Designing a Computer Vision System for Underwater Robotic Interventions

This thesis deals with the challenging problem of designing systems able to perceive objects in underwater environments. In the last few decades research activities in robotics have advanced the state of art regarding intervention capabilities of autonomous systems. State of art in fields such as localization and navigation, real time perception and cognition, safe action and manipulation capabilities, applied to ground environments (both indoor and outdoor) has now reached such a readiness level that it allows high level autonomous operations. On the opposite side, the underwater environment remains a very difficult one for autonomous robots. Water influences the mechanical and electrical design of systems, interferes with sensors by limiting their capabilities, heavily impacts on data transmissions, and generally requires systems with low power consumption in order to enable reasonable mission duration. Interest in underwater applications is driven by needs of exploring and intervening in environments in which human capabilities are very limited. Nowadays, most underwater field operations are carried out by manned or remotely operated vehicles, deployed for explorations and limited intervention missions. Manned vehicles, directly on-board controlled, expose human operators to risks related to the stay in field of the mission, within a hostile environment. Remotely Operated Vehicles (ROV) currently represent the most advanced technology for underwater intervention services available on the market. These vehicles can be remotely operated for long time but they need support from an oceanographic vessel with multiple teams of highly specialized pilots. Vehicles equipped with multiple state-of-art sensors and capable to autonomously plan missions have been deployed in the last ten years and exploited as observers for underwater fauna, seabed, ship wrecks, and so on. On the other hand, underwater operations like object recovery and equipment maintenance are still challenging tasks to be conducted without human supervision since they require object perception and localization with much higher accuracy and robustness, to a degree seldom available in Autonomous Underwater Vehicles (AUV). This thesis reports the study, from design to deployment and evaluation, of a general purpose and configurable platform dedicated to stereo-vision perception in underwater environments. Several aspects related to the peculiar environment characteristics have been taken into account during all stages of system design and evaluation: depth of operation and light conditions, together with water turbidity and external weather, heavily impact on perception capabilities. The vision platform proposed in this work is a modular system comprising off-the-shelf components for both the imaging sensors and the computational unit, linked by a high performance ethernet network bus. The adopted design philosophy aims at achieving high flexibility in terms of feasible perception applications, that should not be as limited as in case of a special-purpose and dedicated hardware. Flexibility is required by the variability of underwater environments, with water conditions ranging from clear to turbid, light backscattering varying with daylight and depth, strong color distortion, and other environmental factors. Furthermore, the proposed modular design ensures an easier maintenance and update of the system over time. Performance of the proposed system, in terms of perception capabilities, has been evaluated in several underwater contexts taking advantage of the opportunity offered by the MARIS national project. Design issues like energy power consumption, heat dissipation and network capabilities have been evaluated in different scenarios. Finally, real-world experiments, conducted in multiple and variable underwater contexts, including open sea waters, have led to the collection of several datasets that have been publicly released to the scientific community. The vision system has been integrated in a state of the art AUV equipped with a robotic arm and gripper, and has been exploited in the robot control loop to successfully perform underwater grasping operations.

Asma, abitudini e stile di vita "Analisi retrospettiva di un campione di pazienti asmatici seguito in ambulatorio di terzo livello"

Growing evidence suggest the importance of different environments in promoting the pathogenesis and/or exacerbation of asthma. Indoor air pollution is a major contributor to human exposure, since people spend up to 90% of their day indoors. Apart from active smoking, indoor pollution is considered one of the major preventable risk factors of chronic respiratory diseases. The professional activity can also be dangerous because it exposes the subject to environments that can promote the onset of asthma or worsening of the latter in those already affected. Even bad habits such as incorrect diet, lead to more difficulty in controlling their disease. However asthma is a multifactorial disease in nature so it is not easy to distinguish the role of occupational exposure, pollution and normal habits such as smoking, nutrition, sports, etc. This retrospective study was conducted on a sample of asthma patients residing in the metropolitan area of Parma. 116 patients were selected among those who are followed up at least two years at the Asthma outpatient Clinic of Parma University Hospital. The sample in question is therefore closely controlled and monitored; it comes to patients who are well educated on the control of their disease, are able to take appropriate measures to minimize the symptomatology. With this tight approach is proposed to minimize the effect of confounding and then traced with greater certainty the possible cause of the failure to control the disease. For this purpose, each patient was subjected to regular checkups; we took as a reference the period of time between April and October 2015. During each visit, in addition to general data for each patient, we were collected personal information about their habits and way of life through a validated questionnaire delivered and completed by the patient during the visit in the presence of the permanent staff. The questionnaire covers mainly the qualification of the patient, its possible occupational exposure, his home, with information about nearby traffic, time spent outside, physical activity (place and time), exposure to chemicals, exposure to various fumes (fireplace or stove) and cigarette smoke, comorbidities and any drugs taken during the visits considered. Regarding the respiratory conditions of patients during every examination we were considered: Asthma Control Test (a test performed by patients to assess the state of the disease during the month preceding the test), the measurement of exhaled nitric oxide (FeNO) as an index of airways inflammation, measuring the resistance level of small airways (R5-R20) and some spirometric values observed in experiment; in particular the forced vital capacity (FVC), forced expiratory volume in the first second (FEV 1), FEV1/FVC ratio, forced expiratory flow rate over the middle 50% of the FVC (FEF25–75) and FEF25-75/FVC were recorded. The sample has been studied considering both the changes of the respiratory parameters for every patient in their examinations, and the respiratory parameters of all the examinations took as a whole in relation with the variables considered. From the results obtained, the patients are clinically stable; their adopted lifestyle and the exposure to possible sources of outdoor pollution, seems not affect the overall control of their disease. Some findings of our study are of interest. First, the subjects who carry a steroid therapy show a clinical worst, as revealed by the decrease of most spirometric indices, particularly FEF25, FEF75, FEF25-75 and R5-R20; also, the presence of comorbidities and the subsequent intake of other drugs, in addition to normal therapy for asthma, seem to be conditions associated with poorer performance in the functional respiratory parameters in particular FEV1/FVC, FEF75 and FEF25-75. Spirometric indexes that are down are mainly those related to obstruction imposed on small airways; this suggests a neglect to the latter on the contrary should be further explored and treated accordingly. It is also observed that both patients are overweight than those living on the lower floors and/or who have the most windows exposed to traffic, showed a decrease of pulmonary function, especially those relate to an obstruction at the small airways level. In conclusion, our results provided the evidence that a most appropriate therapy, specific to reach the small airways, associated with a healthy lifestyle, can help improve the management of asthma.