Search

This paper introduces a novel approach for regulating the pose of a free-flying dual-arm anthropomorphic space manipulator system (SMS) using a finite-time state-dependent Riccati equation (SDRE) controller. The proposed system finds applications in on-orbit satellite inspection, servicing, space structure assembly, and debris manipulation. The dual-arm SMS presented in this work consists of two 7 degrees of freedom (DoF) robotic arms mounted on a free-flying spacecraft, resulting in a complex 20-DoF system. Due to the high number of DoFs, advanced controller design and efficient computations are necessary. The finite-time SDRE controller relies on the state-dependent coefficient (SDC) parameterization matrices, which are nonlinear apparent linearizations of the dynamics. Conventionally, the computation of SDC matrices is offline and relies on the a priori derivation of the analytical equations governing the dynamics of the system. However, this strategy becomes computationally impractical for high DoF plants. To overcome this issue and deliver a more viable solution, a numerical method to construct and update the SDC matrices at each time step is presented. This approach relies on a screw-theory-based recursive Newton–Euler algorithm designed to reconstruct the manipulator inertia and Coriolis matrices. These quantities are the building blocks of the SDC parameters used in the synthesis of the SDRE controller. Simulation results demonstrate the performances of the finite-time SDRE controller augmented with the online update of the state-dependent coefficients.

This paper proposes rigid-body modelling and identification procedures for long-reach dual-arm manipulators in a cable-suspended pendulum configuration. The proposed model relies on a virtually constrained open kinematic chain and lends itself to be simulated through the most commonly used robotic simulators without explicitly account for the cables constraints and flexibility. Moreover, a dynamic parameters identification procedure is devised to improve the simulation model fidelity and reduce the sim-to-real gap for controllers deployment. We show the capability of our model to handle different cable configurations and suspension mechanisms by customising it for two representative cable-suspended dual-arm manipulation systems: the LiCAS arms suspended by a drone and the CRANEbot system, featuring two Pilz arms suspended by a crane. The identified dynamic models are validated by comparing their evolution with data acquired from the real systems showing a high (between 91.3% to 99.4%) correlation of the response signals. In a comparison performed with baseline pendulum models, our model increases the simulation accuracy from 64.4% to 85.9%. The simulation environment and the related controllers are released as open-source code.

This work investigates the dynamics modeling, control, and impact resolution between a floating object and a free-floating space manipulator (FFSM). The controller design is carried out by using an output- and state-dependent Riccati equation (OSDRE) approach. In a collision between an object and a mechanism, the computation of the generalized velocities and the impact force or impulse, which are interrelated, is a challenging problem. Taking into account the free-floating conditions of the space environment, the conservation of linear and angular momentum equations, combined with the conservation of kinetic energy under the elastic impact assumption, are used to find the unknown variables of the impact problem. The control problem addressed for the FFSM is to regulate its end-effector in a point-to-point motion scenario, this while the space manipulator suffers an unintended impact with a floating object, such as a damaged satellite or space debris. By proposing a safety pause starting with the occurrence of impact and for a short duration thereafter, the proposed OSDRE design succeeds in achieving the end-effector regulation control. Although the FFSM can reach the target point, it is shown that maintaining the end-effector regulation at the target is not feasible due to the momentum imparted to the FFSM as a result of the collision. To this end, we employ a simple thruster control on the space manipulator base to complete the regulation task. The theoretical development and controller design are demonstrated through a simulation case study of a spacecraft equipped with a three-link manipulator colliding with an object.

Esta Tesis Doctoral aborda el diseño, desarrollo y validación experimental de diferentes métodos para reforzar la percepción de los robots aéreos en escenarios de Inspección y Mantenimiento de infraestructuras industriales y civiles. Los métodos desarrollados permiten la operación totalmente autónoma de los robots aéreos sin depender de ninguna infraestructura externa, asumiendo que todos los sensores, métodos de percepción y dispositivos de procesamiento se encuentran a bordo del robot, y no requieren ninguna alteración del entorno. A lo largo de la Tesis se han seguido tres enfoques principales para el diseño de los diferentes métodos. Primero, el uso de esquemas multisensor que aprovechan las sinergias entre sensores para mitigar las debilidades de cada dispositivo individual. Segundo, la selección del modelo más adecuado para representar y estimar el estado del robot en cada escenario. Tercero, el uso de técnicas de percepción activa que mejoren la calidad de las entradas de percepción. Los enfoques propuestos aportan soluciones complementarias, que han dado lugar al desarrollo de cinco métodos contenidos en esta tesis, diseñados en función de las necesidades de cada aplicación estudiada. En primer lugar, esta Tesis Doctoral presenta un método de localización robusta basado en un enfoque multisensor y multihipótesis, que permite la navegación segura y autónoma de robots aéreos sin GNSS en escenarios complejos de inspección industrial y civil. El método integra características de cámara RGB y LiDAR en el mismo marco estadístico, y adopta un enfoque iterativo multihipótesis eficiente. En segundo lugar, esta Tesis Doctoral introduce el uso de mallas (meshes) probabilísticas para representar superficies localmente planares en misiones de inspección de largo alcance en escenarios pobres en información geométrica. Las mallas permiten representar de forma coherente las superficies planas y usar técnicas de decimación para mejorar la fidelidad del mapa, reduciendo la in, This PhD Thesis addresses the design, development, and experimental validation of different methods for strengthening the perception of aerial robots in the Inspection and Maintenance of industrial and civil infrastructures. The developed perception methods enable fully autonomous aerial robot operation without depending on any external infrastructure, assuming that all involved sensors, perception methods, or processing computers are onboard the aerial robot, and require no alteration of the setting. This PhD Thesis follows three main approaches for the design of these methods. First, the use of multisensor systems that take advantage of complementary sensor information to mitigate the weaknesses of each individual device. Second, the selection of the most adequate state representation and estimation scheme for each studied scenario. Third, the adoption of active perception techniques that improve the quality of the perception inputs. The proposed approaches provide complementary solutions, that have been combined along five different methods during this PhD Thesis, designed in function on the needs of each studied application. First, this PhD Thesis presents a robust multi-sensor multi-hypothesis robot localization method, that allows the safe and autonomous navigation of aerial robots in complex, GNSS-denied industrial and civil inspection scenarios. The method integrates RGB camera and LiDAR features are in the same statistical framework, and adopts an efficient multi-hypothesis iterative scheme to cope with the potentially strong symmetries in the scenarios. Second, this PhD Thesis introduces the use of probabilistic meshes to represent locally planar surfaces in LiDAR-based long-range inspection missions in scenarios that are poor in geometrical information. Meshes consistently represent planar surfaces and enable the use of decimation techniques to reduce the influence of the measurement noise in the map and improve its fidelity. They are combined with a prob

The growing market in Remotely Piloted Aircraft Systems (RPAS) and the need for cost-effective “Detect and Avoid (DAA)” systems are critical issues up to date towards enabling safe beyond visual line of sight (BVLOS) operations. In hopes of promoting earlier threat detection on DAA systems, we benchmark several object detection algorithms on multiple graphical processing units for the concrete DAA use case. Two state-of-the-art “real-time object detection” and “object detection” model sets are trained using our CENTINELA dataset, and their performances are compared for a wide range of configurations. Results demonstrate that one-stage architecture YOLO variants outperform ViT on all tested hardware in terms of mean average precision and inference speed despite their architecture complexity gap. Additional resources are available to the reader at https://github.com/fada-catec/detection-for-safe-rpas-operation.

Unmanned Aerial Systems (UAS) will become commonplace, the number of UAS flying in European airspace is expected to increase from a few thousand to hundreds of thousands by 2050. To prepare for this approaching, national and international organizations involved in aerial traffic management are now developing new laws and restructuring the airspace to incorporate UAS into civil airspace. The Single European Sky ATM Research considers the development of the U-space, a crucial step to enable the safe, secure, and efficient access of a large set of UAS into airspace. The design, integration, and validation of a set of modules that contribute to our UTM architecture for advanced U-space services are described in this Thesis. With an emphasis on conflict detection and resolution features, the architecture is flexible, modular, and scalable. The UTM is designed to work without the need for human involvement, to achieve U-space required scalability due to the large number of expected operations. However, it recommends actions to the UAS operator since, under current regulations, the operator is accountable for carrying out the recommendations of the UTM. Moreover, our development is based on the Robot Operating System (ROS) and is open source. The main developments of the proposed Thesis are monitoring and tactical deconfliction services, which are in charge of identifying and resolving possible conflicts that arise in the shared airspace of several UAS. By limiting the conflict search to a local search surrounding each waypoint, the proposed conflict detection method aims to improve conflict detection. By splitting the issue down into smaller subproblems with only two waypoints, the conflict resolution method tries to decrease the deviation distance from the initial flight plan. The proposed method for resolving potential threats is based on the premise that UAS can follow trajectories in time and space properly. Therefore, another contribution of the presented Thesis is a, Los sistemas aéreos no tripulados (UAS en inglés) se convertirán en algo habitual. Se prevé que el número de UAS que vuelen en el espacio aéreo europeo pase de unos pocos miles a cientos de miles en 2050. Para prepararse para esta aproximación, las organizaciones nacionales e internacionales dedicadas a la gestión del tráfico aéreo están elaborando nuevas leyes y reestructurando el espacio aéreo para incorporar los UAS al espacio aéreo civil. SESAR (del inglés Single European Sky ATM Research) considera el desarrollo de U-space, un paso crucial para permitir el acceso seguro y eficiente de un gran conjunto de UAS al espacio aéreo. En esta Tesis se describe el diseño, la integración y la validación de un conjunto de módulos que contribuyen a nuestra arquitectura UTM (del inglés Unmanned aerial system Traffic Management) para los servicios avanzados del U-space. Con un énfasis en las características de detección y resolución de conflictos, la arquitectura es flexible, modular y escalable. La UTM está diseñada para funcionar sin necesidad de intervención humana, para lograr la escalabilidad requerida por U-space debido al gran número de operaciones previstas. Sin embargo, la UTM únicamente recomienda acciones al operador del UAS ya que, según la normativa vigente, el operador es responsable de las operaciones realizadas. Además, nuestro desarrollo está basado en el Sistema Operativo de Robots (ROS en inglés) y es de código abierto. Los principales desarrollos de la presente Tesis son los servicios de monitorización y evitación de conflictos, que se encargan de identificar y resolver los posibles conflictos que surjan en el espacio aéreo compartido de varios UAS. Limitando la búsqueda de conflictos a una búsqueda local alrededor de cada punto de ruta, el método de detección de conflictos pretende mejorar la detección de conflictos. Al dividir el problema en subproblemas más pequeños con sólo dos puntos de ruta, el método de resolución de conflictos intenta disminuir la

This paper proposes the application of a very low weight (3.2 kg) anthropomorphic dual-arm system capable of rolling along linear infrastructures such as power lines to perform dexterous and bimanual manipulation tasks like the installation of clip-type bird flight diverters or conduct contact-based inspection operations on pipelines to detect corrosion or leaks. The kinematic configuration of the arms, with three joints at the shoulder and one at the elbow, allows the natural replication of the human movements to conduct these tasks, exploiting also the kinematic redundancy of the shoulder to maintain the equilibrium while perching on the line. The dynamic model of the system is derived to design a self-stabilizing controller that maintains the base of the arms at an equilibrium point. The state-dependent Riccati equation (SDRE) controller is chosen for this purpose since the system is under-actuated and the contribution of the control gain (with nonlinear optimal structure) on all states is critical. The SDRE is a nonlinear optimal controller that extends the margins of stability in comparison with linear ones. Simulation results show that the SDRE performs the regulation to the equilibrium point successfully and evidence better performance with respect to a linear quadratic regulator (LQR). The system is validated in an outdoor testbed consisting of a power line mockup, presenting experimental results to evaluate the SDRE and LQR controllers, demonstrating also the autonomous installation of clip-type bird flight diverters and the aerial deployment using a multirotor platform.

The sampling and monitoring of nature have become an important subject due to the rapid loss of green areas. This work proposes a possible solution for a sampling method of the leaves using an ornithopter robot equipped with an onboard 94.1 g dual-arm cooperative manipulator. One hand of the robot is a scissors-type arm and the other one is a gripper to perform the collection, approximately similar to an operation by human fingers. In the move toward autonomy, a stereo camera has been added to the ornithopter to provide visual feedback for the stem, which reports the position of the cutting and grasping. The position of the stem is detected by a stereo vision processing system and the inverse kinematics of the dual-arm commands both gripper and scissors to the right position. Those trajectories are smooth and avoid any damage to the actuators. The real-time execution of the vision algorithm takes place in the lightweight main processor of the ornithopter which sends the estimated stem localization to a microcontroller board that controls the arms. The experimental results both indoors and outdoors confirmed the feasibility of this sampling method. The operation of the dual-arm manipulator is done after the perching of the system on a stem. The topic of perching has been presented in previous works and here we focus on the sampling procedure and vision/manipulator design. The flight experimentation also approves the weight of the dual-arm system for installation on the flapping-wing flying robot.

The cruising velocity of animals, or robotic vehicles, that use flapping wings or fins to propel themselves is not constant but oscillates around a mean value with an amplitude usually much smaller than the mean, and a frequency that typically doubles the flapping frequency. Quantifying the effect that these velocity fluctuations may have on the propulsion of a flapping and oscillating airfoil is of great relevance to properly modeling the self-propelled performance of these animals or robotic vehicles. This is the objective of the present work, where the force and moment that an oscillating stream exerts on a two-dimensional pitching and heaving airfoil are obtained analytically using the vortical impulse theory in the linear potential flow limit. The thrust force of the flapping airfoil in a pulsating stream in this limit is obtained here for the first time. The lift force and moment derived here contain new terms in relation to the pioneering work by Greenberg (1947), which are shown quantitatively unimportant. The theoretical results obtained here are compared with existing computational data for flapping foils immersed in a stream with velocity oscillating sinusoidally about a mean value. © 2023 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Esta tesis doctoral contribuye al estado actual de la robótica aérea desarrollando sistemas bioinspirados que permiten reducir los riesgos para las personas durante la interacción con los robots. Para ello se require ir más allá de los conceptos tradicionales de la robótica. En cuanto a la interacción, las plataformas aéreas tradicionales, como los multicópteros y alas fijas tienen limitadas capacidades debido al uso de hélices como mecanismos para la generación de propulsión. Esto se hace aún más notorio en los casos en los que se interacciona con usuarios que no están acostumbrados a su uso. Otros riesgos añadidos por estas son la energía de impacto producida, en el caso del ala fija por su velocidad de vuelo, y en el caso de multicopteros, por el peso y la ausencia de superficies aerodinámicas. Esta tesis propone el uso de ornitópteros para mitigar los riesgos generados por las plataformas aéreas tradicionales. Sin embargo, las capacidades de vuelos de estos están limitadas debido a su estado de desarrollo. En esta investigación se propone contribuir al estado actual de los ornitópteros de dos maneras. La primera, desarrollando sistemas de manipulación que les permitan interaccionar con el medio. La segunda, contribuyendo al desarrollo de sistemas de vuelo que le permitan superar las limitaciones actuales. La manipulación era un campo con pocos desarrollos en ornitópteros al comienzo de esta investigación. El sistema tiene que ser capaz de manipular una gran variedad de objetos. A su vez, tiene que mantener la rigidez necesaria para generar el suficiente agarre manteniendo el equilibrio durante el posado en diferentes lugares. También es objetivo de este manipulador incrementar la seguridad de interacción con humanos siendo capaz de realizar el posado en su brazo. Para alcanzar estos objetivos los manipuladores han utilizado dispositivos y materiales de robótica blanda tomando a las aves como inspiración y base del desarrollo. Para ello se ha realizado un profund, This Ph.D. thesis contributes to the current aerial robotics state-of-the-art developing bioinspired systems that reduce the risk during cooperation activities. It implies top abandon the traditional concept that sets the base of robotics. Interaction is the main capability that developed systems want to improve. However, traditional aerial platforms are unsuitable for human interaction. The use of sharp propellers makes this platform dangerous for non-professional users. Other risks, such as flight speed in the case of fixed wings and the absence of glide in the case of multirotors, limit their interaction capabilities. This dissertation proposes using Flapping Wing Aerial Robots (FWAR) to mitigate the risks generated by traditional Unmanned Aerial Vehicles (UAV). However, this platform is under development, and its flight capabilities are limited. The research explores two ways to contribute to the development of ornithopters. The first one is to provide ornithopters with manipulation capabilities. The second one is to develop aerial systems that contribute to the flight phase, overcoming the current limitations of the platform. Manipulation is a new line of research for ornithopters. The developed system must be able to manipulate a wide range of objects and, at the same time, generate enough grip to maintain balance in case of perching. In addition, the system must maintain a soft structure to perch on and cooperate with human arms. The manipulators are based on bird-inspired soft robotics technologies to achieve these goals. It will also involve an in-depth study of material and actuation techniques. The use of novel actuation technologies such as Shape Memory Alloys (SMA) will help overcome the payload limitations of ornithopters. These methods will be studied and described in the dissertation. With the aim of relaxing the payload and maneuverability constraints. This doctoral thesis proposes to mimic the flight devices that birds have. This development will b

Flapping wing robots show promise as platforms for safe and efficient flight in near-human operations, thanks to their ability to agile maneuver or perch at a low Reynolds number. The growing trend in the automatization of these robots has to go hand in hand with an increase in the payload capacity. This work provides a new passive morphing wing prototype to increase the payload of this type of UAV. The prototype is based on a biased elastic joint and the holistic research also includes the modelling, simulation and optimization scheme, thus allowing to adapt the prototype for any flapping wing robot. This model has been validated through flight experiments on the available platform, and it has also been demonstrated that the morphing prototype can increase the lift of the robot under study by up to 16% in real flight and 10% of estimated consumption reduction.

The increasing usage of multi-rotor aerial platforms and the reliability of flights enabled researchers to add equipment and devices to them for application. The addition of lightweight manipulators, grippers, and mechanisms to fulfill specific tasks has been reported frequently recently. This work pushes the idea one step ahead and uses an Artificial Human Hand (AHH) in an uncrewed aerial vehicle for aerial manipulation, device delivery, and co-operation with human workers. This application requires an effective end-effector capable of grasping and holding objects of different shapes. The AHH is a lightweight custom-made human-inspired design actuated using Shape Memory Alloy (SMA) materials. The SMA actuators offer significantly high forces with respect to their light weights though the control of these new actuators is a challenge that has been successfully demonstrated in this paper. The control of the SMA actuators could be achieved via heat exchange on the actuator, indirectly carried out by changing the current. The benefit of using this new actuator is removing the motors and mechanical mechanisms and simplifying the design. A soft cover is developed for the AHH to add friction and make it closer to a human hand. The modeling of the structured actuators on the system through tendons is presented, and a series of experiments for handling and manipulating different objects have been conducted. The objects were chosen with different weights and shapes to show the effectiveness of the design. An analysis of a generated torque of the manipulator for different cylindrical objects has been carried out. An analysis and comparison for grasping a series of items, pressure and temperature analysis, and the weight-to-volume ratio have been presented.

Con el desarrollo de la robótica aérea han aparecido nuevas plataformas de multirotores de actuación completa (fully-actuated en inglés), las cuales tienen la capacidad de desplazarse sin inclinar la plataforma. Este artículo presenta una comparación en cuanto a capacidades de movimiento entre un hexarotor de rotores coplanarios, configuración estándar, y un hexarotor de rotores inclinados, configuración fully-actuated. Para ello, se presenta el diseño, modelo y control de ambas configuraciones. Tras el montaje de las plataformas, se comparan con diferentes trayectorias, mediante simulaciones y experimentos. Asímismo, se muestran capacidades exclusivas de la plataforma fully-actuated, como la capacidad de mantenerse en hover con un ángulo de inclinación. Finalmente, se presenta la aplicación de la plataforma fully-actuated para inspección visual de techos de puentes. Vídeo del artículo: https://youtu.be/d95Qvz5hba4, With the development of aerial robotics, new multi-rotor platforms, known as fully-actuated, have appeared. These platforms have the ability to move without tilting the platform. This article presents a comparison in terms of motion capabilities between a coplanar hexarotor, standard configuration, and a tilted-propellers hexarotor, fully-actuated configuration. For this purpose, this paper presents the design, modelling and control of both configurations. Both platforms are compared with different trajectories through simulations and experiments. Also, unique capabilities of the fully-actuated platform, such as the ability to hover at a tilt angle, are shown. Finally, the use of the fully-actuated platform for visual inspection of bridge beams is included. Video of the paper: https://youtu.be/d95Qvz5hba4

The flapping-wing technology has emerged recently in the application of unmanned aerial robotics for autonomous flight, control, inspection, monitoring, and manipulation. Despite the advances in applications and outdoor manual flights (open-loop control), closed-loop control is yet to be investigated. This work presents a nonlinear optimal closed-loop control design via the state-dependent Riccati equation (SDRE) for a flapping-wing flying robot (FWFR). Considering that the dynamic modeling of the flapping-wing robot is complex, a proper model for the implementation of nonlinear control methods is demanded. This work proposes an alternative approach to deliver an equivalent dynamic for the translation of the system and a simplified model for orientation, to find equivalent dynamics for the whole system. The objective is to see the effect of flapping (periodic oscillation) on behavior through a simple model in simulation. Then the SDRE controller is applied to the derived model and implemented in simulations and experiments. The robot bird is a 1.6 m wingspan flapping-wing system (six-degree-of-freedom robot) with four actuators, three in the tail, and one as the flapping input. The underactuated system has been controlled successfully in position and orientation. The control loop is closed by the motion capture system in the indoor test bed where the experiments of flight have been successfully done.

Motivated by the convenience of improving the performance of long-reach aerial manipulators in the realization of maintenance tasks on high-voltage power lines, this paper proposes a constrained design optimization method for dual-arm aerial manipulators intended to reduce the weight while increasing the workspace of the robot. This configuration, in which the arms are separated from the aerial platform through a long reach link similar to a pendulum, improves safety in the interaction with human workers, reduces the electromagnetic interference of high voltage power lines on the electronics, as well as the aerodynamic downwash effect due to the propellers. However, the long-reach link introduces undesired vibrations on the manipulator due to its flexibility, so its length imposes a trade-off between the safety of operation as a positive side-effect and vibration as a negative one. Therefore, the cost function in the optimization problem also accounts for this factor, limiting the vibration to a fixed predefined value. A recent optimization approach is used here to minimize the cost function and solve the problem, verified by particle swarm optimization as a basis to confirm the correctness of the obtained data.

The closed-loop position control of a flapping-wing flying robot (FWFR) is a challenging task. A complete six-degree-of-freedom (DoF) modeling and control design is preferable though that imposes complexity on the procedure and analysis of the oscillations in the trajectory. Another approach could be studying independent state variables of the system and designing a controller for them. This will provide the possibility of a better understanding of the dynamic, comparing to experimental data, then use this information for moving forward to complete 6-DoF modeling. In this work, a simple linear proportional closed-loop controller is proposed and analyzed for an equivalent dynamic model of the flapping-wing flying robot. The equivalent dynamic modeling considers the flapping motion as a base excitation that disturbs the system in oscillatory behavior. The frequency of the oscillation and data of the motion was obtained from previous experimental results and used in the modeling. The designed controller performed the regulation task easily and regulated the system to a series of set-point control successfully. The motivation for the selection of a proportional control is to keep the design as simple as possible to analyze the excitation and behavior of the flapping more precisely. A discussion on the transient and steady-state flight and the role of control design on them have been presented in this work.

This paper presents an equivalent dynamic model for vertical regulation control of a flapping-wing flying robot. The model is presented based on the data of a series of flight experiments for an available platform. The system shows oscillations in motion in all experiments with an approximate frequency between [3. 5, 4. 5](Hz), changing within a limited range. The behavior of the equivalent model represents a system with base excitation. The displacement transmissibility ratio (TR) is found for the model to investigate the oscillatory behavior in the system during the flight. Reduction of the oscillations through the transmissibility ratio will decrease the uncertainty in flight and consequently, that could increase the success rate of perching on a branch (now it has a 10 - 15(cm) uncertain periodic motion); perching needs precision on the last meter approaching phase. An analytical expression for TR is presented which is used for parameter selection, tuning, and selection of the flapping frequency, as the base excitation source. The study shows that the robot works in a proper zone of the frequency ratio, and also, the sensitivity of the TR is high concerning the changes in the stiffness constant.

This letter is focused on the benchmark evaluation and comparison of the flapping and fixed wing flight modes on an hybrid platform developed for the realization of autonomous inspection operations outdoors. The platform combines the high range and endurance of fixed-wing UAVs (unmanned aerial vehicles), with the higher maneuverability and intrinsic safety of flapping wing in the interaction with humans during the hand launch and capture. A unified model of the hybrid platform is derived for both configurations following the Lagrange formulation to express the multi-body dynamics and aerodynamic forces of the flapping wing and the propellers. The proposed control scheme exploits the similarities of both flight modes in the tail actuation and in the generation of thrust either with the flapping wings or the propellers, in such a way that it can be implemented on conventional autopilots, facilitating in this way the adoption of this type of aerial platforms. To evaluate and compare the performance of both modes, a set of benchmark tests and metrics are defined, including the energy efficiency in forward flight, trajectory tracking, hand launch and capture, and accuracy in visual inspection. Experimental results in outdoors validate the developed prototype, identifying the fixed/flapping transitions, and evidencing the higher energy efficiency of the flapping wing mode compared to the fixed wing.

This work studies a stabilization problem of flapping-wing flying robots (FWFRs) before a take-off phase while a robot is on a branch. The claw of the FWFR grasps the branch with enough friction to hold the system steady in a stationary condition. Before the take-off, the claw opens itself and the friction between the claw and branch vanishes. At that moment, the mechanical model turns into an under-actuated multi-link (serial configuration) robotic system where the first joint can rotate freely without any friction as opposed to rotation. The stabilization and balancing are the crucial tasks before take-off. This work explores a new methodology to control an under-actuated lightweight manipulator for its future adaptation to FWFR to improve the stabilization performance before take-off. The setup tries to mimic the birds with two-link legs, a body link, and 2-DoF (degrees of freedom) arms, being all active links except the first passive one. In contrast to common arms, the lightweight-design restriction limits the frame size and requires micromotors. With all of these constraints, control design is a challenge, hence, the system is categorized: a) the leg subsystem (under-actuated), including the two first links, and b) the body and arm subsystem (fully actuated) with the rest of links. The fully-actuated links are controlled by feedback linearization and the under-actuated part with active disturbance rejection control (ADRC) for estimation and rejection of the coupling between both subsystems. The mechanical design, modeling, and control of the proposed system are reported in this work. Experimental results have been also proposed to present a proof of concept for this modeling and control approach.

This Ph.D. Thesis aims at contributing to the robot perception community by exploring the advantages of event cameras for aerial robotics, in particular on flapping-wing robots in which event-based vision is almost unexplored. It proposes a set of tools and perception algorithms to leverage the advantages of event-based vision in aerial robot applications. The proposed methods are experimentally validated in two types of aerial robots: multirotors and ornithopters. These platforms describe several challenges for vision-based perception. For instance, the agile motion of multirotors and the flapping strokes caused by ornithopters generate blurred images which may hinder the performance of frame-based approaches. Further, ornithopters and multirotors performing fast maneuvers require quick perception algorithms to update as soon as possible the perception information for robot navigation. Besides, both types of robots have limited payload and power capacity to mount and feed perception hardware. In particular, equipping ornithopter robots with additional sensors is a complex task as they have very constrained payload and strict weight distribution. Event cameras offer relevant advantages for robot perception such as microsecond pixel resolution, robustness to motion blur, high dynamic range, and low power consumption. This Ph.D. Thesis focuses on leveraging these advantages for aerial robot perception and validating the use of event-based vision on board these platforms. First, this Ph.D. Thesis presents a set of event-based low-level processing algorithms. These methods intend to contribute to the event-based vision community by providing a set of low-level algorithms that directly process the event stream instead of using frame-based representations. The proposed methods are integrated into the different high-level perception algorithms described in this Ph.D. Thesis. Second, this Ph.D. Thesis proposes an event-vision guidance method for aerial robots. It includes a, Esta Tesis Doctoral tiene como objetivo explorar las ventajas ofrecidas por las cámaras de eventos en la robótica aérea, en particular, en robots de ala batiente en los que la visión basada en eventos se encuentra prácticamente inexplorada. Esta Tesis Doctoral propone un conjunto de herramientas y algoritmos de percepción para aprovechar las ventajas de la visión basada en eventos en aplicaciones de robótica aérea. Los métodos propuestos se validan experimentalmente en dos tipos de robots aéreos: multirotores y ornitópteros. Estas plataformas suponen varios desafíos para la percepción basada en visión artificial. Por ejemplo, el movimiento ágil de los multirotores y los aleteos causados por los ornitópteros generan imágenes con desenfoque por movimiento (o en ingles motion blur ) que pueden afectar al rendimiento de algoritmos de percepción basados en imágenes. Adicionalmente, los ornitópteros y multirrotores que realizan maniobras rápidas requieren algoritmos de percepción que actualicen rápidamente la información usada para la navegación del robot. Además, ambos tipos de plataformas tienen carga útil y potencia reducidas lo que limita el tipo y la cantidad de hardware de percepción a bordo. Equipar ornitópteros con sensores de percepción es una tarea compleja, ya que estas plataformas tienen una carga útil muy restringida y una distribución estricta de peso. Las cámaras de eventos ofrecen varias ventajas para la percepción en robótica: píxeles con resolución de microsegundos, robustez al desenfoque por movimiento, alto rango dinámico y bajo consumo de energía. Esta Tesis Doctoral se enfoca en aprovechar estas ventajas para el desarrollo de sistemas de percepción para robots aéreos y validar su uso a bordo de estas plataformas. Primero, esta Tesis Doctoral presenta un conjunto de algoritmos de procesamiento de eventos de bajo nivel. Estos métodos tienen como objetivo contribuir a la comunidad de visión basada en eventos proporcionando un conjunto de algoritmos que

[Resumen] Este artículo presenta la evaluación experimental de un sistema de teleoperación cinestético desarrollado para la realización de tareas de manipulación diestra con dos brazos robóticos en aplicaciones aéreas o de base fija, tales como operaciones de mantenimiento en entornos industriales, o la recogida y entrega de paquetes en escenarios logísticos. El sistema consta de una pareja de brazos antropomórficos de muy bajo peso con capacidad de acomodación mecánica (LiCAS) en configuración maestro-esclavo, de tal forma que los movimiento aplicados por el usuario humano en el maestro se replican articulación por articulación al robot esclavo, resultando en una interfaz natural e intuitiva que facilita la transferencia de las habilidades de manipulación entre el humano y el robot. El muy bajo peso de los brazos robóticos (1 - 2.5 kg) hace posible su integración en plataformas multi-rotor de medio tamaño y su fácil despliegue en cualquier escenario de interiores o exteriores. Las capacidades del sistema de teloperación LiCAS han sido evaluadas con una placa de prubeas para manipuladores industriales, así como en una operación de manipulación aérea., [Abstract] This paper presents the experimental evaluation of a kinaesthetic teleoperation system developed for the realization of dexterous bimanual manipulation tasks in aerial or ground service applications such as maintenance operations in industrial settings, or in aerial parcel grasping and delivery in logistics scenarios. The system consists of a pair of lightweight and compliant anthropomorphic dual arm manipulators (LiCAS) in leader-follower configuration, in such a way that the motion commands applied by the human user on the leader dual arm are replicated joint by joint in the follower dual arm, resulting in a natural and intuitive interface that facilitates transferring the human manipulation skills to the robot. The very low weight of the robotic arms (1 – 2.5 kg) makes possible their integration in medium scale multi-rotors and the fast deployment in any indoor/outdoor scenario. The performance of the LiCAS teleoperation system is evaluated with a Task Board used for benchmarking industrial manipulators, as well as in an aerial manipulation operation.

Many sensor systems in robotics are bio-inspired by similar mechanisms in living creatures. Birds frequently use their beaks to grasp and manipulate objects. This work proposes a very lightweight sensor system that emulates a bird’s beak, thus allowing flapping aerial robots to interact with the environment, as e.g. to perform grasping or manipulation tasks. The sensor system is composed of a flexible link (beam) actuated by a micro servomotor, two strain gauges placed on different points and a rigid link opposed. Additionally, a new algorithm is also developed that estimates the instant at which the beak impacts with an object, the contact position and the exerted force. Our sensor system outperforms the existing designs in robotics applications, because it is lightweight, small, cheap, with very low computational load and without any complementary perception. It is demonstrated that the adequate placement of two strain gauges allow the estimation of the contact point and the force exerted between the beam and an object, and the accuracy achieved is enough to reckon properties of the object and develop force control systems. The validation has been made and reported through finite-element simulations and experiments, and the results illustrate the efficiency of the prototype and the proposed algorithm.

This work investigates the gravity compensation topic, from a control perspective. Thegravity could be levelled by a compensating mechanical system or in the control law, suchas proportional derivative (PD) plus gravity, sliding mode control, or computed torquemethod. The gravity compensation term is missing in linear and nonlinear optimal con-trol, in both continuous- and discrete-time domains. The equilibrium point of the controlsystem is usually zero and this makes it impossible to perform regulation when the desiredcondition is not set at origin or in other cases, where the gravity vector is not zero at theequilibrium point. The system needs a steady-state input signal to compensate for the grav-ity in those conditions. The stability proof of the gravity compensated control law basedon nonlinear optimal control and the corresponding deviation from optimality, with proof,are introduced in this work. The same concept exists in discrete-time control since it usesanalog to digital conversion of the system and that includes the gravity vector of the sys-tem. The simulation results highlight two important cases, a robotic manipulator and atilted-rotor hexacopter, as an application to the claimed theoretical statements.

The unsteady aerodynamics of flapping low-aspect-ratio ellipsoidal-wings in ornithopters is analyzed and modeled by the use of three dimensional Computational Fluid Dynamics (CFD) simulations. The range of interest is high amplitude, moderate frequency flapping, and low to moderate angles of attack at Reynolds around 105, where autonomous ornithopters like GRIFFIN are able to perform complex maneuvers such as perching. The results obtained show that the Leading Edge Vortex is produced above a certain Strouhal and angle of attack at downstroke. The frequency response of the aerodynamic loads are compared with the classical analytical models, observing that analytical models based on absence of viscosity and small perturbations are not appropriate for the range of interest. Through the 3D CFD aerodynamic loads database, a finite memory Volterra model is identified in order to predict the characteristics of forces and moments produced by the flapping wing. A good agreement with the 3D CFD simulations has been found by considering a reduced-order model depending on the effective angle of attack of the surrogate airfoil located at 70% of the semi-span at three-quarters chord on the airfoil, in agreement with the literature. Finally, a methodology for validation with a high-accuracy Motion Capture System and without the need of wind tunnel is proposed. As a result the proposed model provides better estimates than classical analytical ones.

Multirotor aerial robots are becoming widely used for the inspection of powerlines. To enable continuous, robust inspection without human intervention, the robots must be able to perch on the powerlines to recharge their batteries. Highly versatile perching capabilities are necessary to adapt to the variety of configurations and constraints that are present in real powerline systems. This letter presents a novel perching trajectory generation framework that computes perception-aware, collision-free, and dynamically-feasible maneuvers to guide the robot to the desired final state. Trajectory generation is achieved via solving a Nonlinear Programming problem using the Primal-Dual Interior Point method. The problem considers the full dynamic model of the robot down to its single rotor thrusts and minimizes the final pose and velocity errors while avoiding collisions and maximizing the visibility of the powerline during the maneuver. The generated maneuvers consider both the perching and the posterior recovery trajectories. The framework adopts costs and constraints defined by efficient mathematical representations of powerlines, enabling online onboard execution in resource-constrained hardware. The method is validated on-board an agile quadrotor conducting powerline inspection and various perching maneuvers with final pitch values of up to 180° .

This work proposes a novel proportional-derivative (PD)-type state-dependent Riccati equation (SDRE) approach with iterative learning control (ILC) augmentation. On the one hand, the PD-type control gains could adopt many useful available criteria and tools of conventional PD controllers. On the other hand, the SDRE adds nonlinear and optimality characteristics to the controller, i.e., increasing the stability margins. These advantages with the ILC correction part deliver a precise control law with the capability of error reduction by learning. The SDRE provides a symmetric-positive-definite distributed nonlinear suboptimal gain K(x) for the control input law u = −R−1(x)BT(x)K(x)x. The sub-blocks of the overall gain R−1(x)BT(x)K(x), are not necessarily symmetric positive definite. A new design is proposed to transform the optimal gain into two symmetric-positive-definite gains like PD-type controllers as u = − KSP(x)e-KSD(x)e. The new form allows us to analytically prove the stability of the proposed learning-based controller for mechanical systems; and presents guaranteed uniform boundedness in finite-time between learning loops. The symmetric PD-type controller is also developed for the state-dependent differential Riccati equation (SDDRE) to manipulate the final time. The SDDRE expresses a differential equation with a final boundary condition, which imposes a constraint on time that could be used for finite-time control. So, the availability of PD-type finite-time control is an asset for enhancing the conventional classical linear controllers with this tool. The learning rules benefit from the gradient descent method for both regulation and tracking cases. One of the advantages of this approach is a guaranteed-stability even from the first loop of learning. A mechanical manipulator, as an illustrative example, was simulated for both regulation and tracking problems. Successful experimental validation was done to show the capability of the system in practice by th

This paper presents a novel algorithm to plan energy-efficient trajectories for autonomous ornithopters. In general, trajectory optimization is quite a relevant problem for practical applications with Unmanned Aerial Vehicles (UAVs). Even though the problem has been well studied for fixed and rotatory-wing vehicles, there are far fewer works exploring it for flapping-wing UAVs, like ornithopters. These are of interest for many applica- tions where long-flight endurance, but also hovering capabilities, are required. We propose an efficient approach to plan ornithopter trajectories that minimize energy consumption by combining gliding and flapping maneu- vers. Our algorithm builds a tree of dynamically feasible trajectories and it applies heuristic search for efficient online planning, using reference curves to guide the search and prune states. We present computational ex- periments to analyze and tune the key parameters, as well as a comparison against a recent alternative proba- bilistic planner, showing best performance. Finally, we demonstrate how our algorithm can be used for planning perching maneuvers online

The quaternion is a powerful and common tool to avoid singularity in rotational dynamics in three-dimensional (3D) space. Here it has been particularly used as an alternative to Euler angles and rotation matrix. The application of the quaternion is exercised in quadrotor modeling and control. It changes the dynamics and represents a singularity-free attitude model. Here for the first time (for the best knowledge of authors), the state-dependent differential Riccati equation (SDDRE) control has been implemented on the quaternion-based model of a quadcopter. The proposed control structure is capable of aerobatic flight, and the Pugachev’s Cobra maneuver is chosen to assess the capability of the quaternion-based SDDRE approach. The introduced control simulator is validated by comparison with conventional dynamics based on Euler angles, controlled using a proportional-derivative (PD) controller on a normal regulation flight. The simulator successfully performed the Cobra maneuver and also validated the proposed structure. The more precision in regulation along with lower energy consumption demonstrated the superiority of the introduced approach.

Unmanned Aerial Vehicles (UAVs) endowed with robotic manipulation capabilities, also known as Aerial Robotic Manipulators (ARMs), have demonstrated a promising future in their application for Inspection and Maintenance (I&M) activities. However, their associated capabilities still need to be extended to reach higher levels of autonomy, reliability, accuracy, safety and e ciency, among others. In addition to important improvements in human safety, this will lead to signi cant cost savings, making ARMs an e ective solution to be exploited in real conditions. Motivated by the previous statement, this thesis has found in motion planning a means to endow ARMs with enhanced functionalities. Thus, the presented research has been focused on the design, development and validation of motion planning methods for aerial robotic manipulation in I&M. More in detail, the need of planning has been identi ed for three main topics, which are manipulation using ARMs endowed with robotic arms, manipulation with hybrid-locomotion robots and multiARM manipulation. For each of them, a motion planning method has been formulated and then, several extensions have been introduced to increase its capabilities. Concerning manipulation using ARMs endowed with robotic arms, a motion planner specially oriented to this kind of ARMs has been formulated for both navigation and manipulation phases in cluttered environments. This planner considers the joint operation of the aerial platform and the manipulation system within the planning process. Over the fundamentals of the previous method, three extensions have been proposed. Due to the complex dynamics existing in ARMs, the rst extension introduces Dynamics Awareness (DA) in the planner operation for robust obstacle avoidance. Complementing this DA extension, a new Velocity Adaptation (VA) mechanism allows a better optimisation of the execution time of the planned trajectories but without increasing the computational burden considerably. Alternativel

In this work, the application of an optimization algorithm is investigated to optimize static and dynamic engineering problems. The methodology of the approach is to generate random solutions and find a zone for the initial answer and keep reducing the zones. The generated solution in each loop is independent of the previous answer that creates a powerful method. Simplicity as its main advantage and the interlaced use of intensification and diversification mechanisms--to refine the solution and avoid local minima/maxima--enable the users to apply that for a variety of problems. The proposed approach has been validated by several previously solved examples in structural optimization and scored good results. The method is also employed for dynamic problems in vibration and control. A modification has also been done on the method for high-dimensional test functions (functions with very large search domains) to converge fast to the global minimum or maximum; simulated for several well-known benchmarks successfully. For validation, a number of 9 static and 4 dynamic constrained optimization benchmark applications and 32 benchmark test functions are solved and provided, 45 in total. All the codes of this work are available as supplementary material in the online version of the paper on the journal website.

This paper presents a threat management methodology for Unmanned Aircraft Systems (UAS) operating in the civil airspace. The work is framed within an Unmanned Traffic Management (UTM) system based on the U-space initiative. We propose a new method that focuses on providing the required automated decision-making during real-time threat management and conflict resolution, which is one of the main gaps in the current U-space ecosystem. Our method is capable of handling all commonplace UTM threats, as well as selecting optimal mitigation actions, trading off efficiency and safety. Our implementation is open-source and fully integrated in a UTM software architecture, implementing U-space services related to emergency management and tactical deconfliction. We demonstrate our methodology through a set of realistic use cases with actual UAS operating in civil airspace. For that, we performed field experiments in an aerodrome with segregated airspace, and we showcased that the methodology is capable of autonomously managing heterogeneous threats in real time.

Autonomous flight of flapping-wing robots is a major challenge for robot perception. Most of the previous sense-and-avoid works have studied the problem of obstacle avoidance for flapping-wing robots considering only static obstacles. This letter presents a fully onboard dynamic sense-and-avoid scheme for large-scale ornithopters using event cameras. These sensors trigger pixel information due to changes of illumination in the scene such as those produced by dynamic objects. The method performs event-by-event processing in low-cost hardware such as those onboard small aerial vehicles. The proposed scheme detects obstacles and evaluates possible collisions with the robot body. The onboard controller actuates over the horizontal and vertical tail deflections to execute the avoidance maneuver. The scheme is validated in both indoor and outdoor scenarios using obstacles of different shapes and sizes. To the best of the authors’ knowledge, this is the first event-based method for dynamic obstacle avoidance in a flapping-wing robot.

The manipulation capabilities of flapping-wing flying robots (FWFRs) is a problem barely studied. This is a direct consequence of the load-carrying capacity limitation of the flapping-wing robots. Ornithopters will improve the existent multirotor unmanned aerial vehicles (UAVs) since they could perform longer missions and offer a safe interaction in proximity to humans. This technology also opens the possibility to perch in some trees and perform tasks such as obtaining samples from nature, enabling biologists to collect samples in remote places, or assisting people in rescue missions by carrying medicines or first-aid kits. This paper presents a very lightweight manipulator (79.7g) prototype to be mounted on an ornithopter. The distribution of the mass on the flapping-wing robot is sensitive and an extra lumped mass far from the center-of-mass (CoM) of the robot deteriorates the flight stability. A configuration was proposed to avoid changing the CoM. Flight experiments show that adding the arm to the robot only moved the CoM 6mm and the performance of the flight with the manipulator has been satisfactory. Plucking leaf is chosen as an application to the designed system and several experimental tests confirmed successful sampling of leaves by the prototype.

Most current insect research techniques are ground-based and provide scarce information about flying insects in the planetary boundary layer (PBL), which remains a poorly studied ecological niche. To address this gap, we developed a new insect-sampling method consisting of a fixed-wing drone platform with net traps attached to the fuselage, a mobile design that has optimal aerodynamic characteristics for insect capture in the PBL. We tested the proposed device on 16 flights in Doñana National Park (Spain) with two different trap designs fitted on the fuselage nose and wing. We collected 34 insect specimens belonging to four orders with a representation of twelve families at mean altitudes below 23 m above ground level and sampling altitudes between 9 and 365 m. This drone insect-sampling design constitutes a low-cost and low-impact method for insect monitoring in the PBL, especially in combination with other remote sensing technologies that directly quantify aerial insect abundance but do not provide taxonomic information, opening interesting possibilities for ecology and entomological research, with the possibility of transfer to economically important sectors, such as agriculture and health.

Online event-based perception techniques on board robots navigating in complex, unstructured, and dynamic environments can suffer unpredictable changes in the incoming event rates and their processing times, which can cause computational overflow or loss of responsiveness. This paper presents ASAP: a novel event handling framework that dynamically adapts the transmission of events to the processing algorithm, keeping the system responsiveness and preventing overflows. ASAP is composed of two adaptive mechanisms. The first one prevents event processing overflows by discarding an adaptive percentage of the incoming events. The second mechanism dynamically adapts the size of the event packages to reduce the delay between event generation and processing. ASAP has guaranteed convergence and is flexible to the processing algorithm. It has been validated on board a quadrotor and an ornithopter robot in challenging conditions.

Flapping wings produce lift and thrust in bio-inspired aerial robots, leading to quiet, safe and efficient flight. However, to extend their application scope, these robots must perch and land, a feat widely demonstrated by birds. Despite recent progress, flapping-wing vehicles, or ornithopters, are to this day unable to stop their flight. In this paper, we present a process to autonomously land an ornithopter on a branch. This method describes the joint operation of a pitch-yaw-altitude flapping flight controller, an optical close-range correction system and a bistable claw appendage design that can grasp a branch within 25 milliseconds and re-open. We validate this method with a 700 g robot and demonstrate the first autonomous perching flight of a flapping-wing robot on a branch, a result replicated with a second robot. This work paves the way towards the application of flapping-wing robots for long-range missions, bird observation, manipulation, and outdoor flight.

This paper describes a compensation system for soft aerial vehicle stabilization. Balancing the arms is one of the main challenges of soft UAVs since the propeller is freely tilting together with the flexible arm. In comparison with previous designs, in which the autopilot was adjusted to deal with these imbalances with no extra actuation, this work introduces a soft tendon-actuated system to achieve in-flight stabilization in an energy-efficient way. The controller is specifically designed for disturbance rejection of aeroelastic perturbations using the Ziegler-Nichols method, depending on the flight mode and material properties. This aerodynamics-aware compensation system allows to further bridge the gap between soft and aerial robotics, leading to an increase in the flexibility of the UAV, and the ability to deal with changes in material properties, increasing the useful life of the drone. In energetic terms, the novel system is 15–30% more efficient, and is the basis for future applications such as object grasping.

Los drones se encuentran cada vez más integrados en la vida diaria de las personas. Desde usos industriales como la inspección de líneas de alta tensión o refinerías, pasando por aplicaciones de reconocimiento aéreo como las operaciones de búsqueda y rescate en desastres natural, hasta llegar a un uso recreativo de los mismos, como la grabación de eventos o los espectáculos lumínicos. Uno de los campos en los que el uso de drones autónomos tiene un gran prospecto es en el envío de paquetería y mercancías en entornos urbanos y remotos. Para poder navegar en dichos entornos, el dron necesita conocer su posición GNSS en todo momento, además del punto al que debe desplazarse para realizar la entrega. Dicha localización se obtiene de receptores que indicar directamente la posición del dron en latitud y longitud. Sin embargo, a la hora de implementar algoritmos de posicionamiento junto a otros sensores, esa posición devuelta por el receptor no puede ser utilizada, ya que los algoritmos requieren la posición del dron sin ningún tipo de filtrado adicional, ya que estos se implementarán dentro del propio algoritmo de posicionamiento. El objetivo de este Trabajo Fin de Grado es el de desarollar una aplicación en C++ que obtenga de un receptor una serie de medidas denominadas pseudorangos, que son la distancia aparente entre cada satélite y el receptor, y a través de ellos aplicar un algoritmo de posicionamiento que sea capaz de la posición instantánea del dron sin aplicar ningún filtro o post-procesado extra al posicionamiento. Una vez desarrollado, se comprobarán los resultados obtenidos realizando distintas pruebas de vuelo con el receptor tomando datos abordo de un dron. Se probarán distintas soluciones a la ecuación de posicionamiento, incluyendo un método de ajuste por mínimos cuadrados ponderados., Drones are increasingly integrated into people’s daily lives. From industrial uses such as the inspection of power lines or refineries, through aerial reconnaissance applications such as search and rescue operations in natural disasters, to recreational uses such as the recording of events or light shows. One of the fields in which the use of autonomous drones has great prospects is in the delivery of parcels and goods in urban and remote environments. In order to navigate in such environments, the drone needs to know its GNSS position at all times, as well as the point to which it must travel to make the delivery. This location is obtained from receivers that directly indicate the drone’s latitude and longitude. However, when it comes to implementing localization algorithms fused with other sensors, this position returned by the receiver isn’t suitable, due to the algorithm requiring the position of the drone without any additional filtering, which will be implemented when fusing the localization obtained with other sensors. The objective of this Project is to develop a C++ application that obtains from a receiver a series of measurements called pseudoranges, which are the apparent distance between each observed satellite and the receiver, and feed them to the localization algorithm which should be able to obtain the instantaneous position of the drone without applying any extra filtering or post-processing to the positioning itself. Once developed, the application will be verified by performing different flight tests with the receiver taking data onboard a drone. Different solutions to the positioning equation will be tested, including a weighted least squares fitting method.

La fundación FADA-CATEC desarrolló en 2020 un framework para la creación y ejecución de misiones de seguimiento de waypoints para autopilotos de DJI. El fin, era poder controlar el dron de forma autónoma en escenarios donde la cobertura GPS no estaba disponible, pues esta es necesaria para poder utilizar las herramientas propias del fabricante que ofrecen este tipo de funcionalidades. Dotando a la aeronave de un sistema de localización alternativo y gracias al framework, se consiguió recuperar la funcionalidad de las misiones. Este, además, ofrece la posibilidad de: controlar el armado de los motores, realizar maniobras de despegue y aterrizaje y alternar entre distintos modos de vuelo (manual, automático y asistido). El presente Trabajo de Fin de Grado tiene como objetivo añadir nuevas funcionalidades al framework, centradas principalmente en: • Mejorar la seguridad del sistema mediante la detección de fallos y ejecución de rutinas de prevención de accidentes. • Añadir compatibilidad con el estándar para autopilotos open-source Pixhawk, adaptando las comunicaciones y funciones a la arquitectura de este tipo de sistemas. Se partirá como base del código ya existente, siendo necesario un previo estudio del mismo, con el fin de poder reutilizar las funcionalidades ya implementadas y seguir la línea de diseño ya establecida por los autores originales., In 2020, the FADA-CATEC foundation developed a framework for the creation and execution of waypoint following missions for DJI autopilots. The purpose was to be able to control the drone autonomously in scenarios where GPS coverage was not available, since it is necessary to be use the manufacturer’s own tools that offer this type of functionality. By equipping the aircraft with an alternative location system and thanks to the framework, it was possible to recover the functionality of executing missions. The framework, in addition, offers the possibility of: arming the motors, executing takeoff and landing maneuvers and alternating between different flight modes (manual, automatic and assisted). The purpose of this project is to add new functionalities to the framework, mainly focused on: • Improving system security by detecting faults and executing accident prevention routines. • Adding compatibility with the open-source Pixhawk autopilot standard, adapting communications and functionalities to this new architecture. It will be based on the existing code, requiring a previous study of it, in order to be able to reuse the functionalities already implemented and follow the design line already established by the original authors.

Tren de aterrizaje, acoplable a una superficie inferior de un dron (3), para posicionar sensores sobre una tubería para inspección, que comprende al menos dos mecanismos de pinza (1), acoplables a la superficie inferior del dron (3), cada uno con una estructura de acoplamiento (4) conectada con un cuerpo central (5); dos brazos (6) laterales, que pueden pivotar alrededor de un extremo interior unido al cuerpo central (5), y que comprenden ruedas omnidireccionales (7), acopladas a su cara interna; un primer actuador (9), que mueve los brazos (6); y un mecanismo de rueda tractora (2) orientable, acoplado a la zona central de la superficie inferior del dron (3), mediante una plataforma fija (10), alrededor de la que gira una plataforma móvil (11), mediante un segundo actuador (12); con una rueda tractora (13), unida a la plataforma móvil (11) mediante una primera suspensión (14) articulada, accionada por un tercer actuador (15).

A new forward-flight model for bird-like ornithopters is presented. The flight dynamics model uses results from potential, unsteady aerodynamics to characterize the forces generated by the flapping wings, including the effects of the dynamic variables on the aerodynamic formulation. Numerical results of the model, which are validated with flapping flight experimental data of an ornithopter prototype, show that state variables such as the pitch angle and the angle of attack oscillate with the flapping frequency, while their mean values converge towards steady-state values. The theoretical analysis of the system shows a clear separation of timescales between flapping oscillations and transient convergence towards the final forward-flight state, which is used to substantially simplify both the interpretation and the solution of the dynamic equations. Particularly, the asymptotic separation into three timescales allows for dividing the problem into a much simpler set of linear equations. The theoretical approximation, which fits the numerical results, provides a direct look into the influence of the design and control parameters using fewer computational resources. Therefore, this model provides a useful tool for the design, navigation and trajectory planning and control of flapping wing UAVs.

Drone autonomous operations near power lines are growing steadily and require innovative techniques to keep them on air. This paper presents a novel electromechanical recharging station that can be mounted on energized AC power line to charge the drone battery wirelessly without a need to modify the electrical infrastructure. The work shows a thorough analysis of the electrical and mechanical core components to build a flexible, lightweight and efficient recharging station that can be attached to a robotic arm. The work also discusses the recharging station design and its special robot end effector that mechanically couples the station with an aerial manipulator. Finally, the recharging station has been tested in the lab and in a real power line setup to validate its design and efficiency. The total achieved mass is 2300 grams with a harvesting efficiency of 77% at 250 A primary current.

Con el desarrollo de la robótica aérea han aparecido nuevas plataformas de multirotores de actuación completa (fully-actuated en inglés), las cuales tienen la capacidad de desplazarse sin inclinar la plataforma. Este artículo presenta una comparación en cuanto a capacidades de movimiento entre un hexarotor de rotores coplanarios, configuracióon estándar, y un hexarotor de rotores inclinados, configuración fully-actuated. Para ello, se presenta el diseño, modelo y control de ambas configuraciones. Tras el montaje de las plataformas, se comparan con diferentes trayectorias. Así mismo, se muestran capacidades exclusivas de la plataforma fully-actuated, como la capacidad de mantenerse en hover con un ángulo de inclinación.

[Resumen] Con el desarrollo de la robótica aérea han aparecido nuevas plataformas de multirotores de actuación completa (fully-actuated en inglés), las cuales tienen la capacidad de desplazarse sin inclinar la plataforma. Este artículo presenta una comparación en cuanto a capacidades de movimiento entre un hexarotor de rotores coplanarios, configuración estándar, y un hexarotor de rotores inclinados, configuración fully-actuated. Para ello, se presenta el diseño, modelo y control de ambas configuraciones. Tras el montaje de las plataformas, se comparan con diferentes trayectorias. Así mismo, se muestran capacidades exclusivas de la plataforma fully-actuated, como la capacidad de mantenerse en hover con un ángulo de inclinación., [Abstract] With the development of aerial robotics, new multi-rotor platforms, known as fullyactuated, have appeared. These platforms have the ability to move without tilting the platform. This article presents a comparison in terms of motion capabilities between a coplanar hexarotor, estandar configuration, and a tilted hexarotor, fully-actuated configuration. For this purpose, this paper presents the design, modelling and control of both configurations. The platforms are compared with different trajectories. It also shows capabilities, unique of the fullyactuated platform, such as the ability to hover with a tilt angle

[Abstract] Robust and accurate autonomous navigation is a main challenge in agricultural robotics. This paper presents a LIDAR-based processing system for autonomous robot navigation in crops with high vegetation density. The method detects and locates the crop furrows and provides them to the robot control system, which guides the robot such that its caterpillar tracks move along the furrows preventing damages in the crop. The proposed LIDAR-based processing pipeline includes various inconsistencies removal and template matching steps to deal with the high noise level of LIDAR scans. It has been implemented in C++ using ROS Noetic and validated in two different plantations with different crop growth status.