1,232 research outputs found
Nonlinear Control Strategies for Outdoor Aerial Manipulators
In this thesis, the design, validation and implementation of nonlinear control strategies for aerial manipulators
{i.e. aerial robots equipped with manipulators{ is studied, with special emphasis on the internal coupling of the
system and its resilience against external disturbances. For the rst, di erent decentralised control strategies
{i.e. using di erent control typologies for each one of the subsystems{ that indirectly take into account this
coupling have been analysed. As a result, a nonlinear strategy composed of two controllers is proposed. A higher
priority is given to the manipulation accuracy, relaxing the platform tracking, and hence obtaining a solution
improving the manipulation capabilities with the surrounding environment. To validate these results, thorough
stability and robustness analyses are provided, both theoretically and in simulation.
On the other hand, a signi cant e ort has been devoted to improving the response and applicability of
robot manipulators used in
ight via control. In particular, the design of controllers for lightweight
exible
manipulators {that reduce the consequences of incidents involving unforeseen contacts{ is analysed. Although
their inherent nature perfectly ts for aerial manipulation applications, the added
exibility produces unwanted
behaviours, such as second-order modes and uncertainties. To cope with them, an adaptable position nonlinear
control strategy is proposed. To validate this contribution, the stability of the approach is studied in theory
and its capabilities are proven in several experimental scenarios. In these, the robustness of the solution against
unforeseen impacts and contact with uncharacterised interfaces is demonstrated.
Subsequently, this strategy has been enriched with {multiaxis{ force control capabilities thanks to the
inclusion of an outer control loop modifying the manipulator reference. Accordingly, this additional applicationfocused
capability is added to the controlled system without loosing the modulated response of the inner-loop
position strategy. It is also worth noting that, thanks to the cascade-like nature of the modi cation, the transition
between position and force control modes is inherently smooth and automatic. The stability of this expanded
strategy has been theoretically analysed and the results validated in a set of experimental scenarios.
To validate the rst nonlinear approach with realistic outdoor simulations before its implementation, a
computational
uid dynamics analysis has been performed to obtain an explicit model of the aerodynamic
forces and torques applied to the blunt-body of the aerial platform in
ight. The results of this study have been
compared to the most common alternative nowadays, being highlighted that the proposed model signi cantly
surpasses this option in terms of accuracy. Moreover, it is worth underscoring that this characterisation could
be also employed in the future to develop control solutions with enhanced rejection capabilities against wind
conditions.
Finally, as the focus of this thesis is on the use of novel control strategies on real aerial manipulation outdoors
to improve their accuracy while performing complex tasks, a modular autopilot solution to be able to implement
them has been also developed. This general-purpose autopilot allows the implementation of new algorithms,
and facilitates their theory-to-experimentation transition. Taking into account this perspective, the proposed
tool employs the simple and widely-known MAS interface and the highly reliable PX4 autopilot as backup, thus
providing a redundant approach to handle unexpected incidents in
ight.En esta tesis se ha estudiado el diseño, validación e implementación de estrategias de control
no lineales para robots manipuladores aéreos –esto es, robots aéreos equipados con un sistema
de manipulación robótica–, dándose especial énfasis a las interacciones internas del sistema y a
su resiliencia frente a efectos externos. Para lo primero, se han analizado diferentes estrategias
de control descentralizado –es decir, que usan tipologías de control diferentes para cada uno de
los subsistemas–, pero que tienen indirectamente en consideración la interacción entre manipulación
y vuelo. Como resultado de esta línea, se propone una estretegia de control conformada
por dos controladores. Estos se coordinan de tal forma que se le da prioridad a la manipulación
sobre el seguimiento de posiciones del vehículo, produciéndose un sistema de control que mejora
la precisión de las interacciones entre el sistema manipulador y el entorno. Para validar estos resultados,
se ha analizado su estabilidad y robustez tanto teóricamente como mediante simulaciones
numéricas.
Por otro lado, se ha buscado mejorar la respuesta y aplicabilidad de los manipuladores que se
usan en vuelo mediante su control. Dentro de esta tendencia, la tesis se ha centrado en el diseño
de controladores para manipuladores ligeros flexibles, ya que estos permiten reducir el peso del
sistema completo y reducen el riesgo de incidentes debidos a contactos inesperados. Sin embargo,
la flexibilidad de estos produce comportamientos indeseados durante la operación, como la aparición
de modos de segundo orden y cierta incentidumbre en su comportamiento. Para reducir su
impacto en la precisión de las tareas de manipulación, se ha desarrollado un controlador no lineal
adaptable. Para validar estos resultados, se ha analizado la estabilidad del sistema teóricamente y se
han desarrollado una serie de experimentos. En ellos, se ha comprobado su robustez ante impactos
inesperados y contactos con elementos no caracterizados.
Posteriormente, esta estrategia para manipuladores flexibles ha sido ampliada al añadir un bucle
externo que posibilita el control en fuerzas en varias direcciones. Esto permite, mediante un único
controlador, mantener la suave respuesta de la estrategia. Además cabe destacar que, al contar esta
estrategia con un diseño en cascade, la transición entre los segmentos de desplazamiento del brazo
y de aplicación de fuerzas es fluida y automática. La estabilidad de esta estrategia ampliada ha sido
analizada teóricamente y los resultados han sido validados experimentalmente.
Para validar la primera estrategia mediante simulaciones que representen fielmente las condiciones
en exteriores antes de su implementación, ha sido necesario realizar un estudio mediante
mecánica de fluidos computacional para obtener un modelo explícito de las fuerzas y momentos
aerodinámicos a los que se efrenta la plataforma en vuelo. Los resultados de este estudio han
sido comparados con la alternativa más empleada actualmente, mostrándose que los avances del
método propuesto son sustanciales. Asimismo, es importante destacar que esta caracterización podría
también usarse en el futuro para desarrollar controladores con una respuesta mejorada ante
perturbaciones aerodinámicas, como en el caso de volar con viento. Finalmente, al ser esta una tesis centrada en las estrategias de control novedosas en sistemas
reales para la mejora de su rendimiento en misiones complejas, se ha desarrollado un autopiloto
modular fácilmente modificable para implementarlas. Este permite validar experimentalmente
nuevos algoritmos y facilita la transición entre teoría y práctica. Para ello, esta herramienta se
basa en una interfaz sencilla ampliamente conocida por los investigadores de robótica, Simulink®,
y cuenta con un autopiloto de respaldo, PX4, para enfrentarse a los incidentes inesperados que
pudieran surgir en vuelo
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
Safe local aerial manipulation for the installation of devices on power lines: Aerial-core first year results and designs
Article number 6220The power grid is an essential infrastructure in any country, comprising thousands of kilometers of power lines that require periodic inspection and maintenance, carried out nowadays by human operators in risky conditions. To increase safety and reduce time and cost with respect to conventional solutions involving manned helicopters and heavy vehicles, the AERIAL-CORE project proposes the development of aerial robots capable of performing aerial manipulation operations to assist human operators in power lines inspection and maintenance, allowing the installation of devices, such as bird flight diverters or electrical spacers, and the fast delivery and retrieval of tools. This manuscript describes the goals and functionalities to be developed for safe local aerial manipulation, presenting the preliminary designs and experimental results obtained in the first year of the project.European Union (UE). H2020 871479Ministerio de Ciencia, Innovación y Universidades de España FPI 201
Tracking and Grasping of Moving Objects Using Aerial Robotic Manipulators: A Brief Survey
Unmanned Aerial Vehicles (UAV) has evolved in recent years, their features have changed to be more useful to the society, although some years ago the drones had been thought to be teleoperated by humans and to take some pictures from above, which is useful; nevertheless, nowadays the drones are capable of developing autonomous tasks like tracking a dynamic target or even grasping different kind of objects. Some task like transporting heavy loads or manipulating complex shapes are more challenging for a single UAV, but for a fleet of them might be easier. This brief survey presents a compilation of relevant works related to tracking and grasping with aerial robotic manipulators, as well as cooperation among them. Moreover, challenges and limitations are presented in order to contribute with new areas of research. Finally, some trends in aerial manipulation are foreseeing for different sectors and relevant features for these kind of systems are standing out
On Aerial Robots with Grasping and Perching Capabilities: A Comprehensive Review
Over the last decade, there has been an increased interest in developing aerial robotic platforms that exhibit grasping and perching capabilities not only within the research community but also in companies across different industry sectors. Aerial robots range from standard multicopter vehicles/drones, to autonomous helicopters, and fixed-wing or hybrid devices. Such devices rely on a range of different solutions for achieving grasping and perching. These solutions can be classified as: 1) simple gripper systems, 2) arm-gripper systems, 3) tethered gripping mechanisms, 4) reconfigurable robot frames, 5) adhesion solutions, and 6) embedment solutions. Grasping and perching are two crucial capabilities that allow aerial robots to interact with the environment and execute a plethora of complex tasks, facilitating new applications that range from autonomous package delivery and search and rescue to autonomous inspection of dangerous or remote environments. In this review paper, we present the state-of-the-art in aerial grasping and perching mechanisms and we provide a comprehensive comparison of their characteristics. Furthermore, we analyze these mechanisms by comparing the advantages and disadvantages of the proposed technologies and we summarize the significant achievements in these two research topics. Finally, we conclude the review by suggesting a series of potential future research directions that we believe that are promising
High-Level Modular Autopilot Solution for Fast Prototyping of Unmanned Aerial Systems
Article number 9291382A redundant fast prototyping autopilot solution for unmanned aerial systems has been
developed and successfully tested outdoors. While its low-level backbone is executed in a Raspberry Pi
R
3 +
NAVIO2
R with a backup autopilot, the computational power of an Intel
R NUC mini-computer is employed
to implement complex functionalities directly in Simulink
R
, thus including in-flight debugging, tuning
and monitoring. Altogether, the presented tool provides a flexible and user-friendly high-level environment
with enhanced computational capabilities, which drastically reduces the prototyping timespans of complex
algorithms –between 50% and 75%, according to our long and proven experience in aerial robotics–, while
preventing incidents thanks to its redundant design with a human-in-the-loop pilot on the reliable PX4. Three
typical outdoor cases are carried out for validation in real-life scenarios, all mounted in a DJI
c F550 platform.
Full integration results and telemetry for more than 50 hours of outdoor flight tests are provided.Ministerio de Economía, Industria y Competitividad DPI2017-89790-RPrograma Horizonte 2020. Unión Europea 779411Programa Horizonte 2020. Unión Europea 87147
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