Long range LiDAR characterisation for obstacle detection for use by the visually impaired and blind

Obstacle detection and avoidance is a huge area of interest for autonomous vehicles and, as such, has become an important research topic. Detecting and identifying obstacles enables navigation through an ever changing environment. This work looks at the technology used in self-driving vehicles and examines whether the same technology could be used to aid in navigation for visually impaired and blind (VIB) people. For autonomous vehicles, obstacle detection relies on different sensor modalities to provide information on the vehicles surroundings. A combination of the same sensors placed on a white cane could be used to perform free-space assessment over the whole height of the user and provide additional environmental information not available from the cane alone. This provides its own challenges and advantages. The speeds are much slower when dealing with pedestrians and scanning can be achieved by the movement of the cane. However, the weight and size must be significantly reduced. The full system will be integrated into a smart cane and will consist of four main sensors as well as range sensors. The aim of this work is to report on the characterisation of a long range LiDAR (up to 10m) that will be integrated into a smart white cane developed as part of the INSPEX H2020 project

Representative volume elements for the simulation of isotropic composites highly lled with monosized spheres

A method is proposed for generating reliable representative volume elements (RVEs) that allows reducing the statistical analysis required for the simulation of the mechanical behavior of isotropic composites highly filled with monosized spheres. The method combines (i) an algorithm inspired from molecular dynamics and associated with an analytical equation of state, and (ii) a geometrical analysis using the two-point correlation function and a nearest-neighbor distribution function. A restrictive selection process is defined, which leads to microstructures reasonably close to randomness and isotropy. The pertinence of the proposed generation and selection of RVEs is confirmed by the simulation of their elastic behavior with the nite element method. In particular, it is shown how the selection procedure allows reducing the computational e ort required to reach reliable elastic moduli by operating on a limited number of suitable RVEs. The results are in good agreement with the generalized self-consistent model and with original experimental data obtained on a composite where an acrylate matrix was reinforced by sifted glass beads.ANR contrat ANR-10-EQPX-37, Délégation Générale de l'Armement (DGA) et ArianeGroup

Relationship between local damage and macroscopic response of soft materials highly reinforced by monodispersed particles

A rubberlike matrix highly filled with spherical micrometric glass beads is submitted to uniaxial tension tests until break. X-ray tomography imaging performed on the material while submitted to uniaxial tension reveals early debonding at the matrix/filler interfaces at the poles of the particles followed by void coalescence creating damage localization. The latter causes a downturn of the macroscopic stress-strain response. These phenomena are analyzed further with three-dimensional finite element simulations, where 64 spherical beads are distributed randomly in a periodic cell. A simple version of the Tvergaard-Hutchinson cohesive-zone model allows to reproduce all the experimental trends well. The effects of the three parameters involved are analyzed, and three different types of macroscopic behaviors are observed corresponding to three different microstructure damages. The value of the initial stiffness of the interface, limited by numerical convergence, has little effect on how the local damage evolves but has a significant impact on the overall macroscopic stress values. The local damage is strongly dependent on the critical strength and the separation failure displacement, and the adhesion energy may be considered as a resulting parameter of the two previous ones. The interfacial critical strength appears to have a significant impact on the damage initiation, either spread across the structure for low values, or localized for high values. Increasing the interface separation failure displacement delays the possible loss of adhesion to a higher strain and preserves the integrity of the composite material

Use of a micromechanical approach to understand the mechanical behavior of solid propellants

The development of new generations of propellants with better energetic properties may be hampered by unsatisfactory mechanical behaviors in terms of strength and toughness. A micromechanical approach is adopted to provide a better understanding of the existing links between the constitutive phase behaviors and the local damage, and the macroscopic mechanical behavior of these materials. Three model materials have been made and tested in uniaxial tension. The stress-strain responses were recorded while monitoring their volume changes that quantify the macroscopic damage. A qualitative description of the local damage was obtained thanks to scanning electron microscopy images of samples under loading. The micromechanical approach consists in finite elements analyses on periodic microstructures of non-regular polyhedral particles embedded in a soft matrix. An original microstructure generation tool has been developed specifically in order to obtain highly filled isotropic microstructures. Debonding at the matrix/filler interface was taken into account with a cohesive-zone model (CZM). The impact of the CZM parameters is discussed, in an effort to make the link between the CZM parameters and how the local damage appears and develops, and between the cohesive behavior and the shape of the macroscopic stress-stretch responses of the heterogeneous materials.This work was supported by the ANR (France) under contract num-ber ANR-10-EQPX- 37, and the authors thank the Délégation Générale de l’Armement (DGA) and ArianeGroup, Vert-le-Petit (France), for their financial supports

Comparison of the finite strain macroscopic behavior and local damage of a soft matrix highly reinforced by spherical or polyhedral particles

Motivated by the different uniaxial responses of two actual materials filled with either sifted glass beads or sifted glass grits, the influence of the fillers shape on the finite strain behavior of highly filled composites (>50%) is examined through micromechanical finite element simulations accounting for matrix/filler debonding with a cohesive-zone model. Three-dimensional matrix cells filled with 64 monosized spherical particles are compared to cells filled with the same number of monosized polyhedra. For this purpose, an original generation process was developed to obtain periodic cells with random dispersions of non-regular polyhedra. Finite element simulations of uniaxial tensile tests on the periodic cells allow studying the influence of the fillers shape on the macroscopic behavior and on the local damage at the matrix/filler interfaces. Actually, the presence of sharp edges and apexes for polyhedral particles seems to have a second order impact compared to the cohesive-zone parameters. The damage fields demonstrate the same trends for both particles shapes. The different behaviors observed on actual composites are rather due to different adhesion properties between fillers and matrix than to the shape of particles

Hugs and behaviour points: alternative education and the regulation of 'excluded' youth

In England, alternative education (AE) is offered to young people formally excluded from school, close to formal exclusion or who have been informally pushed to the educational edges of their local school. Their behaviour is seen as needing to change. In this paper, we examine the behavioural regimes at work in 11 AE programmes. Contrary to previous studies and the extensive ‘best practice’ literature, we found a return to highly behaviourist routines, with talking therapeutic approaches largely operating within this Skinnerian frame. We also saw young people offered a curriculum largely devoid of languages, humanities and social sciences. What was crucial to AE providers, we argue, was that they could demonstrate 'progress' in both learning and behaviour to inspectors and systems. Mobilising insights from Foucault, we note the congruence between the external regimes of reward and punishment used in AE and the kinds of insecure work and carceral futures that might be on offer to this group of young people

INSPEX: design and integration of a portable/wearable smart spatial exploration system

The INSPEX H2020 project main objective is to integrate automotive-equivalent spatial exploration and obstacle detection functionalities into a portable/wearable multi-sensor, miniaturised, low power device. The INSPEX system will detect and localise in real-time static and mobile obstacles under various environmental conditions in 3D. Potential applications range from safer human navigation in reduced visibility, small robot/drone obstacle avoidance systems to navigation for the visually/mobility impaired, this latter being the primary use-case considered in the project

The state of professional practice and policy in the English further education system: a view from below

This paper addresses a recurring theme regarding the UK’s Vocational Education and Training (VET) policy in which Further Education (FE) and training are primarily driven by employer demand. It explores the tensions associated with this process on the everyday working practices of FE practitioners and institutions and its impact on FE’s contribution to the wider processes of social and economic inclusion. At a time when Ofsted and employer-led organisations have cast doubt on the contribution of FE, we explore pedagogies of practice that are often unacknowledged by the current audit demands of officialdom. We argue that such practice provides a more enlightened view of the sector and the challenges it faces in addressing wider issues of social justice, employability and civic regeneration. At the same time, the irony of introducing laissez-faire initiatives designed to remove statutory qualifications for FE teachers ignores the progress made over the past decade in raising the professional profile and status of teachers and trainers in the sector. In addressing such issues, the paper explores the limits and possibilities of constructing professional and vocational knowledge from networks and communities of practice, schools, universities, business, employers and local authorities, in which FE already operates