3D-printed flexure-based finger joints for anthropomorphic hands

Flexure-based finger joints for prosthetic hands have been studied, but until now they lack stiffness and load bearing capacity. In this paper we present a design which combines large range of motion, stiffness and load bearing capacity, with an overload protection mechanism. Several planar and non-planar hinge topologies are studied to determine load capacity over the range of motion. Optimized topologies are compared, in 30 degrees deflected state, in terms of stresses by deflection and grasping forces. Additionally, support stiffnesses were computed for all hinges in the whole range of motion (45 degrees). The Hole Cross Hinge presented the best performance over the range of motion with a grasping force up to 15 N while deflected 30 degrees. A new concept, the Angle Three-Flexure Cross Hinge, provides outstanding performance for deflections from 17.5 up to 30 degrees with a 20 N maximum grasping force when fully deflected. Experimental verification of the support stiffness over the range of motion shows some additional compliances, but the stiffness trend of the printed hinge is in line with the model. The presented joints power grasping capability outperform current state flexure-base hands and are comparable to commercial non-flexure-based prosthetic hands. In the event of excessive loads, an overload protection mechanism is in place to protect the flexure- hinges

Inverted curved flexure hinge with torsional reinforcements in a printed prosthetic finger

Flexure-based finger joints for prosthetic hands have been studied, but until now they lack stiffness and load capacity. In this paper we present a design which combines large range of motion, stiffness and load capacity, with a torsional overload protection mechanism. Five design considerations which increase grasp force and limit the stress values are presented: (1) Due to the inverted flexure attachment, the flexures are loaded mainly in tension, avoiding buckling of flexures. (2) Curved flexures have been used of which one straightens out at large deflection angles to improve load capacity at large deflections. (3) To achieve high torsional loads, one of the flexures is outfitted with triangular torsional stiffeners, which increase the out-of-plane stiffness significantly, while only slightly increasing the actuation stiffness. (4) The entire joint is rotated by 20˚ so the combination of actuation and contact forces lead to mainly axial forces in the curved leaf spring, avoiding excessive internal bending. The presented prosthetic flexure-based finger joint is able to achieve 20N of contact force with an additional 5N of out of plane load over the entire 80˚ range of motion, which is a major improvement over existing prosthetic flexure-based finger designs

The Moka cattle, an element of the Reunion Island heritage to preserve

International audienc

The identification of runs of homozygosity give a focus on the genetic diversity and the adaptation of the "Charolais de Cuba" cattle

Altres ajuts: CERCA Programme/Generalitat de Catalunya.Inbreeding and effective population size (Ne) are fundamental indicators for the management and conservation of genetic diversity in populations. Genomic inbreeding gives accurate estimates of inbreeding, and the Ne determines the rate of the loss of genetic variation. The objective of this work was to study the distribution of runs of homozygosity (ROHs) in order to estimate genomic inbreeding (FROH) and an effective population size using 38,789 Single Nucleotide Polymorphisms (SNPs) from the Illumina Bovine 50K BeadChip in 86 samples from populations of Charolais de Cuba (n = 40) cattle and to compare this information with French (n = 20) and British Charolais (n = 26) populations. In the Cuban, French, and British Charolais populations, the average estimated genomic inbreeding values using the FROH statistics were 5.7%, 3.4%, and 4%, respectively. The dispersion measured by variation coefficient was high at 43.9%, 37.0%, and 54.2%, respectively. The effective population size experienced a very similar decline during the last century in Charolais de Cuba (from 139 to 23 individuals), in French Charolais (from 142 to 12), and in British Charolais (from 145 to 14) for the ~20 last generations. However, the high variability found in the ROH indicators and FROH reveals an opportunity for maintaining the genetic diversity of this breed with an adequate mating strategy, which can be favored with the use of molecular markers. Moreover, the detected ROH were compared to previous results obtained on the detection of signatures of selection in the same breed. Some of the observed signatures were confirmed by the ROHs, emphasizing the process of adaptation to tropical climate experienced by the Charolais de Cuba population