Setup of Avionics and Validation of a Surrogate Experiment for Spacecraft Attitude Control with Flexible Appendages

November 18, 2025

This thesis presents the design, development and validation of an experimental platform designed to study spacecraft attitude control in the presence of flexible appendages and time-varying dynamics. The setup consists of a central hub mounted on a low-friction bearing, actuated by a reaction wheel, and equipped with a one-meter flexible beam representing a deformable appendage. A mobile robot, referred to as the walker, moves along the beam, introducing variations in inertia and structural flexibility that emulate changing spacecraft configurations. The work is divided into three main stages. First, the avionics and onboard software were designed and integrated, including sensors, actuators, and data acquisition systems. Second, a system identification campaign was carried out to model the coupled rigid–flexible dynamics. Nonparametric frequency response functions were estimated and used to identify parametric transfer function models at different system configurations, which were then interpolated to obtain a time-varying state-space representation. Finally, attitude control algorithms were developed, implemented, and validated both in simulation and experimentally. A Linear–Quadratic–Gaussian (LQG) controller was adopted, and its performance was evaluated for static and moving walker configurations. The results demonstrate that accurate linear models can be identified for the first flexible mode of the system and that the LQG controller achieves stable attitude regulation across multiple configurations. Gain interpolation was explored as a method to adapt the controller to time-varying dynamics, yielding stable performance, although improvements are possible.

Authors in the community:

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  E

  Eduardo Barroso de Brito

  ist199481

Supervisors of this institution:

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  P

  Pedro Tiago Martins Batista

  ist14388

mechanical-engineering - Mechanical engineering

por - Portuguese

Instituto Superior Técnico