Cette thèse de doctorat s’inscrit dans le cadre des activités de recherche sur les systèmes de lancement aéroporté autonome. L’originalité du travail est basée sur la planification de mission effectuée par un algorithme de type A*(A-étoile). Cet algorithme a été amélioré pour répondre aux besoins de la mission de largage d’un lanceur. Il effectue la planification du chemin le plus court dans un espace tridimensionnel. Le meilleur chemin est choisi à partir de plusieurs points de passage générés dans la région de mission. Une région peut être une phase du vol ou une partie du profil de vol. Le chemin le plus court est identifié par rapport à la présence de différents obstacles dans l’espace de recherche et son objectif consiste à atteindre un point désiré. Les obstacles ont différentes dimensions et orientations dans l’espace. L’étude de leur comportement est associée aux incertitudes en provenance de l’environnement. Ils peuvent représenter des régions interdites au vol ou des conditions atmosphériques défavorables. L’évolution de ces derniers n’est pas prévisible à l’avance, ce qui impose l’addition d’une fonctionnalité dans l’algorithme. Il est possible de replanifier le chemin à partir d’un point de passage appartenant à un chemin généré en fonction de la position détectée récemment de l’obstacle en déplacement pour arriver dans la configuration finale désirée. Cette détection est possible grâce aux capteurs positionnés sur le premier étage de ce système de lancement représenté par un avion-porteur. Les points de passage que le véhicule aérien doit suivre pour atteindre les objectifs importants ne sont pas choisis d’une manière aléatoire. Leur génération dans l’espace de recherche du chemin est définie en rapport aux limitations dynamiques de l’avion. Les modèles cinématique et dynamique du véhicule aérien qui décrivent son évolution sont aussi développés dans cette thèse. Ces modèles sont étudiés dans un système de coordonnées aérodynamiques. Le référentiel traite la présence du vent qui influe sur le comportement du véhicule. Cela nous permet de considérer d’une manière prédictive plusieurs incertitudes en provenance de l’environnement ou internes pour le véhicule. Les perturbations internes sont provoquées par le largage du lanceur. Le régime transitoire est relié à la perte de masse qui pour certaines missions peut atteindre le tiers de la masse totale du système de lancement. L’algorithme de planification traite une autre prévision – la possibilité que le largage ne soit pas réalisé. Cela peut arriver dans le cas où une tempête s’est installée dans la région de lancement ou il y a plusieurs obstacles dont l’évitement risque de consommer trop de carburant et d’empêcher le retour sur le site d’atterrissage. Les connexions entre les différents points de passage peuvent être souvent brutes et difficiles à réaliser par le véhicule aérien. Pour résoudre cette problématique dans le deuxième module développé sur la génération de trajectoire réalisable, nous utilisons l’approche des polynômes de troisième ordre. Ces polynômes par rapport aux autres techniques diminuent le temps du calcul pour générer une trajectoire réalisable entre deux points de passage consécutifs. Le chemin réalisable est facile à suivre par le système. Pour le suivi de la trajectoire, nous avons introduit dans un troisième module – la commande par mode glissant. Le principe de cette commande consiste le choix de la surface de commutation entre la trajectoire actuelle suivie par le véhicule et la trajectoire désirée déterminée par l’algorithme de planification A-étoile et générée par les polynômes cartésiens de troisième ordre. / This Ph.D. thesis deals with the systems of autonomous airborne launch vehicles. The originality of this work is based on the mission planning released by a graph-based A* (A-star) pathfinding algorithm. This algorithm was improved to respond to the specifications of this launching mission. It carries out the planning of the shortest path in a three-dimensional space. The optimal path is selected from the interconnections of several waypoints generated in the mission area. An area can be a specific mission phase or a part of the flight plan. The shortest path is identified according to the presence of various obstacles during the path search and its objective is to reach a desired point in the region. The obstacles have various dimensions and orientations in space. The study of their behavior is associated with disturbances coming from the environment. They could be forbidden flight regions or unfavorable atmospheric conditions. The evolution of the latter cannot be always predicted in advance, which still imposes an improvement that can be added in the operation of the algorithm. The path replanning is also possible. Starting from a safe waypoint from an already generated path according to a recently detected obstacle, a new path can be planned from this point considering the new obstacle coordinates to arrive at the desired final configuration. This detection will be taken into account by the sensors situated on the airborne launcher called a carrier to define the final necessary computing time. The waypoints which the airborne vehicle must follow to achieve the important mission goals are not selected in a random manner. Their generation in the search space is defined according to the dynamic limitations of the vehicle. The kinematic and dynamic models of the carrier are also developed in this thesis. These models are studied in an aerodynamic reference frame. This frame treats the presence of the wind which influences the vehicle evolution in space. That enables to consider in a predictive manner several uncertainties coming from the environment or internal for the vehicle. The internal disturbances are caused by the launching mode relied to a significant loss of mass which for certain missions can reach a half of the total mass of the launching system. The planning algorithm treats in a predictive manner – the possibility that the launching is not executed. That can happen if in the launching region a storm is settled or there are several obstacles that avoidance is likely to consume the fuel of the carrier and to prevent the successful return on the landing site. The interconnections between the various waypoints can be often rough and difficult to execute by the airborne launcher. To solve these problems a second module has to be developed to generate a feasible trajectory using the polynomials of third order.. Compared to other techniques this one decreases the calculation time of the trajectory between two consecutive waypoints. The feasible path is easy to follow by the airborne launcher. For the trajectory tracking we introduced into a third module the sliding mode control. The functionality of this control is in the choice of switching surfaces between the current trajectory tracking by the vehicle and the desired trajectory defined by the A* algorithm waypoints and generated by the third order polynomials.

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Wheelchair users are exposed to whole-body vibrations, particularly when traversing rugged terrain such as in less resourced areas. Suspension systems have been added to wheelchair systems to protect occupants from secondary injuries associated with whole-body vibration. Current suspension systems need to be further developed in order to optimize the protection against these secondary injuries. Until further research finds conclusive evidence for comfort level, and the onset of injury due to vibrations, it has been recommended to reduce whole-body vibration exposure to the lowest possible level. A versatile testing apparatus and method were designed and built to detect the acceleration and frequencies a wheelchair occupant would be exposed to while riding on simulated rough terrain. A novel dummy was instrumented with accelerometers to measure the accelerations and frequencies experienced by the wheelchair user. The apparatus and method was able to detect peak acceleration magnitudes, and was able to detect resonant frequencies and their intensities with either a PSD or FFT analysis. The minimum observable effect of change between two test conditions ranged from 6.0% for peak acceleration analysis when using six tests and a light dummy; to 41.0% for PSD analysis when using three tests and a heavy dummy. This adjustable testing apparatus and method can be used to tune a wheelchair system suspension design because it can elucidate whether or not a design is able to reduce accelerations and attenuate resonant frequencies experienced by a wheelchair occupant. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2010-01-30 12:17:57.181

As UASs (Uncrewed Aerial System) are further integrated into operations, the need for on-board environmental perception and sensing is necessitated. An accurate and reliable creation of a 3D map resembling an aircraft's surrounding is crucial for accurate collision avoidance and path planning. Consumer UASs are now being equipped with sensors to fulfill such a requirement – but no system has been proven as capable of being fully relied upon. With many sensing options available, there are several constraints regarding size, weight, and cost that must be considered when developing a sensing solution. Additionally, the robustness of the system must not be diminished when moving to a system that minimizes size, weight, or cost. An analysis of different sensing technologies that small rotary-wing aircraft (below 25kg) can be outfitted with for collision avoidance is performed. Several sensing technologies are initially compared through technology analyses and controlled experiments. The topmost systems were then further integrated onto a small low-cost quadcopter for flight testing and data acquisition. Ultimately, a fusion between stereo vision imagery and radar was deemed the most reliable method for providing environmental data needed for collision avoidance. / Master of Science / As drones become further integrated in several industries, it is important that their operations are conducted in a safe manner. Most drones today have a limited ability to sense and react to the environment around them. This results in the risk of the drone colliding with people or obstacles such as buildings, trees, light poles, etc. Thus, an accurate and reliable creation of a 3D map resembling a drone's surrounding is crucial for collision avoidance. This would allow for the avoidance of people and obstacles during automated flights where the drone may encounter obstacles during flight. With many sensing options available, there are several constraints regarding size, weight, and cost that must be considered when developing a sensing solution. Additionally, the reliability of the system must be of the topmost priority to ensure safe operations. An analysis of different sensing technologies that small rotary-wing aircraft (below 25kg) can be outfitted with for collision avoidance is performed. Rotary-wing aircraft are a specific subset of drones that are capable of vertical takeoff, landing, and hover (i.e not planes). An analysis regarding the several sensing technologies was first conducted to select the three topmost solutions. These solutions were then integrated onto a small low-cost quadcopter for data collection and flight testing. Ultimately, a combination of stereo vision imagery and radar was deemed the most reliable method for collecting collision avoidance data.

Doctor of Philosophy / Department of Mathematics / Ivan Blank / Under the guidance of Dr. Ivan Blank, I study the obstacle problem with an elliptic operator in divergence form. First, I give all of the nontrivial details needed to prove a mean value theorem, which was stated by Caffarelli in the Fermi lectures in 1998. In fact, in 1963, Littman, Stampacchia, and Weinberger proved a mean value theorem for elliptic operators in divergence form with bounded measurable coefficients. The formula stated by Caffarelli is much simpler, but he did not include the proof. Second, I study the obstacle problem with an elliptic operator in divergence form. I develop all of the basic theory of existence, uniqueness, optimal regularity, and nondegeneracy of the solutions. These results allow us to begin the study of the regularity of the free boundary in the case where the coefficients are in the space of vanishing mean oscillation (VMO).

In today's digital (electronics) world, people's desire for electronic goods that ease their life at work, and leisure is increasing the complexity of the products of the embedded systems industry. For example, MP3 players for listening to music and cell phones for communicating with people.The gap between the hardware and software parts of embedded systems is being reduced by the use of System Level Design Languages (SLDL) that can model both hardware and software simultaneously. One such SLDL is SpecC.In this thesis, a SpecC model of a Real Time Operating System (RTOS) is constructed. It is shown how RTOS features can be incorporated into a SpecC model. The model is used to develop an application involving a robot avoiding obstacles to reach its destination. The RTOS model operates similar to the actual RTOS in the robot.The application includes a testbench model for the robot, including features such as interrupts, sonar sensors and wheel pulses, so that its operation closely resembles the actual robot. The sensor model is programmed to generate the values from the four sensor receivers, similar to the behaviour of the sensors on the actual robot. Also the pulses from the wheels and associated interrupts are programmed in the model so that it resembles the interrupts and wheel pulses present on actual robot.

This thesis presents an indoor obstacle avoidance system for car-like mobile robot. The system consists of stereo vision, map building, and path planning. Stereo vision is performed on stereo images to create a geometric map of the environment. A fast sparse stereo approach is employed. For different areas of the image there are different optimal values of disparity range. A multi-pass method to combine results at different disparity range is proposed. To reduce computational complexity the matching is limited to areas that are likely to generate useful data. The stereo vision system outputs a more complete disparity map. Abstract Map building involves converting the disparity map into map coordinates using triangulation and generating a list of obstacles. Occupancy grids are built to aid a hierarchical collision detection. The fast collision detection method is used by the path planner. Abstract A steering set path planner calculates a path that can be directly used by a car-like mobile robot. An adaptive approach using occupancy grid information is proposed to improve efficiency. Using a non-fixed steering set the path planner spends less computation time in areas away from obstacles. The path planner populates a discrete tree to generate a smooth path. Two tree population methods were trialled to execute the path planner. The methods are implemented and experimented on a real car-like mobile robot.

Abstract: Previous lower limb weighting studies have placed a load on the legs bilaterally and tested different placement locations. It was previously determined that kinematic changes occur with greater masses and at joints proximal to weight placement [1]. Other studies have determined that these changes exist for a short adaptation period before parameters revert to a steady state [2]. Tasks that require voluntary gait modifications such as obstacle clearance have also been performed with lower leg bilateral weight addition [4]. In cases of normal obstacle clearance increased flexion at all three joints in the lower limb is needed to safely traverse the obstacle [3]. The goal of this study was to investigate joint kinematics and kinetics of unilaterally weighted participants using level ground force platform collection techniques, rather than a treadmill. It was hoped that this would allow for new insight into the adaptation periods and strategic motor pattern changes seen at the ankle, knee and hip. Kinematic and force platform data were collected on two groups of 10 healthy male subjects. Group 1 (mean age = 23years, mean weight = 82.181kg, mean height = 1.798m) was a normal walking group and group 2 (mean age = 24.8years, mean weight = 79.901kg, mean height = 1.773m) was an obstacle clearance group. Both groups participated in 20 trials each of three different conditions; normal, weighted and weight off using a 2.27kg limb mass attached just proximal to the right maleoli markers. A repeated-measures two-way ANOVA was carried out on relevant variables in order to determine statistical significance. Weight addition and removal affected the kinematics and kinetics of the normal walking and obstacle clearance groups. This effect was more prominent in the normal walking group. If changes were seen, trials 1 through 3 were the locations showing a quick adaptation followed by a leveling off back to a new steady state in later trials. Participants in the normal walking group chose to utilize the hip joint in order to control for weight addition and removal. Kinematically, changes in the hip joint angle occurred at all instances analyzed throughout the gait cycle with this effect being more prominent in the weight off condition. In conjunction with this, the hip joint energy generation increased during all phases of the gait cycle while the ankle and knee joints either decreased energy generation or increased energy absorption. In the obstacle group, participants also chose to increase flexion at the hip joint. However, the ankle joint also had either decreased plantarflexion or increased dorsiflexion at all the instances analyzed during the gait cycle. However, joint energy generation increases at these joints were only found during stance and at heel contact. The toe obstacle clearance values also showed a marked increase in trial 1 for the weighted condition which demonstrates a voluntary gait modification made by participants to safely traverse the obstacle that was quickly adapted for. Overall, the results found by previous studies using treadmill collection techniques were still seen in overground force platform data but they were not as robust. References: 1.Martin PE et al. J Biomech. 1990; 23(6):529-536. 2.Noble et al. Exp Brain Res. 2006; 169: 482-495. 3.Patla AE et al. Exp Brain Res. 1995; 196: 499-504. 4.Reid MJ et al. Neurosci Res Comm. 2001; 29(2): 79-87.

In this master thesis a control strategy for a Human Power Amplifier (HPA) ispresented. An HPA can be described as a machine that amplifies a force exertedby a human operator. The HPA in this thesis can best be described as a mechanicalore with two degrees of freedom.The approach for the control strategy presented here is to look at the controlproblem not directly as a force amplifying problem, but as coordination problembetween the real system and a virtual system, where the virtual system is used asa reference. If the systems are synchronized then desired force amplification willnaturally follow from that.Furthermore is the possibility to implement guidance and obstacle avoidanceon the machine investigated. The guidance is performed by using velocity fields,i.e., vector fields where a vector represents the desired velocity for each point inthe plane. For the obstacle avoidance potential fields are used, where the idea isthat a high potential should repel the machine from restricted areas.

Abstract: Previous lower limb weighting studies have placed a load on the legs bilaterally and tested different placement locations. It was previously determined that kinematic changes occur with greater masses and at joints proximal to weight placement [1]. Other studies have determined that these changes exist for a short adaptation period before parameters revert to a steady state [2]. Tasks that require voluntary gait modifications such as obstacle clearance have also been performed with lower leg bilateral weight addition [4]. In cases of normal obstacle clearance increased flexion at all three joints in the lower limb is needed to safely traverse the obstacle [3]. The goal of this study was to investigate joint kinematics and kinetics of unilaterally weighted participants using level ground force platform collection techniques, rather than a treadmill. It was hoped that this would allow for new insight into the adaptation periods and strategic motor pattern changes seen at the ankle, knee and hip. Kinematic and force platform data were collected on two groups of 10 healthy male subjects. Group 1 (mean age = 23years, mean weight = 82.181kg, mean height = 1.798m) was a normal walking group and group 2 (mean age = 24.8years, mean weight = 79.901kg, mean height = 1.773m) was an obstacle clearance group. Both groups participated in 20 trials each of three different conditions; normal, weighted and weight off using a 2.27kg limb mass attached just proximal to the right maleoli markers. A repeated-measures two-way ANOVA was carried out on relevant variables in order to determine statistical significance. Weight addition and removal affected the kinematics and kinetics of the normal walking and obstacle clearance groups. This effect was more prominent in the normal walking group. If changes were seen, trials 1 through 3 were the locations showing a quick adaptation followed by a leveling off back to a new steady state in later trials. Participants in the normal walking group chose to utilize the hip joint in order to control for weight addition and removal. Kinematically, changes in the hip joint angle occurred at all instances analyzed throughout the gait cycle with this effect being more prominent in the weight off condition. In conjunction with this, the hip joint energy generation increased during all phases of the gait cycle while the ankle and knee joints either decreased energy generation or increased energy absorption. In the obstacle group, participants also chose to increase flexion at the hip joint. However, the ankle joint also had either decreased plantarflexion or increased dorsiflexion at all the instances analyzed during the gait cycle. However, joint energy generation increases at these joints were only found during stance and at heel contact. The toe obstacle clearance values also showed a marked increase in trial 1 for the weighted condition which demonstrates a voluntary gait modification made by participants to safely traverse the obstacle that was quickly adapted for. Overall, the results found by previous studies using treadmill collection techniques were still seen in overground force platform data but they were not as robust. References: 1.Martin PE et al. J Biomech. 1990; 23(6):529-536. 2.Noble et al. Exp Brain Res. 2006; 169: 482-495. 3.Patla AE et al. Exp Brain Res. 1995; 196: 499-504. 4.Reid MJ et al. Neurosci Res Comm. 2001; 29(2): 79-87.