Optimal detumbling of a large manned spacecraft using an internal moving mass

The use of a movable mass control system to stabilize an arbitrarily tumbling asymmetric vehicle about the maximum inertia axis is considered. A first-order gradient optimization technique is used to minimize angular velocity components along the intermediate and minimum inertia axes. This method permits a wide range of initial guesses for mass position history. Motion of the control mass is along a linear track fixed in the vehicle. The control variable is taken as mass acceleration with respect to body coordinates. Motion is limited to defined quantities and a penalty function is used to insure a given range of positions. Numerical solutions of the optimization equations verify that minimum time detumbling is achieved with the largest permissible movable mass, length of linear track, and positions of the mass on the two coordinates perpendicular to the linear motion

Implementation and validation of the attitude and determination control system of a pico-satellite

This end-of-degree project focuses on the software development of a pico-satellite Attitude Determination and Control System, using MATLAB, as well as its subsequent integration in C. The software carried out will be implemented in a 5 cm sided pico-satellite, called PocketQube. The research project will form part of the IEEE Open PocketQube Kit mission developed in the NanoSat laboratory belonging to the UPC. The pico-satellite attitude system can be broken down into two distinct branches, attitude determination and attitude control. Attitude determination involves the process of determining the orientation of the satellite using the measurements acquired by its sensors (they include photodiodes, gyroscopes, and magnetometers). On the other hand, attitude control is the process by which the orientation of the pico-satellite is controlled using specific control algorithms (such as detumbling and nadir pointing) and actuators, (such as magnetorquers). To analyse and understand the attitude of the pico-satellite, a model is developed that allows simulating the environment in which the satellite is located. This model encompasses pico-satellite dynamics, a model that describes orbital dynamics, and another that represents the various perturbation forces that affect the pico-satellite. In this way, it is possible to describe the orbit followed by the pico-satellite, including its position, speed and the external forces that influence and affect its behaviour during the orbital flight. Once the modelling of the simulation environment is complete, the determination and control algorithms are implemented, as well as the mathematical models that describe the behaviour of the sensors and actuators. These algorithms and models are designed with the aim of meeting the requirements established for the Determination and Control System. Subsequently, an exhaustive analysis of the results obtained during the simulation is carried out. The purpose of this analysis is to verify if the previously established requirements for the Attitude Determination and Control System are met. The conclusion of this work allows to start the test campaigns of this system in the PocketQube hardware, as well as to check if the results obtained in the simulations correspond to reality

The dynamics and optimal control of spinning spacecraft and movable telescoping appendages, part B: Effect of gravity-gradient torques on the dynamics of a spinning spacecraft with telescoping appendages

The effects of gravity gradient torques during boom deployment maneuvers of a spinning spacecraft are examined. Configurations where the booms extended only along the hub principal axes and where one or two booms are offset from the principal axes were considered. For the special case of symmetric deployment (principal axes booms) the stability boundaries are determined, and a stability chart is used to study the system behavior. Possible cases of instability during this type of maneuver are identified. In the second configuration an expression for gravity torque about the hub center of mass was developed. The nonlinear equations of motion are solved numerically, and the substantial influence of the gravity torque during asymmetric deployment maneuvers is indicated

Simultaneous Capture and Detumble of a Resident Space Object by a Free-Flying Spacecraft-Manipulator System

The article of record as published may be found at https://doi.org/10.3389/frobt.2019.00014A maneuver to capture and detumble an orbiting space object using a chaser spacecraft equipped with a robotic manipulator is presented. In the proposed maneuver, the capture and detumble objectives are integrated into a unified set of terminal constraints. Terminal constraints on the end-effector’s position and velocity ensure a successful capture, and a terminal constraint on the chaser’s momenta ensures a post-capture chaser-target system with zero angular momentum. The manipulator motion required to achieve a smooth, impact-free grasp is gradually stopped after capture, equalizing the momenta across all bodies, rigidly connecting the two vehicles, and completing the detumble of the newly formed chaser-target system without further actuation. To guide this maneuver, an optimization-based approach that enforces the capture and detumble terminal constraints, avoids collisions, and satisfies actuation limits is used. The solution to the guidance problem is obtained by solving a collection of convex programming problems, making the proposed guidance approach suitable for onboard implementation and real-time use. This simultaneous capture and detumble maneuver is evaluated through numerical simulations and hardware-in-the-loop experiments. Videos of the numerically simulated and experimentally demonstrated maneuvers are included as Supplementary Material

Canada’s Smallest Satellite: The Canadian Advanced Nanospace Experiment (CanX-1)

The Canadian Advanced Nanospace eXperiment (CanX) Program of the Space Flight Laboratory at the University of Toronto Institute for Aerospace Studies (UTIAS/SFL) is a Canadian first, allowing engineering researchers to test nano- and micro-scale devices rapidly and inexpensively in space. CanX is a “picosatellite” program for research and education, with graduate students leading the design, development, testing, and operations of Canada’s smallest satellites having a mass under 1 kg. The first UTIAS/SFL picosatellite, CanX-1, is scheduled for launch in early 2003 together with CubeSats from other university and industry developers. The objective of the CanX-1 mission is to verify the functionality of several novel electronic technologies in orbital space. This paper outlines the features, capabilities and performance of CanX-1, including horizon and star-tracking experiments using two CMOS imagers, active threeaxis magnetic stabilization, GPS-based position determination, and an ARM7 central processor

Mission analysis and preliminary assessment of the Attitude Determination and Control Subsystem for the D3SAT mission

The D3SAT (Drag make-up and Deorbiting Demonstration Satellite) technology demonstration mission aims to carry out comprehensive performance characterization of SITAEL's low power HT-100D thruster in-orbit ,by mounting it on a microsatellite which has a mass less than 40 kilograms. This thesis deals with the analysis of orbital operations required for performance evaluation,namely drag compensation and end-of-life deorbiting. The mission profile is then proposed, based on constraints imposed by the launch vehicle and by the thruster. The operating phases of the Attitude Determination and Control Subsystem (ADCS) based on the mission are described, and the requirements for each phase are derived. Preliminary design and specification of the ADCS to meet these requirements is then carried out. Interaction of the ADCS with other subsystems is analysed, and the contribution of the ADCS to the conceptual design of the D3SAT is specified. The ADCS is found to be compliant with the stringent volume and power requirements on-board small satellites. The HT-100D is found to efficiently satisfy the mission requirements with very low power requirements and low propellant consumption, thereby proving to be an ideal candidate to enhance the capabilities of small satellites

ESTCube-2 asendi kontrolli režiimide disain ja võrdlus

This thesis presents the attitude control problem of ESTCube-2. ESTCube-2 is a 3U CubeSat with a size of 10 x 10 x 30 cm and a weight of about 4 kg. It is the second satellite to be developed by the ESTCube Team and will be equipped with the E-Sail payload for the plasma break experiment, Earth observation camera, a high speed communication system, and a cold gas propulsion module. The satellite will make use of 3 electromagnetic coils, 3 reaction wheels and the cold gas thruster as actuators. The primary purpose of this work was to develop and compare control laws to ful ll the attitude control requirements of the ESTCube-2 mission. To achieve this, the spacecraft dynamics and environmental models are derived and analyzed. PD like controllers and LQR optimal controls are designed to ful ll the pointing requirements of the satellite in addition to the B-dot detumbling control law. Angular rate control law to spin up the satellite for tether deployment is also derived and presented. Simulations of the di erent controllers shows the performance with disturbances also added to the system. Finally recommendations and optimal control situations are presented based on the results

Simulation of a Commercial Off-The-Shelf ADCS with Design of a Pitch Sun Tracking Attitude Mode for the ORCASat

This MSc thesis has the objectives of simulating the behaviour of a typical COTS ADCS and designing a new attitude mode called Pitch Sun Tracking (PST). The Y-momentum ADCS is comprised of a set of sensors that are able to determine the attitude with an accuracy below 2 deg. The magnetorquers, aided by a momentum wheel, can keep the pointing error below 10 deg in Nadir Pointing (NP) mode. The PST mode proves to be capable of incrementing the power available to the satellite by more than 17%.ope

Design and implementation of an attitude determination and control system for the AntelSat

This thesis describes the design, analysis and construction of the Attitude Determination and Control System (ADCS) for the first Uruguayan nanosatellite, the AntelSat. The AntelSat project is a joint venture between the Electrical Engineering Institute (IIE) of Faculty of Engineering, Universidad de la República (UdelaR University) and Antel, the Uruguayan national telecommunications company. The satellite consists of a two-unit (2U) CubeSat, which implies that the ADCS is designed under tight mass, size, and energy constraints. In addition, these kind of satellites usually have limited sensing, computational and communication capabilities, motivating the need for autonomous and computationally eficient algorithms. Under these strict restraints, developing an effective attitude control system poses a significant challenge. As presented in this thesis, for the attitude determination section of the ADCS, data available from sensors is taken as inputs for the computation of an optimal quaternion estimator. The use of a quaternion implementation of an unscented Kalman filter is also discussed. Additionally, attitude control is based on magnetic actuation with magnetorquers being commanded by pulse width modulation. It is shown that the control system is able to achieve the detumbling of the satellite after separation from the launch interface using the reliable B-dot control law. Nadirpointing control is achieved with the use of a simple Linear Quadratic Regulator. Also pertinent is the simulation environment that was implemented to develop the attitude determination and control algorithms and also to validate their performance. ADCS hardware prototypes and flight versions that were designed and constructed are introduced.Este documento de tesis describe el diseño, análisis y construcción de el Sistema de Determinación y Control de Actitud (ADCS por sus siglas en inglés) del primer satélite uruguayo, el AntelSat. El proyecto AntelSat es una actividad conjunta entre el Instituto de Ingeniería Eléctrica (IIE) de la Facultad de Ingeniería de la Universidad de la República y Antel, la empresa de telecomunicaciones nacional de Uruguay. El satélite consiste en un CubeSat de dos unidades (2U), lo que implica que el ADCS es diseñado bajo estrictas restricciones de masa, tamaño y energía. Además, este tipo de satélites posee una capacidad computacional, de comunicaciones y de medición limitada, lo que motiva la necesidad de lograr algoritmos computacionalmente eficientes. Bajo estas estrictas limitaciones, el desarrollo de un sistema de control de actitud efectivo se traduce en un reto importante. Como se presenta en esta tesis, para el segmento de determinación de actitud del ADCS, la información proveniente de los sensores es tomada como entrada para el cálculo de un estimador de cuaternión óptimo. Se discute también el uso de una implementación con cuaterniones de un filtro de Kalman "unscented". Por otro lado, el control de actitud está basado en actuación magnética con magnetorquers comandados con modulación de ancho de pulso. Se demuestra que el sistema de control es capaz de reducir el valor de velocidad angular del satélite en la fase previa a la separación con la interfaz de lanzamiento, mediante la utilización del algoritmo B-dot. La estabilización de la actitud en modo de apunte al nadir se logra con el uso de un simple regulador lineal cuadrático. Por otra parte, se presenta el entorno de simulación que fue implementado para el desarrollo de algoritmos de determinación y control de actitud, y también para validar el desempeño de los mismos. A su vez, se exhiben el hardware del ADCS que fue diseñado y construido, tanto prototipos como versiones de vuelo

The dynamics and optimal control of spinning spacecraft and movable telescoping appendages, part A

The problem of optimal control with a minimum time criterion as applied to a single boom system for achieving two axis control is discussed. The special case where the initial conditions are such that the system can be driven to the equilibrium state with only a single switching maneuver in the bang-bang optimal sequence is analyzed. The system responses are presented. Application of the linear regulator problem for the optimal control of the telescoping system is extended to consider the effects of measurement and plant noises. The noise uncertainties are included with an application of the estimator - Kalman filter problem. Different schemes for measuring the components of the angular velocity are considered. Analytical results are obtained for special cases, and numerical results are presented for the general case