For a launch vehicle, the Navigation System is responsible for determining the vehicle state and providing state and state derived information for Guidance and Controls. The accuracy required of the Navigation System by the vehicle is dependent upon the vehicle, vehicle mission, and other consideration, such as impact foot print. NASAs Ares I launch vehicle and SLS are examples of launch vehicles with are/where to employ inertial navigation systems. For an inertial navigation system, the navigation system accuracy is defined by the inertial instrument errors to a degree determined by the method of estimating the initial navigation state. Utilization of GPS aiding greatly reduces the accuracy required in inertial hardware to meet the same accuracy at orbit insertion. For a launch vehicle with lunar bound payload, the navigation accuracy can have large implications on propellant required to correct for state errors during trans-lunar injection.

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In October 2017, the first interstellar object, designated 1I/2017 U1 and more commonly referred to as Oumuamua, was detected passing through our solar system by the Pan-STARRS telescope, followed recently by the detection of 2I/Borisov in August 2019. These detections came much sooner than thought possible, and have redefined our understanding of the population of interstellar objects. With the construction of the next generation of powerful observatories, future detections are estimated to occur as frequently as two per year, and while there is significant scientific understanding to be gained from observing these objects remotely, a spacecraft sent to intercept one might be the only way to collect up-close, detailed information on the composition of extra solar object. The ideal mission scenario would be a combination flyby and impact as performed and proven feasible by the Deep Impact encounter with the comet Temple 1. A study has already been done showing that trajectories to interstellar objects are feasible with current chemical propulsion and a “launch on detection” paradigm, with an estimated 10 year wait time between favorable mission opportunities, assuming future detection capabilities. However, while a trajectory to one of these objects might be feasible, accurately performing a flyby and impacting an object with a hyperbolic orbit presents unprecedented navigational challenges. Spacecraft-target relative velocities can range between 10 km/s to 110 km/s with high phase angles between 90° and 180°. The goal of this thesis is to determine the required navigation hardware – an optical navigation camera and attitude determination system – which could provide high mission success probability for many potential encounter scenarios. This work is performed via a simulation program developed at the Jet Propulsion Laboratory that generates simulated images of a target during the terminal guidance phase of a mission, and feeds them into the algorithms behind autonomous navigation software (AutoNav) used for the Deep Impact mission. Observations are derived from the images and used to perform target-relative orbit determination and calculate correction maneuvers.

In response to the striking health and social inequalities existing across communities within a large Southern Ontario City the McMaster University School of Nursing has partnered with the local family health team, municipal government, and other community partners to evaluate a pilot program designed to enhance health and social outcomes within a specific priority neighbourhood. The innovative pilot program is a nursing-based system navigation role, grounded concurrently in the community and a local Primary Care Practice. The role is uniquely designed as the nurse provides navigation for individuals and families while functioning as a networker to facilitate improved service integration at a systems level. This study serves as a narrative person-centered evaluation of the program, emphasizing the impact on the lives of community members. This study employed the Three-Dimensional Narrative Inquiry Space method as described by Clandinin and Connelly (2000) to explore the experience of nine community residents utilizing navigation services through the Community Nurse Navigator/Networker (CNN). Programs tell a story; therefore, the collection and analysis of participants’ life stories, in conjunction with field notes, observations, and documents, created a common narrative of the experience of navigation in a community setting. A thematic analysis of participants’ life stories was conducted to present a common narrative of community members’ experience of navigation. The major finding of this study was the positive experience residents shared interacting with the CNN. Participants valued the development of a therapeutic relationship through social interactions, the significance of place on the impact of the CNN role, and the effect of the navigation role to address health disparities over time. Study findings have implications for continued development of the CNN role and other community-based nurse navigation roles in priority neighbourhoods to address health inequities. / Thesis / Master of Science in Nursing (MSN)

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The clothoid, also known as the Cornu spiral, is a curve generated by linearly increasing or decreasing curvature as a function of arc length. The clothoid has been widely accepted as a logical curve for transitioning from straight segments to circle arcs in roads and railways, because a vehicle following the curve at constant speed will have a constant change of centripetal acceleration. Clothoids have also been widely adopted in planning potential paths for autonomous vehicle navigation. They have been viewed as useful representations of possible trajectories that are dynamically feasible. Surprisingly, the assumptions that underlie this choice appear to be lightly treated or ignored in past literature. This thesis will examine three key assumptions that are implicitly made when assuming that a vehicle will follow a clothoid path. The first assumption is that the vehicle's steering mechanism will produce a linear change in turning radius for a constant rate input. This assumption is loosely referred to as the "bicycle model" and it relates directly to the kinematic parameters of the steering mechanism. The second assumption is that the steering actuator can provide a constant steering velocity. In other words, the actuator controlling the steering motion can instantaneously change from one rate to another. The third assumption is that the vehicle is traveling at a constant velocity. By definition, the clothoid is a perfect representation of a vehicle traveling at constant velocity with a constant rate of change in steering curvature. The goal of this research was to examine the accuracy of these assumptions for a typical Ackermann-steered ground vehicle. Both theoretical and experimental results are presented. The vehicle that was used as an example in this study was a modified Club Car Pioneer XRT 1500. This Ackermann-steered vehicle was modified for autonomous navigation and was one of Virginia Tech's entries in the DARPA 2005 Grand Challenge. As in typical operation, path planning was conducted using the classic clothoid curve model. The vehicle was then commanded to drive a selected path, but with variations in speed and steering rate that are inherent to the real system. The validity of the three assumptions discussed above were examined by comparing the actual vehicle response to the planned clothoid. This study determined that the actual paths driven by the vehicle were generally a close match to the originally planned theoretical clothoid path. In this study, the actual kinematics of the Ackermann vehicle steering system had only a small effect on the driven path. This indicates that the bicycle model is a reasonable simplification, at least for the case studied. The assumption of constant velocity actuation of the steering system also proved to be reasonably accurate. The greatest deviation from the planned clothoid path resulted from the nonlinear velocity of the vehicle along the path, especially when accelerating from a stop. Nevertheless, the clothoid path plan generally seems to be a good representation of actual vehicle motion, especially when the planned path is updated frequently. / Master of Science

MEMS gyroscopes are electromechanical devices that measure rate or angle of rotation. They are one of the fastest growing segments of the microsensor market. Advances in microfabrication technologies have enabled the implementation of chip scale monolithic gyroscopes (MEMS gyroscopes) with very small form factor that are lightweight and consume little power. Over the past decade, significant amount of research have been directed towards the development of high performance and very small size MEMS gyroscopes for applications in consumer electronics such as smart phones. In this dissertation, high aspect-ratio hemispherical shell structure with continuously curved surface is utilized as the high Q resonator. Being an axial symmetric structure, the 3D hemispherical shell is able to achieve low frequency (3 ~ 5 kHz) within 2 mm X 2mm die area. Detailed analysis on energy dissipation also shows its potential to achieve ultra-high quality factor with the selection of high Q material and proper design of support structure. This dissertation presents, for the first time, the analysis, design, fabrication and characterization of a micro-hemispherical resonating gyroscope (μHRG) that has the potential to be used as a whole angle micro-gyroscope. A three-dimensional high aspect-ratio poly- and single crystalline silicon (3D HARPSS) process is developed to fabricate free-standing, stem-supported hemispherical shell with self-aligned deep electrodes for driving, sensing and quadrature control of the gyroscope. This monolithic process consists of seven lithography steps and combines 3D micro-structure with curved surfaces with the HARPSS process to create capacitive electrodes with arbitrary gaps around the micro-hemispherical shell resonator (μHSR). Polysilicon is utilized as the structural material due to its isotropic mechanical properties and the potential of achieving high quality factor. The fabrication is demonstrated successfully by prototypes of polysilicon μHRG with diameter of 1.2 mm and thickness of 700 nm. Frequency response and gyro operation are electronically measured using the integrated electrodes. Quality factor of 8,500 is measured with frequency mismatch of 105 Hz. Electronic mode matching and alignment are successfully performed by applying tuning voltages and quadrature nulling voltages. An open loop rate sensitivity scale factor of 4.42 mV/°/s was measured. Design and process optimization of the support structure improved the quality factor to 40,000. Further improvement of quality factor will enable the demonstration of high performance RIG using polysilicon μHRG.

In global navigation satellite systems (GNSS) a fundamental operational component is the calculation of the orbits of the system spacecraft. This requires understanding and modelling the forces that act on the spacecraft. Solar radiation pressure (SRP) is the force caused by the impact of solar photons on the spacecraft surface. For GNSS spacecraft this is a significant force. If SRP is not included in the force model, then the calculated position of the spacecraft can be in error by between one and two hundred metres after one 12-hour orbit. SRP can be modelled using either analytical or empirical methods, or by some combination of the two. Historically, analytical SRP modelling has been somewhat neglected and high precision orbit estimation has relied upon empirical methods to account for SRP. Even so, most of these empirical methods start the estimation process with an a priori analytical model. The success of this empirical approach relies upon having many observations of the range between the system spacecraft and ground-based tracking stations, and works well within the context of the International Global Positioning System Service (IGS) network, which provides the necessary data volume. However, empirical methods do not work as well in operational GNSS, as these typically have a relatively small number of tracking stations. Moreover, empirical methods cannot be applied at the GNSS design stage, where knowledge of the system dynamics plays a key role. Existing methods for calculating analytical SRP models can only be used with relatively simple spacecraft structures, and lack flexibility as tools for analysis. In this study a new method is developed for calculating analytical SRP models that can cope with a high level of complexity in the spacecraft structure. The method is based upon simulating the solar photon flux with a pixel array. Using the method, models are calculated and tested for the Russian GLONASS IIv spacecraft. This particular spacecraft was used as the testbed because, at the time the study was being conducted, an international scientific campaign - called IGEX-98, the International GLONASS Experiment - was being carried out to analyse the Russian system. Developing force models for the spacecraft was one of the campaign goals, and the IGEX-98 steering committee accepted a proposal to use SRP models for GLONASS from this study. A detailed description is given of all the mathematics and physics that was used to develop the modelling technique. The method by which the models can be calculated and applied in practical orbit determination is also provided. In order to test the performance of the SRP models computed for the GLONASS spacecraft using the new method, comparisons were made between two kinds of trajectory. The first kind was calculated by numerical integration of the spacecraft's second order differential equation of motion, where this force model included the custom SRP models developed in the thesis. The second kind of trajectory, which is used as a 'truth' model in the study, was a precise orbit computed by the University of Berne using IGS range data and an empirical SRP model. Such precise orbits are the best estimates available of the true trajectories, as they are derived from the simultaneous estimation of multiple receiver tracking station network positions and spacecraft force model parameters. The repeatability of the Berne orbit is circa 0.75m. The RMS differences between the two trajectories over one twelve-hour orbit (an arc length of circa 160,000km) were 0.7m in height, 1.3m across track and 3.5m along track. This shows that the trajectory derived from the force model alone is very close to the precise orbit. The time-varying pattern of the differences between the two trajectories strongly indicates that the residual mismodelling of the forces acting on the spacecraft is due to thermal re-radiation effects. Further tests of the method were also conducted using satellite laser ranging (SLR) data to calculate arc lengths of 400 days, again using SRP models from the study. This enabled the calculation of model scale factors and additional empirical terms. The average SRP model scale factor was circa 1.01, which implies that the average error in the a priori SRP models calculated for the GLONASS IIv spacecraft is at the 1% level. This is consistent with an error budget based on an assessment of the accuracy of the source data supplied by the Russian authorities. The magnitude and parameterisation of the SLR empirical terms again strongly suggest that most of the remaining mis-modelling is caused by thermal effects. An analysis is given of the effect on the a priori SRP model of unmodelled, SRP-related forces acting along the spacecraft Y-axis. This is the so-called Y-bias. It is shown that whilst Y-bias effects are important in orbit determination, they are less critical in the process of calculating the a priori SRP model. A discussion is provided on how the new method can be adapted to improve the modelling and understanding of thermal re-radiation and Y-bias effects, and also on what benefits might accrue from such studies. The new method is an improvement over existing techniques as it enables the calculation of high precision SRP models that can be applied in the design, operation and scientific analysis of GNSS. A UK patent application has been made in respect of the new method.