The effect of end boundary conditions on the three-dimensionality of the vortex shedding from a circular cylinder in sub-critical flow has been studied experimentally, with a focus on the unsteady nature of the vortex filaments. Analysis of the near-wake of the cylinder was undertaken to determine the dependency of the spanwise uniformity of the vortex shedding on the end conditions. Flow visualization was performed downstream of the cylinder, and the temporal variation of the vortex filament angle was observed. Vortex dislocations were found to occur in this Reynolds Number regime regardless of the end boundary conditions. Having a cylinder bounded by two elliptical leading edge geometry endplates at an L/D value of five yielded parallel shedding with a reduction in the time-based variation of the vortex filament angle, and was shown to be the ideal end conditions for modeling an infinite cylinder in a free-surface water channel.

The problem of stand-off tracking of a moving target using a quadrotor unmanned aerial vehicle (UAV) based on vision-sensing is investigated. A PID (Proportional-Integral-Derivative) controller is implemented for attitude stabilization of the quadrotor. An LQG-based (Linear-Quadratic-Gaussian) control law is designed and implemented for position control of the quadrotor for a moving target tracking task. A novel vision-based estimation algorithm is developed, enabling estimation of quadrotor’s position, altitude and yaw relative to the target based on limited information about the target. Two image processing algorithms are implemented and compared for the task of feature detection and feature tracking in a series of images. Image processing algorithms are integrated with quadrotor control and experiments are performed to validate proposed control and estimation approaches.

The Space Flight Laboratory (SFL) at the University of Toronto Institute for Aerospace Studies is currently designing CanX-4 and CanX-5, a pair of formation-flying nanosatellites that will target centimeter-level position determination and sub-meter control. Once formation flight has been demonstrated, future missions can carry payloads designed to exploit these capabilities. Earth Observation is one such application that can benefit greatly from the availability of multiple platforms with precise position determination and attitude control. This work explores multistatic interferometric synthetic aperture radar (InSAR) as a particularly promising implementation of formation flight. Several mission scenarios are considered, including three commonly proposed InSAR constellation configurations, namely the Cartwheel, the Cross-Track Pendulum, and the Car-Pe configuration, as well as three large ( kilowatt) SAR transmitters (L-, C- and X-band) and one microsatellite transmitter (X-band, 150W). Using a framework of STK and MATLAB simulation and analysis tools, each case is evaluated with respect to the available interferometric baselines, ground coverage, resolution, and utility for selected applications including digital elevation modeling, moving target detection, and superresolution imagery. The “large” X-band transmitter is found to produce the most favorable operating area and resolution, and the Car-Pe configuration provides the greatest utility and flexibility for a combination of the three selected applications.

Ethylene/Air diffusion flames were studied at sub and super-atmospheric pressures to simulate a microgravity environment at fuel flow rates of 0.482 mg/s and 1.16 mg/s. Flame properties including flame dimensions, soot formation, temperature, and attachment mechanisms were investigated. Overall, luminous flame height decreased with decreasing pressure to the point of visible luminosity disappearance, resulting in blue flames. Flame width increased with decreasing pressure until the flame was almost spherical. Soot formation decreased with decreasing pressure to negligible concentrations in a near vacuum. At 0.482 mg/s, the percentage of carbon converted into soot was between 0.01% and 0.12%, whereas at 1.16 mg/s, this percentage was between 0.5% and 11% at sub-atmospheric pressures. Maximum flame temperatures increased with decreasing pressure. Regardless of fuel flow rate, the diffusion flames remained attached to the exterior of the burner. This attachment point moved further down the burner exterior as pressure decreased until a near vacuum.

This work focuses on an investigation of multi-modality in typical aerodynamic shape optimization problems and development of optimization algorithms that can find a global optimum. First, a classification of problems based on the degree of multi-modality is introduced. Then, two optimization algorithms are described that can find a global optimum in a computationally efficient manner: a gradient-based multi-start Sobol algorithm, and a hybrid optimization algorithm. Two additional algorithms are considered as well: a gradient-based optimizer and a genetic algorithm. Finally, we consider a set of typical aerodynamic shape optimization problems. In each problem, the primary objectives are to classify the problem according to the degree of multi-modality, and to select the preferred optimization algorithm for the problem. We find that typical two-dimensional airfoil shape optimization problems are unimodal. Three-dimensional shape optimization problems may contain local optima. In these problems, the gradient-based multi-start Sobol algorithm is the most efficient algorithm.

As the potential uses of nanosatellites become apparent, their numbers keep increasing. This is evident at the Space Flight Laboratory (SFL) located at the University of Toronto Institute for Aerospace Studies which has seen a rapid growth in satellite missions in recent years. By leveraging the use of the Generic Nanosatellite Bus developed at SFL, satellites can be rapidly developed to carry science payloads or demonstrate the capabilities of new technologies on orbit. Testing satellite systems in an Earth environment is an important step in qualifying them for space. This thesis describes the development of ground support equipment for testing SFL’s nanosatellite separation system, XPOD, and characterizing the performance of the propulsion system, CNAPS. Also, the thermal behaviour of a pressure regulator valve on CNAPS is examined for various flow conditions.

The Space Flight Lab (SFL) at the University of Toronto Institute for Aerospace Studies (UTIAS) has developed an ambitious satellite program called the Canadian Advanced Nanospace eXperiment (CanX). The newest generation of CanX missions are based on the Generic Nanosatellite Bus (GNB). This bus was designed to accommodate many missions using a single, common platform. Currently, there are three nanosatellite missions using the GNB design. These missions include AISSat-1, CanX-3 (BRITE) and CanX-4&5. This thesis describes the high level embedded software design for the on-board computer (OBC), as part of the generic nanosatellite bus. The software discussed includes the Universal Asynchronous Receiver/Transmitter (UART) Thread, Serial Communications Controller (SCC) Thread, Inter-Integrated Circuit (I2C) Thread, Serial Peripheral Interface (SPI) Thread, Communications Thread, Memory Management Thread, Power Thread, House Keeping Computer (HKC) Thread, AISSat-1 Payload Thread and the Time Tag Thread. In addition to the application threads mentioned above, the software design and validation of the On Board Computer (OBC) design for the AISSat-1 mission is also discussed.

The development of a multi-mission small spacecraft power system is described. This system has been designed for the University of Toronto Space Flight Laboratory Generic Nanosatellite Bus (GNB), an approximately 20cm cubical spacecraft with no deployed solar arrays. The GNB is inherently power-generation limited, and consequently, all available power must be utilized with maximum efficiency. This efficiency is achieved using an unconventional parallel-regulated architecture with Peak Power Tracking (PPT) functionality, and is shown to be the PPT design of highest efficiency for spacecraft of this class. In support of this design, a novel spacecraft power simulation suite has been developed, enabling parametric satellite power analysis with high fidelity. Finally, a unique variation on peak power tracking---referred to as peak current tracking---is described. This method is shown to reduce battery depth-of-discharge by as much as 20% over baseline architectures, and furthermore exhibits beneficial emergent behaviour for battery charge management.

This thesis describes, in chronological order, the design and implementation of four separate ground control applications for use of the Generic Nanosatellite Bus, a multi-purpose satellite platform developed at the UTIAS Space Flight Laboratory. A direct ground control application and time-tagged remote control application are used to provide full control over a Generic Nanosatellite Bus satellite for short and long term operational and testing purposes. Similarly, a direct control application and a scheduling application are implemented for the control of the payload computer on CanX-3 BRIght-star Target Explorer, a stellar-observation satellite based on the Generic Nanosatellite Bus platform. This thesis goes into details on how the display and control interface is implemented and used, what set of actions are taken to create and interpret packets exchanged over a communications link, and what precautions are taken in the face of expected issues.

The work described in this thesis summarizes the author's contributions to the design, development, and testing of embedded systems for SFL spacecraft. The unique environment of space and the constraints it imposes on embedded systems is described, and the testing methodologies employed to qualify spacecraft hardware for this environment are presented. The implementation of an automated functional test framework for SFL's Generic Nanosatellite Bus satellites and the role it plays in the spacecraft development cycle is also discussed. Application software and device drivers in support of the BRITE mission were designed and developed. Finally, a controller was implemented for thermal control of the BRITE optical instrument. These contributions play an important role in the continual efforts to expand access to space and to prove the feasibility of the microspace approach in doing so.