Session
Technical Session XI: Advanced Subsystem or Component Developments I
Abstract
UoSAT-12 is a low-cost minisatellite built by Surrey Satellite Technology Ltd. (SSTL), it is amongst other objectives also a technology demonstrator for high performance attitude control and orbit maintenance on a future constellation of earth observation satellites. The satellite uses a 3-axis reaction wheel configuration and a cold gas propulsion system to enable precise and fast control of its attitude, for example, during orbit manoeuvres. Magnetorquer coils assist the wheels mainly for momentum dumping. This paper describes the various attitude control modes required to support: 1) the initial attitude acquisition phase, 2) a high resolution imager payload during pointing and tracking of targets, 3) the propulsion system during orbit manoeuvres. The specific attitude controllers and estimators used during these control modes are explained. Various simulation and in-orbit test results are presented to evaluate the performance and design objectives. To improve the control and estimation accuracy, on-board calibration and alignment procedures for the sensors and actuators are utilised. Some calibration results and the resulting improvement in accuracy from these procedures are shown.
An Attitude Control System for a Low-Cost Earth Observation Satellite with Orbit Maintenance Capability
UoSAT-12 is a low-cost minisatellite built by Surrey Satellite Technology Ltd. (SSTL), it is amongst other objectives also a technology demonstrator for high performance attitude control and orbit maintenance on a future constellation of earth observation satellites. The satellite uses a 3-axis reaction wheel configuration and a cold gas propulsion system to enable precise and fast control of its attitude, for example, during orbit manoeuvres. Magnetorquer coils assist the wheels mainly for momentum dumping. This paper describes the various attitude control modes required to support: 1) the initial attitude acquisition phase, 2) a high resolution imager payload during pointing and tracking of targets, 3) the propulsion system during orbit manoeuvres. The specific attitude controllers and estimators used during these control modes are explained. Various simulation and in-orbit test results are presented to evaluate the performance and design objectives. To improve the control and estimation accuracy, on-board calibration and alignment procedures for the sensors and actuators are utilised. Some calibration results and the resulting improvement in accuracy from these procedures are shown.
