Design and implementation of a relative localization system for ground and aerial robotic teams

The main focus of this thesis is to address the relative localization problem of a heterogenous team which comprises of both ground and micro aerial vehicle robots. This team configuration allows to combine the advantages of increased accessibility and better perspective provided by aerial robots with the higher computational and sensory resources provided by the ground agents, to realize a cooperative multi robotic system suitable for hostile autonomous missions. However, in such a scenario, the strict constraints in flight time, sensor pay load, and computational capability of micro aerial vehicles limits the practical applicability of popular map-based localization schemes for GPS denied navigation. Therefore, the resource limited aerial platforms of this team demand simpler localization means for autonomous navigation. Relative localization is the process of estimating the formation of a robot team using the acquired inter-robot relative measurements. This allows the team members to know their relative formation even without a global localization reference, such as GPS or a map. Thus a typical robot team would benefit from a relative localization service since it would allow the team to implement formation control, collision avoidance, and supervisory control tasks, independent of a global localization service. More importantly, a heterogenous team such as ground robots and computationally constrained aerial vehicles would benefit from a relative localization service since it provides the crucial localization information required for autonomous operation of the weaker agents. This enables less capable robots to assume supportive roles and contribute to the more powerful robots executing the mission. Hence this study proposes a relative localization-based approach for ground and micro aerial vehicle cooperation, and develops inter-robot measurement, filtering, and distributed computing modules, necessary to realize the system. The research study results in three significant contributions. First, the work designs and validates a novel inter-robot relative measurement hardware solution which has accuracy, range, and scalability characteristics, necessary for relative localization. Second, the research work performs an analysis and design of a novel nonlinear filtering method, which allows the implementation of relative localization modules and attitude reference filters on low cost devices with optimal tuning parameters. Third, this work designs and validates a novel distributed relative localization approach, which harnesses the distributed computing capability of the team to minimize communication requirements, achieve consistent estimation, and enable efficient data correspondence within the network. The work validates the complete relative localization-based system through multiple indoor experiments and numerical simulations. The relative localization based navigation concept with its sensing, filtering, and distributed computing methods introduced in this thesis complements system limitations of a ground and micro aerial vehicle team, and also targets hostile environmental conditions. Thus the work constitutes an essential step towards realizing autonomous navigation of heterogenous teams in real world applications.

The development and preliminary testing of an instrument to measure the perceived economic burden of a subtype of arrhythmogenic right ventricular cardiomyopathy (ARVC) on patients and families in Newfoundland

The goal of this thesis was to develop, construct, and validate the Perceived Economic Burden scale to quantitatively measure the burden associated with a subtype Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) in families from the island of Newfoundland. An original 76 item self-administered survey was designed using content from existing literature as well as themes from qualitative research conducted by our team and distributed to individuals of families known to be at risk for the disease. A response rate of 37.2% (n = 64) was achieved between December 2013 and May 2014. Tests for data quality, Likert scale assumptions and scale reliability were conducted and provided preliminary evidence of the psychometric properties of the final constructed perceived economic burden of ARVC scale comprising 62 items in five sections. Findings indicated that being an affected male was a significant predictor of increased perceived economic burden in the majority of economic burden measures. Affected males also reported an increased likelihood of going on disability and difficulty obtaining insurance. Affected females also had an increased perceived financial burden. Preliminary results suggest that a perceived economic burden exists within the ARVC population in Newfoundland.