{"id":{"repo_id":"stellenbosch","oai_identifier":"oai:scholar.sun.ac.za:10019.1/135688"},"canonical_url":"https://search.dev.ndltd.org/etd/stellenbosch/oai:scholar.sun.ac.za:10019.1/135688","repository":{"repo_id":"stellenbosch","name":"Stellenbosch University","base_url":"https://scholar.sun.ac.za/server/oai/request"},"display":{"title":"Development of Hardware and Efficient, Robust Control Algorithms for a Nanosatellite Reaction Control System","abstract":"Nanosatellites are currently being proposed for missions which place increasingly demanding requirements on the attitude and orbit determination and control system. Traditionally, magnetic actuators are used to manage angular momentum buildup in the satellite, which is not possible in beyond-low Earth orbit environments. For this reason, actuators which generate external control forces and torques, such as reaction control thrusters, are required. Such actuators are also required when performing precise orbit adjustments in missions involving rendezvous and docking operations. This study addresses the relative lack of research into using these actuators on nanosatellites by developing hardware prototypes and efficient, robust control algorithms for a variety of common attitude control tasks. A modular simulation environment is built which models the rotational and translati-onal dynamics of satellites. Accurate models are included of the common disturbances encountered in the space environment, including magnetic and gravity gradient torques, aerodynamic forces, solar radiation pressure, and propellant sloshing. Iterative hardware development is performed of a thruster module suitable for use on nanosatellites, including detailed evaluations of different component and propellant choices, resulting in two functional prototypes. The performance of the prototypes, including pressure and temperature regulation, minimum impulse bit and thrust force magnitude, are characterized and used to inform control system development. Novel control algorithms are developed to allow the use of thruster modules with arbitrary thruster locations for various attitude control tasks, while minimizing propellant usage. Multi-axis adaptations of phase plane and pulse-width pulse-frequency modulated controllers are proposed for fine pointing control of satellites. Performance of these controllers are studied across a range of disturbance torque magnitudes and pointing accuracy requirements, and compared to existing methods where possible. Successive convexification is studied as a method of generating optimal slew trajectories, and a novel approach is presented to improve robustness of this process and allow its use in a model predictive control scheme. The efficiency and robustness of this method is evaluated across a range of maneuver durations and parameter uncertainties. To improve robustness to in-orbit faults and other unexpected variations of control authority, extended Kalman filters are designed to estimate thruster torques online. The effect of propellant sloshing on filter performance is addressed, and the performance of the above control schemes studied when enhanced with accurate parameter estimates.","abstract_html":"Nanosatellites are currently being proposed for missions which place increasingly demanding requirements on the attitude and orbit determination and control system. Traditionally, magnetic actuators are used to manage angular momentum buildup in the satellite, which is not possible in beyond-low Earth orbit environments. For this reason, actuators which generate external control forces and torques, such as reaction control thrusters, are required. Such actuators are also required when performing precise orbit adjustments in missions involving rendezvous and docking operations. This study addresses the relative lack of research into using these actuators on nanosatellites by developing hardware prototypes and efficient, robust control algorithms for a variety of common attitude control tasks. A modular simulation environment is built which models the rotational and translati-onal dynamics of satellites. Accurate models are included of the common disturbances encountered in the space environment, including magnetic and gravity gradient torques, aerodynamic forces, solar radiation pressure, and propellant sloshing. Iterative hardware development is performed of a thruster module suitable for use on nanosatellites, including detailed evaluations of different component and propellant choices, resulting in two functional prototypes. The performance of the prototypes, including pressure and temperature regulation, minimum impulse bit and thrust force magnitude, are characterized and used to inform control system development. Novel control algorithms are developed to allow the use of thruster modules with arbitrary thruster locations for various attitude control tasks, while minimizing propellant usage. Multi-axis adaptations of phase plane and pulse-width pulse-frequency modulated controllers are proposed for fine pointing control of satellites. Performance of these controllers are studied across a range of disturbance torque magnitudes and pointing accuracy requirements, and compared to existing methods where possible. Successive convexification is studied as a method of generating optimal slew trajectories, and a novel approach is presented to improve robustness of this process and allow its use in a model predictive control scheme. The efficiency and robustness of this method is evaluated across a range of maneuver durations and parameter uncertainties. To improve robustness to in-orbit faults and other unexpected variations of control authority, extended Kalman filters are designed to estimate thruster torques online. The effect of propellant sloshing on filter performance is addressed, and the performance of the above control schemes studied when enhanced with accurate parameter estimates.","abstract_has_math":false,"creators":["Cilliers, Tian"],"institution":"Stellenbosch : Stellenbosch University","degree_name":null,"degree_level":null,"degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":["Jordaan, H. W.","Steyn, W. H."],"committee_chairs":[],"committee_members":[],"year":2026,"date_issued":"2026-03","date_published":"2026-03","updated_at":"2026-07-24T04:40:06Z","subjects":[],"languages":["en"],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://scholar.sun.ac.za/handle/10019.1/135688","outbound_label":"Repository record","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.advisor","label":"Advisor","values":["Jordaan, H. W.","Steyn, W. H."]},{"key":"dc:contributor.other","label":"Dc Contributor Other","values":["Stellenbosch University. Faculty of Engineering. 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Development of Hardware and Efficient, Robust Control Algorithms for a Nanosatellite Reaction Control System. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/3632d0b6-a04a-452e-96e9-5d1c635cec35"]},{"key":"dc:description.abstract","label":"Abstract","values":["Nanosatellites are currently being proposed for missions which place increasingly demanding requirements on the attitude and orbit determination and control system. Traditionally, magnetic actuators are used to manage angular momentum buildup in the satellite, which is not possible in beyond-low Earth orbit environments. For this reason, actuators which generate external control forces and torques, such as reaction control thrusters, are required. Such actuators are also required when performing precise orbit adjustments in missions involving rendezvous and docking operations. This study addresses the relative lack of research into using these actuators on nanosatellites by developing hardware prototypes and efficient, robust control algorithms for a variety of common attitude control tasks. A modular simulation environment is built which models the rotational and translati-onal dynamics of satellites. Accurate models are included of the common disturbances encountered in the space environment, including magnetic and gravity gradient torques, aerodynamic forces, solar radiation pressure, and propellant sloshing. Iterative hardware development is performed of a thruster module suitable for use on nanosatellites, including detailed evaluations of different component and propellant choices, resulting in two functional prototypes. The performance of the prototypes, including pressure and temperature regulation, minimum impulse bit and thrust force magnitude, are characterized and used to inform control system development. Novel control algorithms are developed to allow the use of thruster modules with arbitrary thruster locations for various attitude control tasks, while minimizing propellant usage. Multi-axis adaptations of phase plane and pulse-width pulse-frequency modulated controllers are proposed for fine pointing control of satellites. Performance of these controllers are studied across a range of disturbance torque magnitudes and pointing accuracy requirements, and compared to existing methods where possible. Successive convexification is studied as a method of generating optimal slew trajectories, and a novel approach is presented to improve robustness of this process and allow its use in a model predictive control scheme. The efficiency and robustness of this method is evaluated across a range of maneuver durations and parameter uncertainties. To improve robustness to in-orbit faults and other unexpected variations of control authority, extended Kalman filters are designed to estimate thruster torques online. The effect of propellant sloshing on filter performance is addressed, and the performance of the above control schemes studied when enhanced with accurate parameter estimates."]},{"key":"dc:title","label":"Title","values":["Development of Hardware and Efficient, Robust Control Algorithms for a Nanosatellite Reaction Control System"]}]}],"canonical_facts":{"dc:contributor.advisor":["Jordaan, H. W.","Steyn, W. H."],"dc:contributor.other":["Stellenbosch University. Faculty of Engineering. Dept. of Electrical & Electronic Engineering."],"dc:creator":["Cilliers, Tian"],"dc:date.accessioned":["2026-04-08T06:38:53Z"],"dc:date.available":["2026-04-08T06:38:53Z"],"dc:date.issued":["2026-03"],"dc:description":["Thesis (PhD)--Stellenbosch University, 2026.","Cilliers, T. 2026. 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This study addresses the relative lack of research into using these actuators on nanosatellites by developing hardware prototypes and efficient, robust control algorithms for a variety of common attitude control tasks. A modular simulation environment is built which models the rotational and translati-onal dynamics of satellites. Accurate models are included of the common disturbances encountered in the space environment, including magnetic and gravity gradient torques, aerodynamic forces, solar radiation pressure, and propellant sloshing. Iterative hardware development is performed of a thruster module suitable for use on nanosatellites, including detailed evaluations of different component and propellant choices, resulting in two functional prototypes. The performance of the prototypes, including pressure and temperature regulation, minimum impulse bit and thrust force magnitude, are characterized and used to inform control system development. Novel control algorithms are developed to allow the use of thruster modules with arbitrary thruster locations for various attitude control tasks, while minimizing propellant usage. Multi-axis adaptations of phase plane and pulse-width pulse-frequency modulated controllers are proposed for fine pointing control of satellites. Performance of these controllers are studied across a range of disturbance torque magnitudes and pointing accuracy requirements, and compared to existing methods where possible. Successive convexification is studied as a method of generating optimal slew trajectories, and a novel approach is presented to improve robustness of this process and allow its use in a model predictive control scheme. The efficiency and robustness of this method is evaluated across a range of maneuver durations and parameter uncertainties. To improve robustness to in-orbit faults and other unexpected variations of control authority, extended Kalman filters are designed to estimate thruster torques online. The effect of propellant sloshing on filter performance is addressed, and the performance of the above control schemes studied when enhanced with accurate parameter estimates."],"dc:identifier.uri":["https://scholar.sun.ac.za/handle/10019.1/135688"],"dc:language.iso":["en"],"dc:publisher":["Stellenbosch : Stellenbosch University"],"dc:title":["Development of Hardware and Efficient, Robust Control Algorithms for a Nanosatellite Reaction Control System"],"dc:type":["Thesis"]},"updated_at":"2026-07-24T04:40:06Z"}