Academic literature on the topic 'Précision de tracking'

The relationship of Le Corbusier with the street is complex and sometimes contradictory. young Jeanneret seems to be persuaded by certain sites, which we may define as urban scenarios, during his visits to cities like Istanbul in his formative years. Unlike his hometown La Chaux-de-Fonds – identified by a regular set of streets – these places may have been a picturesque coun- terpoint activated by a significant topography. Streets meandering along a set of ‘Dom-ino’ houses in the Oeuvre complete, as the tracking rails of a long shot recording, offer a changing viewpoint that may be considered in relation with such casual arrangements. The claim to kill the ‘rue corridor’ made in Précisions, together with his later writings, deeply contrast with his own comments on an empty Paris in the summer of 1942 – as published in Les Trois Établissements Humains – praising the same streets he pretended to erase by means of operations like the ‘Ilôt Insalubre No 6′.

Cognitive biases, or systematic errors in cognition, are important contributors to diagnostic error in medicine. In our review, we explore the psychological underpinnings of cognitive bias and highlight several common biases using clinical cases. We conclude by reviewing strategies to improve diagnostic accuracy and by discussing controversies and future research directions.RésuméLes préjugés cognitifs, ou les erreurs systématiques dans la cognition, sont des contributeurs importants à l'erreur diagnostique dans la médecine. Dans notre examen, nous explorons les fondements psychologiques du biais cognitif et soulignons plusieurs préjugés communs en utilisant des cas cliniques. Nous concluons en examinant les stratégies visant à améliorer la précision diagnostique et en discutant des controverses et des futures orientations de recherche.Research in the field of behavioural psychology and its application to medicine has been ongoing for several decades in an effort to better understand clinical decision making.1 Cognitive biases (systematic errors in cognition) are increasingly recognized in behavioural economics2 and more recently have been shown to affect medical decision making.3 Over 100 such cognitive biases have been identified and several dozen are postulated to play a major role in diagnostic error.4 Cognitive errors can take many forms and in one study contributed to as many as 74% of diagnostic errors by internists. 5 Most of these errors were due to “faulty synthesis” of information, including premature diagnostic closure and failed use of heuristics.5 Inadequate medical knowledge, on the other hand, was rare and mostly identified in cases concerning rare conditions. 5 Professional organizations such as the Royal College of Physicians and Surgeons of Canada and the Canadian Medical Protective Association have since been working to raise awareness of cognitive bias in clinical practice.6In our review, we explore the role of cognitive bias in diagnostic error through the use of clinical cases. We also review the literature on de-biasing strategies and comment on limitations and future directions of research.The Dual Process TheoryA prevailing theory to explain the existence of cognitive bias is the dual process theory, which asserts that two cognitive systems are used in decision making, herein called System 1 and System 2 (Table 1). 2,7System 1 can be thought of as our intuitive mode of thinking. It generates hypotheses rapidly, operates beneath our perceptible consciousness and makes judgments that are highly dependent on contextual clues. System 1 is characterized by heuristics (short cuts, or “rules of thumb”) and is an important component of clinical judgment or expertise. In contrast, System 2 is slow, deliberate, analytical and more demanding on cognition. It applies rules that are acquired through learning and it can play a “monitoring role” over System 1, and thus overrides heuristics when their use is inappropriate. The dual process theory implies that errors result when inappropriate judgments generated by System 1 fail to be recognized and corrected by System 2. Maintaining constant vigilance over System 1 would be both impractical and time consuming for routine decisions and would diminish the value of intuition. It follows that a more practical way of improving reasoning is to identify the most common biases of System 1 and to recognize situations when mistakes are most likely to occur.2Alternative Theories of CognitionVariations of dual process theory have further refined our understanding of medical decision making. Fuzzy trace theory, for example, proposes that individuals process information through parallel gist and verbatim representations.8 The “gist” is analogous to System 1 and represents the bottom-line “meaning” of information. This representation is subject to an individual’s worldview, emotions and experiences. In contrast, verbatim representations are precise, literal and analogous to System 2. Fuzzy trace theory is particularly useful in explaining how patients might interpret health information. Proponents of this theory contend that in order for information to lead to meaningful behavioural change, physicians must appeal to both gist and verbatim representations when communicating with patients.8 Other models, such as dynamic graded continuum theory, do away with the dichotomy of System 1 and System 2 and instead represent implicit, automatic and explicit cognitive processes on a continuous scale.9 These single system models are useful to compare against dual process theory but have not replaced it as a well-established framework for understanding and mitigating cognitive bias in clinical decision making.7Case 1: A 55-Year-Old Male with Retrosternal Chest PainA 55year-old non-smoking male was assessed in a busy Emergency Department (ED) for retrosternal chest pain. Past medical history is significant for osteoarthritis for which he takes naproxen. On review of his history, the patient has had multiple visits for retrosternal chest pain in the previous two months. At each encounter, he was discharged home after a negative cardiac workup.Vital signs in the ED were within normal limits except for sinus tachycardia at 112 beats per minute. On exam, the patient was visibly distressed. Cardiac and respiratory exams were normal. There was mild tenderness in the epigastrium. Basic blood-work revealed leukocytosis (16.0 × 109/L), a mildly elevated high sensitivity cardiac troponin, and no other abnormalities. An ECG revealed T wave flattening in leads V3-V4.The patient was referred to the internal medicine service with a diagnosis of non-ST-elevation myocardial infarction and treated with aspirin, clopidogrel, and fondaparinux. Several hours later, the patient became more agitated and complained of worsening retrosternal and epigastric pain. On re-examination, heart rate had increased to 139 beats per minute, blood pressure dropped to 77/60 and he had a rigid abdomen. Abdominal radiography revealed free air under the right hemi-diaphragm and the patient was rushed to the operating room where a perforated gastric ulcer was detected and repaired. The case above illustrates numerous cognitive biases, including:1. Premature diagnostic closure: the tendency to accept a diagnosis before it is fully verified.42. Anchoring: the tendency to over-emphasize features in the patient’s initial presentation and failing to adjust the clinical impression after learning new information.43. Confirmation bias: the tendency to look for confirming evidence to support a diagnosis, rather than to look for (or explain) evidence which puts the diagnosis in question.4In this case, the physician based the diagnosis of myocardial infarction primarily on symptoms of chest pain and an elevated cardiac troponin. However, several other objective findings were present and when taken together, suggested a diagnosis other than myocardial infarction. These included a tender epigastrium, leukocytosis, and resting sinus tachycardia. These symptoms/signs were not explicitly explained or investigated before a treatment decision was made. Premature diagnostic closure is one of the most common cognitive biases underlying medical errors5 and it affects clinicians at all levels of training.10 It is multifactorial in origin5 and is especially common in the face of other cognitive biases such as anchoring and confirmation bias.The physician in this case “anchored” to a diagnosis of cardiac chest pain given the patient’s previous ED visit history and his/her best intentions of ruling out a “worst case scenario.” Anchoring can be especially powerful in the face of abnormal screening investigations that have been reviewed even before the physician has acquired a history or performed a physical examination. If the physician had reviewed the screening investigations before seeing the patient, he/she might have narrowed the differential diagnosis prematurely, failed to gather all the relevant information and failed to adjust the clinical impression based on new information.The physician demonstrated confirmation bias by failing to explain the abnormalities that put the diagnosis of myocardial infarction in question (e.g. tender epigastrium, leukocytosis). Confirmation bias arises from an attempt to avoid cognitive dissonance, a distressing psychological conflict which occurs when inconsistent beliefs or theories are held simultaneously.11 In one study evaluating clinical decision making amongst 75 psychiatrists and 75 medical students,12 13% of psychiatrists and 25% of medical students demonstrated confirmation bias when searching for information after having made a preliminary diagnosis. In this study, confirmation bias resulted in more frequent diagnostic errors and predictably impacted subsequent treatment decisions.An appropriate consideration of all diagnostic possibilities is the first step in avoiding diagnostic error. While acquiring information, physicians should step back and consolidate new data with the working diagnosis, as failure to do so can result in confirmation bias.13 All abnormal findings and tests, especially if considered clinically relevant should be explained by the most probable diagnosis. An alternate diagnosis or the possibility of more than one diagnosis should be considered when an abnormal finding or test cannot reasonably be explained by the working diagnosis.Tschen et al observed a team of physicians working through a simulated scenario which had diagnostic ambiguity.14 Two approaches were found to be effective in reducing the effect of confirmation bias: explicit reasoning and talking to the room. Explicit reasoning involves making causal inferences when interpreting and communicating information. Talking to the room is a process whereby diagnostic reasoning is explained in an unstructured way to a team member or colleague in the room. This allows the clinician the opportunity to elaborate on their thoughts and observers to point out errors or suggest alternate diagnoses in a shared mental model.Case 2: A 30-Yearold Male with Confusion and SeizuresA 30-year-old homeless male is found confused on the street by paramedics and brought to the ED for assessment. Empty bottles of alcohol were noted at the scene. The CIWA (Clinical Institute Withdrawal Assessment for Alcohol) protocol is initiated and he is given several doses of lorazepam to minimal effect. Several hours after the patient is admitted, a resident on-call is paged for elevated CIWA scores on the basis of diaphoresis and agitation. Several additional doses of lorazepam are ordered which fail to completely resolve the symptoms. Gradually, the patient becomes more obtunded. The on-call resident orders a capillary blood glucose and it measures 1.1 mmol/L. Intravenous D50W is promptly administered, the blood glucose normalizes and the patient’s level of consciousness improves.The case above illustrates the following biases:1. Availability bias: the tendency to weigh a diagnosis as being more likely if it comes to mind more readily.42. Diagnostic momentum: the tendency for labels to “stick” to patients and become more definite with time.4Although the symptoms of diaphoresis and agitation are not specific to alcohol withdrawal, this diagnosis was deemed most likely based on how readily it came to mind, the empty alcohol bottles at the scene, and potentially on the patient’s demographics. The unproven diagnosis of alcohol withdrawal “stuck” with the patient despite minimal improvement after a therapeutic trial of benzodiazepines.Availability bias has been shown to affect internal medicine residents. In one single-centre study,15 18 first-year and 18 second-year residents were exposed to case descriptions with associated diagnoses as part of an exercise. They were then asked to diagnose a series of new cases, some of which appeared similar to those they had previously encountered but with pertinent differences that made an alternate diagnosis more likely. Second year residents had lower diagnostic accuracy on these similar-appearing cases; a result consistent with availability bias. First year residents were less prone to this bias because of their limited clinical experience. Most importantly, subsequent reflective diagnostic reasoning countered the bias and improved accuracy.General Strategies to Avoid Cognitive BiasInterventions aimed at mitigating diagnostic error due to cognitive bias take several approaches.1. Improving clinical reasoning2. Reducing cognitive burden3. Improving knowledge and experienceDespite a large number of proposed interventions, there is a lack of empirical evidence supporting the efficacy of many de-biasing strategies. 16 What follows is a brief review of the current evidence.Improving Clinical ReasoningSeveral “de-biasing” strategies have been proposed to improve clinical reasoning. De-biasing strategies assume that System 1 processes are more prone to bias due to their heavy reliance on heuristics and therefore the solution is to activate System 2 at critical points in decision making. De-biasing occurs in several stages: at first an individual is educated about the presence of a cognitive bias, they then employ strategies to eliminate that bias and finally they maintain those strategies in the long term.17Metacognition, or “thinking about thinking,” involves reflecting on one’s own diagnostic reasoning. Internal reflection along with awareness of potential biases should allow the clinician to identify faulty reasoning. However, the evidence underlying reflective practice is mixed.16 Several studies have tried to encourage reflective practice and System 2 processes by instructing participants to proceed slowly through their reasoning18 or by giving participants the opportunity to review their diagnoses.19 These studies have found minimal or no impact on reducing the rate of diagnostic error. On the other hand, some studies have shown improved diagnostic accuracy when physicians are asked to explicitly state their differential diagnoses along with features that are consistent or inconsistent with each diagnosis.20 These results suggest that if reflective practice is to be effective, it must involve a thorough review of the differential diagnosis as opposed to simply taking additional time.Reducing Cognitive BurdenTools that reduce the cognitive burden placed on physicians may reduce the frequency of diagnostic errors. One suggestion has been to incorporate the use of checklists in the diagnostic process. These checklists would be matched to common presenting symptoms and include a list of possible diagnoses. One randomized controlled trial failed to show a statistically significant reduction in the diagnostic error rate with the use of checklists, except in a small subgroup of patients treated in the ED. 21 These findings challenge the results of two other studies that found checklists to be effective in improving scrutiny22 and diagnostic accuracy23 when interpreting electrocardiograms. More advanced forms of clinician decision support systems have also been studied.24 Software programs such as DXplain generate a list of potential diagnoses based on a patient’s chief complaint. In one study, when the software provided physicians a list of possible diagnoses before evaluating patients, diagnoses were 1.31 times more likely to be correct. 25 The use of diagnostic support tools may grow in the future as they are integrated into electronic medical record systems.Improving Knowledge and ExperienceA combination of experience, knowledge and feedback are integral in developing a clinician’s intuition to produce the best hypotheses. Experience without feedback can lead to overconfidence, which itself is a cognitive bias. The evidence supporting feedback is strong. Fridriksson et al showed a significant reduction in diagnostic error when referring doctors were provided feedback on the identification of subarachnoid hemorrhage.26 A systematic review of 118 randomized trials concluded that feedback was effective in improving professional practice.27 The specific characteristics of the best feedback were elusive. In general, however, feedback was thought to be most effective when it was explicit and delivered close to the time of decision making. ConclusionsIn our review, we explore clinical decision making through the lens of dual-process theory. However, multiple different dual-processing models are still being explored and fundamental questions are still under debate. For example, some experts believe that instead of focusing on de-biasing strategies, the key to improving intuitive (System 1) processes is simply to acquire more formal and experiential knowledge.19 Other unanswered questions include: the impact and magnitude of cognitive bias in actual clinical practice, which biases are most prevalent in each medical specialty and which strategies are the most effective in mitigating bias. Further study is also needed to assess the impact of novel educational methods, such as case-based and simulation-based learning, which are promising venues where trainees may identify and correct cognitive biases in a directly observed setting. References 1. Norman G. Research in clinical reasoning: past history and current trends. Med Educ 2005;39:418–27.2. Kahneman D. Thinking, fast and slow. Farrar, Straus and Giroux; 2011.3. Croskerry P. From mindless to mindful practice — cognitive bias and clinical decision making. N Engl J Med 2013;368:2445–8.4. Croskerry P. The importance of cognitive errors in diagnosis and strategies to minimize them. Academic Medicine 2003;78:775–80.5. Graber ML, Franklin N, Gordon R. Diagnostic error in internal medicine. Arch Intern Med 2005;165:1493–9.6. Parush A, Campbell C, Hunter A, et al. Situational awareness and patient safety - a short primer. Ottawa ON: The Royal College of Physicians and Surgeons of Canada; 2011.7. Pelaccia T, Tardif J, Triby E, Charlin B. An analysis of clinical reasoning through a recent and comprehensive approach: the dual-process theory. Med Educ Online 2011;16.8. Reyna VF. A theory of medical decision making and health: fuzzy trace theory. Med Decis 2008;28:850–65.9. Osman M. An evaluation of dual-process theories of reasoning. Psychonom Bull review 2004;11:988–1010.10. Dubeau CE, Voytovich AE, Rippey RM. Premature conclusions in the diagnosis of iron-deficiency anemia: cause and effect. Med Dec Mak 1986;6:169–73.11. Nickerson RS. Confirmation bias: A ubiquitous phenomenon in many guises. Rev Gen Psychol 1998;2:175.12. Mendel R, Traut-Mattausch E, Jonas E, et al. Confirmation bias: why psychiatrists stick to wrong preliminary diagnoses. Psychol Med 2011;41:2651–9.13. Pines JM. Profiles in patient safety: confirmation bias in emergency medicine. Acad Emerg Med 2006;13:90–4.14. Tschan F, Semmer NK, Gurtner A, et al. Explicit reasoning, confirmation bias, and illusory transactive memory: a simulation study of group medical decision making. Small Group Res 2009;40:271–300.15. Mamede S, van Gog T, van den Berge K, et al. Effect of availability bias and reflective reasoning on diagnostic accuracy among internal medicine residents. JAMA 2010;304:1198–203.16. Graber ML, Kissam S, Payne VL, et al. Cognitive interventions to reduce diagnostic error: a narrative review. BMJ Qual Safe 2012;21:535–57.17. Croskerry P, Singhal G, Mamede S. Cognitive debiasing 2: impediments to and strategies for change. BMJ Qual Saf 2013.18. Norman G, Sherbino J, Dore K, et al. The etiology of diagnostic errors: a controlled trial of system 1 versus system 2 reasoning. Acad Med 2014;89:277–84.19. Monteiro SD, Sherbino J, Patel A, Mazzetti I, Norman GR, Howey E. Reflecting on diagnostic errors: taking a second look is not enough. J Gen Intern Med 2015;30:1270–4.20. Bass A, Geddes C, Wright B, Coderre S, Rikers R, McLaughlin K. Experienced physicians benefit from analyzing initial diagnostic hypotheses. Can Med Educ J 2013;4:e7–e15.21. Ely JW, Graber MA. Checklists to prevent diagnostic errors: a pilot randomized controlled trial. Diagnosis 2015;2.22. Sibbald M, de Bruin ABH, Yu E, van Merrienboer JJG. Why verifying diagnostic decisions with a checklist can help: insights from eye tracking. Adv Health Sci Educ Theory Pract 2015;20:1053–60.23. Sibbald M, de Bruin ABH, van Merrienboer JJG. Checklists improve experts' diagnostic decisions. Med Educ 2013;47:301–8.24. Garg AX, Adhikari NKJ, McDonald H, et al. Effects of computerized clinical decision support systems on practitioner performance and patient outcomes: a systematic review. JAMA 2005;293:1223–38.25. Kostopoulou O, Rosen A, Round T, et al. Early diagnostic suggestions improve accuracy of GPs: a randomised controlled trial using computer-simulated patients. Br J Gen Pract 2015;65:e49–54.26. Fridriksson S, Hillman J, Landtblom AM, Boive J. Education of referring doctors about sudden onset headache in subarachnoid hemorrhage. A prospective study. Acta Neurol Scand 2001;103:238–42.27. Jamtvedt G, Young JM, Kristoffersen DT, O'Brien MA, Oxman AD. Does telling people what they have been doing change what they do? A systematic review of the effects of audit and feedback. Qual Saf Health Care 2006;15:433–6.

Face aux sources d’énergie épuisables et polluantes, la production d’électricité par énergie solaire à concentration photovoltaïque (CPV) connaît depuis 2010 une croissance significative. Les systèmes ayant les plus hauts rendements (< 29%) sont constitués de trackers à deux axes combinés à des modules à modules (CPV) allant de 300x à 2500x, intégrant des cellules PV à triple jonction, dont l’efficacité mesurée en laboratoire est supérieure à 35%. Les pertes des systèmes sont dues aux conditions de fonctionnement extérieures fluctuantes, parmi lesquelles : la température, le contenu spectral du flux lumineux, la taille variable du disque solaire et la précision du suivi soumis à des limites physiques et des charges de vents variables. L’industrie tente de pallier à ces difficultés par des dispositifs à concentrations optique à angle d’acceptance (AA) large. Mais la caractérisation en laboratoire de tout dispositif doit être complétée par des tests en conditions externes. Ce projet consiste en la conception et la réalisation d’un banc d’essai extérieur de caractérisation de modules CPV, sous conditions réelles et variables, au moyen de tests I-V. Les données sont archivées sur une base de données, et prétraitées pour analyses des résultats. Les objectifs de caractérisation ont été atteints, soit le positionnement ponctuel précis en azimut et en élévation lors d’un test I-V, la répétition de cette étape selon des protocoles ajustables. Six dispositifs CPV à large AA ont été caractérisés en même temps (plus de 146 000 lectures). Des suggestions sont faites pour corriger les problèmes rencontrés. Des questions de recherches ultérieures sont posées, l’ensemble confirmant la pertinence de ce type de banc d’essai.

L'objectif de cette thèse est de réaliser la modélisation, la planification de trajectoire et le contrôle d'un robot hélicoptère sans pilote pour la surveillance de grandes surfaces, en particulier dans des applications d'agriculture de précision. Dans les missions de surveillance des ravageurs, les drones seront équipés de caméras spécialisées. Une trajectoire sera créée pour permettre aux aéronefs sans pilote de capturer des images de zones de cultures entières et d'éviter les obstacles pendant le vol. Les zones infectées seront identifiées en analysant les images prises. Lors de la pulvérisation d'insecticides, l'aéronef doit être contrôlé pour voler selon une trajectoire préprogrammée et pulvériser l'insecticide sur toutes les zones de culture infectées.Dans la première partie, nous présentons un nouvel algorithme de planification de chemin de couverture complet en proposant une nouvelle décomposition cellulaire qui repose sur une généralisation de la variante Boustrophédon, à l'aide de fonctions Morse, avec une extension de la représentation des points critiques. Cette extension conduit à un nombre réduit de cellules après décomposition. L'algorithme génétique (GA) et l'algorithme de problème du voyageur de commerce (TSP) sont appliqués pour obtenir le chemin le plus court pour une couverture complète. A partir des informations sur la carte concernant les coordonnées des obstacles, des zones infectées et non infectées, les zones infectées sont divisées en plusieurs régions non chevauchantes en utilisant une technique de regroupement. Un algorithme est proposé pour générer le meilleur chemin pour qu'un véhicule aérien sans pilote (UAV) distribue des médicaments à toutes les zones infectées d'un environnement agricole qui contient des obstacles non convexes, des zones exemptes de parasites et des zones infestées de parasites.Dans la deuxième partie, nous étudions la conception d'un système de contrôle robuste qui permet au véhicule de suivre la trajectoire prédéfinie d'un hélicoptère à modèle dynamique variable en raison des changements de coefficients dynamiques tels que la masse et les moments d'inertie. Par conséquent, les lois robustes d'observation et de contrôle sont nécessaires pour adopter les changements des paramètres dynamiques ainsi que l'impact des forces externes. La méthode proposée consiste à explorer les techniques de modélisation, de planification et de contrôle par l’approche Takagi-Sugeno. Pour avoir des algorithmes facilement implantables et adaptables aux changements de paramètres et de conditions d'utilisation, nous privilégions la synthèse de l'Observateur d'Entrées Inconnues (UIO) à Paramètre Linéaire Variable (LPV), et des contrôleurs retour d'état quadratique LPV, retour d'état robuste et retour de sortie statique. L'observateur et les contrôleurs sont conçus en résolvant un ensemble d'inégalités matricielles linéaires (LMI) obtenues à partir du lemme réel borné et de la caractérisation des régions LMI.Enfin, pour mettre en évidence les performances des algorithmes de planification de trajectoire et des lois de contrôle générées, nous effectuons une série de simulations à l’aide de MATLAB Simulink. L'algorithme de planification de trajectoire de couverture suggère que la trajectoire générée raccourcit la distance de vol de l'aéronef mais évite toujours les obstacles et couvre toute la zone d'intérêt. Les simulations pour l’observateur LPV UIO et les contrôleurs LPV sont effectuées avec les cas où la masse et les moments d'inertie changent brusquement et lentement. Le LPV UIO est capable d'estimer les variables d'état et les perturbations inconnues et les valeurs estimées convergent vers les vraies valeurs des variables d'état et les perturbations inconnues de manière asymptotique. Les contrôleurs LPV fonctionnent bien pour divers signaux de référence (impulsion, aléatoire, constant et sinusoïdale) et plusieurs types de perturbations (impulsionnelle, aléatoire, constante et sinusoïdale)
The objective of this thesis is to realize the modeling, trajectory planning, and control of an unmanned helicopter robot for monitoring large areas, especially in precision agriculture applications. Several tasks in precision agriculture are addressed. In pest surveillance missions, drones will be equipped with specialized cameras. A trajectory will be researched and created to enable unmanned aircraft to capture images of entire crop areas and avoid obstacles during flight. Infected areas will be then identified by analyzing taken images. In insecticides spraying, the aircraft must be controlled to fly in a pre-programmed trajectory and spray the insecticide over all the infected crop areas.In the first part, we present a new complete coverage path planning algorithm by proposing a new cellular decomposition which is based on a generalization of the Boustrophedon variant, using Morse functions, with an extension of the representation of the critical points. This extension leads to a reduced number of cells after decomposition. Genetic Algorithm (GA) and Travelling Salesman Problem (TSP) algorithm are then applied to obtain the shortest path for complete coverage. Next, from the information on the map regarding the coordinates of the obstacles, non-infected areas, and infected areas, the infected areas are divided into several non-overlapping regions by using a clustering technique. Then an algorithm is proposed for generating the best path for a Unmanned Aerial Vehicle (UAV) to distribute medicine to all the infected areas of an agriculture environment which contains non-convex obstacles, pest-free areas, and pests-ridden areas.In the second part, we study the design of a robust control system that allows the vehicle to track the predefined trajectory for a dynamic model-changing helicopter due to the changes of dynamic coefficients such as the mass and moments of inertia. Therefore, the robust observer and control laws are required to adopt the changes in dynamic parameters as well as the impact of external forces. The proposed approach is to explore the modeling techniques, planning, and control by the Takagi-Sugeno type technique. To have easily implantable algorithms and adaptable to changes in parameters and conditions of use, we favor the synthesis of Linear Parameter Varying (LPV) Unknown Input Observer (UIO), LPV quadratic state feedback, robust state feedback, and static output feedback controllers. The observer and controllers are designed by solving a set of Linear Matrix Inequality (LMI) obtained from the Bounded Real Lemma and LMI regions characterization.Finally, to highlight the performances of the path planning algorithms and generated control laws, we perform a series of simulations in MATLAB Simulink. Simulation results are quite promising. The coverage path planning algorithm suggests that the generated trajectory shortens the flight distance of the aircraft but still avoids obstacles and covers the entire area of interest. Simulations for the LPV UIO and LPV controllers are conducted with the cases that the mass and moments of inertias change abruptly and slowly. The LPV UIO is able to estimate state variables and the unknown disturbances and the estimated values converge to the true values of the state variables and the unknown disturbances asymptotically. The LPV controllers work well for various reference signals (impulse, random, constant, and sine) and several types of disturbances (impulse, random, constant, and sine)

Les travaux présentés dans ce mémoire portent sur l'étude, la conception et le développement de deux nouveaux prototypes de reconstruction tridimensionnelle, spécifique aux objets transparents. La numérisation 3D d'objets opaques est abondamment traitée dans la littérature et de nombreux systèmes sont d'ailleurs commercialisés. Cependant, lorsqu'il s'agit de la numérisation 3D d'objets transparents, les publications se font rares et aucun système de scanning n'existe sur le marché. La technique de numérisation de surfaces transparentes demeure compliquée et non maîtrisée à l'heure actuelle. L'opacification de la surface avant le scanning s'avère être la solution retenue dans le domaine du contrôle qualité. Néanmoins, cette alternative n'est pas optimale en raison du coût de traitements et du manque de précision éventuellement engendré. Afin de solutionner les problèmes de la numérisation d'objets transparents, nous avons développé deux approches dites non conventionnelles en étendant les méthodes existantes (dans le visible) aux longueurs d'onde dans lesquelles les sujets apparaissent opaques (IR et UV). Les deux méthodes de mesure sans contact retenues sont : - la reconstruction par polarisation dans l'IR, en vue de s'affranchir des problèmes d'inter-réflexions; - le scanning par laser UV, pour satisfaire les contraintes industrielles (précision, rapidité et coût) tout en résolvant de manière efficace le problème de réfraction. La première approche est fondée sur la réflexion spéculaire de l'objet dans l'IR tandis que la seconde exploite la propriété de l'objet à fluorescer sous l'irradiation UV. L'inexistence des lentilles télécentriques dans l'IR nous a conduits à adapter la reconstruction par polarisation dans l'IR à l'aide d'une lentille non télécentrique. Pour ce faire, une méthode d'approximation du modèle orthographique a été développée et une méthode de validation visant à améliorer la précision des résultats a été en outre intégrée dans le processus de reconstruction après l'étape d'estimation des paramètres de Stokes. Nos résultats sont très satisfaisants et attestent la faisabilité de la reconstruction par polarisation dans l'IR. Quatre configurations de système de scanning par triangulation ont été déployées afin d'exploiter la propriété de fluorescence des objets transparents irradiés sous un rayonnement UV. Des expérimentations visant à caractériser la fluorescence induite à la surface des objets considérés et à vérifier l'éligibilité de notre approche ont été menées. Les mesures spectroscopiques nous ont permis d'élaborer des critères de "tracking" (détection et localisation) des points fluorescents en présence des bruits inhérents à l'acquisition. Nous avons également mis au point des méthodes de validation des paramètres du modèle de reconstruction 3D estimés lors de la calibration, permettant ainsi d'optimiser la configuration du système de scanning. Les méthodes de "tracking" et de validation ont contribué considérablement à l'amélioration de la précision des résultats. Par ailleurs, la précision obtenue n'a jamais été atteinte au regard de ce que l'on trouve dans la littérature.

Les travaux présentés dans ce mémoire portent sur l'étude, la conception et le développement de deux nouveaux prototypes de reconstruction tridimensionnelle, spécifique aux objets transparents. La numérisation 3D d'objets opaques est abondamment traitée dans la littérature et de nombreux systèmes sont d'ailleurs commercialisés. Cependant, lorsqu'il s'agit de la numérisation 3D d'objets transparents, les publications se font rares et aucun système de scanning n'existe sur le marché. La technique de numérisation de surfaces transparentes demeure compliquée et non maîtrisée à l'heure actuelle. L'opacification de la surface avant le scanning s'avère être la solution retenue dans le domaine du contrôle qualité. Néanmoins, cette alternative n'est pas optimale en raison du coût de traitements et du manque de précision éventuellement engendré. Afin de solutionner les problèmes de la numérisation d'objets transparents, nous avons développé deux approches dites non conventionnelles en étendant les méthodes existantes (dans le visible) aux longueurs d'onde dans lesquelles les sujets apparaissent opaques (IR et UV). Les deux méthodes de mesure sans contact retenues sont : - la reconstruction par polarisation dans l'IR, en vue de s'affranchir des problèmes d'inter-réflexions; - le scanning par laser UV, pour satisfaire les contraintes industrielles (précision, rapidité et coût) tout en résolvant de manière efficace le problème de réfraction. La première approche est fondée sur la réflexion spéculaire de l'objet dans l'IR tandis que la seconde exploite la propriété de l'objet à fluorescer sous l'irradiation UV. L'inexistence des lentilles télécentriques dans l'IR nous a conduits à adapter la reconstruction par polarisation dans l'IR à l'aide d'une lentille non télécentrique. Pour ce faire, une méthode d'approximation du modèle orthographique a été développée et une méthode de validation visant à améliorer la précision des résultats a été en outre intégrée dans le processus de reconstruction après l'étape d'estimation des paramètres de Stokes. Nos résultats sont très satisfaisants et attestent la faisabilité de la reconstruction par polarisation dans l'IR. Quatre configurations de système de scanning par triangulation ont été déployées afin d'exploiter la propriété de fluorescence des objets transparents irradiés sous un rayonnement UV. Des expérimentations visant à caractériser la fluorescence induite à la surface des objets considérés et à vérifier l'éligibilité de notre approche ont été menées. Les mesures spectroscopiques nous ont permis d'élaborer des critères de "tracking" (détection et localisation) des points fluorescents en présence des bruits inhérents à l'acquisition. Nous avons également mis au point des méthodes de validation des paramètres du modèle de reconstruction 3D estimés lors de la calibration, permettant ainsi d'optimiser la configuration du système de scanning. Les méthodes de "tracking" et de validation ont contribué considérablement à l'amélioration de la précision des résultats. Par ailleurs, la précision obtenue n'a jamais été atteinte au regard de ce que l'on trouve dans la littérature
Two non-conventional methods for the 3D digitization of transparent objects via non-contact measurement are reported in this thesis. 3D digitization is a well acknowledged technique for opaque objects and various commercial solutions based on different measurement approaches are available in the market offering different types of resolution at different prices. Since these techniques require a diffused or lambertian surface, their application to transparent surfaces fails. Indeed, rays reflected by the transparent surface are perturbed by diverse inter-reflections induced by the refractive properties of the object. Therefore, in industrial applications like quality control, the transparent objects are powder coated followed by their digitization. However, this method is expensive and can also produce inaccuracies. Among the rare methods suggested in the literature, shape from polarization provides reliable results even though their accuracy had to be improved by coping with the inter-reflections. The two proposed solutions handle the extension of the existing methods to wavelengths beyond visible ranges: - shape from polarization in Infra Red (IR) range to deal with the above-mentioned inter-reflections; - scanning by Ultra Violet (UV) laser (based on triangulation scheme) to overcome the refraction problem that can be feasibly applied in industrial applications. The characteristic physical properties of transparent objects led us to explore the IR and UV ranges; since, transparent glass has strong absorption bands in the IR and UV ranges and therefore has opaque appearance. The first approach exploits the specular reflection of the considered object surface in IR and the second one exploits the fluorescence property of the object when irradiated with UV rays. Shape from polarization traditionally based on telecentric lenses had to be adapted with non-telecentric lenses to be used in the IR range. Thus, an approximation of the orthographic model is developed in this thesis while a validation method is implemented and integrated in the reconstruction process after Stokes parameters estimation, in order to improve the accuracy of the results. Some results of digitized objects are presented, which prove the feasibility of the shape from polarization method in the IR range to be used for transparent objects. A total of four configurations of the triangulation system are implemented in this thesis to exploit fluorescence produced by the UV laser scanning of the second approach. Experimental investigations aimed at characterizing the fluorescence are done. A specific fluorescence tracking method is carried out to deal with the inherent noise in the acquisitions. The uniqueness of the method relies on the criteria that are derived from the analysis of spectroscopic results. A validation method is made to optimize the configuration system while reducing the accuracy of reconstruction error. The results of some object digitization are presented with accuracies better than previously reported works

Les réseaux de capteurs sans fil est une technologie nouvelle dont les applications s'étendent sur plusieurs domaines: militaire, scientifique, médicale, industriel, etc. La collaboration entre les noeuds capteurs, caractérisés par des capacités minimales en termes de capture, de transmission, de traitement et d'énergie, est une nécessité pour réaliser des tâches aussi complexes que la collecte des données, le pistage des objets mobiles, la surveillance des zones sensibles, etc. La contrainte matérielle sur le développement des ressources énergétiques des noeuds capteurs est persistante. D'où la nécessité de l'optimisation logicielle dans les différentes couches de la pile protocolaire et du système d'exploitation des noeuds. Dans cette thèse, nous approchons le problème d'optimisation d'énergie pour les applications collaboratives via les méthodes de sélection des capteurs basées sur la prédiction et la corrélation des données issues du réseau lui-même. Nous élaborons plusieurs méthodes pour conserver les ressources énergétiques du réseau en utilisant la prédiction comme un moyen pour anticiper les actions des noeuds et leurs rôles afin de minimiser le nombre des noeuds impliqués dans la tâche en question. Nous prenons l'application de pistage d'objets mobiles comme un cas d'étude. Ceci, après avoir dresser un état de l'art des différentes méthodes et approches récentes utilisées dans ce contexte. Nous formalisons le problème à l'aide d'un programme linéaire à variables binaires dans le but de trouver une solution générale exacte. Nous modélisons ainsi le problème de minimisation de la consommation d'énergie des réseaux de capteurs sans fil, déployé pour des applications de collecte de données soumis à la contrainte de précision de données, appelé EMDP. Nous montrons que ce problème est NP-Complet. D'où la nécessité de solutions heuristiques. Comme solution approchée, nous proposons un algorithme de clustering dynamique, appelé CORAD, qui adapte la topologie du réseau à la dynamique des données capturées afin d'optimiser la consommation d'énergie en exploitant la corrélation qui pourrait exister entre les noeuds. Toutes ces méthodes ont été implémentées et testées via des simulations afin de montrer leur efficacité
Wireless Sensor Networks is an emerging technology enabled by the recent advances in Micro-Electro-Mechanical Systems, that led to design tiny wireless sensor nodes characterized by small capacities of sensing, data processing and communication. To accomplish complex tasks such as target tracking, data collection and zone surveillance, these nodes need to collaborate between each others to overcome the lack of battery capacity. Since the development of the batteries hardware is very slow, the optimization effort should be inevitably focused on the software layers of the protocol stack of the nodes and their operating systems. In this thesis, we investigated the energy problem in the context of collaborative applications and proposed an approach based on node selection using predictions and data correlations, to meet the application requirements in terms of energy-efficiency and quality of data. First, we surveyed almost all the recent approaches proposed in the literature that treat the problem of energy-efficiency of prediction-based target tracking schemes, in order to extract the relevant recommendations. Next, we proposed a dynamic clustering protocol based on an enhanced version of the Distributed Kalman Filter used as a prediction algorithm, to design an energy-efficient target tracking scheme. Our proposed scheme use these predictions to anticipate the actions of the nodes and their roles to minimize their number in the tasks. Based on our findings issued from the simulation data, we generalized our approach to any data collection scheme that uses a geographic-based clustering algorithm. We formulated the problem of energy minimization under data precision constraints using a binary integer linear program to find its exact solution in the general context. We validated the model and proved some of its fundamental properties. Finally and given the complexity of the problem, we proposed and evaluated a heuristic solution consisting of a correlation-based adaptive clustering algorithm for data collection. We showed that, by relaxing some constraints of the problem, our heuristic solution achieves an acceptable level of energy-efficiency while preserving the quality of data