Exoskeleton-covered soft finger with vision-based proprioception and tactile sensing

Soft robots offer significant advantages in adaptability, safety, and dexterity compared to conventional rigid-body robots. However, it is challenging to equip soft robots with accurate proprioception and tactile sensing due to their high flexibility and elasticity. In this work, we describe the development of a vision-based proprioceptive and tactile sensor for soft robots called GelFlex, which is inspired by previous GelSight sensing techniques. More specifically, we develop a novel exoskeleton-covered soft finger with embedded cameras and deep learning methods that enable high-resolution proprioceptive sensing and rich tactile sensing. To do so, we design features along the axial direction of the finger, which enable high-resolution proprioceptive sensing, and incorporate a reflective ink coating on the surface of the finger to enable rich tactile sensing. We design a highly underactuated exoskeleton with a tendon-driven mechanism to actuate the finger. Finally, we assemble 2 of the fingers together to form a robotic gripper and successfully perform a bar stock classification task, which requires both shape and tactile information. We train neural networks for proprioception and shape (box versus cylinder) classification using data from the embedded sensors. The proprioception CNN had over 99\% accuracy on our testing set (all six joint angles were within 1 degree of error) and had an average accumulative distance error of 0.77 mm during live testing, which is better than human finger proprioception. These proposed techniques offer soft robots the high-level ability to simultaneously perceive their proprioceptive state and peripheral environment, providing potential solutions for soft robots to solve everyday manipulation tasks. We believe the methods developed in this work can be widely applied to different designs and applications.Comment: Accepted to ICRA202

Precipitation of high Mg-calcite and protodolomite using dead biomass of aerobic halophilic bacteria

The microbial dolomite model has been used to interpret the origin of sedimentary dolomite. In this model， the formation of low-temperature protodolomite， an important precursor to sedimentary dolomite， can be facilitated either by actively metabolizing cells of anaerobic microbes and aerobic halophilicarchaea or by their inactive biomass. Aerobic halophilic bacteria are widely distributed in （proto-）dolomite-depositing evaporitic environments and their biomass might serve as a template for the crystallization of protodolomite. To test this hypothesis， carbonation experiments were conducted using dead biomass of an aerobic halophilic bacterium （Exiguobacterium sp. strain JBHLT-3）. Our results show that dead biomass of JBHLT-3 can accelerate Mg2+ uptake in carbonate mineral precipitates. In addition， the amount of Mg incorporated into Ca-Mg carbonates is proportional to the concentration of biomass. High Mg-calcite is produced with 0.25 or 0.5 g/L biomass， whereasprotodolomite forms with 1 g/L biomass. This is confirmed by the main Raman peak of Ca-Mg carbonates， which shifts towards higher wavenumbers with increased Mg substitution. Microbial cells and their imprints are preserved on the surface of high Mg-calcite and protodolomite. Hence， this study furthers our understanding of the dolomitization within buried and dead microbial mats， which provides useful insights into the origin of ancient dolomite

Early Triassic oceanic red beds coupled with deep sea oxidation in South Tethys

Carbonate oceanic red beds (ORBs) are unusual in Phanerozoic shelf settings but can be widespread during discrete intervals. Several scenarios have been invoked to explain the origin of these ORBs but there remains uncertainty about the process by which the red pigmentation of ORBs forms. Here, we propose that the occurrence of ORBs at intermediate water depths in shelf regions is controlled by fluctuations in the redox state of deeper waters. We have examined Early Triassic Peri-Gondwana shelf sections in South Tibet which show the development of Spathian (late Early Triassic) ORBs at intermediate water depths. The red color of these ORBs is imparted by randomly dispersed hematite crystals that are microns in size, showing weak alteration by late burial diagenesis. Widespread anoxia, in both shelf seas and the oceanic realm, was well developed in the Early Triassic. Synchronous occurrence of Spathian ORBs in deep shelf regions is closely related to the improved oxidation in deeper settings, from anoxia to dysoxia, based on changes in the redox proxy of pyrite framboid sizes. It is, therefore, inferred that prolonged deep-water anoxia might serve as source of Fe (II) for the formation of ORBs when intensified upwelling develops. The global occurrence of Early Triassic ORBs is coincident with the significant rebound of biodiversity after the Permian-Triassic mass extinction, indicating the occurrence of ORBs marks the terminal stage of an oceanic anoxic event and ORBs can serve as an indicator of the ameliorated marine ecosystem

A Note on Noncommutative Brane Inflation

In this paper, we investigate the noncommutative KKLMMT D3/anti-D3 brane inflation scenario in detail. Incorporation of the brane inflation scenario and the noncommutative inflation scenario can nicely explain the large negative running of the spectral index as indicated by WMAP three-year data and can significantly release the fine-tuning for the parameter $\beta$. Using the WMAP three year results (blue-tilted spectral index with large negative running), we explore the parameter space and give the constraints and predictions for the inflationary parameters and cosmological observables in this scenario. We show that this scenario predicts a quite large tensor/scalar ratio and what is more, a too large cosmic string tension (assuming that the string coupling $g_s$ is in its likely range from 0.1 to 1) to be compatible with the present observational bound. A more detailed analysis reveals that this model has some inconsistencies according to the fit to WMAP three year results.Comment: 20 pages, 5 figures; accepted for publication in JCA