Improvement of the odometry accuracy of a crawler vehicle with consideration of slippage

Abstract-Crawler mechanisms have the advantage of stable navigation on uneven terrain; as a result, such mechanisms have been adopted for many types of locomotion of outdoor robots, including "search and rescue robots". However, crawler mechanisms always slip when tracking curved paths, and it generates a large accumulating positioning error in vehicles as opposed to conventional wheeled mobile robots. To measure the velocity of the vehicle correctly and improve the accuracy of the odometry, consideration of crawlers' slippage is very important. In this research, we propose a more accurate odometry method for crawler vehicles. In the proposed method, the vehicle can estimate the slip ratios using information from encoders (attached to the actuators) and gyro-sensors. The validity of the method was confirmed by experiments using our crawler vehicle. I. Introduction Crawler mechanisms offer large advantages for the locomotion of vehicles because of their large contact area, which allows them to adapt to bumpy grounds. Therefore, such mechanisms are used in many robotic vehicles for "search and rescue" applications in disaster areas, such as collapsed buildings, underground stairs, or wide cracks in the ground. Our research group also uses crawler vehicles as research platforms of remote control for search and rescue applications. In this research, we aim to realize multi-vehicle control from a distant location with lowbandwidth communication. In this case, it is impossible to realize a conventional vision-based remote control (in which an operator controls a control-joystick by watching continuous vision information from a camera mounted on the vehicle), because of the low-bandwidth communication. To solve this problem, we proposed another remote control system[1] based on three-dimensional range sensor information, as follows: step1: [vehicle side] Obtaining local 3-dimensional environmental information in the neighborhood of the vehicle (called "3D-info") and sending the information to the operator side step2: [vehicle side] Obtaining the vehicle's position and orientation using an odometry system and sending the information to the operator side step3: [operator side] Displaying the 3D-info on the monitor, and super-imposing the vehicle model on it using the odometry informatio

Stair Climbing Control for 4-DOF Tracked Vehicle Based on Internal Sensors

In search-and-rescue missions, multi-degrees-of-freedom (DOF) tracked robots that are equipped with subtracks are commonly used. These types of robots have superior locomotion performance on rough terrain. However, in teleoperated missions, the performance of tracked robots depends largely on the operators’ ability to control every subtrack appropriately. Therefore, an autonomous traversal function can significantly help in the teleoperation of such robots. In this paper, we propose a planning and control method for 4-DOF tracked robots climbing up/down known stairs automatically based on internal sensors. Experimental results obtained using mockup stairs verify the effectiveness of the proposed method

USP8 prevents aberrant NF-κB and Nrf2 activation by counteracting ubiquitin signals from endosomes

K63-linked ubiquitin chains attached to plasma membrane proteins serve as tags for endocytosis and endosome-to-lysosome sorting. USP8 is an essential deubiquitinase for the maintenance of endosomal functions. Prolonged depletion of USP8 leads to cell death, but the major effects on cellular signaling pathways are poorly understood. Here, we show that USP8 depletion causes aberrant accumulation of K63-linked ubiquitin chains on endosomes and induces immune and stress responses. Upon USP8 depletion, two different decoders for K63-linked ubiquitin chains, TAB2/3 and p62, were recruited to endosomes and activated the TAK1-NF-κB and Keap1-Nrf2 pathways, respectively. Oxidative stress, an environmental stimulus that potentially suppresses USP8 activity, induced accumulation of K63-linked ubiquitin chains on endosomes, recruitment of TAB2, and expression of the inflammatory cytokine. The results demonstrate that USP8 is a gatekeeper of misdirected ubiquitin signals and inhibits immune and stress response pathways by removing K63-linked ubiquitin chains from endosomes.</p

Enhanced Recombinant Protein Productivity by Genome Reduction in Bacillus subtilis

The emerging field of synthetic genomics is expected to facilitate the generation of microorganisms with the potential to achieve a sustainable society. One approach towards this goal is the reduction of microbial genomes by rationally designed deletions to create simplified cells with predictable behavior that act as a platform to build in various genetic systems for specific purposes. We report a novel Bacillus subtilis strain, MBG874, depleted of 874 kb (20%) of the genomic sequence. When compared with wild-type cells, the regulatory network of gene expression of the mutant strain is reorganized after entry into the transition state due to the synergistic effect of multiple deletions, and productivity of extracellular cellulase and protease from transformed plasmids harboring the corresponding genes is remarkably enhanced. To our knowledge, this is the first report demonstrating that genome reduction actually contributes to the creation of bacterial cells with a practical application in industry. Further systematic analysis of changes in the transcriptional regulatory network of MGB874 cells in relation to protein productivity should facilitate the generation of improved B. subtilis cells as hosts of industrial protein production

Functional shell matrix proteins tentatively identified by asymmetric snail shell morphology

Molluscan shell matrix proteins (SMPs) are essential in biomineralization. Here, we identify potentially important SMPs by exploiting the asymmetric shell growth in snail, Lymnaea stagnalis. Asymmetric shells require bilaterally asymmetric expression of SMP genes. We examined expression levels of 35,951 transcripts expressed in the left and right sides of mantle tissue of the pond snail, Lymnaea stagnalis. This transcriptome dataset was used to identify 207 SMPs by LC-MS/MS. 32 of the 207 SMP genes show asymmetric expression patterns, which were further verified for 4 of the 32 SMPs using quantitative PCR analysis. Among asymmetrically expressed SMPs in dextral snails, those that are more highly expressed on the left side than the right side are 3 times more abundant than those that are more highly expressed on the right than the left, suggesting potentially inhibitory roles of SMPs in shell formation. The 32 SMPs thus identified have distinctive features, such as conserved domains and low complexity regions, which may be essential in biomineralization

Cooking Vessels, Volumes, and Venues: Evidence from LM IIIC Kavousi Vronda and Karphi

Glowacki, K.T., and L.P. Day. “Cooking Vessels, Volumes, and Venues: Evidence from LM IIIC Kavousi Vronda and Karphi.” Abstract of paper read at Διατροφικές συνήθειες και πρακτικές στην Κρήτη διαχρονικά [Dietary Habits and Practices in Crete over Time], Museum of Cretan Ethnology, Voroi, Crete, Greece, September 9–10, 2017.Our understanding of diet and culinary practices at the Late Minoan IIIC settlement sites of Kavousi Vronda and Karphi is based upon several different types of physical evidence that have been recovered through excavation. These include the botanical and faunal remains of plants and animals available to and consumed by the inhabitants; ceramic vessels used for the cooking and consumption of food and drink; built and fixed cooking installations, such as hearths and ovens; and the architectural spaces within the settlements where food preparation and consumption most likely took place. Each type of evidence is, by itself, incomplete and dependent upon differential preservation resulting from site formation processes specific to each archaeological context. Taken together, however, they allow us to gain important insights into key aspects of food cultivation, provisioning, processing, preparation, and convivial practices on Crete in the 12th and 11th centuries BC. In this paper, we will compare and contrast the evidence for food preparation and dining at each site, paying special attention to the forms and sizes of ceramic vessels used for cooking and consumption

Two distinct modes of DNMT1 recruitment ensure stable maintenance DNA methylation

Stable inheritance of DNA methylation is critical for maintaining differentiated phenotypes in multicellular organisms. We have recently identified dual mono-ubiquitylation of histone H3 (H3Ub2) by UHRF1 as an essential mechanism to recruit DNMT1 to chromatin. Here, we show that PCNA-associated factor 15 (PAF15) undergoes UHRF1-dependent dual mono-ubiquitylation (PAF15Ub2) on chromatin in a DNA replication-coupled manner. This event will, in turn, recruit DNMT1. During early S-phase, UHRF1 preferentially ubiquitylates PAF15, whereas H3Ub2 predominates during late S-phase. H3Ub2 is enhanced under PAF15 compromised conditions, suggesting that H3Ub2 serves as a backup for PAF15Ub2. In mouse ES cells, loss of PAF15Ub2 results in DNA hypomethylation at early replicating domains. Together, our results suggest that there are two distinct mechanisms underlying replication timing-dependent recruitment of DNMT1 through PAF15Ub2 and H3Ub2, both of which are prerequisite for high fidelity DNA methylation inheritance

Structural analysis of crystalline R(+)-α-lipoic acid-α-cyclodextrin complex based on microscopic and spectroscopic studies

R(+)-α-lipoic acid (RALA) is a naturally-occurring substance, and its protein-bound form plays significant role in the energy metabolism in the mitochondria. RALA is vulnerable to a variety of physical stimuli, including heat and UV light, which prompted us to study the stability of its complexes with cyclodextrins (CDs). In this study, we have prepared and purified a crystalline RALA-αCD complex and evaluated its properties in the solid state. The results of 1H NMR and PXRD analyses indicated that the crystalline RALA-αCD complex is a channel type complex with a molar ratio of 2:3 (RALA:α-CD). Attenuated total reflection/Fourier transform infrared analysis of the complex showed the shift of the C=O stretching vibration of RALA due to the formation of the RALA-αCD complex. Raman spectroscopic analysis revealed the significant weakness of the S–S and C–S stretching vibrations of RALA in the RALA-αCD complex implying that the dithiolane ring of RALA is almost enclosed in glucose ring of α-CD. Extent of this effect was dependent on the direction of the excitation laser to the hexagonal morphology of the crystal. Solid-state NMR analysis allowed for the chemical shift of the C=O peak to be precisely determined. These results suggested that RALA was positioned in the α-CD cavity with its 1,2-dithiolane ring orientated perpendicular to the plane of the α-CD ring. © 2015 by the authors; licensee MDPI, Basel, Switzerland