This paper describes the design concept and implementation of a software platform for realization of symbiotic robots that interact intelligently with human in symbiosis manner. Such robots require proper combination of various technologies on a common platform that allows them to work co-operatively. "SPAK" has been developed to serve this purpose. It is a Java-based software platform to support knowledge processing and co-ordination of tasks among several software modules and agents representing the robotic hardware connected on a network. SPAK features frame-based knowledge system, a GUI knowledge building tool, forward and backward chaining engines, networking support, and class libraries for building software agent components. Beside the robotic applications, SPAK can be used as a general-purpose frame system as well. An experimental application of SPAK in human-robot interaction is also given.

We discuss photonic crystals (PhCs) with advanced micro/nano-structres which are semiconductor quantum dots (QDs) and micro electro-mechanical systems (MEMS) for the purpose of realizing novel classes of PhC devices in future photonic network system. After brief introduction on advantages to implement QDs and MEMS with PhCs, we discuss optical characterization of PhC microcavity containing self-assembled InAs QDs. Modification of emission spectrum of a QD ensemble due to the resonant cavity modes is demonstrated. We also point out the feasibility of low-threshold PhC lasers with QD active media in numerical analysis. A very low threshold current of 10 µA is numerically obtained for lasing action in the multi dimensional distributed feedback mode by using realistic material parameters. Then, the basic concept for MEMS-controlled PhC slab devices is described. We show numerical results that demonstrate some of interesting functions such as the intensity modulation and the tuning of resonant frequency of cavity mode. Finally, a preliminary experiment of MEMS-based switching operation in a PhC line-defect waveguide is demonstrated.

An adaptive backstepping and high order sliding modes control algorithm is proposed for output tracking of mobile robots. The controller can greatly reduce the chattering due to conventional sliding modes technique. The proposed algorithm has certain robustness with respect to the external random disturbances and good adaptability with respect to the parametric uncertainty. The effectiveness of the proposed control strategy is demonstrated by simulations studies.

A computed torque controller for a dynamic model of nonholonomic mobile robots with bounded external disturbance is proposed to treat the adaptive tracking control problem using the separated design method. A velocity controller is first designed for the kinematic steering system to make the tracking error approaching to zero asympotically. Then, a computed torque controller is designed such that the true mobile robot velocity converges to the desired velocity controller. In each step, the controllers are designed independently, and this will simplify the design of controllers. A novel stability analysis involving the estimation of some differential inequalities is also given to guarantee the stability of the closed-loop system. Moreover, the regulation problem and the tracking problem will be treated using the proposed controller. In particular, the mobile robots can globally follow any path such as a straight-line, a circle and the path approaching to the origin. Furthermore, the problems of back-into-garage parking and the parallel parking problem can also be solved using the proposed controller. Some interesting simulation results are given to illustrate the effectiveness of the proposed tracking control law.

Decreased power dissipation and transient voltage drops in CMOS power distribution networks are important for high-speed deep submicrometer CMOS integrated circuits. In this paper, three CMOS buffers based on the charge-transfer, split-path and bootstrapped techniques to reduce the power dissipation and transient voltage drop in power supply are proposed. First, the inverted-delay-unit is used in the low-power inverted-delay-unit (LPID) CMOS buffer to eliminate the short-circuit current of the output stage. Second, the low-swing bootstrapped feedback-controlled split-path (LBFS) CMOS buffer is proposed to eliminate the short-circuit current of the output stage by using the feedback-controlled split-path method. The dynamic power dissipation of the LBFS CMOS buffer can be reduced by limiting the gate voltage swing of the output stage. Moreover, the propagation delay of the LBFS CMOS buffer is also reduced by non-full-swing gate voltage of the output stage. Third, the charge-recovery scheme is used in the charge-transfer feedback-controlled 4-split-path (CRFS) CMOS buffer to recovery and pull up the gate voltage of the output stage for reducing power-delay product and power line noise. Based on HSPICE simulation results, the power-delay product and the transient voltage drop in power supply of the proposed three CMOS buffers can be reduced by 20% to 40% as compared to conventional CMOS tapered buffer under various capacitive load.

A pass-transistor logic is enhanced with a bootstrap configuration for sub-1 V operation at high speed and low power. The bootstrap configuration drives the output to full swing, which accelerates the signal transition and cuts off the short-circuit current of subsequent CMOS logic gates. The asynchronous or synchronous timing sequence of the input (drain) and the control (gate) signals ensures bootstrap operation. A 1-b arithmetic logic unit (ALU) and an EXNOR gate built with the bootstrap pass-transistor logic outperforms those built with other types of pass-transistor logic. An experimental 16-b pass-transistor adder operates down to 0.4 V with a delay time of 4.2 ns and a power dissipation of 2.8 µ W/MHz at 0.5 V.

In this paper, we investigate the electron-hole energy states and energy gap in three-dimensional (3D) InAs/GaAs quantum rings and dots with different shapes under external magnetic fields. Our realistic model formulation includes: (i) the effective mass Hamiltonian in non-parabolic approximation for electrons, (ii) the effective mass Hamiltonian in parabolic approximation for holes, (iii) the position- and energy-dependent quasi-particle effective mass approximation for electrons, (iv) the finite hard wall confinement potential, and (v) the Ben Daniel-Duke boundary conditions. To solve the 3D nonlinear problem without any fitting parameters, we have applied the nonlinear iterative method to obtain self-consistent solutions. Due to the penetration of applied magnetic fields into torus ring region, for ellipsoidal- and rectangular-shaped quantum rings we find nonperiodical oscillations of the energy gap between the lowest electron and hole states as a function of external magnetic fields. The nonperiodical oscillation is different from 1D periodical argument and strongly dependent on structure shape and size. The result is useful to study magneto-optical properties of the nanoscale quantum rings and dots.

This paper addresses a high-order sliding mode control strategy for output tracking of nonholonomic mobile robots. First, we introduce the dynamic model of robots, driving motors and nonslipping kinematics constraint conditions. Second, we decompose the system into linear and nonlinear components via diffeomorphism and nonlinear input transformation. Also we consider parameter variations of robots and deduce the uncertain model of robots. Third, we design a high order sliding mode controller for output tracking of known and uncertain systems, respectively. Finally, we perform numerical simulations, demonstrating that the proposed high-order sliding mode control not only reduces the chattering problem of sliding mode systems, but also has certain robustness properties with respect to uncertainties of robots.

This paper presents a child verb learning model mainly based on syntactic bootstrapping. The model automatically learns 4-5-year-old children's linguistic knowledge of verbs, including subcategorization frames and thematic roles, using a text in dialogue format. Subcategorization frame acquisition of verbs is guided by the assumption of the existence of nine verb prototypes. These verb prototypes are extracted based on syntactic bootstrapping and some psycholinguistic studies. Thematic roles are assigned by syntactic bootstrapping and other psycholinguistic hypotheses. The experiments are performed on the data from the CHILDES database. The results show that the learning model successfully acquires linguistic knowledge of verbs and also suggest that psycholinguistic studies of child verb learning may provide important hints for linguistic knowledge acquisition in natural language processing (NLP).

Optical properties and growth of self-assembled quantum dots (SAQDs) for optoelectronic device applications are discussed. After briefly reviewing the history of research on QD lasers, we discuss growth of InAs SAQDs including the light emission at the wavelength of 1.52-µm with a narrow linewidth (22 meV) and the area-controlled growth which demonstrates formation of SAQDs in selected local areas on a growth plane using a SiO2 mask with MOCVD growth. Then properties of the InGaAs AQDs are investigated by the near-field photoluminescence excitation spectroscopy which reveals gradually increasing continuum absorption connected with the two-dimensional-like (2D-like) wetting layer, resulting in faster relaxation of electrons due to a crossover between 0D and 2D character in the density of states. In the coherent excitation spectroscopy, the decoherence time is determined to be about 15 ps, which is well explained by the phonon induced relaxation mechanism in the SAQDs. Finally, nitride-based SAQDs and perspective of QD optical devices are also discussed.

A general tracking control problem for mobile robots is proposed and solved using the backstepping technique. A global result is given for the kinematic steering system to make the tracking error approaching to zero asymptotically. Based on our efforts, the proposed controller can solve both the tracking problem and the regulation problem of mobile robots. In particular, mobile robots can now globally follow any differentiable with bounded velocities path such as a straight line, a circle and the path approaching to the origin using the proposed controller. Moreover, the problem of back-into-garage parking is also solved by our approach. Some interesting simulation results are given to illustrate the effectiveness of the proposed tracking control laws.

The constriction resistance of an electric contact has frequently been obtained using a model of only one circular contact spot of radius a. However, cases of a single contact spot are extremely rare as the interface of the electrical contact actually consists of numerous micro-contact spots. A contact is therefore regarded as the aggregate of several micro-contact spots, which are referred to collectively as a cluster. The constriction resistance of the cluster can be calculated as the sum of the self-resistance and mutual resistance of individual micro-contact spots. In the present study, this model is expanded slightly for practical application by normalizing a previous theoretical formula. In order to obtain the constriction resistance for contacts between composite materials and mating metals, EPMA analysis is applied so as to determine real micro-contact spots. Theoretical calculations of the constriction resistance of multiple contact spots is shown to be reasonably consistent with experimental results. In addition, the contact of a composite material and a mating metal is shown to be made up of multispots. The current was recognized experimentally to flow more easily at micro-contact spots in the cluster periphery. These experimental findings coincide with simulation results obtained by theoretical calculations.

The optimization of channel assignment in cellular mobile networks is an NP-complete combinatorial optimization problem. For any reasonable size network, only sub-optimal solutions can be obtained by heuristic algorithms. In this paper, six channel assignment heuristic algorithms are proposed and evaluated. They are the combinations of three channel assignment strategies and two cell ordering methods. What we found are (i) the node-color ordering of cells is a more efficient ordering method than the node-degree ordering; (ii) the frequency exhaustive strategy is more suitable for systems with highly non-uniformly distributed traffic, and the requirement exhaustive strategy is more suitable for systems with less non-uniformly distributed traffic; and (iii) the combined frequency and requirement exhaustive strategy with node-color re-ordering is the most efficient algorithm. The frequency spans obtained using the proposed algorithms are much lower than that reported in the literature, and in many cases are equal to the theoretical lower bounds.

In industrial assembly lines, seam sealing is a painting process used for making watertight seals or for preventing rusting. In the process, sealant is painted on seams located at the joints of pressed metal parts. We developed a sealing robot system that adjusts the sealing gun motion adaptively to the seam position sensed by a range sensor (a scanning laser rangefinder which senses profile range data). In this paper, we propose a high-speed and highly reliable algorithm for seam position computation from the sensed profile range data around the seam. It is proved experimentally that the sealing robot system used with the developed algorithm is very effective, especially for reducing wasted sealant.

Our recent progress in GaN-based nanostructures for quantum dot (QD) lasers and vertical microcavity surface emitting lasers (VCSELs) is discussed. We have grown InGaN self-assembled QDs on a GaN epitaxial layer, using atmospheric-pressure metalorganic chemical vapor deposition. The average diameter of the QDs was as small as 8.4 nm and strong photoluminescence emission from the QDs was observed at room temperature. Furthermore, we found that InGaN QDs could be formed even after 10 QD layers were stacked, thus increasing the total QD density. Using these growth results, we fabricated a laser structure with InGaN QDs embedded in the active layer. A clear threshold was observed in the dependence of the emission intensity on the excitation energy at room temperature under optical excitation. We succeeded in demonstrating in lasing action in vertical cavity surface emitting lasers at room temperature with a cavity finesse of over 200.

We discuss optimal estimation of the current location of a mobile robot by matching an image of the scene taken by the robot with the model of the environment. We first present a theoretical accuracy bound and then give a method that attains that bound, which can be viewed as describing the probability distribution of the current location. Using real images, we demonstrate that our method is superior to the naive least-squares method. We also confirm the theoretical predictions of our theory by applying the bootstrap procedure.

This paper proposes genetic algorithms (GAs) for path planning and trajectory planning of an autonomous mobile robot. Our GA-based approach has an advantage of adaptivity such that the GAs work even if an environment is time-varying or unknown. Therefore, it is suitable for both off-line and on-line motion planning. We first presents a GA for path planning in a 2D terrain. Simulation results on the performance and adaptivity of the GA on randomly generated terrains are shown. Then, we discuss an extension of the GA for solving both path planning and trajectory planning simultaneously.

Simple expressions for constriction resistance of multitude conducting spots were analytically formulated by Greenwood. These expressions, however, include some approximations. Nakamura presented that the constriction resistance of one circular spot computed using the BEM is closed to Maxwell's exact value. This relative error is only e=0. 00162 [%]. In this study, the constriction resistances of two, five and ten conducting spots are computed using the boundary element method (BEM), and compared with those obtained using Greenwood's expressions. As the conducting spots move close to each other, the numerical deviations between constriction resistances computed using Greenwood's expressions and the BEM increase. As a result, mutual resistance computed by the BEM is larger than that obtained from Greenwood's expressions. The numerical deviations between the total resistances computed by Greenwood's expressions and that by the BEM are small. Hence, Greenwood's expressions are valid for the total constriction resistance calculation and can be applied to problems where only the total resistance of two contact surfaces, such as a relay and a switch, is required. However, the numerical deviations between the partial resistances computed by Greenwood's expression and that by the BEM are very large. The partial resistance calculations of multitude conducting spots are beyond the applicable range of Greenwood's expression, since Greenwood's expression for constriction resistance of two conducting spots is obtained by assuming that the conducting spots are equal size. In particular, the deviation between resistances of conducting spots, which are close to each other, is very large. In the case of partial resistances which are significant in semiconductor devices, Greenwood's expressions cannot be used with high precision.

We discuss optimal rotation estimation from two sets of 3-D points in the presence of anisotropic and inhomogeneous noise. We first present a theoretical accuracy bound and then give a method that attains that bound, which can be viewed as describing the reliability of the solution. We also show that an efficient computational scheme can be obtained by using quaternions and applying renormalization. Using real stereo images for 3-D reconstruction, we demonstrate that our method is superior to the least-squares method and confirm the theoretical predictions of our theory by applying bootstrap procedure.

ATM technology can integrate not only new multimedia services but also existing services such as plain old telephone services (POTS) and narrow-band ISDN (N-ISDN) services. We developed ATM subscriber line interface circuits (ATM-SLIC), which can accommodate POTS or N-ISDN subscribers, and a trial ATM access switching system using the ATM-SLICs. This paper proposes embedded trunk functions, a message-type signaling transfer method, an economical ATM interface structure, and a cell-based system control method. Moreover, it shows the main characteristics and efficiency of these proposals in terms of experimental data.