A Novel Practical Technique to Integrate Inequality Control Objectives and Task Transitions in Priority Based Control

The task priority based control is a formalism which allows to create complex control laws with nice invariance properties, i.e. lower priority tasks do not affect the execution of higher priority ones. However, the classical task priority framework (Siciliano and Slotine) lacked the ability of enabling and disabling tasks without causing discontinuities. Furthermore, tasks corresponding to inequality control objectives could not be efficiently represented within that framework. In this paper we present a novel technique to integrate both the activation and deactivation of tasks and the inequality control objectives in the priority based control. The technique, called iCAT (inequality control objectives, activations and transitions) task priority framework, exploits novel regularization methods to activate and deactivate any row of a given task in a prioritized hierarchy without incurring in practical discontinuities, while maintaining as much as possible the invariance properties of the other active tasks. Finally, as opposed to other techniques, the proposed approach has a linear cost in the number of tasks. Simulations, experimental results and a time analysis are presented to support the proposed technique

Flexible human-robot cooperation models for assisted shop-floor tasks

The Industry 4.0 paradigm emphasizes the crucial benefits that collaborative robots, i.e., robots able to work alongside and together with humans, could bring to the whole production process. In this context, an enabling technology yet unreached is the design of flexible robots able to deal at all levels with humans' intrinsic variability, which is not only a necessary element for a comfortable working experience for the person but also a precious capability for efficiently dealing with unexpected events. In this paper, a sensing, representation, planning and control architecture for flexible human-robot cooperation, referred to as FlexHRC, is proposed. FlexHRC relies on wearable sensors for human action recognition, AND/OR graphs for the representation of and reasoning upon cooperation models, and a Task Priority framework to decouple action planning from robot motion planning and control.Comment: Submitted to Mechatronics (Elsevier

State-of-the-art all-silicon sub-bandgap photodetectors at telecom and datacom wavelengths

Silicon-based technologies provide an ideal platform for the monolithic integration of photonics and microelectronics. In this context, a variety of passive and active silicon photonic devices have been developed to operate at telecom and datacom wavelengths, at which silicon has minimal optical absorption - due to its bandgap of 1.12 eV. Although in principle this transparency window limits the use of silicon for optical detection at wavelengths above 1.1 μm, in recent years tremendous advances have been made in the field of all-silicon sub-bandgap photodetectors at telecom and datacom wavelengths. By taking advantage of emerging materials and novel structures, these devices are becoming competitive with the more well-established technologies, and are opening new and intriguing perspectives. In this paper, a review of the state-of-the-art is presented. Devices based on defect-mediated absorption, two-photon absorption and the internal photoemission effect are reported, their working principles are elucidated and their performance discussed and compared

Intravitreal Bevacizumab in Neovascular Age-Related Macular Degeneration as First Choice: a New Italian Ruling

Background: Intravitreal vascular endothelial growth factor (VEGF) inhibitors represent the mainstay of neovascular age-related macular degeneration (nAMD) treatment. Although bevacizumab has been the first anti-VEGF used in ophthalmology, it is unlicensed for intraocular use. However, the favourable cost-benefit balance has favoured its widespread use. We aimed to present relevant literature regarding the safety profile and the regulatory issues of intravitreal bevacizumab use. Methods: In this narrative review we report relevant studies regarding the safety profile of intravitreal bevacizumab. Expert commentary is provided and an overview of the current scenario and possible future directions discussed. Results: Randomized controlled trials have demonstrated that bevacizumab is not inferior to the licensed anti-VEGF agents showing similar efficacy and safety profiles. However, a significant debate on the regulatory issues of intravitreal bevacizumab used as ‘off label’ first-line treatment in nAMD still persists. Recently, the Regional Health System of Lombardia in Italy decided to only cover the expenses of bevacizumab, forcing clinicians to use bevacizumab as the first choice in the treatment of nAMD. Issues about the practical implications of this decision are discussed. Conclusion: The use of intravitreal bevacizumab as first-line therapy in nAMD remains controversial. Many differences in the regulatory aspects still persist among the European countries and sometimes within the same countries, like Italy. Of note the clinical scenario will be modified in future by the introduction of newly developed anti-VEGF agents and anti-VEGF biosimilars

A task-priority based control approach to distributed data-driven ocean sampling

The paper illustrates the basic ideas and relevant algorithmic developments underlying the proposal for a task-priority based control approach to distributed data-driven ocean sampling applications. This approach is deemed allowing a better formalization of the overall motion problem of the involved team of agents; that apart the ultimate mission objective, also result characterized by other different control objectives directly related with both operability and safety aspects of the entire sampling system. Also, the proposed approach, other than leading to a unifying algorithmic structure, also seems allowing to foresee good possibilities for different types of downgrading toward efficient decentralized implementations

Robotized underwater interventions

Working in underwater environments poses many challenges for robotic systems. One of them is the low bandwidth and high latency of underwater acoustic communications, which limits the possibility of interaction with submerged robots. One solution is to have a tether cable to enable high speed and low latency communications, but that requires a support vessel and increases costs. For that reason, autonomous underwater robots are a very interesting solution. Several research projects have demonstrated autonomy capabilities of Underwater Vehicle Manipulator Systems (UVMS) in performing basic manipulation tasks, and, moving a step further, this chapter will present a unifying architecture for the control of an UVMS, comprehensive of all the control objectives that an UVMS should take into account, their different priorities and the typical mission phases that an UVMS has to tackle. The proposed strategy is supported both by a complete simulated execution of a test-case mission and experimental results

Tomographic Biomarkers Predicting Progression to Fibrosis in Treated Neovascular Age-Related Macular Degeneration: A Multimodal Imaging Study.

Purpose: To describe the photoreceptor–retinal pigment epithelium (RPE) interface changes and to analyze the relationships between these features and hyperreflective material (HRM) with scarring and atrophy at the macula of patients with neovascular age-related macular degeneration (nAMD). Design: Retrospective single-center observational study. Participants: A total of 150 eyes from 144 patients with naive nAMD were included. Methods: All patients had OCT (HRA-OCT Spectralis, Heidelberg Engineering, Heidelberg, Germany) at baseline and at 1, 3, 6, and 12 months. Macular scar and macular atrophy (MA) were determined on multimodal imaging, including color fundus (CF) and near-infrared imaging at baseline and month 12 (M12). Main Outcome Measures: Change in HRM type (undefined and well-defined) and location, development of fibrotic or nonfibrotic macular scar, MA, and best-corrected visual acuity (BCVA) at M12. Results: At baseline, eyes with fibrin on CF had thicker and wider HRM on OCT that correlated strongly with presence of undefined HRM. The proportion of eyes with undefined HRM fell dramatically by month 1 but well-defined HRM increased. At M12 defined HRM was strongly associated with macular scar (chi-square, 82.1; P < 0.001). Ordinal regression showed that both the thickness and the width of HRM were significant risk factors for development of fibrotic scar (P < 0.001 and P = 0.02) but not nonfibrotic scars (P = 0.67 and P = 0.65). Fibrotic macular scar (P = 0.001) but not nonfibrotic scar (P = 0.129) negatively affected visual acuity at M12. Ordinal regression showed that the risk factors for progression to MA were reticular pseudodrusen and thinner HRM (P = 0.017 and P = 0.028, respectively). MA negatively affected BCVA at M12 (P < 0.001). Conclusion: Our study supports the role of HRM as an important biomarker for the evolution of macular scar and atrophy in patients with nAMD undergoing treatment with anti-VEGF therapies. Undefined HRM can resolve with treatment, whereas well-defined HRM likely contains vascular complexes and fibrotic elements

Neuro-Fuzzy Model for the Prediction and Classification of the Fused Zone Levels of Imperfections in Ti6Al4V Alloy Butt Weld

Weld imperfections are tolerable defects as stated from the international standard. Nevertheless they can produce a set of drawbacks like difficulty to assembly, reworking, limited fatigue life, and surface imperfections. In this paper Ti6Al4V titanium butt welds were produced by CO2laser welding. The following tolerable defects were analysed: weld undercut, excess weld metal, excessive penetration, incomplete filled groove, root concavity, and lack of penetration. A neuro-fuzzy model for the prediction and classification of the defects in the fused zone was built up using the experimental data. Weld imperfections were connected to the welding parameters by feed forward neural networks. Then the imperfections were clustered using the C-means fuzzy clustering algorithm. The clusters were named after the ISO standard classification of the levels of imperfection for electron and laser beam welding of aluminium alloys and steels. Finally, a single-value metric was proposed for the assessment of the overall bead geometry quality. It combined an index for each defect and functioned according to the criterion "the-smallest-the-best.