In recent years, the demand for advanced control systems, along with the need to validate them under realistic conditions, has driven the development of attitude simulators—essential tools for testing and verifying algorithms and technologies before launch [1-5]. The Attitude Determination and Control System (ADCS) is responsible for determining and controlling a satellite’s orientation in orbit. Since these systems operate under microgravity and minimal friction, ground-based simulation and testing pose significant challenges. Consequently, ADCS simulation plays a crucial role in reducing mission risks and enhancing system reliability. In particular, hardware-in-the-loop (HIL) simulations involving the complete ADCS allow engineers to better understand system behaviour and minimise the likelihood of unforeseen anomalies during actual mission operations.

Several laboratories have successfully developed testbeds, such as the system presented in [3], which employs sliding balancing masses driven by linear motors. In these implementations, however, the payload is typically assumed to be rigid. No studies in the current literature report testbeds that incorporate flexible components (e.g., solar array dynamics) or dynamic imbalances (e.g., those introduced by moving bodies such as robotic arms or antennas), largely due to the difficulty of implementing active balancing algorithms that do not dynamically interact with the payload’s ADCS. Access to an experimental platform capable of handling such complexities would enable the validation of attitude determination and control algorithms for advanced mission scenarios—such as robotic rendez-vous [6] or radio-frequency sensing with scanning antennas [like for the BIOMASS mission].

ISAE-SUPAERO has previously developed a first prototype of an attitude simulator in its laboratory. This system is based on a hemispherical air-bearing platform combined with sliding masses for preliminary structural balancing. The simulator was modeled using the Simscape Multibody environment in MATLAB, where calibration and attitude control algorithms were implemented to guide the hardware design and component selection. The hardware realisation of this initial system is currently in progress.

The objective of this Ph.D. project is to design the next-generation version of an experimental testbed capable of assessing attitude control algorithms under highly realistic conditions. The new design aims to eliminate disturbances that would not occur in orbit and to handle active dynamic imbalances at the payload level.

The ultimate goal is to establish a robust hardware and software foundation for a fully functional attitude simulation testbed, capable of overcoming the performance limitations observed in existing platforms described in the literature (i.e. no flexible appendages, pointing performance).

To achieve this objective, three key research questions are proposed:

- Building upon ISAE-SUPAERO’s experience with miniaturised Control Moment Gyroscopes (CMGs) [7, 8], can these devices be employed to develop agile balancing algorithms, and what are their theoretical and practical limitations?

- How can an agile balancing system be effectively decoupled from the payload’s ADCS to ensure reliable microgravity simulations in terrestrial conditions, while maintaining a controlled level of gravitational perturbation?

- How can nonlinear multibody simulations, such as those proposed in [9], be numerically optimised to create an efficient digital twin for prototyping and validating control algorithms prior to hardware implementation in the attitude simulator?

[1] S. Chesi et al., “Automatic mass balancing of a spacecraft three-axis simulator: Analysis and experimentation,” JGCD, vol. 37, no. 1, pp. 197–206, 2014.

[2] J. J. Kim et al., “Automatic mass balancing of air-bearing-based three-axis rotational spacecraft simulator,” JGCD, vol. 32, no. 3, pp. 1005–1017, 2009.

[3] D. Modenini et al., “A dynamic testbed for nanosatellites attitude verification,” Aerospace, vol. 7, no. 3, p. 31, 2020.

[4] R. C. da Silva et al., “A review of balancing methods for satellite simulators,” Acta Astronautica, vol. 187, pp. 537–545, 2021.

[5] K. Saulnier et al., “A six-degree-of-freedom hardware-in-the-loop simulator for small spacecraft,” Acta Astronautica, vol. 105, no. 2, pp. 444–462, 2014.

[6] V. Dubanchet et al., “Eross project–european autonomous robotic vehicle for on-orbit servicing,” in i-SAIRAS’20. USA, Pasadena, California, 2020.

[7] H. Evain et al., “Satellite attitude control with a six-control moment gyro cluster tested under microgravity conditions,” in ISSFD 2019, 2019, pp. 1387–1392.

[8] E. Kassarian et al., "Convergent ekf-based control allocation: general l formulation and application to a control moment gyro cluster,” in 2020 ACC. IEEE, 2020, pp. 4454–4459.

[9] D. Alazard et al., “Non-linear dynamics of multibody systems: a system-based approach,” arXiv preprint arXiv:2505.03248, 2025.

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - francesco.sanfedino@isae.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online  before March 13th, 2026 Midnight Paris time!