The general properties of a harmonic oscillation with damping proportional to the fractional time derivative of the displacement of order 1 / 2 is studied. It is shown that vibration decays when the damping coefficient is positive, implying that the model is thermodynamically valid. The center of the oscillation is a curve that approaches the time axis algebraically, so that after the oscillation damps out, there is a long trailing tail. There is no critical value of the damping coefficient that distinguishes the pattern of damping. For a negative damping coefficient, oscillation grows exponentially. An equivalent oscillator model with ordinary damping may be constructed for small damping, which shows that fractional damping acts partly as a supplementary spring, reflecting the recoil effect of a viscoelastic material.

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In this work a recently developed robustness margin index is used for analysis of typical single input single output(SISO)control systems with plant parametric uncertainty. This easily computed index is very useful in that it considers the magnitude of the errors in the plant parameters explicitly rather than implicitly as is done with other existing techniques such as the open loop frequency response gain and phase margins. The usefulness of this robustness margin index is underlined by the three treated examples.

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The stability and instability of motion of an artificial Earth satellite equipped with a cylindrical electrostatic shield in a circular equatorial orbit is studied. The satellite traveling through the Earth's magnetic field causes Lorentz forces. For the sake of accuracy, the second-order terms of R^-1are retained for the potential function of the Newtonian central force field. The Lorentz forces and Newtonian central force field have an effect on the stability and instability affect the conditions. Right equilibrium positions of the satellite in the orbital coordinate system are considered. Furthermore, we study the stability of motion when the axisymmetric shielded satellite rotates at an arbitrary speeds in a circular orbit under the influence of gravitational forces and Lorentz forces. Finally, as the numerical examples show, the stable results present periodic oscillation about the zero solutions. The Lorentz forces lead to low frequency in the system, the third mass moment in the Newtonian central force field becomes more accurate, and the cumulative effect is considerable.

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VSS observers are considered for continuous-time systems, in which the nominal plant model is linear, but there exist bounded plant and output uncertainties. We first present a design method of a VSS observer based on use of some extensions of a conventional approach that uses an algebraic Lyapunov equation. It is then shown that such a method cannot be successfully applied to the system with any linear part, if we desire to use a unique solution to the algebraic Lyapunov equation. Namely, this method is only applicable to a restricted class of systems. In order to develop a VSS observer applicable to a wider class of systems, we next propose a design method based on use of an algebraic Riccati equation, associated with a linear filtering problem. A relationship between the two design methods is also discussed. Simulation results show that the proposed method is effective for designing a VSS observer for a second-order nonlinear system with band limited output noise, as the output uncertainty.

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A new wheelchair capable of negotiating steps with a height of up to 10 cm has been developed. Pneumatic pumps are installed on its rear wheels. The pneumatic pumps generate pressurized air, with the pressure proportional to the extent of rear wheel rotation, and supply it to a reservoir. Travel over a distance of about 12 m is needed to reach full pressure. The required air is introduced from the reservoir into two driving cylinders, fixed to the front support frames of the wheelchair, that lift the front wheels. The operation is performed by manipulation of the braking levers. Our experimental design system shows the feasibility of using pneumatic pumps for such lifting.

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This paper presents an autonomous wheelchair system with the capability of self-localization. In our system, the ceiling lights are chosen as landmarks to realize the self-localization and auto-navigation of the wheelchair. An approach to landmark recognition is described, and a technique of self-localization for the wheelchair is proposed. Subsequently, the path planning for navigation is discussed. Finally, the total system for our wheelchair is introduced, and a navigation experiment is described. Experimental results indicate the effectiveness of our system.

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Recently, several differential methods have been developed to cancel datum errors of the scanning stages in the measurement of straightness and sectional surface profiles. Some of these methods are being extended to the case of 2-D surface profile measurements. Although datum errors are removed by the differential calculation of the sensor's outputs, some other measurement errors remain, and some new errors are introduced into the results of the measurement because more than one sensor is used to construct a differential measuring probe. In this paper, some of the measurement errors of the 2-D differential methods presented in the previous report are evaluated by analysis of the transfer function and the differential output of the software datum. Zero adjustment errors caused by misalignment of the sensors zero outputs are also analyzed, and a self-correction method for compensating zero adjustment errors is presented.

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In this paper, a novel signal processing tool, the wavelet transform, was applied to monitor the flank wear states in turning. The wavelet transforms were implemented by FWT(fast wavelet transform)based on a QMF(quadrature mirror filter). The expansion coefficients d(j, k)with time-frequency feature obtained by FWT were used as recognition parameters of the flank wear states. The dynamic characteristics of the cutting force signals were analyzed separately using the wavelet transform and the Fourier transform. The abilities of these two transforms for analyzing and recognizing the flank wear states were compared. The experimental and analytical results show that when monitoring the flank wear states during turning, the wavelet analysis is more sensitive, more reliable and faster than the Fourier analysis.

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For the dynamic analysis, Hamilton's principle and Lagrange multiplier method are applied to formulate the equations of the motion of a quick return mechanism driven by a DC motor. The coordinate partitioning theorem is applied here to provide a theoretical reduction of differential-algebraic equations to differential equation form. In this work, we are concerned with the analysis and design a modified proportional-integral-derivative(PID)controller which was based on the principles of conventional PID controller to keep the driving crank with a constant angular velocity. Results of numerical simulations show that the angular velocity fluctuation can be reduced substantially and this modified PID controller also can give reasonably good results whatever it have or not considered cutting force in the system.

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A new method for designing a two-degree-of-freedom robust controller is formulated in the framework of the standard H_∞ optimization problem. The method can deal with the time domain requirements such as transient response characteristics and multivariable interaction between output channels by introducing a desired closed-loop model into the problem formulation, and produces a low order two-degree-of-freedom controller because the feedback and feedforward controllers share the same state space. The method is applied to design a robust controller of a seeker scan loop system. It is illustrated that the proposed two-degree-of-freedom control system satisfies design requirements, and shows good scanning performance for conical, rosette, and spiral scan patterns.

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In the study, instead of using expensive servo valves, three inexpensive high-speed solenoid valves were adopted and a fuzzy PWM controller was designed to control the linear and rotational positions of a pneumatic robot cylinder. The modified differential PWM method is proposed to eliminate the dead zone and to improve the nonlinear characteristics between the pressure difference of the cylinder and the duty ratio of the PWM control signal. The experimental results have shown that the servo pneumatic system with the proposed fuzzy PWM controller exhibits good performance.

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This paper presents a servo control scheme for control of the motion of a five-axis machine tool. In the proposed scheme, control of the five-axis system is operated with regard to the workpiece-coordinate basis, in which the relative motion between the tool and the workpiece is described. In practice, the available feedback signals are the positions along the driving axes that are defined in the drive-coordinate basis. Accordingly, the proposed five-axis servo controller is constructed based on the coordinate transformation between the workpiece-coordinate and the drive-coordinate bases.

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This paper presents a discussion of the issues related to force control in closed-loop kinematically constrained mechanisms. Unlike many of the analyses presented in robotics literature, which tend to model the contact with a stiff, but finite, compliance, the analysis in this paper focuses on the issues particular to mechanisms in which the contact relationship is kinematic. Motions of these kinematically constrained points thus give rise to contact force fluctuations which are related to both the inertial properties of the mechanism and the nonlinear kinematics. By modelling the constrained system as a closed-loop mechanism, it is possible to take into account both the kinematic constraint and the dynamic properties of the mechanism in order to derive force control laws which can be used to regulate contact forces even in the presence of contact point disturbances. Simulations and experiments with a simple one-link constrained mechanism underscore the importance of inertial force and contact point disturbance consideration in force control.

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A robust adaptive terminal sliding mode tracking control is proposed for rigid robotic manipulators. First, it is shown that, when a rigid robotic manipulator is treated as a partially known system, the system uncertainty is not only related to the model properties but also to the structure of the controllers. It is also proved that, if the control input vector does not contain the acceleration signals, the system uncertainty is upper bounded by a positive function of the position and velocity measurements. The property is very useful for the design of robust and adaptive controllers where only position and velocity measurements are available. Second, an MIMO terminal sliding mode is defined for the error dynamics of the robot control system, and an adaptive mechanism is introduced to estimate the upper bounds of system uncertainty in the Lyapunov sense. The estimates are then used as controller parameters so that the effects of uncertain dynamics can be eliminated and a finite time error convergence can be guaranteed. A simulation is given in support of the proposed control scheme.

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This paper outlines the theoretical and experimental analyses of the kinematic and kinetostatic characteristics of a variable lead screw mechanism(VLSM)used in high-speed shuttleless weaving looms. The mechanism consists of a slider-crank submechanism equipped with four conic frustum meshing elements with a 3° conical alngle to drive the variable lead screw in an oscillating manner. The screw and meshing elements act as a spatial cam pair. The conjugate surface theory and coordinate transformation are applied to develop the theoretical models used to analyze the mechanism. The kinematic curve is synthesized using optimization techniques that minimize the dissipated power due to the friction between the screw and meshing elements. The power equation is applied to analyze the input power of the VLSM, and the generalized Lanchester balancer technique is used in the design of the counterweight to reduce the shaking force. Experimental instruments are used for measuring the characteristics of the mechanism, including the angular velocity of the crank, the motion(including angular displacement, velocity and acceleration)of the screw, the input power, and the shaking forces before and after adding the counter-weight. Using a specified constant speed or the measured state of motion of the crank, the VLSM is analyzed theoretically, and results are compared with the measured results. It is shown that the input power of the prototype proposed is about one-quarter less than that of a commercial product, and the shaking force of the mechanism can be reduced by 46% once the proposed counterweight is added.

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For handling of a micromachine element and / or its parts, use of a micromechanical system is suitable. Thus, a pantograph mechanism is made from a plastic resin and superelastic hinges simultaneously using a small injection molding machine. The shape memory alloy having an effect of superelasticity is used as superelastic hinges. Therefore it is possible for superelastic hinges to have large bending displacements. The input and output displacements of the pantograph mechanism with superelastic hinges are measured and their linear relationship is confirmed. Then a micromechanical system for microbonding by adhesives is constructed using piezoelectric actuators, the pantograph mechanism and a needle. We confirmed that the proposed mechanical system performs well for microbonding by adhesives.

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Differential speed rolling of electrolytic copper powder is conducted under conditions of carefully controlled powder feed volume. Roll speed ratios are changed in the range of 1.00 to 1.50 by choosing different combinations of roll diameters. The rolling load increases with an increase in the ratio of the powder feed volume to the strip speed. The strip thickness increases with an increase in the rolling load for each roll gap, regardless of the roll speed ratio. The relative density of the strip is greater than that achieved using conventional powder rolling.

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A Drop-hammer compression apparatus with a controlled stopping device is developed. A check test for the stopping device is carried out by compression of a short circular bar. The accuracy of the device is confirmed to be satisfactory for practical use. It works well without redundant jumping motion of the drop-hammer. Application of the apparatus is performed to the bonding test, in which two rectangular blocks piled-up with a sawtoothed interface are compressed under plane strain condition. Soft pure aluminum(A1050-O), soft and a quarter hard aluminum alloy(A5056-O, 1 / 4H)and pure copper(C1100-O, H)are used. The initial hammer velocity is set to be 10 m / s in the high rate test. The corresponding low speed test is also carried out. The sawtoothed interface is degreased by liquid acetone and the naturally oxidized surface layer is removed by use of a dilute sulfuric acid solution before the test. The bondability in low speed compression is generally better than that in high rate compression in the cases of A1050-O and C1100-H. Shear-band type strain localization followed by shear fracture occurs in high rate compression of A5056-O and -1 / 4H specimens, and their bondability is rather low in low speed compression. Moreover, with respect to the hard pure copper, it is also tested for the case where the sawtoothed interface is scratched by a steel wire brush after removal of the oxidized surface layer. The remarkable improvement of bondability in low speed is attained by the scratching operation. Furthermore, the strain-rate sensitivity exponent(m-value)for the high strain-rate(∼500 / s)of the tested materials is estimated by compressing a short circular bar, in which the method of direct comparison between the load-time curves by experiment and theory is used. The m-value of A1050-O is found 0.34, which is much higher than that for low speed compression. A5056 shows tendency such that its m-value decreases rapidly as the strain increases. The shear fracture of A5056 mentioned above may be due to this characteristics of its m-value.

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Concurrent, cooperative and consistent product design by multiple designers and engineers is a key concept for success in a quickly changing market. For such design, the product modeling system is considered to be the common work space that integrates both design activities and design information from multiple designers and engineers. In this paper a framework of feature-based modeling is proposed to support concurrent, cooperative and consistent product desing involving functional design, machining, assembly and maintenance. The framework defines a mechanism for interpreting shape descriptions from the viewpoint of different applications into a unified representation. With this mechanism, designers and engineers can deal cooperatively with product shapes in an environment of concurrent engineering. Based on this framework, a feature-based modeling system has been developed and an example of implementation is briefly introduced.

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With assistance from DNA, mRNA, tRNA, RNA polymerase and aminoacyl-tRNA synthetase, biological systems synthesize amino acids in a particular sequence to produce a specific protein for a particular activity. On the other hand, using the parameters of some physical objects, such as, namely, parts design, machine tools, cutting tools and their machinability data, optimum tool selection for machining a particular part is accomplished. Analogizing the optimum tool selection process to the protein synthesis process, the above-mentioned objects were organized using the Protein Synthesis Algorithm derived from the protein synthesis mechanism. Unlike other related methods, this new method uses only a single database and avoids complex simulations. From an experiment in which the Protein Synthesis Algorithm was applied to turning tool selection, the claimed lucidity and straightforwardness of this method was confirmed.

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