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Rapid Rotational Maneuvering of Rigid Satellites with Hybrid Actuators Configuration

Kamath, Santhosh G (2014) Rapid Rotational Maneuvering of Rigid Satellites with Hybrid Actuators Configuration. Masters thesis, Manipal Institute of Technology, Manipal.

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Abstract

An advanced attitude control method for agile rigid spacecraft’s that is based on combining single gimbal control moment gyro together with reaction wheels will be introduced in this thesis. This method of attitude control is believed to suit remote sensing satellites that are required to perform multiple rapid retargeting of their line of sight in order to be able to provide more data. The main advantage of single gimbal control moment gyros is rapid rotational maneuvering due to their large torque capability, but their application for high quality pointing or tracking control requires a very precise gimbal mechanism. Besides, the reaction wheels may be more easily applied for accurate pointing, but their torque-to-power performance is inferior for maneuvering compared to single gimbal control moment gyros. This thesis will show the careful coordination between single gimbal control moment gyro and reaction wheels so as to bring out the hybrid actuators configuration wherein single gimbal control moment gyro will be used during maneuvering period and reaction wheels will be used for pointing or tracking control. In this thesis, an attitude control model of a spacecraft is designed for one axis control using one single gimbal control moment gyro in MATLAB/SIMULINK. Later, this model is integrated with the reaction wheel dynamics so as to show the hybrid configuration. Three axes control model is also shown using one single gimbal control moment gyro and four reaction wheels. In all, the attitude controller of spacecraft involves two levels of control. The high-level control is based on a braking curve that relates angular rate to any given attitude. The lower level control is based on the steering law. Control Moment Gyros can be steered either in angular momentum domain or gimbal angle’s domain. This thesis explores both domain of control and compares their performance One of the major hurdles involved in using the single gimbal control moment gyros for attitude control is the presence of geometric singularities at certain gimbal configurations. In order to develop effective algorithms to bypass such situations, better understanding of singularities associated with single gimbal control moment gyros is required. Thus, all the singularities associated with single gimbal control moment gyros will be studied in this thesis along with their avoiding/escaping algorithms available in literature. Based on the better understanding of singularities associated with single gimbal control moment gyros, a singularity avoidance algorithm known as “Constrained Steering Law” is developed using simulated input profile method. The advantage of constrained based steering law is that they have no inherent torque error and do not require pre-computed CMG paths while maintaining singularity-free motion. Validation of this steering law is shown for popular Control Moment Gyros configuration such as scissor paired configuration and pyramid configuration.

Item Type: Thesis (Masters)
Subjects: Engineering > MIT Manipal > Instrumentation and Control
Depositing User: MIT Library
Date Deposited: 13 Nov 2014 11:05
Last Modified: 13 Nov 2014 11:05
URI: http://eprints.manipal.edu/id/eprint/141072

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