Effects of the Artificial Skin's Thickness on the Subsurface Pressure Profiles of Flat, Curved, and Braille Surfaces

Abstract

The primary interface of contact between a robotic or prosthetic hand and the external world is through the artificial skin. To make sense of that contact, tactile sensors are needed. These sensors are normally embedded in soft synthetic materials for protecting the subsurface sensor from damage or for better hand-to-object contact. It is important to understand how the mechanical signals transmit from the artificial skin to the embedded tactile sensors. In this paper, we made use of a finite element model of an artificial fingertip with viscoelastic and hyperelastic behaviors to investigate the subsurface pressure profiles when flat, curved, and Braille surfaces were indented on the surface of the model. Furthermore, we investigated the effects of 1, 3, and 5 mm thickness of the skin on the subsurface pressure profiles. The simulation results were experimentally validated using a 25.4 µm thin pressure detecting film that was able to follow the contours of a non-planar surface, which is analogous to an artificial bone. Results show that the thickness of the artificial skin has an effect on the peak pressure, on the span of the pressure distribution, and on the overall shape of the pressure profile that was encoded on a curved subsurface structure. Furthermore, the flat, curved, and Braille surfaces can be discriminated from one another with the 1 and 3 mm artificial skin layers, but not with the 5 mm thick skin.

Discrimination of Dynamic Tactile Contact by Temporally Precise Event Sensing in Spiking Neuromorphic Networks

“…Pressure was used as the input parameter to the computational model since it well describes the transduction of tactile sensors (Cabibihan et al, 2014 ). We extracted pressure estimates from elements of the same depth within the sensing region and mapped them to an exponential scale.…”

Suitability of the Openly Accessible 3D Printed Prosthetic Hands for War-Wounded Children

“…This numerical method approximates the system solution under the given initial and boundary conditions (Biddis et al, 2004 ; Mollica and Ambrosio, 2009 ). The FE method was earlier used in the analysis of prosthetic fingers and structures (Cabibihan et al, 2006a , b , 2014 ). In the current work, the locations with potentially high stress concentration were predicted to be at the distal finger phalange, proximal finger phalange, and at the pin.…”

Data for benchmarking low-cost, 3D printed prosthetic hands

“…Finite Element Analysis has been an effective tool for analyzing contact interactions between artificial fingers and various objects [6], [7], [8], [9], [10], [11], [12]. For this data set, the index finger of the low-cost 3D printed prosthetic hand was subjected to numerical failure analysis using LS-DYNA software (mmps R8.1.1, Livermore Software Technology Corporation (LSTC), USA) [13].…”