Vision and SLAM on a highly dynamic mobile two-wheeled robot

This thesis examines a sparse feature based visual monocular simultaneous localization and mapping (SLAM) approach with the intension of stabilizing a two-wheeled balancing robot. The first part introduces the basics like camera geometry, image processing and filtering. Further on, the thesis treats the details of a monocular SLAM system and shows some specialties to keep the computational effort low. The last part deals with Andrew Davison's "SceneLib" library and how it can be used to obtain the camera state vector.Die vorliegende Arbeit gibt einen Einblick in das Thema der auf wenigen Bildfeatures basierenden simultanen Lokalisierung und Karten Erstellung (SLAM) mittels monokularer Kamera zum Zwecke der Regelung eines zweirädrigen balancierenden Roboters. Im ersten Teil werden grundlegende Themen wie die Kamerageometrie, Bildverarbeitung und Filtertechniken besprochen. Darauf aufbauend werden im zweiten Abschnitt Details und effizienzsteigernde Maßnahmen erläutert, die ein monokulares Echtzeit-Kamera-SLAM System möglich machen. Im letzten Teil der Arbeit wird beschrieben wie mittels Andrew Davisons "SceneLib" Bibliothek die aktuelle Kamera Pose bestimmt werden kann

The elastic modulus of isolated polytetrafluoroethylene filaments

We report vibrational Raman spectra of small extended perfluoro-n-alkanes (C{n}F{2n+2} with n=6, 8-10, 12-14) isolated in supersonic jet expansions and use wavenumbers of longitudinal acoustic vibrations to extrapolate the elastic modulus of cold, isolated polytetrafluoroethylene filaments. The derived value E = 209(10) GPa defines an upper limit for the elastic modulus of the perfectly crystalline, non-interacting polymer at low temperatures and serves as a benchmark for quantum chemical predictions

Postoperative Betreuung nach operativer Frakturbehandlung

The postoperative management after open reduction and internal fixation (ORIF) of fractures is addressed with this article. The topics selected focus on topics that are of relevance for the family practitioner. Because of large differences in the treatment of adult - and geriatric fracture patients these two groups are separately looked at in Part 1 and Part 2 of the article. Fractures in children or fractures of the growing skeleton are not addressed. In the early postoperative phase, the fracture patient might seek for advice in case of complications, such as wound infection or complex regional pain syndrome (CRPS). After fracture healing, the decision on implant removal has to be made. Geriatric fracture patients mostly cannot return back home directly from the hospital. Instead they are transferred to a rehabilitation center. In these patients secondary fracture prevention should be in the focus of the family practitioner. This means osteoporosis diagnostics and treatment shall be initiated, if not done before. Another important task is to guarantee for compliance with the therapy once it is initiated

Minimally invasive anterior muscle-sparing versus a transgluteal approach for hemiarthroplasty in femoral neck fractures-a prospective randomised controlled trial including 190 elderly patients

Abstract Background The relevance of femoral neck fractures (FNFs) increases with the ageing of numerous societies, injury-related decline is observed in many patients. Treatment strategies have evolved towards primary joint replacement, but the impact of different approaches remains a matter of debate. The aim of this trial was to evaluate the benefit of an anterior minimally-invasive (AMIS) compared to a lateral Hardinge (LAT) approach for hemiarthroplasty in these oftentimes frail patients. Methods Four hundred thirty-nine patients were screened during the 44-months trial, aiming at the evaluation of 150 patients > 60 yrs. of age. Eligible patients were randomised using an online-tool with completely random assignment. As primary endpoint, early mobility, a predictor for long-term outcomes, was evaluated at 3 weeks via the “Timed up and go” test (TUG). Secondary endpoints included the Functional Independence Measure (FIM), pain, complications, one-year mobility and mortality. Results A total of 190 patients were randomised; both groups were comparable at baseline, with a predominance for frailty-associated factors in the AMIS-group. At 3 weeks, 146 patients were assessed for the primary outcome. There was a reduction in the median duration of TUG performance of 21.5% (CI [− 41.2,4.7], p = 0.104) in the AMIS-arm (i.e., improved mobility). This reduction was more pronounced in patients with signs of frailty or cognitive impairment. FIM scores increased on average by 6.7 points (CI [0.5–12.8], p = 0.037), pain measured on a 10-point visual analogue scale decreased on average by 0.7 points (CI: [− 1.4,0.0], p = 0.064). The requirement for blood transfusion was lower in the AMIS- group, the rate of complications comparable, with a higher rate of soft tissue complications in the LAT-group. The mortality was higher in the AMIS-group. Conclusion These results, similar to previous reports, support the concept that in elderly patients at risk of frailty, the AMIS approach for hemiarthroplasty can be beneficial, since early mobilisation and pain reduction potentially reduce deconditioning, morbidity and loss of independence. The results are, however, influenced by a plethora of factors. Only improvements in every aspect of the therapeutic chain can lead to optimisation of treatment and improve outcomes in this growing patient population. Trial registration www.clinicaltrials.gov: NCT01408693 (registered August 3rd 2011)

Dimensioning a full color LED microdisplay for augmented reality headset in a very bright environment

International audienceThis paper focuses on the dimensioning of a very bright full color 10 μm-pitch light-emitting device (LED) microdisplay for avionics application. Starting from the specifications of head-mounted display to be used in an augmented reality optical system, a theoretical approach is proposed that enables predicting the specifications of the main technology building blocks enteringinto the microdisplay manufacturing process flow. By taking into account various material and technological parameters, kept as realistic as possible, it is possible to assess the feasibility of a very bright LED microdisplay (1 Mcd/m2 full white) and to point out the main limitations. The theoretical specifications are then compared with the technical results obtained so far in the framework of the H2020 Clean Sky “HILICO” project. It shows that 350 000 cd/m2 of white emission may be accessible with the present gallium nitride (GaN)-micro-LED technology provided a color conversion solution with stable external quantum efficiency of 30% is available. Beyond such level of luminance, the inherent limitations of driving circuit (4 V, 15 μA per pixel) commandsworking with materials enabling higher external quantum efficiency (EQE). In particular, 10-μm-pitch micro-LEDs with electroluminescence EQE of 15% and color conversion EQE approaching 60% are needed, opening the way to future challenging material and technology research developments