Fully actuated aerial robots have shown superiority in Aerial Physical Interaction (APhI) in recent years. This work presents a minimal setup for aerial telemanipulation, improving accessibility to such technologies. The design and control of a 6-Degrees of Freedom (DoF) joystick with 4-DoF haptic feedback are detailed. It is the first haptic device with standard Remote Controller (RC) form factor for APhI. Miniaturizing the haptic device adds sense of touch to RC, enhancing physical awareness. The goal is to provide operators with an extra sense-beyond vision and sound-to support safe APhI. To the best of the authors' knowledge, this is the first 6-DoF aerial teleoperation system capable of decoupling singleaxis input commands. The proposed robot hardware design reduces number of components, aiming for easier maintenance and improved force and thrust-to-weight ratios. Open-source physics-based simulation and successful early flight tests highlight the tool's promise for future APhI applications.

The measurement of ultrasonic surface velocity in concrete and the ultrasonic Time Of Flight method for estimating the depth of surface opening cracks in concrete are important techniques for maintenance of constructions, which are currently performed manually. This paper demonstrates the possibility to automate these measurements by means of an Unmanned Aerial Vehicle (UAV) equipped with a robotic arm, avoiding the risks and costs related to the manual methods. The automated measurements are performed by a special end effector with closed-loop force control that maintains the flying UAV stable while the robotic arm contacts the concrete surface with two piezoelectric transducers for the ultrasonic tests. The system is successfully validated by performing ultrasound measurements from the flying UAV on a test specimen with artificial cracks and on the T9 Metsovo bridge in Greece during an on-field trial, demonstrating an error margin lower than 1 % on crack depth.

Coaxial multirotors, characterized by overlapping rotors, represent a common solution to increasing payload capacity while maintaining a compact platform size. However, the overlap between motors generates airflow disturbances that, if not taken into account properly, may decrease the system’s overall performance. In this paper, aerodynamic interactions for coaxial multirotors are analyzed and characterized. Two rotor models are introduced, which account for the aerodynamic interaction between the upper and the lower rotor. Each model is accompanied by its corresponding mixer design and analyzed with respect to the state-of-the-art mixer solution for classical multirotor systems. The proposed approaches are tested through rotor stand experiments, simulations, and implementation on an actual coaxial platform. The results demonstrate the effectiveness of these models in mitigating the adverse aerodynamic effects, thereby improving the performance and efficiency of coaxial multirotor systems.

The paper introduces a novel framework for safe and autonomous aerial physical interaction in industrial settings. It comprises two main components: a neural network-based target detection system enhanced with edge computing for reduced onboard computational load, and a control barrier function (CBF)-based controller for safe and precise maneuvering. The target detection system is trained on a dataset under challenging visual conditions and evaluated for accuracy across various unseen data with changing lighting conditions. Depth features are utilized for target pose estimation, with the entire detection framework offloaded into low-latency edge computing. The CBF-based controller enables the UAV to converge safely to the target for precise contact. Simulated evaluations of both the controller and target detection are presented, alongside an analysis of real-world detection performance.

Ensuring the integrity and reliability of power lines is essential to maintain continuous service and avoid potential catastrophes. However, the increasingly extensive infrastructure represents formidable challenges in terms of inspection, maintenance, and worker safety. This paper presents the design, development and experimental validation of the Main Local Manipulation Platform (MLMP), a versatile aerial manipulator designed to install and remove a wide variety of devices on power lines while perched, without interrupting the power. The paper outlines the main design considerations, challenges encountered and solutions applied, including electrical protection, device manipulation and perching strategies. Multiple validation experiments, both in controlled and real scenarios, demonstrated the platform's effectiveness in the installation of clip-type bird diverters, cable separators and charging stations. The results underscore the potential of the MLMP to transform power line inspection and maintenance operations, improving the efficiency, reducing costs and ensuring worker safety.

This paper introduces a novel compliant mechanism combining lightweight and energy dissipation for aerial physical interaction. Weighting 400 g at take-off, the mechanism is actuated in the forward body direction, enabling precise position control for force interaction and various other aerial manipulation tasks. The robotic arm, structured as a closed-loop kinematic chain, employs two deported servomotors. Each joint is actuated with a single tendon for active motion control in compression of the arm at the end-effector. Its elasto-mechanical design reduces weight and provides flexibility, allowing passive-compliant interactions without impacting the motors' integrity. Notably, the arm's damping can be adjusted based on the proposed inner frictional bulges. Experimental applications showcase the aerial system performance in both free-flight and physical interaction. The presented work may open safer applications for Micro Aerial Vehicle (MAV) in real environments subject to perturbations during interaction.

Developing a new UAV platform is a long and iterative process that requires a lot of time and effort to be successful. The difficulty of performing a realistic evaluation of system performance during the development process represents a major drawback. As a matter of fact, in most contexts, the first proof of UAVs' capabilities arrives only during the first flights of the real platform. This may lead, in case of possible issues detected in the platform, to a revaluation of the design, which is not optimal at the very last stage of platform development. To overcome this issue, we propose AIRFRAME, a framework for fast-developing UAV prototypes in simulation to allow for systematic evaluation and analysis of UAV performance during the development process. The developed prototype integrates software and hardware for a better evaluation of the system's capability and performance at an early stage. The implementation of the framework has succeeded with Gazebo-ROS-Matlab in Docker Environment. It allows high integrability and fast evaluation of multiple UAV designs.

In this paper, we present the development of a multi-UAV system for operations of surveillance or search&rescue. The operation of this kind of systems has been limited in the past because of the dependency on the communications infrastructure. With the deployment of 5G cellular networks, new opportunities arise in the development of this field and its real-world applications. This paper includes the development of four different guidance algorithms to manage the whole team of UAVs during its search and rescue mission. The main functionalities implemented are the ones described in this paper: formation flight for an efficient sweep of the terrain, collision avoidance between other agents and possible environmental obstacles, cooperative target searching in order to minimize the time of the mission, and a cooperative target tracking that minimize losing the target and allows an increased accuracy. The developed UAV system has been successfully deployed and tested in an emulated search and tracking operation of both, a vehicle and a human, using a 5G network. The 5G network provided real-time communications with the ground control station, enabling the transmission of telemetry and high-resolution video from each UAV. A demonstration of the system was performed to a law enforcement entity involving three UAVs.

Bridge inspections have a large variety of procedures to ensure the safety of its facilities and personnel, and at the same time tightly budget constraints. These procedures involve extensive inspections, most of which should be performed at height and using both cameras and other sensors that require to be in contact with the surfaces being inspected. Then, bridge inspections traditionally require access to specific inspection points using man-lifts, cranes, scaffolds, or rope-access techniques, which increments importantly the costs of these inspections. This work will present a system formed by two drones that will perform complete inspection operations in bridges in less time, reducing costs, improving quality of the inspection, and increasing safety of operators. The first one is an aerial robot that can obtain pictures of the overall bridge fully autonomously thanks to a GPS-free navigation system. The second one is the AeroX drone platform, a novel solution for inspection of difficult access areas. The AeroX can perform contact inspection due to its robotic contact device, which is equipped with an end-effector. Finally, both drones will be presented with videos of the validation experiments.

Urban air mobility is raising a lot of attention from both research and industrial communities. In near future UAM vehicles will be manned aircrafts with vertical take-off and landing capabilities, being this use case one of the priorities of current UAM regulations. Yet, the complete potential of UAS will arrive when autonomous UAS could be adapted to be used under addressing the standards. This papers aims to contribute to this activity proposing a way to execute a new autonomous landing in vertiports maneuver that follows the recently published standard presented by EASA. The landing maneuver has been studied and tested in simulation, analysing its complete casuistry. Its implementation is also described and could be deployed in the most common open-source autopilots available today.

En este artículo se describen los primeros robots manipuladores aéreos dotados con brazos robóticos de seis grados de libertad y capacidades de percepción y planificación que se han desarrollado en el mundo. Estos robots son el resultado del proyecto ARCAS (Aerial Robotics Cooperative Assembly System) coordinado por el primero de los autores y financiado por el Séptimo Programa Marco de la Unión Europea. Los resultados de este proyecto han comenzado a emplearse, entre otros, en el proyecto H2020 AEROARMS y en el español AEROMAIN. El artículo introduce las diferentes plataformas utilizadas en el proyecto y a continuación resume las principales características de los sistemas de control, percepción y planificación desarrollados. Se resume también la integración y validación del sistema.

Extreme weather conditions, climate change, damages to the infrastructure (caused by natural and man-made hazards) and traffic impediments negatively impact the reliability of mobility solutions. Risk analysis, adaptation measures and strategies that enable minimizing the impact of both natural and man-made extreme events on seamless transport operation, protect the users of the transport network in case of extreme conditions, as well as provide optimal information to operators and users of the transport infrastructure, need to be developed. Road transport is vulnerable to extreme weather events, while bridges and tunnels are among the most critical land transport structures. A large number of bridges and tunnels have been in operation for more than 50 years and there are widespread signs of deterioration. They need inspection, vulnerability assessment and, when needed, appropriate interventions. Inspection, though, in inaccessible areas, or structures with high volumes of traffic, is expensive, time-consuming, and potentially dangerous. At the same time, structural/vulnerability assessment is also a lengthy process which is especially painful after extreme events. The overall goal of RESIST (RESilient transport InfraSTructure to extreme events) a RIA H2020 project funded by the EU commission with grant number 769,066 is to increase the resilience of seamless transport operation to natural and man-made extreme events, protect the users of the European transport infrastructure and provide optimal information to the operators and users of the transport infrastructure. In the context of RESIST, robotics for visual and contact inspection of structures, structural vulnerability assessment, infrastructure risk management as well as mobility continuity applications considering stress levels of the drivers are being developed towards a high level of resilience of the transport infrastructure.

This paper describes the state machine of an autonomous contact UAV for assisted inspection tasks. The UAV is able to control its position using on-board sensors, while the human operator sends the high-level directives. The internal controller of the robot is aware of the state machine status, granting that the control signals that reach the autopilot are smooth, when transitioning between the different control modes. The article summarizes the control modes associated to state machine's states, describes the rules for the smooth transitions, and shows experimental results. Indoor experiments are evaluated with a VICON system, and outdoors experiments show a qualitative representation of those smooth shifts between the states.

The inspection of public infrastructure, such as viaducts and bridges, is crucial for their proper maintenance given the heavy use of many of them. Current inspection techniques are very costly and manual, requiring highly qualified personnel and involving many risks. This article presents a novel solution for the detailed inspection of viaducts using aerial robotic platforms. The system provides a highly automated visual inspection platform that does not rely on GPS and could even fly underneath the infrastructure. Unlike commercially available solutions, our system automatically references the inspection to a global coordinate system usable throughout the lifespan of the infrastructure. In addition, the system includes another aerial platform with a robotic arm to make contact inspections of detected defects, thus providing information that cannot be obtained only with images. Both aerial robotic platforms feature flexibility in the choice of camera or contact measurement sensors as the situation requires. The system was validated by performing inspection flights on real viaducts.

This work describes the methodology for detecting pipes and their pose in refineries inspection using Unmanned Aerial Vehicles (UAV s) for remote Ultrasonic Testing (UT). Segmentation techniques such as the Hough Transform and its variations, and Random Sample Consensus have been widely used. This paper is therefore focused on the development of an efficient computer vision algorithm to detect the position and orientation of the pipes in order to land on them autonomously to perform the inspection, by using 3D point cloud information from depth cameras. Applying a methodology based on Random Sample Consensus and point cloud pre-processing to fasten the algorithm performance has led to robust estimations of the pipes and their poses in an indoor testbed using a realistic environment, allowing the autonomous landing and the subsequent inspection.

This paper presents a novel method for motion planning of aerial long-reach manipulators that considers the aerodynamic effects generated by close surfaces in the trajectory generation process. The aerial manipulation system consists of a multirotor equipped with a robotic long-reach arm that enables multidirectional inspection and also increases considerably the safety distance between the rotors and the inspected elements. Since these systems operate in the proximity of elements that can modify significantly the rotors' airflow, the inclusion of Aerodynamics Awareness within the motion planning process is required to ensure robust obstacle avoidance. To this end, a proper characterisation of the aerodynamic effects based on both theoretical and experimental considerations has been derived. This characterisation is taken into account in the trajectory generation process to discard states whose associated aerodynamic phenomena are not well compensated by the system controller and to explore alternatives that lead to the most efficient trajectories within the area of safe operation. Moreover, the motion planner also stands out for three other relevant features: the joint consideration of the multirotor and the robotic long-reach arm, the generation of efficient trajectories in terms of energy consumption, and the Dynamics Awareness of the strong coupling between the aerial platform and the robotic arm. The resulting motion planner has been successfully tested in a simulated environment that faithfully reflects an application scenario strongly affected by aerodynamic effects: the inspection of bridges to find potential cracks in the surface of pillars.

A novel Micro-Opto-Mechanical acoustic sensor that can be utilized to measure the width of surface opening cracks in concrete structures from aerial robots is presented. The sensor is used in combination with a piezoelectric emitter operating at 54 kHz in a crack width measurement procedure that provides a resolution around 0.2 mm. The method is tolerant to pressure variations during contact with concrete, which may easily occur when operating the sensors from aerial robots.

There is a strong demand in the oil and gas industry to develop alternatives to manual inspection. This paper presents AeroX, a novel aerial robotic manipulator that provides physical contact inspection with unprecedented capabilities. AeroX has a semi-autonomous operation, which provides interesting advantages in contact inspection. In the free-flight mode, the pilot guides the robot until performing contact with its end-effector on the surface to be inspected. During contact, AeroX is in its fully-autonomous global navigation satellite system (GNSS)-free contact–flight mode, in which the robot keeps its relative position w.r.t. the surface contact point using only its internal sensors. During autonomous flight, the inspector can move—with uninterrupted contact—the end-effector on the surface for accurately selecting the points where to perform A-scan measurements or continuous B-scan or C-scan inspections. AeroX adopts an eight-tilted rotor configuration and a simple and efficient design, which provides high stability, maneuverability, and robustness to rotor failure. It can perform contact inspection on surfaces at any orientation, including vertical, inclined, horizontal-top or horizontal-bottom, and its operation can be easily integrated into current maintenance operations in many industries. It has been extensively validated in outdoor experiments including a refinery and has been awarded the EU Innovation Radar Prize 2017.