Geometric Tracking Control of Omnidirectional Multirotors for Aggressive Maneuvers (2209.10024v2)

Abstract: An omnidirectional multirotor has the maneuverability of decoupled translational and rotational motions, superseding the traditional multirotors' motion capability. Such maneuverability is achieved due to the ability of the omnidirectional multirotor to frequently alter the thrust amplitude and direction. In doing so, the rotors' settling time, which is induced by inherent rotor dynamics, significantly affects the omnidirectional multirotor's tracking performance, especially in aggressive flights. To resolve this issue, we propose a novel tracking controller that takes the rotor dynamics into account and does not require additional rotor state measurement. We prove that the proposed controller yields almost global exponential stability. The proposed controller is validated in experiments, where we demonstrate significantly improved tracking performance in multiple aggressive maneuvers compared with a baseline geometric PD controller.

• The paper introduces a novel controller that integrates rotor dynamics to achieve almost global exponential stability during aggressive flights.
• It employs Lyapunov's direct method for rigorous stability analysis that ensures robust performance under dynamic conditions.
• Experimental validation on an eight-rotor platform confirms enhanced translational and rotational tracking compared to traditional PD controllers.

Geometric Tracking Control of Omnidirectional Multirotors for Aggressive Maneuvers

The paper "Geometric Tracking Control of Omnidirectional Multirotors for Aggressive Maneuvers" presents a significant advancement in the control of omnidirectional multirotor vehicles. This paper focuses on enhancing the maneuverability and tracking performance of omnidirectional multirotors, particularly during aggressive flights where the dynamics of the rotors can significantly impact performance.

Technical Contributions

The authors introduce a novel geometric tracking controller that incorporates the dynamics of rotors directly into the control design without the need for additional rotor state measurements. Traditional multirotors often face limitations in aggressive maneuvers due to the time delay induced by rotor dynamics. This paper addresses this issue by proposing a control strategy that accounts for these dynamics, thereby ensuring almost global exponential stability. The specific contributions of this work are as follows:

1. Controller Design: The paper proposes a controller that integrates rotor dynamics into its design process. Unlike other methods that assume ideal rotor dynamics or require additional state measurements, this approach considers the rotor dynamics explicitly. This design feature enables enhanced control and stability, particularly under aggressive flight conditions.
2. Stability Analysis: The authors rigorously demonstrate the almost global exponential stability of their proposed controller using Lyapunov's direct method. This theoretical foundation provides confidence in the controller's performance and robustness.
3. Experimental Validation: The proposed controller was validated experimentally using an eight-rotor omnidirectional multirotor. The results showcased significant improvements in tracking performance compared to a baseline geometric PD controller, which did not account for rotor dynamics.

Experimental Results and Implications

The experiments conducted highlight the substantial improvements in both translational and rotational tracking control afforded by the proposed controller. Specifically, the enhancement in performance was most notable in scenarios demanding high precision and rapid responsiveness, such as aggressive maneuvering in dynamic environments. The inclusion of rotor dynamics in the control architecture mitigated errors introduced by rotor settling time, which is exacerbated during aggressive translational and rotational maneuvers.

Future Developments

The paper's findings suggest several directions for future research. One prominent direction is the potential refinement of rotor dynamic models. The authors utilized a simplified thrust dynamics model for controller design. Exploring more sophisticated models, such as the DC motor dynamics model, could further enhance controller precision and adaptability. Additionally, integrating adaptive control strategies to dynamically adjust to changing operational conditions and rotor characteristics could provide further improvements in robustness and adaptability.

Conclusion

This research makes a substantial contribution to the field of multirotor control, particularly in enhancing the maneuverability of omnidirectional multirotors under challenging conditions. By incorporating rotor dynamics into the control design, the paper sets a new standard for achieving high-performance control in complex flight scenarios. The innovative controller design promises significant advancements in applications requiring precise and dynamic flight, such as aerial robotics and autonomous navigation in uncertain environments.