This assignment follows the model and control scheme proposed in [1] for the manipulation of elastic and flexible cables by two aerial robots. The assignment is in the scope of the Flyflic project application scenario for the collection of floating objects on the surface of the water. The differential flatness of the aforementioned system has been proven used for control in [1] in a simulated environment. However, the method has not yet been tested in a real-world environment. The mismatch between the model of the cable used in the controller and the behavior of the real cable, as well as aerodynamic interferences caused, e.g., by the propellers of the robots, could affect the performance.
Moreover, more advanced control laws can potentially improve the behavior of the considered aerial manipulation system. In recent years, Nonlinear Model Predictive Control (NMPC) has become a popular tool for aerial vehicles [2] in general, but also for Aerial Physical Interaction [3]. Given the nonlinear nature of the system, this control scheme also seems well-suited for this application. However, since this algorithm requires repeated calculations of the system dynamics, it remains to be seen if implementing NMPC is feasible for this system.
Therefore, this assignment aims to answer the following questions:
What is the error obtained when the controller proposed in [1] is used in a real indoor setup?
Is implementing NMPC to control this system? If not, what are the encountered challenges?
If it is feasible, how much does its error differ from the one obtained when applying the simpler controller proposed in [1]?
[1] Gabellieri, C., and Franchi A., Differential Flatness and Manipulation of Elasto-flexible Cables Carried by Aerial Robots in a Possibly Viscous Environment, 2023 International Conference on Unmanned Aircraft Systems (ICUAS), 963-968
[2] Nguyen, H., Kamel, M., Alexis, K., & Siegwart, R. (2021). Model Predictive Control for Micro Aerial Vehicles: A Survey. 2021 European Control Conference, ECC 2021, 1556–1563. https://doi.org/10.23919/ECC54610.2021.9654841
[3] Alharbat, A., Esmaeeli, H., Bicego, D., Mersha, A., & Franchi, A. (2022). Three Fundamental Paradigms for Aerial Physical Interaction Using Nonlinear Model Predictive Control. 2022 International Conference on Unmanned Aircraft Systems, ICUAS 2022, 39–48. https://doi.org/10.1109/ICUAS54217.2022.9836221