75 research outputs found
Efficiently Combining Human Demonstrations and Interventions for Safe Training of Autonomous Systems in Real-Time
This paper investigates how to utilize different forms of human interaction
to safely train autonomous systems in real-time by learning from both human
demonstrations and interventions. We implement two components of the
Cycle-of-Learning for Autonomous Systems, which is our framework for combining
multiple modalities of human interaction. The current effort employs human
demonstrations to teach a desired behavior via imitation learning, then
leverages intervention data to correct for undesired behaviors produced by the
imitation learner to teach novel tasks to an autonomous agent safely, after
only minutes of training. We demonstrate this method in an autonomous perching
task using a quadrotor with continuous roll, pitch, yaw, and throttle commands
and imagery captured from a downward-facing camera in a high-fidelity simulated
environment. Our method improves task completion performance for the same
amount of human interaction when compared to learning from demonstrations
alone, while also requiring on average 32% less data to achieve that
performance. This provides evidence that combining multiple modes of human
interaction can increase both the training speed and overall performance of
policies for autonomous systems.Comment: 9 pages, 6 figure
Master of Science
thesisFlying rotorcraft, such as helicopters and quadrotors, can gather useful information without the need for human presence, but they consume a great deal of power and have limited on-board energy resources. Our work aims to provide a passive perching mechanism so that a rotorcraft is able to grip branch-like perches and resist external wind disturbances, using only the weight of the rotorcraft to maintain the grip. Deviating from previous bio-inspired approaches, in this thesis, we propose a mechanism that incorporates a Sarrus linkage to convert the weight of the rotorcraft into grip force. We provide an analysis of the mechanism's kinematics, we present the static force equations that describe how the weight of the rotorcraft is converted into grip force onto a cylindrical perch, and we describe how grip forces relate to the ability to reject horizontal disturbances such as wind gusts. The mechanism is then optimized for use on a single perch size, and then for a range of perch sizes. We conclude by constructing a prototype mechanism, and we demonstrate its use with a remote-controlled helicopter
Robust Active Visual Perching with Quadrotors on Inclined Surfaces
Autonomous Micro Aerial Vehicles are deployed for a variety tasks including
surveillance and monitoring. Perching and staring allow the vehicle to monitor
targets without flying, saving battery power and increasing the overall mission
time without the need to frequently replace batteries. This paper addresses the
Active Visual Perching (AVP) control problem to autonomously perch on inclined
surfaces up to . Our approach generates dynamically feasible
trajectories to navigate and perch on a desired target location, while taking
into account actuator and Field of View (FoV) constraints. By replanning in
mid-flight, we take advantage of more accurate target localization increasing
the perching maneuver's robustness to target localization or control errors. We
leverage the Karush-Kuhn-Tucker (KKT) conditions to identify the compatibility
between planning objectives and the visual sensing constraint during the
planned maneuver. Furthermore, we experimentally identify the corresponding
boundary conditions that maximizes the spatio-temporal target visibility during
the perching maneuver. The proposed approach works on-board in real-time with
significant computational constraints relying exclusively on cameras and an
Inertial Measurement Unit (IMU). Experimental results validate the proposed
approach and shows the higher success rate as well as increased target
interception precision and accuracy with respect to a one-shot planning
approach, while still retaining aggressive capabilities with flight envelopes
that include large excursions from the hover position on inclined surfaces up
to 90, angular speeds up to 750~deg/s, and accelerations up to
10~m/s
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
A review of aerial manipulation of small-scale rotorcraft unmanned robotic systems
Small-scale rotorcraft unmanned robotic systems (SRURSs) are a kind of unmanned rotorcraft with manipulating devices. This review aims to provide an overview on aerial manipulation of SRURSs nowadays and promote relative research in the future. In the past decade, aerial manipulation of SRURSs has attracted the interest of researchers globally. This paper provides a literature review of the last 10 years (2008–2017) on SRURSs, and details achievements and challenges. Firstly, the definition, current state, development, classification, and challenges of SRURSs are introduced. Then, related papers are organized into two topical categories: mechanical structure design, and modeling and control. Following this, research groups involved in SRURS research and their major achievements are summarized and classified in the form of tables. The research groups are introduced in detail from seven parts. Finally, trends and challenges are compiled and presented to serve as a resource for researchers interested in aerial manipulation of SRURSs. The problem, trends, and challenges are described from three aspects. Conclusions of the paper are presented, and the future of SRURSs is discussed to enable further research interests
Master of Science
thesisAutonomous and teleoperated flying robots capable of perch-and-stare are desirable for reconnaissance missions. Current solutions for perch-and-stare applications utilize various methods to enable aircraft to land on a limited set of surfaces that are typically horizontal or vertical planes. Motivated by the fact that songbirds are able to sleep in trees, without requiring active muscle control to stay perched, the research presented here details a concept that allows for passive perching of rotorcraft on a variety of surfaces. This thesis presents two prototype iterations, where perching is accomplished through the integration of two components: a compliant, underactuated gripping foot and a collapsing leg mechanism that converts aircraft weight into tendon tension in order to passively actuate the foot. This thesis presents the design process and analysis of the mechanisms. Additionally, stability tests were performed on the second prototype, attached to a quadrotor, that detail the versatility of the system and ability of the system to support external moments. The results show promise that it is possible to passively perch a rotorcraft on multiple surfaces and support reasonable environmental disturbances
Enabling technologies for precise aerial manufacturing with unmanned aerial vehicles
The construction industry is currently experiencing a revolution with automation techniques
such as additive manufacturing and robot-enabled construction. Additive Manufacturing (AM)
is a key technology that can o er productivity improvement in the construction industry by
means of o -site prefabrication and on-site construction with automated systems. The key
bene t is that building elements can be fabricated with less materials and higher design freedom
compared to traditional manual methods.
O -site prefabrication with AM has been investigated for some time already, but it has limitations
in terms of logistical issues of components transportation and due to its lack of design
exibility on-site. On-site construction with automated systems, such as static gantry systems
and mobile ground robots performing AM tasks, can o er additional bene ts over o -site
prefabrication, but it needs further research before it will become practical and economical.
Ground-based automated construction systems also have the limitation that they cannot extend
the construction envelope beyond their physical size. The solution of using aerial robots
to liberate the process from the constrained construction envelope has been suggested, albeit
with technological challenges including precision of operation, uncertainty in environmental
interaction and energy e ciency.
This thesis investigates methods of precise manufacturing with aerial robots. In particular,
this work focuses on stabilisation mechanisms and origami-based structural elements that allow
aerial robots to operate in challenging environments. An integrated aerial self-aligning delta
manipulator has been utilised to increase the positioning accuracy of the aerial robots, and
a Material Extrusion (ME) process has been developed for Aerial Additive Manufacturing
(AAM). A 28-layer tower has been additively manufactured by aerial robots to demonstrate the
feasibility of AAM. Rotorigami and a bioinspired landing mechanism demonstrate their abilities
to overcome uncertainty in environmental interaction with impact protection capabilities and
improved robustness for UAV. Design principles using tensile anchoring methods have been
explored, enabling low-power operation and explores possibility of low-power aerial stabilisation.
The results demonstrate that precise aerial manufacturing needs to consider not only just the
robotic aspects, such as
ight control algorithms and mechatronics, but also material behaviour
and environmental interaction as factors for its success.Open Acces
Small Unmanned Aircraft Systems for Project-Based Engineering Education
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143092/1/6.2017-1377.pd
Developing a 3-DOF Compliant Perching Arm for a Free-Flying Robot on the International Space Station
This paper presents the design and control of the 3-DOF compliant perching arm for the free-flying Astrobee robots that will operate inside the International Space Station (ISS). The robots are intended to serve as a flexible platform for future guest scientists to use for zero-gravity robotics research - thus, the arm is designed to support manipulation research. It provides a 1-DOF underactuated tendon-driven gripper capable of enveloping a range of objects of different shapes and sizes. Co-located RGB camera and LIDAR sensors provide perception. The Astrobee robots will be capable of grasping each other in flight, to simulate orbital capture scenarios. The arm's end-effector module is swappable on-orbit, allowing guest scientists to add upgraded grippers, or even additional arm degrees of freedom. The design of the arm balances research capabilities with Astrobee's operational need to perch on ISS handrails to reduce power consumption. Basic arm functioning and grip strength were evaluated using an integrated Astrobee prototype riding on a low-friction air bearing
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