262 research outputs found
Geometric Surface-Based Tracking Control of a Quadrotor UAV
New quadrotor UAV control algorithms are developed, based on nonlinear
surfaces composed of tracking errors that evolve directly on the nonlinear
configuration manifold, thus inherently including in the control design the
nonlinear characteristics of the SE(3) configuration space. In particular,
geometric surface-based controllers are developed and are shown, through
rigorous stability proofs, to have desirable almost global closed loop
properties. For the first time in regards to the geometric literature, a region
of attraction independent of the position error is identified and its effects
are analyzed. The effectiveness of the proposed "surface based" controllers are
illustrated by simulations of aggressive maneuvers in the presence of
disturbances and motor saturation.Comment: 2018 26th Mediterranean Conference on Control and Automation (MED
Extended Kalman Filter on SE(3) for Geometric Control of a Quadrotor UAV
An extended Kalman filter (EKF) is developed on the special Euclidean group,
SE(3) for geometric control of a quadrotor UAV. It is obtained by performing an
extensive linearization on SE(3) to estimate the state of the quadrotor from
noisy measurements. Proposed estimator considers all the coupling effects
between rotational and translational dynamics, and it is developed in a
coordinate-free fashion. The desirable features of the proposed EKF are
illustrated by numerical examples and experimental results for several
scenarios. The proposed estimation scheme on SE(3) has been unprecedented and
these results can be particularly useful for aggressive maneuvers in GPS denied
environments or in situations where parts of onboard sensors fail.Comment: arXiv admin note: text overlap with arXiv:1304.6765, arXiv:1411.298
Advanced Feedback Linearization Control for Tiltrotor UAVs: Gait Plan, Controller Design, and Stability Analysis
Three challenges, however, can hinder the application of Feedback
Linearization: over-intensive control signals, singular decoupling matrix, and
saturation. Activating any of these three issues can challenge the stability
proof. To solve these three challenges, first, this research proposed the drone
gait plan. The gait plan was initially used to figure out the control problems
in quadruped (four-legged) robots; applying this approach, accompanied by
Feedback Linearization, the quality of the control signals was enhanced. Then,
we proposed the concept of unacceptable attitude curves, which are not allowed
for the tiltrotor to travel to. The Two Color Map Theorem was subsequently
established to enlarge the supported attitude for the tiltrotor. These theories
were employed in the tiltrotor tracking problem with different references.
Notable improvements in the control signals were witnessed in the tiltrotor
simulator. Finally, we explored the control theory, the stability proof of the
novel mobile robot (tilt vehicle) stabilized by Feedback Linearization with
saturation. Instead of adopting the tiltrotor model, which is over-complicated,
we designed a conceptual mobile robot (tilt-car) to analyze the stability
proof. The stability proof (stable in the sense of Lyapunov) was found for a
mobile robot (tilt vehicle) controlled by Feedback Linearization with
saturation for the first time. The success tracking result with the promising
control signals in the tiltrotor simulator demonstrates the advances of our
control method. Also, the Lyapunov candidate and the tracking result in the
mobile robot (tilt-car) simulator confirm our deductions of the stability
proof. These results reveal that these three challenges in Feedback
Linearization are solved, to some extents.Comment: Doctoral Thesis at The University of Toky
Grasping, Perching, And Visual Servoing For Micro Aerial Vehicles
Micro Aerial Vehicles (MAVs) have seen a dramatic growth in the consumer market because of their ability to provide new vantage points for aerial photography and videography. However, there is little consideration for physical interaction with the environment surrounding them. Onboard manipulators are absent, and onboard perception, if existent, is used to avoid obstacles and maintain a minimum distance from them. There are many applications, however, which would benefit greatly from aerial manipulation or flight in close proximity to structures. This work is focused on facilitating these types of close interactions between quadrotors and surrounding objects. We first explore high-speed grasping, enabling a quadrotor to quickly grasp an object while moving at a high relative velocity. Next, we discuss planning and control strategies, empowering a quadrotor to perch on vertical surfaces using a downward-facing gripper. Then, we demonstrate that such interactions can be achieved using only onboard sensors by incorporating vision-based control and vision-based planning. In particular, we show how a quadrotor can use a single camera and an Inertial Measurement Unit (IMU) to perch on a cylinder. Finally, we generalize our approach to consider objects in motion, and we present relative pose estimation and planning, enabling tracking of a moving sphere using only an onboard camera and IMU
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