57 research outputs found
The Phoenix Drone: An Open-Source Dual-Rotor Tail-Sitter Platform for Research and Education
In this paper, we introduce the Phoenix drone: the first completely
open-source tail-sitter micro aerial vehicle (MAV) platform. The vehicle has a
highly versatile, dual-rotor design and is engineered to be low-cost and easily
extensible/modifiable. Our open-source release includes all of the design
documents, software resources, and simulation tools needed to build and fly a
high-performance tail-sitter for research and educational purposes. The drone
has been developed for precision flight with a high degree of control
authority. Our design methodology included extensive testing and
characterization of the aerodynamic properties of the vehicle. The platform
incorporates many off-the-shelf components and 3D-printed parts, in order to
keep the cost down. Nonetheless, the paper includes results from flight trials
which demonstrate that the vehicle is capable of very stable hovering and
accurate trajectory tracking. Our hope is that the open-source Phoenix
reference design will be useful to both researchers and educators. In
particular, the details in this paper and the available open-source materials
should enable learners to gain an understanding of aerodynamics, flight
control, state estimation, software design, and simulation, while experimenting
with a unique aerial robot.Comment: In Proceedings of the IEEE International Conference on Robotics and
Automation (ICRA'19), Montreal, Canada, May 20-24, 201
Trajectory Generation and Tracking Control for Aggressive Tail-Sitter Flights
We address the theoretical and practical problems related to the trajectory
generation and tracking control of tail-sitter UAVs. Theoretically, we focus on
the differential flatness property with full exploitation of actual UAV
aerodynamic models, which lays a foundation for generating dynamically feasible
trajectory and achieving high-performance tracking control. We have found that
a tail-sitter is differentially flat with accurate aerodynamic models within
the entire flight envelope, by specifying coordinate flight condition and
choosing the vehicle position as the flat output. This fundamental property
allows us to fully exploit the high-fidelity aerodynamic models in the
trajectory planning and tracking control to achieve accurate tail-sitter
flights. Particularly, an optimization-based trajectory planner for
tail-sitters is proposed to design high-quality, smooth trajectories with
consideration of kinodynamic constraints, singularity-free constraints and
actuator saturation. The planned trajectory of flat output is transformed to
state trajectory in real-time with consideration of wind in environments. To
track the state trajectory, a global, singularity-free, and
minimally-parameterized on-manifold MPC is developed, which fully leverages the
accurate aerodynamic model to achieve high-accuracy trajectory tracking within
the whole flight envelope. The effectiveness of the proposed framework is
demonstrated through extensive real-world experiments in both indoor and
outdoor field tests, including agile SE(3) flight through consecutive narrow
windows requiring specific attitude and with speed up to 10m/s, typical
tail-sitter maneuvers (transition, level flight and loiter) with speed up to
20m/s, and extremely aggressive aerobatic maneuvers (Wingover, Loop, Vertical
Eight and Cuban Eight) with acceleration up to 2.5g
Disturbance observer-based backstepping control of tail-sitter UAVs
The application scope of unmanned aerial vehicles (UAVs) is increasing along with commensurate advancements in performance. The hybrid quadrotor vertical takeoff and landing (VTOL) UAV has the benefits of both rotary-wing aircraft and fixed-wing aircraft. However, the vehicle requires a robust controller for takeoff, landing, transition, and hovering modes because the aerodynamic parameters differ in those modes. We consider a nonlinear observer-based backstepping controller in the control design and provide stability analysis for handling parameter variations and external disturbances. We carry out simulations in MATLAB Simulink which show that the nonlinear observer contributes more to robustness and overall closed-loop stability, considering external disturbances in takeoff, hovering and landing phases. The backstepping controller is capable of decent trajectory-tracking during the transition from hovering to level flight and vice versa with nominal altitude drop.Web of Science106art. no. 11
Nonlinear robust control of tail-sitter aircrafts in flight mode transitions
© 2018 Elsevier Masson SAS In this paper, a nonlinear robust controller is proposed to deal with the flight mode transition control problem of tail-sitter aircrafts. During the mode transitions, the control problem is challenging due to the high nonlinearities and strong couplings. The tail-sitter aircraft model can be considered as a nominal part with uncertainties including nonlinear terms, parametric uncertainties, and external disturbances. The proposed controller consists of a nominal H∞controller and a nonlinear disturbance observer. The nominal H∞controller based on the nominal model is designed to achieve the desired trajectory tracking performance. The uncertainties are regarded as equivalent disturbances to restrain their influences by the nonlinear disturbance observer. Theoretical analysis and simulation results are given to show advantages of the proposed control method, compared with the standard H∞control approach
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