Showing papers by "University of Electro-Communications published in 2007"
TL;DR: Efficient switching of the vortex core without magnetic-field application is achieved owing to resonance, which opens up the potentiality of a simple magnetic disk as a building block for spintronic devices such as a memory cell where the bit data is stored as the direction of the nanometre-scale core magnetization.
Abstract: A magnetic vortex is a curling magnetic structure realized in a ferromagnetic disk, which is a promising candidate for a memory cell for future non-volatile data-storage devices. Thus, an understanding of the stability and dynamical behaviour of the magnetic vortex is a major requirement for developing magnetic data-storage technology. Since the publication of experimental proof for the existence of a nanometre-scale core with out-of-plane magnetization in a magnetic vortex, the dynamics of vortices have been investigated intensively. However, a way to electrically control the core magnetization, which is a key for constructing a vortex-core memory, has been lacking. Here, we demonstrate the electrical switching of the core magnetization by using the current-driven resonant dynamics of the vortex; the core switching is triggered by a strong dynamic field that is produced locally by a rotational core motion at a high speed of several hundred metres per second. Efficient switching of the vortex core without magnetic-field application is achieved owing to resonance. This opens up the potentiality of a simple magnetic disk as a building block for spintronic devices such as a memory cell where the bit data is stored as the direction of the nanometre-scale core magnetization.
477 citations
TL;DR: It is shown that fluorescence of a very small number of atoms, around the nanofiber can be readily observed through a single-mode optical fiber, and that such a technique enables us to probe the van der Waals interaction between atoms and surface with high precision by observing the fluorescence excitation spectrum through the nan ofiber.
Abstract: We experimentally demonstrate efficient coupling of atomic fluorescence to the guided mode of a subwavelength-diameter silica fiber, an optical nanofiber. We show that fluorescence of a very small number of atoms, around the nanofiber can be readily observed through a single-mode optical fiber. We also show that such a technique enables us to probe the van der Waals interaction between atoms and surface with high precision by observing the fluorescence excitation spectrum through the nanofiber.
255 citations
16 Apr 2007
TL;DR: This paper presents a simplified bit-decomposition protocol by analyzing the original protocol and constructs more efficient protocols for a comparison, interval test and equality test of shared secrets without relying on the bit- Decomposition Protocol.
Abstract: Damgard et al. [11] showed a novel technique to convert a polynomial sharing of secret a into the sharings of the bits of a in constant rounds, which is called the bit-decomposition protocol. The bit-decomposition protocol is a very powerful tool because it enables bitoriented operations even if shared secrets are given as elements in the field. However, the bit-decomposition protocol is relatively expensive.
In this paper, we present a simplified bit-decomposition protocol by analyzing the original protocol. Moreover, we construct more efficient protocols for a comparison, interval test and equality test of shared secrets without relying on the bit-decomposition protocol though it seems essential to such bit-oriented operations. The key idea is that we do computation on secret a with c and r where c = a + r, c is a revealed value, and r is a random bitwise-shared secret. The outputs of these protocols are also shared without being revealed.
The realized protocols as well as the original protocol are constantround and run with less communication rounds and less data communication than those of [11]. For example, the round complexities are reduced by a factor of approximately 3 to 10.
251 citations
TL;DR: In this article, the authors derived a formula to calculate the ballistic thermal conductance of a two-dimensional system directly from the dispersion relations of phonons and electrons, and applied the method to a graphene and investigated both the temperature and the Fermi energy dependences of the ballistic conductance.
Abstract: We derive a formula to calculate the ballistic thermal conductance of a two-dimensional system directly from the dispersion relations of phonons and electrons. We apply the method to a graphene and investigate both the temperature and the Fermi energy dependences of the ballistic thermal conductance. The ballistic thermal conductance per unit length of a graphene becomes isotropic from the threefold rotational symmetry. In the intrinsic graphene where the Fermi energy crosses the Dirac point, the thermal conductance of electrons increases in proportion to ${T}^{2}$ with temperature, while the phonon conductance increases in proportion to ${T}^{1.5}$ due to the quadratic dispersion relation of the out-of-plane acoustic mode and prevails over the electron-derived conductance irrespective of temperature. As the Fermi energy is moved from the Dirac point for the gated graphenes, the thermal conductance of electrons increases monotonically and the temperature dependence changes from a ${T}^{2}$ dependence in the intrinsic graphene to a $T$-linear one at low temperatures. The electron thermal conductance of the gated graphenes dominates over the phonon contribution at low temperatures.
241 citations
05 Aug 2007
TL;DR: A wearable haptic display to present the weight sensation of a virtual object, which is based on the novel insight that the deformation on fingerpads makes a reliable weight sensation even when the proprioceptive sensation is absent, is proposed.
Abstract: We propose a wearable haptic display to present the weight sensation of a virtual object, which is based on our novel insight that the deformation on fingerpads makes a reliable weight sensation even when the proprioceptive sensation is absent. This device will provide a new form of ubiquitous haptic interaction.
217 citations
TL;DR: In this paper, the authors pin down the origin of the coexistence of large thermopower and the low resistivity in Na x CoO 2, revealing that not just the density of states (DOS), the effective mass, nor the band width, but the peculiar shape of the 1 g band referred to as the "pudding mold" type, which consists of a dispersive portion and a somewhat flat portion, is playing an important role in this phenomenon.
Abstract: In the present study, we pin down the origin of the coexistence of the large thermopower and the low resistivity in Na x CoO 2 . It is revealed that not just the density of states (DOS), the effective mass, nor the band width, but the peculiar shape of the a 1 g band referred to as the “pudding mold” type, which consists of a dispersive portion and a somewhat flat portion, is playing an important role in this phenomenon. The present study provides a new guiding principle for designing good thermoelectric materials.
204 citations
TL;DR: An exact and efficient branch-and-bound algorithm MCR for finding a maximum clique in an arbitrary graph that decidedly outperforms other existing algorithms on random graphs and on DIMACS benchmark graphs.
Abstract: We present an exact and efficient branch-and-bound algorithm MCR for finding a maximum clique in an arbitrary graph. The algorithm is not specialized for any particular type of graph. It employs approximate coloring to obtain an upper bound on the size of a maximum clique along with an improved appropriate sorting of vertices. We demonstrate by computational experiments on random graphs with up to 15,000 vertices and on DIMACS benchmark graphs that in general, our algorithm decidedly outperforms other existing algorithms. The algorithm has been successfully applied to interesting problems in bioinformatics, image processing, design of quantum circuits, and design of DNA and RNA sequences for biomolecular computation.
199 citations
01 Jun 2007
TL;DR: Adapt robust force/motion control strategies are presented for mobile manipulators under both holonomic and nonholonomic constraints in the presence of uncertainties and disturbances and guarantee that the system motion converges to the desired manifold with prescribed performance and the bounded constraint force.
Abstract: In this paper, adaptive robust force/motion control strategies are presented for mobile manipulators under both holonomic and nonholonomic constraints in the presence of uncertainties and disturbances. The proposed control is robust not only to parameter uncertainties such as mass variations but also to external ones such as disturbances. The stability of the closed-loop system and the boundedness of tracking errors are proved using Lyapunov stability synthesis. The proposed control strategies guarantee that the system motion converges to the desired manifold with prescribed performance and the bounded constraint force. Simulation results validate that the motion of the system converges to the desired trajectory, and the constraint force converges to the desired force
174 citations
TL;DR: In this paper, a flashlamp-pumped laser operation with the ceramic rod was demonstrated and a laser diode (LD) pumped composite ceramic laser was also demonstrated, where the optical properties and microstructure of those ceramics were investigated.
167 citations
TL;DR: An adaptive model predictive control algorithm is proposed for a class of constrained linear systems, which estimates system parameters on-line and produces the control input satisfying input/state constraints for possible parameter estimation errors.
166 citations
TL;DR: In this article, the authors present a network of ULF monitoring in the Tokyo area by describing their ULF magnetic sensors and finally present a few, latest results on seismogenic electromagnetic emissions for recent large earthquakes with the use of sophisticated signal processing.
Abstract: ULF (ultra-low-frequency) electromagnetic emission is recently recognized as one of the most promising candidates for short-term earthquake prediction. This paper reviews previous convincing evidence on the presence of ULF emissions before a few large earthquakes. Then, we present our network of ULF monitoring in the Tokyo area by describing our ULF magnetic sensors and we finally present a few, latest results on seismogenic electromagnetic emissions for recent large earthquakes with the use of sophisticated signal processings.
TL;DR: In this paper, the authors proposed a possible use of VLF/LF (very low frequency (3-30 kHz) /low frequency (30-300 kHz)) radio sounding of the seismo-ionospheric perturbations.
Abstract: It is recently recognized that the ionosphere is very sensitive to seismic effects, and the detection of ionospheric perturbations associated with earthquakes, seems to be very promising for short-term earthquake prediction. We have proposed a possible use of VLF/LF (very low frequency (3-30 kHz) /low frequency (30-300 kHz)) radio sounding of the seismo-ionospheric perturbations. A brief history of the use of subionospheric VLF/LF propagation for the short-term earthquake prediction is given, followed by a significant finding of ionospheric perturbation for the Kobe earthquake in 1995. After showing previous VLF/LF results, we present the latest VLF/LF findings; One is the statistical correlation of the ionospheric perturbation with earthquakes and the second is a case study for the Sumatra earthquake in December, 2004, indicating the spatical scale and dynamics of ionospheric perturbation for this earthquake.
TL;DR: This paper proposes a fast approximation algorithm for the single linkage method that reduces the time complexity to O(nB) by rapidly finding the near clusters to be connected by Locality-Sensitive Hashing, a fast algorithms for the approximate nearest neighbor search.
Abstract: The single linkage method is a fundamental agglomerative hierarchical clustering algorithm. This algorithm regards each point as a single cluster initially. In the agglomeration step, it connects a pair of clusters such that the distance between the nearest members is the shortest. This step is repeated until only one cluster remains. The single linkage method can efficiently detect clusters in arbitrary shapes. However, a drawback of this method is a large time complexity of O(n 2), where n represents the number of data points. This time complexity makes this method infeasible for large data. This paper proposes a fast approximation algorithm for the single linkage method. Our algorithm reduces the time complexity to O(nB) by rapidly finding the near clusters to be connected by Locality-Sensitive Hashing, a fast algorithm for the approximate nearest neighbor search. Here, B represents the maximum number of points going into a single hash entry and it practically diminishes to a small constant as compared to n for sufficiently large hash tables. Experimentally, we show that (1) the proposed algorithm obtains clustering results similar to those obtained by the single linkage method and (2) it runs faster for large data than the single linkage method.
TL;DR: In this article, it was shown that spin vortices are created through the Kibble-Zurek mechanism in the quantum phase transition of a spin-1 ferromagnetic Bose-Einstein condensate when the applied magnetic field is quenched to below a critical value.
Abstract: It is shown that spin vortices are created through the Kibble-Zurek mechanism in the quantum phase transition of a spin-1 ferromagnetic Bose-Einstein condensate when the applied magnetic field is quenched to below a critical value. It is also shown that the spin correlation functions have finite correlation lengths, and that the magnetization at widely separated positions grows in random directions, resulting in spontaneous creation of spin vortices. We numerically confirm the scaling laws that the winding number of spin vortices is proportional to the square root of the length of a closed path and, for a slow quench, is proportional to ${\ensuremath{\tau}}_{\text{Q}}^{\ensuremath{-}1∕6}$ with ${\ensuremath{\tau}}_{\text{Q}}$ being the quench time. The relevance of spin conservation to the Kibble-Zurek mechanism is discussed.
TL;DR: Efficient laser-diode pumped picosecond self-Q-switched all-ceramic composite Yb:YAG/Cr(4+):YAG microchip lasers with 0.72 MW peak power has been developed.
Abstract: Efficient laser-diode pumped picosecond self-Q-switched all-ceramic composite Yb:YAG/Cr4+:YAG microchip lasers with 0.72 MW peak power has been developed. Lasers with nearly diffraction-limited beam quality (M2 < 1.09), oscillate at stable single- and multi- longitudinal-modes due to the combined etalon effects in the Yb:YAG and Cr4+:YAG parts of its binary structure.
TL;DR: In this article, the elastic modulus and thermal conductivity of transparent single and polycrystalline Y 3 Al 5 O 12 (YAG) used for laser materials or arc tubes for lamps were measured.
TL;DR: Heavy-doped Yb:YAG ceramic is more suitable for a thin disk laser than a single-crystal with the same Yb(3+)-ion lasants.
Abstract: Laser performance of heavy-doped Yb:YAG ceramics was investigated using a two-pass pumping miniature laser configuration. Slope efficiency of 52% and optical-to-optical efficiency of 48% have been achieved for 1-mm-thick YAG ceramic doped with 20 at.% ytterbium ions. Laser spectra of Yb:YAG ceramic and single-crystal lasers were addressed under different intracavity laser intensities. Heavy-doped Yb:YAG ceramic is more suitable for a thin disk laser than a single-crystal with the same Yb3+-ion lasants.
TL;DR: In this paper, the two-dimensional electron momentum spectra of Ar by femtosecond intense laser pulses with mean wavelength from $400\phantom{\rule{0.3em}{0ex}}\mathrm{nm}\phantom{1.3m}
Abstract: We studied the two-dimensional electron momentum spectra of Ar by femtosecond intense laser pulses with mean wavelength from $400\phantom{\rule{0.3em}{0ex}}\mathrm{nm}\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}800\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$, to compare with experimental results of Maharjan et al. [J. Phys. B 39, 1955 (2006)]. At the higher intensities we found that the effects of ground-state depletion and laser-focus volume are very important such that the peak laser field strength is not reached in experiment. The ubiquitous fanlike stripes in the low-energy electron momentum spectra and the evidence of Freeman resonances in the experimental data are well reproduced in the theoretical calculations. We emphasize that depletion of the initial state should be carefully evaluated for ionization of atoms in the tunneling region.
TL;DR: The feasibility and effectiveness as well as the significant performance improvements of the nonlinear MPC design proposed is demonstrated with a real industrial application to the nitrogen oxide (NOx) decomposition process in thermal power plants.
Abstract: A Gaussian radial basis function (RBF) neural networks-based local linearization autoregressive with exogenous (ARX) model is utilized for describing the dynamics of a class of smooth nonlinear and nonstationary industrial processes. The dynamics of the underlying processes may be treated as the system operating-point-dependent time-varying locally-linear behavior. The RBF-ARX model is a pseudo-linear ARX model identified offline, and its functional coefficients are composed of the operating-point-dependent RBF neural networks. The RBF-ARX model-based predictive control (MPC) design to the nonlinear process is presented, and stability analysis of the nonlinear MPC under some conditions is discussed. Especially, the feasibility and effectiveness as well as the significant performance improvements of the nonlinear MPC design proposed is demonstrated with a real industrial application to the nitrogen oxide (NOx) decomposition (de-NOx) process in thermal power plants
TL;DR: An on-chip thermal switch operated by a focused argon-ion laser is developed that operates as an on/off switch of the supercurrent or as a device to set the current to a specific value with the aid of an external magnetic field.
Abstract: Rubidium-87 atoms are trapped in an Ioffe-Pritchard potential generated with a persistent supercurrent that flows in a loop circuit patterned on a sapphire surface. The superconducting circuit is a closed loop made of a $100\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ wide molecular-beam epitaxy-grown ${\mathrm{MgB}}_{2}$ stripe carrying a supercurrent of 2.5 A. To control the supercurrent in the stripe, an on-chip thermal switch operated by a focused argon-ion laser is developed. The switch operates as an on/off switch of the supercurrent or as a device to set the current to a specific value with the aid of an external magnetic field. The current can be set even without an external source if the change is in the decreasing direction.
TL;DR: In this article, a strain-induced evolution of ultrafine grains in pure copper was studied in multidirectional forging (MDF) at 195 K. The structural changes were associated with the development of high-density microshear bands crossed by MDF.
Abstract: Strain-induced evolution of ultrafine grains in pure copper was studied in multidirectional forging (MDF) at 195 K. The stress–strain behaviour was characterized by rapid strain hardening during early processing and the rate of strain hardening gradually decreased with straining, leading to an apparent steady-state flow at large cumulative strains of more than 5. The structural changes were associated with the development of high-density microshear bands crossed by MDF. The new fine grains 0.16 µm in size, which was smaller than the subgrain size evolved during early deformation, were evolved primarily at microshear band intersections, and then the new fine grains filled out the whole sample as the number of microshear band intersections increased at large strains. This is essentially similar to continuous dynamic recrystallization. The size of new grains can be expressed by a power law function of flow stress with a grain size exponent of about –0.3. The kinetics of the strain-induced grain evolution is ...
TL;DR: A new neurofuzzy based adaptive Kalman filtering algorithm for simultaneous localization and mapping of mobile robots or vehicles, which attempts to estimate the elements of the R matrix of the EKF algorithm, at each sampling instant when a ldquomeasurement updaterdquo step is carried out.
Abstract: Extended Kalman filter (EKF) has been a popular choice to solve simultaneous localization and mapping (SLAM) problems for mobile robots or vehicles. However, the performance of the EKF depends on the correct a priori knowledge of process and sensor/measurement noise covariance matrices (Q and R, respectively). Imprecise knowledge of these statistics can cause significant degradation in performance. The present paper proposes the development of a new neurofuzzy based adaptive Kalman filtering algorithm for simultaneous localization and mapping of mobile robots or vehicles, which attempts to estimate the elements of the R matrix of the EKF algorithm, at each sampling instant when a ldquomeasurement updaterdquo step is carried out. The neuro-fuzzy based supervision for the EKF algorithm is carried out with the aim of reducing the mismatch between the theoretical and the actual covariance of the innovation sequences. The free parameters of the neuro-fuzzy system are learned offline, by employing particle swarm optimization in the training phase, which configures the training problem as a high-dimensional stochastic optimization problem. By employing a mobile robot to localize and simultaneously acquire the map of the environment, under several benchmark environment situations with varying landmarks and under several conditions of wrong knowledge of sensor statistics, the performance of the proposed scheme has been evaluated. It has been successfully demonstrated that in each case, the neuro-fuzzy assistance is able to improve highly unpredictable, degrading performance of the EKF and can provide robust and accurate solutions.
22 Mar 2007
TL;DR: It is found that the deformation of the fingerpads can generate the reliable gravity sensation even when the proprioceptive sensation on the wrist or arm is absent, implying that a non-grounded gravity display can be realized by reproducing the fingerpad deformation.
Abstract: We propose a wearable, ungrounded haptic display that presents the realistic gravity sensation of a virtual object We focused on the shearing stress on the fingerpads duo to the weight of the object, and found that the deformation of the fingerpads can generate the reliable gravity sensation even when the proprioceptive sensation on the wrist or arm is absent This implies that a non-grounded gravity display can be realized by reproducing the fingerpad deformation According to our observations, we had evaluation tests for device design We implemented the prototype device which has simple structure using dual motors, and then evaluated the recognition ability of the gravity sensation presented on operator's fingerpads with this method
TL;DR: Testing the hypothesis that muscle microvascular O2 pressure would be lowered in the spinotrapezius muscle of Goto-Kakizaki Type II diabetic rats at rest and during twitch contractions when compared to control rats found that this decreased PmvO2 across the transition to a higher metabolic rate in Type II diabetes would be expected to impair blood-muscle O2 exchange and contractile function.
TL;DR: The experimental observation of rectified momentum transport for a Bose-Einstein condensate kicked at the Talbot time (quantum resonance) by an optical standing wave is reported and an interpretation based on matter-wave interference is offered, showing that the observed effect is uniquely quantum.
Abstract: We report the experimental observation of rectified momentum transport for a Bose-Einstein condensate kicked at the Talbot time (quantum resonance) by an optical standing wave. Atoms are initially prepared in a superposition of the 0 and $\ensuremath{-}2\ensuremath{\hbar}{k}_{l}$ momentum states using an optical $\ensuremath{\pi}/2$ pulse. By changing the relative phase of the superposed states, a momentum current in either direction along the standing wave may be produced. We offer an interpretation based on matter-wave interference, showing that the observed effect is uniquely quantum.
TL;DR: In this article, the Bogoliubov analysis showed that two Goldstone modes associated with U(1) and SO(2) symmetry breakings exist, in which phonons and magnons are coupled to restore the two broken symmetries.
Abstract: A spin-1 ferromagnetic Bose-Einstein condensate subject to a certain magnetic field exhibits a broken-axisymmetry phase in which the magnetization tilts against the applied magnetic field due to the competition between ferromagnetism and linear and quadratic Zeeman effects. The Bogoliubov analysis shows that in this phase two Goldstone modes associated with U(1) and SO(2) symmetry breakings exist, in which phonons and magnons are coupled to restore the two broken symmetries.
TL;DR: In this article, the authors have fabricated Cr 3+ and Nd 3+ co-doped YAG (Cr;Nd:YAG) ceramics, and investigated their optical properties and laser characteristics.
Abstract: We have fabricated Cr 3+ and Nd 3+ co-doped YAG (Cr;Nd:YAG) ceramics, and investigated their optical properties and laser characteristics. The Cr;Nd:YAG has two broad absorption bands at around 440 nm ( 4 A 2 → 4 T 1 ) and 600 nm ( 4 A 2 → 4 T 2 ) respectively, caused by Cr 3+ ions. In the case of pumping at 440 nm, the maximum effective lifetime of the Cr;Nd:YAG was 737 μs with a 0.1 at% Cr 3+ and 1.0 at% Nd 3+ co-doped YAG sample. Cr 3+ ions take a role of an effective sensitizer to convert the UV light of flashlamp. For single-shot laser operation, a 10.4 J output energy at 1064 nm was obtained with 0.1 at% Cr 3+ and 1.0 at% Nd 3+ co-doped YAG ceramic rod with a laser efficiency of 4.9%. The laser efficiency was found to be more than twice that of a 1.0 at % Nd 3+ :YAG ceramic rod.
25 Jan 2007-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: Grain refinement taking place during equal-channel angular pressing (ECAP) was studied in a commercial Al 6% Mg 0.4% Mn 0.3% Sc alloy at a temperature of 450°C (∼0.8 T m ) as discussed by the authors.
Abstract: Grain refinement taking place during equal-channel angular pressing (ECAP) was studied in a commercial Al–6% Mg–0.4% Mn–0.3% Sc alloy at a temperature of 450 °C (∼0.8 T m ) to demonstrate the feasibility of obtaining new fine-grained structure in a hard-to-deform Al–Mg–Sc alloy under hot intense plastic straining (IPS) conditions and investigate the evolution process of new grains. Inhomogeneous deformation occurring during hot ECAP leads to formation of deformation bands. Repeated ECAP results in mutual crossing and increase in number and the misorientation of deformation bands, followed by transformation of the boundaries of deformation bands into high-angle ones. As a result, a new fine-grained microstructure with an average crystallite size of 2.8 μm develops at large strains above 8. It is concluded that grain refinement occurs in accordance with deformation-induced continuous reactions; that is similar to in-situ or continuous dynamic recrystallization. The mechanisms of new grain evolution, as well as factors promoting grain refinement, are discussed in detail.
TL;DR: In this paper, variations of the LF subionospheric signal amplitude and phase from JJY transmitter in Japan (F=40 kHz) received in Petropavlovsk-Kamchatsky station during seismically quiet and active periods including also periods of magnetic storms were analyzed.
Abstract: . We analyze variations of the LF subionospheric signal amplitude and phase from JJY transmitter in Japan (F=40 kHz) received in Petropavlovsk-Kamchatsky station during seismically quiet and active periods including also periods of magnetic storms. After 20 s averaging, the frequency range of the analysis is 0.28–15 mHz that corresponds to the period range from 1 to 60 min. Changes in spectra of the LF signal perturbations are found several days before and after three large earthquakes, which happened in November 2004 (M=7.1), August 2005 (M=7.2) and November 2006 (M=8.2) inside the Fresnel zone of the Japan-Kamchatka wavepath. Comparing the perturbed and background spectra we have found the evident increase in spectral range 10–25 min that is in the compliance with theoretical estimations on lithosphere-ionosphere coupling by the Atmospheric Gravity Waves (T>6 min). Similar changes are not found for the periods of magnetic storms.
10 Apr 2007
TL;DR: The construction of the hardware and the control system of KOHGA2, the basic mobility performance, and the stuck avoidance strategy are reported.
Abstract: To search victims in the narrow space at the disaster site, we have developed the snake-like rescue robot called "KOHGA". The robot is constructed by connecting multiple crawler vehicles serially by active joints. KOHGA has a problem that obstacles are caught to the joints and then the robot is stuck. To solve this problem, we developed an unit assembled robot "KOHGA2". It can be rearranged. The robot can swing crawler-arms and avoid the stuck. In this paper, we report the construction of the hardware and the control system of KOHGA2, the basic mobility performance, and the stuck avoidance strategy.