899 research outputs found
Visual Servoing Approach for Autonomous UAV Landing on a Moving Vehicle
We present a method to autonomously land an Unmanned Aerial Vehicle on a
moving vehicle with a circular (or elliptical) pattern on the top. A visual
servoing controller approaches the ground vehicle using velocity commands
calculated directly in image space. The control laws generate velocity commands
in all three dimensions, eliminating the need for a separate height controller.
The method has shown the ability to approach and land on the moving deck in
simulation, indoor and outdoor environments, and compared to the other
available methods, it has provided the fastest landing approach. It does not
rely on additional external setup, such as RTK, motion capture system, ground
station, offboard processing, or communication with the vehicle, and it
requires only a minimal set of hardware and localization sensors. The videos
and source codes can be accessed from http://theairlab.org/landing-on-vehicle.Comment: 24 page
Dynamic Landing of an Autonomous Quadrotor on a Moving Platform in Turbulent Wind Conditions
Autonomous landing on a moving platform presents unique challenges for
multirotor vehicles, including the need to accurately localize the platform,
fast trajectory planning, and precise/robust control. Previous works studied
this problem but most lack explicit consideration of the wind disturbance,
which typically leads to slow descents onto the platform. This work presents a
fully autonomous vision-based system that addresses these limitations by
tightly coupling the localization, planning, and control, thereby enabling fast
and accurate landing on a moving platform. The platform's position,
orientation, and velocity are estimated by an extended Kalman filter using
simulated GPS measurements when the quadrotor-platform distance is large, and
by a visual fiducial system when the platform is nearby. The landing trajectory
is computed online using receding horizon control and is followed by a boundary
layer sliding controller that provides tracking performance guarantees in the
presence of unknown, but bounded, disturbances. To improve the performance, the
characteristics of the turbulent conditions are accounted for in the
controller. The landing trajectory is fast, direct, and does not require
hovering over the platform, as is typical of most state-of-the-art approaches.
Simulations and hardware experiments are presented to validate the robustness
of the approach.Comment: 7 pages, 8 figures, ICRA2020 accepted pape
Effective Target Aware Visual Navigation for UAVs
In this paper we propose an effective vision-based navigation method that
allows a multirotor vehicle to simultaneously reach a desired goal pose in the
environment while constantly facing a target object or landmark. Standard
techniques such as Position-Based Visual Servoing (PBVS) and Image-Based Visual
Servoing (IBVS) in some cases (e.g., while the multirotor is performing fast
maneuvers) do not allow to constantly maintain the line of sight with a target
of interest. Instead, we compute the optimal trajectory by solving a non-linear
optimization problem that minimizes the target re-projection error while
meeting the UAV's dynamic constraints. The desired trajectory is then tracked
by means of a real-time Non-linear Model Predictive Controller (NMPC): this
implicitly allows the multirotor to satisfy both the required constraints. We
successfully evaluate the proposed approach in many real and simulated
experiments, making an exhaustive comparison with a standard approach.Comment: Conference paper at "European Conference on Mobile Robotics" (ECMR)
201
Robust Reinforcement Learning Algorithm for Vision-based Ship Landing of UAVs
This paper addresses the problem of developing an algorithm for autonomous
ship landing of vertical take-off and landing (VTOL) capable unmanned aerial
vehicles (UAVs), using only a monocular camera in the UAV for tracking and
localization. Ship landing is a challenging task due to the small landing
space, six degrees of freedom ship deck motion, limited visual references for
localization, and adversarial environmental conditions such as wind gusts. We
first develop a computer vision algorithm which estimates the relative position
of the UAV with respect to a horizon reference bar on the landing platform
using the image stream from a monocular vision camera on the UAV. Our approach
is motivated by the actual ship landing procedure followed by the Navy
helicopter pilots in tracking the horizon reference bar as a visual cue. We
then develop a robust reinforcement learning (RL) algorithm for controlling the
UAV towards the landing platform even in the presence of adversarial
environmental conditions such as wind gusts. We demonstrate the superior
performance of our algorithm compared to a benchmark nonlinear PID control
approach, both in the simulation experiments using the Gazebo environment and
in the real-world setting using a Parrot ANAFI quad-rotor and sub-scale ship
platform undergoing 6 degrees of freedom (DOF) deck motion
Towards an autonomous vision-based unmanned aerial system againstwildlife poachers
Poaching is an illegal activity that remains out of control in many countries. Based on the 2014 report of the United Nations and Interpol, the illegal trade of global wildlife and natural resources amounts to nearly $213 billion every year, which is even helping to fund armed conflicts. Poaching activities around the world are further pushing many animal species on the brink of extinction. Unfortunately, the traditional methods to fight against poachers are not enough, hence the new demands for more efficient approaches. In this context, the use of new technologies on sensors and algorithms, as well as aerial platforms is crucial to face the high increase of poaching activities in the last few years. Our work is focused on the use of vision sensors on UAVs for the detection and tracking of animals and poachers, as well as the use of such sensors to control quadrotors during autonomous vehicle following and autonomous landing.Peer Reviewe
Towards an autonomous vision-based unmanned aerial system against wildlife poachers.
Poaching is an illegal activity that remains out of control in many countries. Based on the 2014 report of the United Nations and Interpol, the illegal trade of global wildlife and natural resources amounts to nearly $ 213 billion every year, which is even helping to fund armed conflicts. Poaching activities around the world are further pushing many animal species on the brink of extinction. Unfortunately, the traditional methods to fight against poachers are not enough, hence the new demands for more efficient approaches. In this context, the use of new technologies on sensors and algorithms, as well as aerial platforms is crucial to face the high increase of poaching activities in the last few years. Our work is focused on the use of vision sensors on UAVs for the detection and tracking of animals and poachers, as well as the use of such sensors to control quadrotors during autonomous vehicle following and autonomous landing
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
- …