Autonomous pointing control of a large satellite antenna subject to parametric uncertainty

With the development of satellite mobile communications, large antennas are now widely used. The precise pointing of the antenna’s optical axis is essential for many space missions. This paper addresses the challenging problem of high-precision autonomous pointing control of a large satellite antenna. The pointing dynamics are firstly proposed. The proportional–derivative feedback and structural filter to perform pointing maneuvers and suppress antenna vibrations are then presented. An adaptive controller to estimate actual system frequencies in the presence of modal parameters uncertainty is proposed. In order to reduce periodic errors, the modified controllers, which include the proposed adaptive controller and an active disturbance rejection filter, are then developed. The system stability and robustness are analyzed and discussed in the frequency domain. Numerical results are finally provided, and the results have demonstrated that the proposed controllers have good autonomy and robustness

Control oriented modelling of an integrated attitude and vibration suppression architecture for large space structures

This thesis is divided into two parts. The main focus of the research, namely active vibration control for large flexible spacecraft, is exposed in Part I and, in parallel, the topic of machine learning techniques for modern space applications is described in Part II. In particular, this thesis aims at proposing an end-to-end general architecture for an integrated attitude-vibration control system, starting from the design of structural models to the synthesis of the control laws. To this purpose, large space structures based on realistic missions are investigated as study cases, in accordance with the tendency of increasing the size of the scientific instruments to improve their sensitivity, being the drawback an increase of its overall flexibility. An active control method is therefore investigated to guarantee satisfactory pointing and maximum deformation by avoiding classical stiffening methods. Therefore, the instrument is designed to be supported by an active deployable frame hosting an optimal minimum set of collocated smart actuators and sensors. Different spatial configurations for the placement of the distributed network of active devices are investigated, both at closed-loop and open-loop levels. Concerning closed-loop techniques, a method to optimally place the poles of the system via a Direct Velocity Feedback (DVF) controller is proposed to identify simultaneously the location and number of active devices for vibration control with an in-cascade optimization technique. Then, two general and computationally efficient open-loop placement techniques, namely Gramian and Modal Strain Energy (MSE)-based methods, are adopted as opposed to heuristic algorithms, which imply high computational costs and are generally not suitable for high-dimensional systems, to propose a placement architecture for generically shaped tridimensional space structures. Then, an integrated robust control architecture for the spacecraft is presented as composed of both an attitude control scheme and a vibration control system. To conclude the study, attitude manoeuvres are performed to excite main flexible modes and prove the efficacy of both attitude and vibration control architectures. Moreover, Part II is dedicated to address the problem of improving autonomy and self-awareness of modern spacecraft, by using machine-learning based techniques to carry out Failure Identification for large space structures and improving the pointing performance of spacecraft (both flexible satellite with sloshing models and small rigid platforms) when performing repetitive Earth Observation manoeuvres

SPHERES Reconfigurable Framework and Control System Design for Autonomous Assembly

Reconfigurable control system design is a key component for enabling autonomous on-orbit assembly. Current research on reconfigurable control systems focuses on adapting to failures. However, for assembly scenarios, the reconfiguration is necessitated by changing mass and stiffness properties. This paper provides a brief description of existing reconfigurable control system technology and develops a framework to incorporate reconfiguration into an existing baseline system to account for mass property variations. The reconfigurable control system framework has been developed and implemented using the SPHERES (Synchronized Position Hold Engage Reorient Experimental Satellites) testbed as the baseline system. The framework highlights the elements that need to be updated, introduces a variable p that captures the configuration, and details the updates necessary in the key algorithms to calculate the model online using p. Results are presented from the implementation on the SPHERES, focusing on the reconfigurable estimator. Plans are presented for an integrated assembly test that demonstrates the maintenance of stability, fuel efficiency, and accuracy throughout configuration changes that occur during assembly

An Innovative Approach for Validation of Large Space Structure Controls - Structures Interaction Technologies (CSI-SAT)

In-space flight experiments are required to validate dynamic response and control characteristics of ground experiments and their models in order to support future DoD/NASA Large Precision Space Structures missions. This paper, based on an ongoing Small Business Innovation Research (SBIR) Program with the Air Force Astronautics Laboratory, will describe an innovative approach for space flight experiments to demonstrate and validate Control-Structures Interaction (CSI) technologies and methodologies based on emerging Small Satellite Initiatives. The current trends in DoD/NASA missions, the existing CSI ground experiments and the planned space experiments are presented. A concept is identified for a Control-Structures Interaction satellite (CSI-SAT) and compatible launching platform necessary for performing affordable on-orbit testing of CSI technologies which cannot be accommodated in ground tests. Selected technologies and technology suites (integrated at subsystem level) for space testing are identified

Technology for large space systems: A bibliography with indexes (supplement 14)

This bibliography lists 645 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1, 1985 and December 31, 1985. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems

Automated System Identification for Satellite Attitude Control

A novel approach to on-obit system identification of satellite attitude control dynamics is presented. The approach is fully automated and will thus enable a variety of satellite applications, including high-performance proliferated constellations and modular payloads. The key enabling feature of the approach is the ability to estimate the uncertainty in the model and then perform additional data collections specifically to reduce the uncertainty. A prototype software implementation of the algorithm accurately estimated multiple structural modes in a CubeSat simulation and a CubeSat reaction wheel testbed in preparation for an on-orbit demonstration as part of the The Aerospace Corporation’s Slingshot 1 mission

Space station systems: A bibliography with indexes (supplement 2)

This bibliography lists 904 reports, articles and other documents introduced into the NASA scientific and technical information system between July 1, 1985 and December 31, 1985. Its purpose is to provide helpful information to the researcher, manager, and designer in technology development and mission design according to system, interactive analysis and design, structural and thermal analysis and design, structural concepts and control systems, electronics, advanced materials, assembly concepts, propulsion, and solar power satellite systems. The coverage includes documents that define major systems and subsystems, servicing and support requirements, procedures and operations, and missions for the current and future space station

Technology for large space systems: A bibliography with indexes (supplement 07)

This bibliography lists 366 reports, articles and other documents introduced into the NASA scientific and technical information system between January 1, 1982 and June 30, 1982. Subject matter is grouped according to systems, interactive analysis and design, structural concepts, control systems, electronics, advanced materials, assembly concepts, propulsion, solar power satellite systems, and flight experiments

Technology for the Future: In-Space Technology Experiments Program, part 2

The purpose of the Office of Aeronautics and Space Technology (OAST) In-Space Technology Experiments Program In-STEP 1988 Workshop was to identify and prioritize technologies that are critical for future national space programs and require validation in the space environment, and review current NASA (In-Reach) and industry/ university (Out-Reach) experiments. A prioritized list of the critical technology needs was developed for the following eight disciplines: structures; environmental effects; power systems and thermal management; fluid management and propulsion systems; automation and robotics; sensors and information systems; in-space systems; and humans in space. This is part two of two parts and contains the critical technology presentations for the eight theme elements and a summary listing of critical space technology needs for each theme