Data-Driven MPC for Quadrotors
Aerodynamic forces render accurate high-speed trajectory tracking with quadrotors extremely challenging. These complex aerodynamic effects become a significant disturbance at high speeds, introducing large positional tracking errors, and are extremely difficult to model. To fly at high speeds, feedb...
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Published in | IEEE robotics and automation letters Vol. 6; no. 2; pp. 3769 - 3776 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Piscataway
IEEE
01.04.2021
The Institute of Electrical and Electronics Engineers, Inc. (IEEE) |
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Abstract | Aerodynamic forces render accurate high-speed trajectory tracking with quadrotors extremely challenging. These complex aerodynamic effects become a significant disturbance at high speeds, introducing large positional tracking errors, and are extremely difficult to model. To fly at high speeds, feedback control must be able to account for these aerodynamic effects in real-time. This necessitates a modeling procedure that is both accurate and efficient to evaluate. Therefore, we present an approach to model aerodynamic effects using Gaussian Processes, which we incorporate into a Model Predictive Controller to achieve efficient and precise real-time feedback control, leading to up to 70% reduction in trajectory tracking error at high speeds. We verify our method by extensive comparison to a state-of-the-art linear drag model in synthetic and real-world experiments at speeds of up to 14 m/s and accelerations beyond 4 g. |
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AbstractList | Aerodynamic forces render accurate high-speed trajectory tracking with quadrotors extremely challenging. These complex aerodynamic effects become a significant disturbance at high speeds, introducing large positional tracking errors, and are extremely difficult to model. To fly at high speeds, feedback control must be able to account for these aerodynamic effects in real-time. This necessitates a modeling procedure that is both accurate and efficient to evaluate. Therefore, we present an approach to model aerodynamic effects using Gaussian Processes, which we incorporate into a Model Predictive Controller to achieve efficient and precise real-time feedback control, leading to up to 70% reduction in trajectory tracking error at high speeds. We verify our method by extensive comparison to a state-of-the-art linear drag model in synthetic and real-world experiments at speeds of up to 14 m/s and accelerations beyond 4 g. Aerodynamic forces render accurate high-speed trajectory tracking with quadrotors extremely challenging. These complex aerodynamic effects become a significant disturbance at high speeds, introducing large positional tracking errors, and are extremely difficult to model. To fly at high speeds, feedback control must be able to account for these aerodynamic effects in real-time. This necessitates a modeling procedure that is both accurate and efficient to evaluate. Therefore, we present an approach to model aerodynamic effects using Gaussian Processes, which we incorporate into a Model Predictive Controller to achieve efficient and precise real-time feedback control, leading to up to 70% reduction in trajectory tracking error at high speeds. We verify our method by extensive comparison to a state-of-the-art linear drag model in synthetic and real-world experiments at speeds of up to 14 m/s and accelerations beyond 4 g. |
Author | Torrente, Guillem Kaufmann, Elia Fohn, Philipp Scaramuzza, Davide |
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Cites_doi | 10.1109/ROBOT.2010.5509980 10.1007/978-3-540-36119-0_4 10.1109/LRA.2019.2929987 10.15607/RSS.2020.XVI.087 10.1007/978-3-319-54927-9_1 10.1177/0278364918793717 10.1109/MRA.2012.2206474 10.1109/ICRA.2015.7139420 10.1109/IROS.2004.1389727 10.1109/LRA.2019.2926677 10.15607/RSS.2020.XVI.040 10.1007/s00162-020-00520-4 10.23919/ECC.2009.7074482 10.1109/ICRA.2017.7989202 10.1109/ICRA.2016.7487274 10.2514/1.C035135 10.1109/TCST.2020.3001117 10.1109/IROS.2017.8206343 10.1109/TCST.2019.2949757 10.15607/RSS.2020.XVI.081 10.1007/s10846-017-0549-y 10.1109/IROS.2018.8593739 10.1016/j.ifacol.2018.11.062 10.1007/978-3-319-26054-9_23 10.23919/ECC51009.2020.9143655 10.15607/RSS.2015.XI.012 10.1109/ICUAS.2017.7991347 10.1109/ROBOT.2010.5509452 10.1177/0278364911434236 10.1109/LRA.2017.2776353 10.1007/s12532-018-0139-4 10.1109/ChiCC.2015.7260264 10.1007/s10846-020-01250-9 |
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Snippet | Aerodynamic forces render accurate high-speed trajectory tracking with quadrotors extremely challenging. These complex aerodynamic effects become a significant... |
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SubjectTerms | Aerial systems: perception and autonomy Aerodynamic forces Aerodynamics Computational modeling Control systems Feedback control Gaussian process Gaussian processes model learning for control model predictive control Predictive control Predictive models Real time Rotary wing aircraft Rotors Stability Tracking errors Trajectory Vehicle dynamics |
Title | Data-Driven MPC for Quadrotors |
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