Effects of model fidelity and uncertainty on a model-based attitude controller for satellites with flexible appendages

Gordon, R., Ceriotti, M. and Worrall, K. (2024) Effects of model fidelity and uncertainty on a model-based attitude controller for satellites with flexible appendages. Acta Astronautica, 214, pp. 30-45. (doi: 10.1016/j.actaastro.2023.10.011)

Abstract

This paper investigates the effects of model fidelity and parameter uncertainty on the performance of a hybrid model-based feedback-feedforward control scheme for attitude tracking of a satellite with flexible appendages. The feedforward component is an inverse model-based term produced through a computational approach known as inverse simulation (InvSim), which works by iteratively solving a discretised reference trajectory. The hybrid controller's feedback is proportional-derivative (PD) based, using body attitude and rate feedback to provide stability and robustness. Furthermore, to ensure that the flexible modes do not trigger instability, the PD control gains are tuned to give a closed-loop response that is significantly slower than the flexible modes. Additionally, excitation of the flexible modes is reduced by minimising jerk through polynomial rest-to-rest manoeuvres, following the shortest quaternion path using spherical-linear-interpolation (SLERP). The effects of the appendage flexing on attitude tracking are then compensated through the feedforward element of the hybrid controller, with performance being compared to a traditional PD tracking law. The effect of the model fidelity on the performance of the hybrid controller is investigated through the use of both rigid body and multiple-fidelity finite-element mathematical models. Additionally, the effect of uncertainties in the model parameters is investigated to determine the accuracy of the model required to obtain significant improvement in attitude tracking. It is found that in the absence of any model parameter uncertainty, the hybrid controller outperforms the PD tracking control law by at least one order of magnitude when the finite-element model is used. Increasing the number of finite elements was found to provide no significant improvement in performance, with one element being sufficient and favourable with its lower computational overhead. It was also found that to ensure good performance compared to the PD tracking controller, the uncertainty in the inertia tensor should be <1%. Similarly, uncertainty in the first flexible modal frequency should be <0.5 rad/s.

• Item Type: Articles
• Additional Information: This work is supported by the Engineering and Physical Sciences Research Council, grant number 2442761.
• Keywords: Inverse simulation, attitude control, flexible appendages.
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Worrall, Dr Kevin and Gordon, Robbie and Ceriotti, Dr Matteo
• Authors: Gordon, R., Ceriotti, M., and Worrall, K.
• College/School: College of Science and Engineering > School of Engineering > Autonomous Systems and Connectivity; College of Science and Engineering > School of Engineering > Systems Power and Energy
• Journal Name: Acta Astronautica
• Publisher: Elsevier
• ISSN: 0094-5765
• ISSN (Online): 1879-2030
• Published Online: 14 October 2023
• Copyright Holders: Copyright © 2023 The Author(s)
• First Published: First published in Acta Astronautica 214: 30-45
• Publisher Policy: Reproduced under a Creative Commons licence

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
312561		EPSRC DTP 2020/21	Christopher Pearce	Engineering and Physical Sciences Research Council (EPSRC)	EP/T517896/1	Research and Innovation Services