1,721,022 research outputs found
CORA hand: a 3D printed robotic hand designed for robustness and compliance
No full textThis work presents design and experimental evaluation of CORA (COmpliant Robotic hAnd), a robotic hand designed for easy manufacturing and maintenance, and for robustness and compliance in real operational environments. It takes advantage of recent soft-polymer printable filaments to obtain intrinsic compliance during grasping and accidental contacts. All parts are designed and optimized for manufacturing with conventional fused deposition modeling 3D printers, in order to allow simple fabrication and replacement of parts. In this paper design of the CORA hand is presented, focusing on specific design solutions adopted for improving robustness of the final 3D printed parts and for obtaining compliance in interaction with the environment. A prototype of the CORA hand was built and experimentally tested in terms of grasping capabilities, measuring contact forces and the distributed grasping pressure. Compliance introduced by soft polymer links was evaluated with finite element method simulation and experimental bending tests. A collision test evidenced robustness of the finger mechanism and transmission to pronounced passive deformations, induced by lateral contacts possibly occurring in common manipulation tasks
Braille Cursor: An Innovative and Affordable Refreshable Braille Display Designed for Inclusion
No full textIn this work we present an innovative, low-cost Refreshable Braille Display (RBD): the key feature of the developed method is represented by a single actuated cursor that refreshes Braille cells composed of mechanically simple, passive pins. In particular, a single electromagnetic actuator, moved on a linear slider, is capable of refreshing a full row of passive pins: each pin consists in a simple metal cylinder and can be reconfigured in a low or high state by an external magnetic field. The design based on passive pins, operated by a single moving actuator, makes the cost of the device almost independent on the number of Braille cells. This is suitable for application in either portable (up to 40 Braille cells) or desktop use (more than 40 Braille cells). Moreover, once the line is refreshed, the pins require no energy to hold their configuration and can withstand very high forces applied by the reading fingers. Finally, dimensions of the passive pins, differently from traditional piezo-actuated RBDs, allow for implementation in matrices of tactile pins displaying not only Braille characters but also generic two dimensional shapes
A 3-RSR Haptic Wearable Device for Rendering Fingertip Contact Forces
No full textA novel wearable haptic device for modulating contact forces at the fingertip is presented. Rendering of forces by skin deformation in 3 degrees of freedom (DoF), with contact - no contact capabilities, was implemented through rigid parallel kinematics. The novel asymmetrical three revolute-spherical-revolute (3-RSR) configuration allowed compact dimensions with minimum encumbrance of the hand workspace. The device was designed to render constant to low frequency deformation of the fingerpad in 3 DoF, combining light weight with relatively high output forces. A differential method for solving the non-trivial inverse kinematics is proposed and implemented in real time for controlling the device. The first experimental activity evaluated discrimination of different fingerpad stretch directions in a group of 5 subjects. The second experiment, enrolling 19 subjects, evaluated cutaneous feedback provided in a virtual pick-and-place manipulation task. Stiffness of the fingerpad plus device was measured and used to calibrate the physics of the virtual environment. The third experiment with 10 subjects evaluated interaction forces in a virtual lift-and-hold task. Although with different performance in the two manipulation experiments, overall results show that participants better controlled interaction forces when the cutaneous feedback was active, with significant differences between the visual and visuo-haptic experimental conditions
A comparison of algorithms for motor imagery BCI under different sensory feedback conditions
No full textA survey on innovative refreshable braille display technologies
No full textThis works presents a survey on recent technologies applied for Refreshable Braille Displays (RBD): these devices allow the dynamic rendering of refreshable Braille characters, analogously to a computer monitor rendering text and other visual information. Although commercially available RBD share a similar technology based on piezo actuators, and feature a single line of characters at a relatively high cost, alternative solutions have been proposed in recent years. They include adaptation of existing actuators and technologies to the rendering of Braille, and innovative materials used for developing actuators appositely designed for RBDs. In this survey, we compare performance of the above methods analyzing potential benefits and limitations of the different technologies
Multisensory Feedback Can Enhance Embodiment Within an Enriched Virtual Walking Scenario
No full textColab NAS: Obtaining lightweight task-specific convolutional neural networks following Occam's razor
Full text linkThe current trend of applying transfer learning from convolutional neural
networks (CNNs) trained on large datasets can be an overkill when the target
application is a custom and delimited problem, with enough data to train a
network from scratch. On the other hand, the training of custom and lighter
CNNs requires expertise, in the from-scratch case, and or high-end resources,
as in the case of hardware-aware neural architecture search (HW NAS), limiting
access to the technology by non-habitual NN developers.
For this reason, we present ColabNAS, an affordable HW NAS technique for
producing lightweight task-specific CNNs. Its novel derivative-free search
strategy, inspired by Occam's razor, allows to obtain state-of-the-art results
on the Visual Wake Word dataset, a standard TinyML benchmark, in just 3.1 GPU
hours using free online GPU services such as Google Colaboratory and Kaggle
Kernel
Nonlinear Characterization of a Compact Series Visco-Elastic Element for Tendon-Driven Actuation
No full textThe design of a new series-viscous-elastic (SVE) linear joint using a silicone spring is presented. The use of silicone introduces an internal damping, which enhances system performance allowing a simpler and more stable control. Moreover, it introduces compliance between the motor and the environment, enhancing safety for robotic devices interacting with humans. In this paper, the system is modeled using the Neo-Hookean material model and then characterized through experiments. A nonlinear identification model is used to build a state-dependent force estimator. The proposed solution is compact and cheap, thus being suitable for future integration in wearable assistive exoskeletons and exosuits
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