Mobile parallel manipulator consisting of two nonholonomic carts and their path planning

Mobile manipulators are widely used to transport and manipulate objects in industrial settings. In this paper, we propose a mobile manipulator that consists of a parallel mechanism and two two-wheel-drive carts. The planar motions of the carts are transmitted to a platform through three screw pairs of the parallel mechanism, allowing the pose of the platform to be controlled by only four motors. Kinematic analysis for such a two-cart mobile manipulator gives a Jacobian matrix, reveals the effects of nonholonomic constraints, and demonstrates that the yaw angle of the platform must be limited to avoid singular and failure configurations, and that the pitch angle is quite sensitive to uncertainties. Based on these analysis results, we present a custom path planning method for the carts. This method provides a non-optimal but easily realizable path planning algorithm with low computational cost, since the complex constraint conditions of this two-cart mobile manipulator have little influence on the proposed path generation process. The path planning process consists of four steps. We describe the motions of the carts in each step and establish a path tracking control system for the carts. Some simulations are conducted to show the motions of the carts, investigate the changes in the pose of the platform, and quantitatively evaluate the sensitivity of the platform’s pitch angle. Moreover, we construct an experimental prototype and conduct experiments to verify the validity and usefulness of the proposed mechanism and path planning method

ホウ素触媒によるカルボン酸エノラート生成法の開発とその応用展開

学位の種別: 課程博士審査委員会委員 : （主査）東京大学教授 金井 求, 東京大学教授 内山 真伸, 東京大学准教授 花岡 健二郎, 東京大学講師 占部 大介, 東京大学講師 宮本 和範University of Tokyo(東京大学

IR Absorption Nnalysis of Oxidation Behaviors of Nano-composite Phases with β-FeSi2 Nanocrystals and Si

We have investigated oxidation behaviors of nano-composite phase with β-FeSi2 nanocrystals (β-NCs) and Si on Si substrates. IR absorption measurements revealed that only oxidation of Si into SiO2 proceeded in the nano-composite phase. This fact is very important for realization of a novel composite phase with β-NCs and SiO2, which may contribute to enhancement of light emission and to prevent a large thermal quenching of light emission observed in the composite phase with β-NCs and Si.International Conference and Summer School on Advanced Silicide Technology 2014, July 19–21, 2014, Tokyo, Japa

Enhancement of Photoluminescence from Cu-doped β-FeSi2/Si Heterostructures

We have investigated photoluminescence (PL) behaviors of the Cu-doped β-FeSi2 thin film/Si heterostructure. Pronounced enhancement of an intrinsic A band and an impurity-related C band emissions has been observed in all the Cu-doped samples. The photo-carrier injection (PCI)-PL measurements have revealed that the PL enhancement is attributed to dynamic process of migration of holes where a repeated trap process of holes can be controlled by Cu-doping.International Conference and Summer School on Advanced Silicide Technology 2014, July 19–21, 2014, Tokyo, Japa

Photoluminescence Property of Nano-composite Phases of β-FeSi2 Nanocrystals Embedded in SiO2

We have investigated photoluminescence (PL) behaviors of nano-composite phase of β-NCs embedded in SiO2 (β-NCs/SiO2). The inhomogeneous spectra consisting of the A, B, and C emission bands were observed. PL enhancement also was confirmed in comparison with β-NCs/Si. Under high pumping rate, we observed PL spectra near room temperatures (~270 K). This fact means that oxidation of the nano-composite phase can contribute to reduction of thermal quenching, which may come from increase of band offsets around β-NCs.International Conference and Summer School on Advanced Silicide Technology 2014, July 19–21, 2014, Tokyo, Japa

Effects of hydrogen-rich water on aging periodontal tissues in rats

Oxidative damage is involved in age-related inflammatory reactions. The anti-oxidative effects of hydrogen-rich water suppress oxidative damage, which may aid in inhibiting age-related inflammatory reactions. We investigated the effects of drinking hydrogen-rich water on aging periodontal tissues in healthy rats. Four-month-old male Fischer 344 rats (n = 12) were divided into two groups: the experimental group (hydrogen-rich water treatment) and the control group (distilled water treatment). The rats consumed hydrogen-rich water or distilled water until 16 months of age. The experimental group exhibited lower periodontal oxidative damage at 16 months of age than the control group. Although protein expression of interleukin-1 beta did not differ, gene expression of Nod-like receptor protein 3 inflammasomes was activated in periodontal tissues from the experimental group as compared with the control group. Drinking hydrogen-rich water is proposed to have anti-aging effects on periodontal oxidative damage, but not on inflammatory reactions in healthy rats

Reducer-integrated motor using simultaneous engagement of gear pairs with small and no differences in teeth number

The motors for industrial robots and transporting robots require high-precision positioning, large torque output, and downsizing. However, conventional motors have difficulties in downsizing or supporting large torque. In this research, we propose a novel reducer-integrated motor to solve the problems of existing motors. The proposed reducer-integrated motor has a differential gear mechanism using the simultaneous engagement of two kinds of external and internal gear pairs: one with a small difference in teeth number and the other with no difference in teeth number. Inside the reducer, linear actuators are installed. Two gear pairs with no difference in teeth number are fixed on the base and the gear pair with a small difference in teeth number is set between them. When the linear actuators revolve the external gear, the two kinds of the gear pairs engage simultaneously and the internal gear of the gear pair with a small difference in teeth number outputs the rotation. It is thought that the structure of the proposed motor can realize downsizing of the entire motor system, high load-supporting capacity, and high stiffness. In this paper, the structure and movement of the proposed motor are explained. The geometrical conditions for simultaneous engagement of the two gear pairs with small and no differences in teeth number are clarified. Through the discussion on the solution satisfying the conditions and the relation with the bending strength, a design method for the reducer of this motor is proposed. An experiment conducted on a prototype verifies that the proposed motor works as expected

Spatial Distributions of GABA Receptors and Local Inhibition of Ca2+ Transients Studied with GABA Uncaging in the Dendrites of CA1 Pyramidal Neurons

GABA(γ-amino-butylic acid)-mediated inhibition in the dendrites of CA1 pyramidal neurons was characterized by two-photon uncaging of a caged-GABA compound, BCMACM-GABA, and one-photon uncaging of RuBi-GABA in rat hippocampal slice preparations. Although we found that GABAA-mediated currents were diffusely distributed along the dendrites, currents elicited at the branch points of the apical dendritic trunk were approximately two times larger than those elsewhere in the dendrite. We examined the inhibitory action of the GABA-induced currents on Ca2+ transients evoked with a single back-propagating action potential (bAP) in oblique dendrites. We found that GABA uncaging selectively inhibited the Ca2+ transients in the region adjacent (<20 µm) to the uncaging site, and that GABA uncaging was effective only within a short period after bAP (<20 ms). The strength of inhibition was linearly related to the amplitudes of the GABA currents, suggesting that the currents inhibited a sustained, subthreshold after-depolarization without preventing propagation of bAP. GABA uncaging at the dendritic branch points inhibited Ca2+ transients farther into dendritic branches (>20 µm). Our data indicate that GABA inhibition results in spatially confined inhibition of Ca2+ transients shortly after bAP, and suggest that this effect is particularly potent at the dendritic branch points where GABA receptors cluster

Five-minute resolved spatial distribution of radiocesium in sea sediment derived from the Fukushima Dai-ichi Nuclear Power Plant

AbstractThe spatial distributions of radiocesium concentration in sea sediment to a core depth of 14 cm were investigated in the offshore region from the Fukushima Prefecture to the northern part of the Ibaraki Prefecture in February and July 2012, at a spatial resolution of 5 min of latitude and longitude. The concentrations in the area south of the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) were generally higher than those in the area north of it. In the southern area, a band of especially high concentration with a width about 20 km was present in the region shallower than 100 m, and a narrow minimal concentration band was found along the 200-m isobaths. In more than half of all cases, the vertical core profiles of radiocesium concentration generally showed an exponential decreasing trend with depth. However, in the area north of the FDNPP, where the radiocesium concentrations tended to be very low, radiocesium concentrations that had similar or larger magnitude compared with those of the most-surface layer were often found in deeper layers. Relatively good correlations were found between radiocesium concentrations and grain sizes of the most-surface sediment. The vertical profile of radiocesium concentration also had a relationship with grain size. In other case, the radiocesium concentration in the sediment seems to have had a dependence on the radiocesium concentration in bottom seawater, suggesting that the quantity of radiocesium supplied and the grain size were major factors determining the spatial distribution pattern of the radiocesium concentration after the FDNPP accident