Attitude profile generator algorithm for a LEO avionic architecture based on high torque actuators.

Paper number

IAC-06-C1.P.1.03

Author

Mr. Mauro Pantaleoni, Alcatel Alenia Space Italia, Italy

Coauthor

Mr. Giovanni Campolo, Thales Alenia Space, Italy

Coauthor

Mr. Leonardo Mazzini, Thales Alenia Space, Italy

Year

2006

Abstract

This paper discusses the improvement that can be introduced in the already qualified avionic system, developed by Alcatel Alenia Space Italy for LEO multi-mission platforms using the Single-Gimbal Control Moment Gyros (SCMG) technology. 

This avionic is a robust and flexible subsystem, based on a deeply modular architecture, which provides state-of-the-art design features for the management of the AOCS, Data Handling and Command and Control functions of the spacecraft, adaptable to a wide range of mission requirements and so to a broad variety of S/C missions.

The current configuration of the avionic system provides a level of the agility well in line with a typical remote sensing mission mostly in the Radar payload applications. For specific optical mission where an higher level of agility is required (up to 3-4 °/s), it is necessary to use new technology like Control Moment Gyros to meet this new system requirement.

Using Single-Gimbal Control Moment Gyros (SCMGs) system for attitude control of spacecraft it is possible to have also many advantages compared with other actuators offering a better figure of power consumption with respect to more traditional Reaction Wheel Assembly. The high torque generated makes CMGs systems suitable for very agile spacecraft performing fast slew manoeuvre or following profiles at high speed, specifically required by payload needs.

When a scenario is defined, according to specific mission need, it become important to define an opportune attitude profile that allows to follow the desired scan line. To select the best profile with respect to all possible manoeuvres, an optimization technique has been developed, in order to find a manoeuvre profile that is “optimal”  in the sense that satisfy all given requirements and minimize the control effort.

The proposed approach is based on two optimization levels. The first level assigns time intervals among the manoeuvre, and find a first optimal solution that minimize a cost function composed by torque supplied and angular momentum. A linear least-squares optimization is used satisfying the mission linear constrains, in order to achieve a target attitude, while the inequality constrains express the performance of the actuator system in terms of maximum torque and angular momentum capability. A second level of optimization consist to find the optimal time interval between each target visited. These two steps are executed more times, until a minimum solution is reached. The algorithm has been employed with different actuators configuration on typical mission scenario.

Abstract document

IAC-06-C1.P.1.03.pdf

Manuscript document

IAC-06-C1.P.1.03.pdf (🔒 authorized access only).

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