Body-powered upper-limb prostheses remain a popular option for those with limb absence due to their passive nature. These devices typically feature a constant transmission ratio between the forces input by the user and the grasp forces output by the prosthetic gripper. Work incorporating continuously variable transmissions into robotic hands has demonstrated a number of benefits in terms of their motion and forces. In this work, we use a custom prosthesis emulator to evaluate the viability of applying variable transmissions to a body-powered prosthetic context. With this haptics test bed, we measured user performance during a grasping and lift task under a variety of transmission ratio conditions and with three different test objects. Results indicate that use of a variable transmission leads to the successful manipulation of a wider variety of objects than the constant transmission ratio systems, while requiring less shoulder motion. Analysis also shows a potential tendency for users to apply higher grasp forces than necessary, when compared to constant transmission conditions. These findings suggest a multifaceted effect on grasp performance with both benefits and drawbacks when considering a variable approach that supports the continued study of variable transmissions in assisted grasping.
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http://dx.doi.org/10.1109/ICORR55369.2022.9896542 | DOI Listing |
Nat Nanotechnol
January 2025
Bay Area Center for Electron Microscopy, Songshan Lake Materials Laboratory, Dongguan, China.
Skyrmions can form regular arrangements, so-called skyrmion crystals (SkXs). A mode with multiple wavevectors q then describes the arrangement. While magnetic SkXs, which can emerge in the presence of Dzyaloshinskii-Moriya interaction, are well established, polar skyrmion lattices are still elusive.
View Article and Find Full Text PDFSci Rep
January 2025
UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, PO Box 392, Pretoria, South Africa.
This research successfully synthesized semiconductive magnesioferrite (MgFeO) nanomaterials using a green chemistry method that utilizes the natural extract of Moringa olefeira serving as both a reducing and oxidizing agent. The optical characteristics and crystalline structure of the MgFeO nanomaterials were analysed using photoluminescence, diffuse reflectance spectroscopy, and X-ray diffraction. Additionally, Fourier transform infrared spectroscopy provided valuable insights into the chemical bonding and composition.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
Department of Physics and Astronomy and Thomas Young Centre, University College London, London WC1E 6BT, United Kingdom.
Atomic-scale understanding of important geochemical processes including sorption, dissolution, nucleation, and crystal growth is difficult to obtain from experimental measurements alone and would benefit from strong continuous progress in molecular simulation. To this end, we present a reactive neural network potential-based molecular dynamics approach to simulate the interaction of aqueous ions on mineral surfaces in contact with liquid water, taking Fe(II) on hematite(001) as a model system. We show that a single neural network potential predicts rate constants for water exchange for aqueous Fe(II) and for the exergonic chemisorption of aqueous Fe(II) on hematite(001) in good agreement with experimental observations.
View Article and Find Full Text PDFAcc Chem Res
January 2025
Department of Chemistry, University of California, Berkeley, California 94720, United States.
ConspectusThe electronic properties of atomically thin van der Waals (vdW) materials can be precisely manipulated by vertically stacking them with a controlled offset (for example, a rotational offset─i.e., twist─between the layers, or a small difference in lattice constant) to generate moiré superlattices.
View Article and Find Full Text PDFAvian Pathol
January 2025
College of Animal Science and Technology/Veterinary Medicine, Anhui Agricultural University, Hefei, PR China.
Goose astrovirus (GoAstV) has emerged as a significant pathogen affecting the goose industry in China, with GoAstV-2 becoming the dominant genotype since 2017. This study explores the genetic and structural factors underlying the prevalence of GoAstV-2, focusing on codon usage bias, spike protein variability, and structural stability. Phylogenetic and effective population size analyses revealed that GoAstV-2 experienced rapid expansion between 2017 and 2018, followed by population stabilization.
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