI instructions, are defined by the status combinations of Index finger, Middle finger, Ring finger and Little finger. Hand shape features, the relative heights of the fingertips, are extracted through the singularity detection with wavelet transform on hand shape contour. The hand shape recognition of this system is based on an optimized Bayesian decision binary tree. The design of 2 types of classifier in the tree and the corresponding error rates of the classifiers are analyzed. Implemented by a DSP processor, a correctness ratio of over 98% is obtained in the identification of 12 hand shapes. Experiments show that this system can provide a flexible, humanized and expendable HMI for service robot, as well as for other applications.

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This paper is the first of two companion papers on active control based on two independent contributors to the structural kinetic and acoustic potential energy: vibroacoustic modes and clusters. An understanding of the vibroacoustic independent contributors clarifies the main causes of vibrations and sound, and facilitates a reasonable control system design, as reported in earlier literatures. In this paper, the theory of vibroacoustic modal control is applied to a double wall. The double wall consisted of a pair of panels, separated by an air gap and connected by mechanical springs, where the receiver panel is coupled with an acoustic enclosure. Velocity distributions on the panel's surface, which independently contribute to the sum of the structural kinetic energy of the panel and the acoustic potential energy in the enclosure, are derived. These velocity distributions are vibroacoustic modes. Filters are formulated to extract the individual vibroacoustic modes from the measured velocities. The validity of the developed theory is verified through numerical simulations.

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This paper is the second of two dealing with independent contributors to the structural kinetic and acoustic potential energy: vibroacoustic modes and clusters. In this paper, the theory of clusters is applied to a symmetric double wall composed of a pair of uniform flat panels, separated by an air gap and connected by mechanical springs, where the receiver panel is coupled to an enclosure. It is found that in the symmetric double wall, shapes of the uncoupled structural modes of the panels are clustered into an even or odd function, and these clusters independently contribute to both the structural kinetic energy of the panels and the acoustic potential energy in the air gap and the enclosure. Spatial filters to extract the individual clusters from the measured velocities of the panels are derived for the symmetric double wall. The performance of the active control system, using each cluster as the error criterion, is numerically simulated.

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This paper investigates the vibration of one-degree-of-freedom magnetically levitated body. Especially, the influences of the nonlinearity of the system and the dynamical characteristics of electric circuit and magnetic circuit are focused. This paper's object is extended to the case that electric current supplied from a power-operational amplifier is limited in a positive range. Thus, the system may have piecewise nonlinearity when the vibration amplitude is large. The nonlinear analysis for this system is discussed. The dynamical characteristics of the system are clarified by numerical simulation and theoretical analysis. These obtained results are confirmed by experiment.

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The analytical solution of vertical, pitching, yawing, lower rolling, and higher rolling frequency expressions for linear guideway type (LGT) recirculating rollers with arbitrarily crowned profiles was explored. Each roller inside LGT recirculating roller is divided into three parts: two crowned and one cylindrical. The superposition method is introduced to obtain the stiffness equation for rollers compressed between the carriage and profile rail, and a model of discrete normal springs is used to construct the stiffness equation for LGT recirculating roller. Five equations of motion were obtained using Lagrange's equation. The results reveal that the frequencies are affected by the value of preload and of stiffness. The natural frequency of the exponential profile is close to that of the forth power profile. Therefore, recirculating rollers with an exponential profile, a small crowned depth, and a large crowned length seem to be optimal, having a higher frequency of LGT recirculating roller and a lower edge stress concentration.

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The friction force is effective for dissipating seismic energy. Therefore, in recent years, the installation of a frictional isolator in industrial facilities has been investigated. When a system including this isolator is regarded as multi-dof system, however, the seismic response of the system is obtained only by non-linear time history analysis. A great deal of time is required for non-linear analysis. In the present study, the easy estimation of seismic response for a multi-dof system with friction is considered. The seismic response of a multi-dof linear system can be obtained by the response spectrums method. This estimation is based on the modal analysis method. In the present paper, a method of modal separation for a 2-dof system with friction is presented. However, the accuracy of the proposed method depends on the mass ratio γ, the frequency ratio R_ƒ and the friction force. The proposed method is compared with 2-dof non-linear time history analysis, and the accuracy of the proposed method is calculated at γ ≤ 0.1 and R_ƒ ≤ 3. The present study defines the area within an error of 10% as the applicable area of the modal analysis method for a friction system and shows the range of error over 10%. The proposed method can be useful for obtaining the seismic response of a 2-dof friction system without non-linear time history analysis.

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Statistical Energy Analysis (SEA) is widely used for high frequency analysis. This paper particularly deals with a beam-plate coupled system in the SEA framework. An asymptotic representation for the CLFs of this beam-plate system when the plate is excited is investigated by assuming that a diffuse vibrational field exists on the semi-infinite plate. For this, the corresponding wave transmission coefficient into an infinite beam is derived and its dynamic characteristics are discussed. A comparable representation for the beam-excited case, so-called an equivalent loss factor (ELF), is also discussed based on the wave approach. The energy normalised by the power input is predicted using an SEA model involving these coupling parameters. It shows that such coupling parameters can be used for the particular coupling situation. For comparison, an exact response of the beam-plate coupled system is derived using a Fourier technique, which is not presented in this paper.

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Composite sandwich panels have been employed in many structural applications. Therefore, it is very important to obtain the dynamical properties of the composite sandwich panels. Also, an inverse analysis method has already been proposed by one of the authors to identify the layer elastic parameters of laminated plates and shells using the FEM eigenvalue analysis and the nonlinear optimization algorithm. The purpose of this study is to improve the already proposed identification method to apply to a sandwich panel and to identify the equivalent core elastic parameters. By applying the experimental modal analysis technique to the sandwich panel, natural frequencies and mode shapes of the panel are obtained. From the obtained natural frequencies and mode shapes, the equivalent core elastic parameters are identified numerically. Furthermore, the usefulness of the improved identification method is clarified.

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