This paper presents the design, development, and validation of a fully autonomous dual-arm aerial robot capable of mapping, localizing, planning, and grasping parcels in an intra-logistics scenario. The aerial robot is intended to operate in a scenario comprising several supply points, delivery points, parcels with tags, and obstacles, generating the mission plan from the voice commands given by the user. The paper derives a transferability model of the scenario, the robot, and the task, so that the proposed system design can be generalized to different scenarios (environment transfer) and platforms (embodiment transfer). The proposed transferable system architecture allows the integration of software modules managed by the Aerial Delivery Robot Operations Manager (ADROM) through the Module Interface Instances (MII) that handle the requests and the signals involved during the execution of the operation. The performance of the developed system was evaluated as part of the euROBIN Nancy Competition, conducting more than 50 flight tests. The software modules are open source, making the flight dataset also publicly available.

Ground testing is of paramount importance to verify and validate space operations and the associated control algorithms before on-orbit deployment. Although state-of-the-art facilities are capable of reproducing zero-G environment with high degree of fidelity, these infrastructures can be complemented with multi-rotors emulating free flying or free floating conditions, exploiting the similarities and analogies between both domains in terms of floating nature, attitude dynamics, and thrust-wrench relation through the mixer matrix. Furthermore, the effective workspace of the testbed can be extended to the dimensions of the flight area and the coverage of the positioning system. Therefore, this papers introduces a new way to recreate orbital motion within an indoor facility, considering the case study of trajectories derived from the Clohessy–Wiltshire equations. This advancement opens up avenues for replicating close-proximity operations between chaser and target satellites employing fully-actuated multi-rotors that allow decoupling translational and attitude dynamics.

This paper presents a bilateral teleoperation system based on smart servos for the realization of dexterous manipulation tasks with aerial robots or in ground service applications, facilitating the transferability of cognitive capabilities of human workers to robots operating remotely or in high altitude workspaces. The system consists of a pair of lightweight and compliant anthropomorphic dual arm manipulators (LiCAS) in leader-follower configuration. The leader dual arm (LDA) captures the movements of the operator’s arms to obtain the desired joint references, sent to the follower dual arm (FDA) to reproduce in a natural and intuitive way the manipulation task. A model of the smart servos is derived, exploiting the feedback from the FDA actuators to provide the kinesthetic feedback to the LDA, using the pulse width modulation signal (PWM) along with the joint speed to estimate the interaction torque. The mechanical joint compliance of the FDA allows the passive accommodation of the arms to the physical interactions with the manipulated objects or the environment, whereas the very low weight of the arms (1.0 kg LDA, 2.5 kg FDA) and the human-size and human-like kinematics facilitate their use in a wide variety of applications. The performance of the system is evaluated using an industrial task board for benchmarking, and in two illustrative bimanual aerial manipulation tasks.

The state-dependent Riccati equation (SDRE) is a nonlinear optimal controller with a flexible structure which is one of the main advantages of this method. Here in this work, this flexibility is used to present a novel design for handling a soft constraint for state variables (trajectories). The concept is applied to a large-scale swarm control system, with more than 1000 agents. The control of the swarm satellite system is devoted to two modes of orbit-to-orbit and in-same-orbit cases. Keeping the satellites in one orbit in regulation (point-to-point motion) requires additional constraints while they are moving in Cartesian coordinates. For a small number of agents trajectory design could be done for each satellite individually, though, for a swarm with many agents, that is not practical. The constraint has been incorporated into the cost function of optimal control and resulted in a modified SDRE control law. The proposed method successfully controlled a swarm case of 1024 agents in leader-follower mode for orbit-to-orbit and in-same-orbit simulations. The soft constraint presented a percentage of 0.05 in the error of the satellites with respect to travel distance, in in-same-orbit regulation. The presented approach is systematic and could be performed for larger swarm systems with different agents and dynamics.

This paper presents a comparative performance evaluation of three different teleoperation interfaces for very low weight (<3 kg) anthropomorphic dual arms intended to conduct complex manipulation tasks involving a certain level of dexterity, accuracy and agility, either in ground service or in aerial manipulation applications. A visual human pose estimation system is developed to obtain the Cartesian and joint values of the user, which are mapped to the corresponding pose of the dual arm manipulator exploiting the equivalent human-robot kinematics. A leader-follower scheme is also presented, using a reduced scale dual arm that can replicate directly the joint positions of the leader arms to the follower arms. A 6-DOF (degrees of freedom) joystick is proposed to generate linear motions more accurately. A total of 60 ground tests were conducted involving 10 participants to determine the accuracy and time performance in two benchmarks (box edges and S contour tracking). Finally, the visual and leader-follower interfaces were evaluated with the dual arm aerial manipulator on flight tests, reporting several findings derived from the system evaluation.

This article analyzes the evolution and current trends in aerial robotic manipulation, comprising helicopters, conventional underactuated multirotors, and multidirectional thrust platforms equipped with a wide variety of robotic manipulators capable of physically interacting with the environment. It also covers cooperative aerial manipulation and interconnected actuated multibody designs. The review is completed with developments in teleoperation, perception, and planning. Finally, a new generation of aerial robotic manipulators is presented with our vision of the future.

In this paper, we propose a new concept of robot which is hybrid, including aerial and crawling subsystems and an arm, and also modular with interchangeable crawling subsystems for different pipe configurations, since it has been designed to cover most industrial oil & gas end-users' requirements. The robot has the same ability than aerial robots to reach otherwise inaccessible locations, but makes the inspection more efficient, increasing operation time since crawling requires less energy than flying, and achieving better accuracy in the inspection. It also integrates safety-related characteristics for operating in the potentially explosive atmosphere of a refinery, being able to immediately interrupt the inspection if a hazardous situation is detected and carry the sensible parts such as batteries and electronic devices away as soon as possible. The paper presents the design of this platform in detail and shows the feasibility of the whole system performing indoor experiments.

The paper presents a multiple task-priority inverse kinematics algorithm for a dual-arm aerial manipulator. Both tasks defined as equality constraints and inequality constraints are handled by means of a singularity robust method based on the Null-Space based Behavioral control. The proposed schema is constituted by the inverse kinematics control, that receives the desired behavior of the system and outputs the reference values for the motion variables, i.e. the UAV pose and the arm joints position, and a motion control, that computes the vehicle thrusts and the joint torques. The method has been experimentally validated on a system composed by an underactuated aerial hexarotor vehicle equipped with two lightweight 4-DOF manipulators, involved in operations requiring the coordination of the two arms and the vehicle.

Winged aerial robots represent an evolution of aerial manipulation robots, replacing the multirotor vehicles by fixed or flapping wing platforms. The development of this morphology is motivated in terms of efficiency, endurance and safety in some inspection operations where multirotor platforms may not be suitable. This paper presents a first prototype of compliant dual arm as preliminary step towards the realization of a winged aerial robot capable of perching and manipulating with the wings folded. The dual arm provides 6 DOF (degrees of freedom) for end effector positioning in a human-like kinematic configuration, with a reach of 25 cm (half-scale w.r.t. the human arm), and 0.2 kg weight. The prototype is built with micro metal gear motors, measuring the joint angles and the deflection with small potentiometers. The paper covers the design, electronics, modeling and control of the arms. Experimental results in test-bench validate the developed prototype and its functionalities, including joint position and torque control, bimanual grasping, the dynamic equilibrium with the tail, and the generation of 3D maps with laser sensors attached at the arms.

This paper presents the motion planning of a novel aerial robotic system with a long-bar extension and two arms for long-reach manipulation in cluttered environments. The novel aerial long-reach manipulator includes a passive revolute joint between the aerial platform and the dual arm. This feature minimises the torque induced to the aerial system in case of unexpected collisions of the manipulator. The motion planning problem is addressed considering jointly the complete set of configuration variables for the aerial platform and the dual arm. Furthermore, the planner has been built over the fundamentals of RRT* algorithms in order to optimise the performance of the trajectories in terms of energy and time. The proposed planning method has been experimentally validated in a realistic industrial scenario, the transportation of a long bar through a cluttered environment consisting of several pipe structures.

The proximity between the multirotor blades and the environmental obstacles restricts the application of aerial manipulators in inspection tasks due to the risk of impacts, the limitation in the reach of the arm, and the physical interactions. This paper presents a long reach aerial manipulator consisting of a hexarotor platform equipped with a 2-DOF compliant joint arm attached at the tip of a one-meter-length link in passive pendulum configuration. The arm integrates magnetic encoders for force/torque estimation-control based on joint deflection, a range sensor in the forearm link for measuring the distance to the contact point, and a camera for visual inspection. A 2-DOF wearable exoskeleton interface has been developed, allowing the teleoperation of the arm with visual feedback in a more intuitive way. The paper also covers the kinematics and dynamics of the aerial manipulator, including the dynamics of the flexible long reach link. The developed system has been evaluated in test-bench and in outdoor flight tests.

This paper presents a low weight (1.3 kg), human size dual arm system with compliant joints designed for aerial manipulation with a multirotor platform. Each arm provides four degrees of freedom (DOF) for end effector positioning in a kinematic configuration close to the human arm: shoulder pitch, roll and yaw, and elbow pitch. The aluminum frame structure of the arms has been designed with a double purpose: protecting the servo actuators against direct impacts and overloads, and allowing the integration of a compliant transmission mechanism with deflection measurement between the servo shaft and the output link Mechanical joint compliance increases safety in the physical interactions with the environment, removing also joint overloads typical in closed kinematic chain configurations. The dual arm system has been integrated in a hexarotor platform with a visual servoing system for object grasping, evaluating its performance first in a fixed base test bench and later in outdoor flight tests.

This paper presents the design and experimental validation of a Fault Detection, Identification and Recovery (FDIR) system intended for multi-UAV applications. The system exploits the information provided by internal position, attitude and visual sensors onboard the UAVs of the fleet for detecting faults in the measurements of the position and attitude sensors of any of the member vehicles. Considering the observations provided by two or more UAVs in a cooperative way, it is possible to identify the source of the fault, but also implement a Cooperative Virtual Sensor (CVS) which provides a redundant position and velocity estimation of the faulty UAV that can be used for replacing its internal sensor. The vision-based FDIR system has been validated experimentally with quadrotors in an indoor testbed. In particular, fault detection and identification has been evaluated injecting a fault pattern offline on the position measurements, while the CVS has been applied in real time for the recovery phase.

This paper presents the design and experimental validation of a compliant and lightweight 3-DOF robotic arm - shoulder yaw, shoulder pitch and elbow pitch joints - equipped with a compliant finger module intended for aerial inspection and manipulation in contact with the environment. A simple transmission mechanism consisting in a pair of compression springs and a flange bearing is integrated in the shoulder pitch and elbow pitch joints between the servo shaft and the output frame. Joint deflection measurement with potentiometer allows joint torque but also contact force estimation and control. The low stiffness of the compliant finger has been exploited for soft collision detection and obstacle localization, in such a way that the contact forces do not significantly disturb the UAV. Fixed-base experiments have been performed with the arm, including the characterization of the compliant joints and the control of the contact force at wrist point.

This paper presents the design and experimental validation of a low weight compliant arm for aerial manipulation, which uses a linear actuator to move the elbow joint. The proposed arm design allows for estimating payload mass, as well as detecting collisions against obstacles in the forearm. The compliant arm design is intended to be applied in aerial manipulation and transportation, being mounted on the base of an Unmanned Aerial Vehicle (UAV) like a multirotor or a small autonomous helicopter. The payload mass estimation can be useful in the adaptation and stabilization of UAV altitude and attitude controllers when objects of unknown weight are grasped by the arm, while compliance reduces the effect of physical interaction when lifting an object on UAV stability. The paper addresses the mechanical design and construction of a three DoF arm prototype (elbow, wrist roll and pitch), deriving the equations for estimating the payload mass. A set of experiments for payload mass estimation and collision detection and reaction have been performed to test the validity of the approach.