May 11, 2017 Kirk Hovell The space industry is changing, and the Spacecraft Robotics and Control Laboratory is a research facility that embraces the new direction the space industry is headed. This presentation discusses the hardware and software present in the Spacecraft Proximity Operations Testbed, and how it enables the next generation of space research in Canada.
Jian-Feng Shi This presentation investigates the rotational invariance of various image features extracted from monocular thermal and photo camera images that can be used for robot navigation. In addition to the conventional SIFT, SURF, ORB, AKAZE, and BRIEF image features, a new non-Gaussian binary feature descriptor is introduced using Levy-Laplace probability density functions. The rotational, viewpoint and noise invariance of all features are compared.
May 18, 2017 Alexander Crain Debris removal has become a vital area of research in the space industry, as without any further actions it is estimated that orbital debris has reached the point where any collisions among large-body debris will lead to an unstable growth in debris. Robotic manipulators represent a classical approach to removing debris, and in this presentation the dynamics for free-floating spacecraft will be discussed and the nonlinear optimal guidance problem of planning trajectories for a three degree-of-freedom space manipulator with path constraints will be solved using a Gaussian pseudospectral collocation scheme.
Cory Fraser Recent advances in formation flying technologies have demonstrated that on-board autonomous control of low Earth orbit spacecraft can be achieved. To enhance the reliability and fidelity of these autonomous systems, a navigation algorithm is being developed which utilizes a Fuzzy Adaptive Extended Kalman Filter (EKF) based on GPS measurements. After introducing the dynamics and filtering theory, simulation results from the non-adaptive EKF will be discussed and a brief overview of potential adaptation schemes will be given.
June 1, 2017 Jeffrey Hough Globally-stable Lyapunov guidance and control laws are developed for various maneuvers regarding the tracking and convergence of a chaser spacecraft onto a target, which may in general be tumbling and orbiting the Earth elliptically. Maneuvers such as circular-shaped formation flying, obstacle avoidance, and docking are first developed. A modified, time-varying guidance law using a proportional-controller is then developed, capable of performing such maneuvers while holding commanded thrusts under user-defined thresholds. Applications/limitations of this new guidance law are discussed. Numerical simulation results are presented.
June 22, 2017 Justin Kernot A consequence of using classical control theory in real systems is that the stability of the closed loop system cannot be guaranteed if there are any uncertainties associated with the mathematical model describing the plant. To address this problem, robust control theory was developed to ensure that the system will remain stable in the presence of such uncertainties. A common method of synthesizing a robust controller is by solving the H-infinity optimization problem; which minimizes the closed loop disturbance sensitivity and control effort while ensuring robust stability. This presentation covers the fundamentals of robust control theory and presents a worked example of generating an H-infinity controller for the SPOT platforms.
Bradley Kuiack One of the challenges of autonomous guidance and control of formation flying is related to the on-board prediction of the relative motion between both spacecraft, which has to remain accurate over long propagation periods and be valid for large separation distances on highly elliptical orbits. In this context, this presentation addresses the problem of nonlinear analytical guidance for spacecraft formation flying reconfiguration maneuvers. Specifically, a nonlinear analytical solution for predicting the radial, along-track, and cross-track relative motion on J2-perturbed elliptical orbits is presented and the solution is used in a back-propagation scheme for closed-loop guidance purposes.
June 29, 2017 Gabrielle Sévigny This presentation looks into the IDVD-SGRA guidance strategy, which is a real-time suboptimal guidance strategy. It calculates a trajectory from one spacecraft to another that will minimize either the time or fuel required to complete the trajectory while avoiding obstacles along the path. After discussing the method used to make this feasible in real-time, simulation results will be shown
Maude Bettez Guardian maps are utilized as a tool for determining generalized stability for a family of matrices and polynomials. Guardian map theory has been proposed for a number of aerospace applications when implementing a control law that requires gain scheduling. In this presentation the three most common stability regions will be examined as well as the bi-alternate product. After the theory has been presented, numerical simulation results will be discussed.
July 6, 2017 Jayant Sachdev This presentation will discuss the design, implementation and validation of the L1 adaptive controller for spacecraft formation flying. A brief review of formation flying control is presented; followed by an overview of the formation flying dynamics and the L1 adaptive control architecture. The main design criteria of the L1 adaptive control for formation flying is shown and on-orbit simulation results are discussed. Hardware experimental results are also presented.
July 13, 2017 Kevin Stadnyk Space debris are an ever growing problem which has led to the mitigation and removal of debris to become a key area of research around the world. This presentation gives an update on the research and development of a viso-elastic tether deployment mechanism which directly builds upon the theoretical and experimental work recently done by Kirk Hovell in his 2015-2017 conference papers as well as MASc thesis.