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9 pages, 217 KiB

Open AccessEditorial

Special Issue “Advances in Aerial, Space, and Underwater Robotics”

by Silvio Cocuzza, Alberto Doria and Benedetto Allotta

Appl. Sci. 2023, 13(1), 484; https://doi.org/10.3390/app13010484 - 30 Dec 2022

Viewed by 1524

Abstract

Free-base robotic systems are extensively used in underwater, air, and space environments [...] Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

Research

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27 pages, 8337 KiB

Open AccessFeature PaperArticle

Zero Reaction Torque Trajectory Tracking of an Aerial Manipulator through Extended Generalized Jacobian

by Alberto Pasetto, Yash Vyas and Silvio Cocuzza

Appl. Sci. 2022, 12(23), 12254; https://doi.org/10.3390/app122312254 - 30 Nov 2022

Cited by 3 | Viewed by 1629

Abstract

Aerial manipulators are used in industrial and service robotics tasks such as assembly, inspection, and maintenance. One of the main challenges in aerial manipulation is related to the motion of the UAV base caused by manipulator disturbance torques and forces, which jeopardize the [...] Read more.

Aerial manipulators are used in industrial and service robotics tasks such as assembly, inspection, and maintenance. One of the main challenges in aerial manipulation is related to the motion of the UAV base caused by manipulator disturbance torques and forces, which jeopardize the precision of the robot manipulator. In this paper, we propose two novel inverse kinematic control methods used to track a trajectory with an aerial manipulator while also considering resultant UAV base motions. The first method is adapted from the generalized Jacobian formulation used in space robotics and includes the change in system momentum resulting from gravity and UAV control forces in the inverse kinematic control equation. This approach is simulated for a 2 and 3 degree-of-freedom aerial manipulator tracking trajectories with the end-effector. Although the end-effector position error is approximately zero throughout the simulated task, we see significant undesired UAV base motions of several centimeters in magnitude. To ameliorate this by exploiting the kinematic redundancy, we modify the generalized Jacobian by adding an additional task constraint which minimizes the reaction torques from the manipulator, to form the extended generalized Jacobian. While the second approach results in improved precision and reduced base motion by an order of magnitude as compared to the generalized Jacobian, a drawback is the reduction in the available workspace as the solution seeks to minimize the manipulator center of gravity translation. We also demonstrate and compare both approaches in a load picking task. All the algorithms are completed computationally faster than real time in the MATLAB simulations, illustrating their potential for application in real-world experiments. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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21 pages, 8380 KiB

Open AccessArticle

Modified A-Star (A*) Approach to Plan the Motion of a Quadrotor UAV in Three-Dimensional Obstacle-Cluttered Environment

by Ghulam Farid, Silvio Cocuzza, Talha Younas, Asghar Abbas Razzaqi, Waqas Ahmad Wattoo, Ferdinando Cannella and Hongwei Mo

Appl. Sci. 2022, 12(12), 5791; https://doi.org/10.3390/app12125791 - 07 Jun 2022

Cited by 17 | Viewed by 2486

Abstract

Motion-planning algorithms play a vital role in attaining various levels of autonomy for any ground or flying agent. Three-dimensional (3D) motion-planning is interesting, but rather complex, especially for flying agents such as autonomous unmanned aerial vehicles (UAVs), due to the increased dimensionality of [...] Read more.

Motion-planning algorithms play a vital role in attaining various levels of autonomy for any ground or flying agent. Three-dimensional (3D) motion-planning is interesting, but rather complex, especially for flying agents such as autonomous unmanned aerial vehicles (UAVs), due to the increased dimensionality of space and consideration of dynamical constraints for a feasible trajectory. Usually, in 3D path search problems, it is hard to avoid extra expanded nodes due to increased dimensionality with various available search options. Therefore, this paper discusses and implements a modified heuristic-based A* formalism that uses a truncation mechanism in order to eradicate the mentioned problem. In this formalism, the complete motion planning is divided into shortest path search problem and smooth trajectory generation. The shortest path search problem is subdivided into an initial naïve guess of the path and the truncation of the extra nodes. To find a naïve shortest path, a conventional two-dimensional (2D) A* algorithm is augmented for 3D space with six-sided search. This approach led to the inclusion of extra expanded nodes and, therefore, it is not the shortest one. Hence, a truncation algorithm is developed to further process this path in order to truncate the extra expanded nodes and then to shorten the path length. This new approach significantly reduces the path length and renders only those nodes that are obstacle-free. The latter is ensured using a collision detection algorithm during the truncation process. Subsequently, the nodes of this shortened path are used to generate a dynamically feasible and optimal trajectory for the quadrotor UAV. Optimal trajectory generation requires that the plant dynamics must be differentially flat. Therefore, the corresponding proof is presented to ensure generation of the optimal trajectory. This optimal trajectory minimizes the control effort and ensures longer endurance. Moreover, quadrotor model and controllers are derived as preliminaries, which are subsequently used to track the desired trajectory generated by the trajectory planner. Finally, results of numerical simulations which ultimately validate the theoretical developments are presented. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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19 pages, 1526 KiB

Open AccessFeature PaperArticle

Control of an Omnidirectional UAV for Transportation and Manipulation Tasks

by Michelangelo Nigro, Francesco Pierri and Fabrizio Caccavale

Appl. Sci. 2021, 11(22), 10991; https://doi.org/10.3390/app112210991 - 19 Nov 2021

Cited by 5 | Viewed by 2050

Abstract

This paper presents a motion control scheme for a new concept of omnidirectional aerial vehicle for transportation and manipulation tasks. The considered aerial platform is a novel quadrotor with the capability of providing multi-directional thrust by adding an actuated gimbal mechanism in charge [...] Read more.

This paper presents a motion control scheme for a new concept of omnidirectional aerial vehicle for transportation and manipulation tasks. The considered aerial platform is a novel quadrotor with the capability of providing multi-directional thrust by adding an actuated gimbal mechanism in charge of modifying the orientation of the frame on which the four rotors are mounted. The above mechanical design, differently from other omnidirectional unmanned aerial vehicles (UAVs) with tilted propellers, avoids internal forces and energy dissipation due to non-parallel propellers’ axes. The proposed motion controller is based on a hierarchical two-loop scheme. The external loop computes the force to be applied to the vehicle and the reference values for the additional joints, while the inner loop computes the joint torques and the moment to be applied to the multirotor. In order to make the system robust with respect to the external loads, a compensation of contact forces is introduced by exploiting the estimate provided by a momentum based observer. The stability of the motion control scheme is proven via Lyapunov arguments. Finally, two simulation case studies prove the capability of the omnidirectional UAV platform to track a 6-DoFs trajectory both in free motion and during a task involving grasping and transportation of an unknown object. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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37 pages, 13483 KiB

Open AccessArticle

A Conceptual Design Methodology for e-VTOL Aircraft for Urban Air Mobility

by Giuseppe Palaia, Karim Abu Salem, Vittorio Cipolla, Vincenzo Binante and Davide Zanetti

Appl. Sci. 2021, 11(22), 10815; https://doi.org/10.3390/app112210815 - 16 Nov 2021

Cited by 26 | Viewed by 8616

Abstract

Recent progress of electric systems has raised attention towards hybrid-electric and full-electric aircraft. Nevertheless, the current low battery energy density limits the application of these propulsive architectures to large transport aircraft. In the context of the general aviation category, full-electric aircraft for the [...] Read more.

Recent progress of electric systems has raised attention towards hybrid-electric and full-electric aircraft. Nevertheless, the current low battery energy density limits the application of these propulsive architectures to large transport aircraft. In the context of the general aviation category, full-electric aircraft for the so-called Urban Air Mobility scenario are gaining increasing interest. These air taxis, also called e-VTOL, are conceived to exploit vertical take-off and landing capabilities, to carry people from one point to another, typically within the same city. In this paper, a new conceptual design methodology for urban air vehicles is presented and applied to an innovative convertiplane, called TiltOne, based on a box-wing architecture coupled with tilt-wing mechanisms. Several TiltOne configurations have been designed according to the current regulations imposed by European Union Aviation Safety Agency, and sensitivity analyses have been carried out on the varying main design parameters, such as wing loading and propellers’ disk loading, as well as main top-level aircraft requirements. The results provide an overview for today’s operational capabilities of such aircraft and, in addition, depict possible scenarios for a near-future horizon, based on the assumption of increased performance levels for the electric powertrain components. In such scenario, two different concepts of operations are analysed and discussed: the first is based on a given design range, long enough to cover the urban distances; the second is conceived to exploit the capability of flying multiple shorter missions with a single battery charge. The designed TiltOne configurations derived from these different approaches are presented, highlighting their potential capabilities and possible drawbacks. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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18 pages, 2794 KiB

Open AccessArticle

Coupled Dynamic Modeling and Control of Aerial Continuum Manipulation Systems

by Zahra Samadikhoshkho, Shahab Ghorbani and Farrokh Janabi-Sharifi

Appl. Sci. 2021, 11(19), 9108; https://doi.org/10.3390/app11199108 - 30 Sep 2021

Cited by 10 | Viewed by 2015

Abstract

Aerial continuum manipulation systems (ACMSs) were newly introduced by integrating a continuum robot (CR) into an aerial vehicle to address a few issues of conventional aerial manipulation systems such as safety, dexterity, flexibility and compatibility with objects. Despite the earlier work on decoupled [...] Read more.

Aerial continuum manipulation systems (ACMSs) were newly introduced by integrating a continuum robot (CR) into an aerial vehicle to address a few issues of conventional aerial manipulation systems such as safety, dexterity, flexibility and compatibility with objects. Despite the earlier work on decoupled dynamic modeling of ACMSs, their coupled dynamic modeling still remains intact. Nonlinearity and complexity of CR modeling make it difficult to design a coupled ACMS model suitable for practical applications. This paper presents a coupled dynamic modeling for ACMSs based on the Euler–Lagrange formulation to deal with CR and the aerial vehicle as a unified system. For this purpose, a general vertical take-off and landing vehicle equipped with a tendon-driven continuum arm is considered to increase the dexterity and compliance of interactions with the environment. The presented model is independent of the motor’s configuration and tilt angles and can be applied to model any under/fully actuated ACMS. The modeling approach is complemented with a Lyapunov-wise stable adaptive sliding mode control technique to demonstrate the validity of the proposed method for such a complex system. Simulation results in free flight motion scenarios are reported to verify the effectiveness of the proposed modeling and control techniques. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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16 pages, 2825 KiB

Open AccessArticle

Repetitive Learning Sliding Mode Stabilization Control for a Flexible-Base, Flexible-Link and Flexible-Joint Space Robot Capturing a Satellite

by Xiaodong Fu, Haiping Ai and Li Chen

Appl. Sci. 2021, 11(17), 8077; https://doi.org/10.3390/app11178077 - 31 Aug 2021

Cited by 15 | Viewed by 1664

Abstract

During the process of satellite capture by a flexible base–link–joint space robot, the base, joints, and links vibrate easily and also rotate in a disorderly manner owing to the impact torque. To address this problem, a repetitive learning sliding mode stabilization control is [...] Read more.

During the process of satellite capture by a flexible base–link–joint space robot, the base, joints, and links vibrate easily and also rotate in a disorderly manner owing to the impact torque. To address this problem, a repetitive learning sliding mode stabilization control is proposed to stabilize the system. First, the dynamic models of the fully flexible space robot and the captured satellite are established, respectively, and the impact effect is calculated according to the motion and force transfer relationships. Based on this, a dynamic model of the system after capturing is established. Subsequently, the system is decomposed into slow and fast subsystems using the singular perturbation theory. To ensure that the base attitude and the joints of the slow subsystem reach the desired trajectories, link vibrations are suppressed simultaneously, and a repetitive learning sliding mode controller based on the concept of the virtual force is designed. Moreover, a multilinear optimal controller is proposed for the fast subsystem to suppress the vibration of the base and joints. Two sub-controllers constitute the repetitive learning sliding mode stabilization control for the system. This ensures that the base attitude and joints of the system reach the desired trajectories in a limited time after capturing, obtain better control quality, and suppress the multiple flexible vibrations of the base, links and joints. Finally, the simulation results verify the effectiveness of the designed control strategy. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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17 pages, 4534 KiB

Open AccessArticle

Robust Flow Field Signal Estimation Method for Flow Sensing by Underwater Robotics

by Xinghua Lin, Qing Qin, Xiaoming Wang and Junxia Zhang

Appl. Sci. 2021, 11(16), 7759; https://doi.org/10.3390/app11167759 - 23 Aug 2021

Cited by 2 | Viewed by 1806

Abstract

The flow field is difficult to evaluate, and underwater robotics can only partly adapt to the submarine environment. However, fish can sense the complex underwater environment by their lateral line system. In order to reveal the fish flow sensing mechanism, a robust nonlinear [...] Read more.

The flow field is difficult to evaluate, and underwater robotics can only partly adapt to the submarine environment. However, fish can sense the complex underwater environment by their lateral line system. In order to reveal the fish flow sensing mechanism, a robust nonlinear signal estimation method based on the Volterra series model with the Kautz kernel function is provided, which is named KKF-VSM. The flow field signal around a square target is used as the original signal. The sinusoidal noise and the signal around a triangular obstacle are considered undesired signals, and the predicting performance of KKF-VSM is analyzed after introducing them locally in the original signals. Compared to the radial basis function neural network model (RBF-NNM), the advantages of KKF-VSM are not only its robustness but also its higher sensitivity to weak signals and its predicting accuracy. It is confirmed that even for strong nonlinear signals, such as pressure responses in the flow field, KKF-VSM is more efficient than the commonly used RBF-NNM. It can provide a reference for the application of the artificial lateral line system on underwater robotics, improving its adaptability in complex environments based on flow field information. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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31 pages, 2819 KiB

Open AccessArticle

Optimization of PID Controller to Stabilize Quadcopter Movements Using Meta-Heuristic Search Algorithms

by Alaa Sheta, Malik Braik, Dheeraj Reddy Maddi, Ahmed Mahdy, Sultan Aljahdali and Hamza Turabieh

Appl. Sci. 2021, 11(14), 6492; https://doi.org/10.3390/app11146492 - 14 Jul 2021

Cited by 17 | Viewed by 4762

Abstract

Quadrotor UAVs are one of the most preferred types of small unmanned aerial vehicles, due to their modest mechanical structure and propulsion precept. However, the complex non-linear dynamic behavior of the Proportional Integral Derivative (PID) controller in these vehicles requires advanced stabilizing control [...] Read more.

Quadrotor UAVs are one of the most preferred types of small unmanned aerial vehicles, due to their modest mechanical structure and propulsion precept. However, the complex non-linear dynamic behavior of the Proportional Integral Derivative (PID) controller in these vehicles requires advanced stabilizing control of their movement. Additionally, locating the appropriate gain for a model-based controller is relatively complex and demands a significant amount of time, as it relies on external perturbations and the dynamic modeling of plants. Therefore, developing a method for the tuning of quadcopter PID parameters may save effort and time, and better control performance can be realized. Traditional methods, such as Ziegler–Nichols (ZN), for tuning quadcopter PID do not provide optimal control and might leave the system with potential instability and cause significant damage. One possible approach that alleviates the tough task of nonlinear control design is the use of meta-heuristics that permit appropriate control actions. This study presents PID controller tuning using meta-heuristic algorithms, such as Genetic Algorithms (GAs), the Crow Search Algorithm (CSA) and Particle Swarm Optimization (PSO) to stabilize quadcopter movements. These meta-heuristics were used to control the position and orientation of a PID controller based on a fitness function proposed to reduce overshooting by predicting future paths. The obtained results confirmed the efficacy of the proposed controller in felicitously and reliably controlling the flight of a quadcopter based on GA, CSA and PSO. Finally, the simulation results related to quadcopter movement control using PSO presented impressive control results, compared to GA and CSA. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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21 pages, 1843 KiB

Open AccessArticle

Bounded Attitude Control with Active Disturbance Rejection Capabilities for Multirotor UAVs

by José Fermi Guerrero-Castellanos, Sylvain Durand, German Ardul Munoz-Hernandez, Nicolas Marchand, Lorenzo L. González Romeo, Jesús Linares-Flores, Gerardo Mino-Aguilar and Wuiyevaldo F. Guerrero-Sánchez

Appl. Sci. 2021, 11(13), 5960; https://doi.org/10.3390/app11135960 - 26 Jun 2021

Cited by 6 | Viewed by 1994

Abstract

This paper addresses an attitude tracking control design applied to multirotor unmanned aerial vehicles (UAVs) based on an ADRC approach. The proposed technique groups the endogenous and exogenous disturbances into a total disturbance, and then this is estimated online via an extended state [...] Read more.

This paper addresses an attitude tracking control design applied to multirotor unmanned aerial vehicles (UAVs) based on an ADRC approach. The proposed technique groups the endogenous and exogenous disturbances into a total disturbance, and then this is estimated online via an extended state observer (ESO). Further, a quaternion-based feedback is developed, which is assisted by a feedforward term obtained via the ESO to relieve the total disturbance actively. The control law is bounded; consequently, it takes into account the maximum capabilities of the actuators to reject the disturbances. The stability is analyzed in the ISS framework, guaranteeing that the closed loop (controller-ESO-UAV) is robustly stable. The simulation results allow validation of the theoretical features. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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19 pages, 3295 KiB

Open AccessArticle

Buffer Compliance Control of Space Robots Capturing a Non-Cooperative Spacecraft Based on Reinforcement Learning

by Haiping Ai, An Zhu, Jiajia Wang, Xiaoyan Yu and Li Chen

Appl. Sci. 2021, 11(13), 5783; https://doi.org/10.3390/app11135783 - 22 Jun 2021

Cited by 22 | Viewed by 2077

Abstract

Aiming at addressing the problem that the joints are easily destroyed by the impact torque during the process of space robot on-orbit capturing a non-cooperative spacecraft, a reinforcement learning control algorithm combined with a compliant mechanism is proposed to achieve buffer compliance control. [...] Read more.

Aiming at addressing the problem that the joints are easily destroyed by the impact torque during the process of space robot on-orbit capturing a non-cooperative spacecraft, a reinforcement learning control algorithm combined with a compliant mechanism is proposed to achieve buffer compliance control. The compliant mechanism can not only absorb the impact energy through the deformation of its internal spring, but also limit the impact torque to a safe range by combining with the compliance control strategy. First of all, the dynamic models of the space robot and the target spacecraft before capture are obtained by using the Lagrange approach and Newton-Euler method. After that, based on the law of conservation of momentum, the constraints of kinematics and velocity, the integrated dynamic model of the post-capture hybrid system is derived. Considering the unstable hybrid system, a buffer compliance control based on reinforcement learning is proposed for the stable control. The associative search network is employed to approximate unknown nonlinear functions, an adaptive critic network is utilized to construct reinforcement signal to tune the associative search network. The numerical simulation shows that the proposed control scheme can reduce the impact torque acting on joints by 76.6% at the maximum and 58.7% at the minimum in the capturing operation phase. And in the stable control phase, the impact torque acting on the joints were limited within the safety threshold, which can avoid overload and damage of the joint actuators. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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17 pages, 7416 KiB

Open AccessArticle

Model-Based Slippage Estimation to Enhance Planetary Rover Localization with Wheel Odometry

by Anna Maria Gargiulo, Ivan di Stefano and Antonio Genova

Appl. Sci. 2021, 11(12), 5490; https://doi.org/10.3390/app11125490 - 13 Jun 2021

Cited by 8 | Viewed by 2053

Abstract

The exploration of planetary surfaces with unmanned wheeled vehicles will require sophisticated software for guidance, navigation and control. Future missions will be designed to study harsh environments that are characterized by rough terrains and extreme conditions. An accurate knowledge of the trajectory of [...] Read more.

The exploration of planetary surfaces with unmanned wheeled vehicles will require sophisticated software for guidance, navigation and control. Future missions will be designed to study harsh environments that are characterized by rough terrains and extreme conditions. An accurate knowledge of the trajectory of planetary rovers is fundamental to accomplish the scientific goals of these missions. This paper presents a method to improve rover localization through the processing of wheel odometry (WO) and inertial measurement unit (IMU) data only. By accurately defining the dynamic model of both a rover’s wheels and the terrain, we provide a model-based estimate of the wheel slippage to correct the WO measurements. Numerical simulations are carried out to better understand the evolution of the rover’s trajectory across different terrain types and to determine the benefits of the proposed WO correction method. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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25 pages, 49297 KiB

Open AccessFeature PaperArticle

Development of Modular Bio-Inspired Autonomous Underwater Vehicle for Close Subsea Asset Inspection

by Wael Gorma, Mark A. Post, James White, James Gardner, Yang Luo, Jongrae Kim, Paul D. Mitchell, Nils Morozs, Marvin Wright and Qing Xiao

Appl. Sci. 2021, 11(12), 5401; https://doi.org/10.3390/app11125401 - 10 Jun 2021

Cited by 9 | Viewed by 4372

Abstract

To reduce human risk and maintenance costs, Autonomous Underwater Vehicles (AUVs) are involved in subsea inspections and measurements for a wide range of marine industries such as offshore wind farms and other underwater infrastructure. Most of these inspections may require levels of manoeuvrability [...] Read more.

To reduce human risk and maintenance costs, Autonomous Underwater Vehicles (AUVs) are involved in subsea inspections and measurements for a wide range of marine industries such as offshore wind farms and other underwater infrastructure. Most of these inspections may require levels of manoeuvrability similar to what can be achieved by tethered vehicles, called Remotely Operated Vehicles (ROVs). To extend AUV intervention time and perform closer inspection in constrained spaces, AUVs need to be more efficient and flexible by being able to undulate around physical constraints. A biomimetic fish-like AUV known as RoboFish has been designed to mimic propulsion techniques observed in nature to provide high thrust efficiency and agility to navigate its way autonomously around complex underwater structures. Building upon advances in acoustic communications, computer vision, electronics and autonomy technologies, RoboFish aims to provide a solution to such critical inspections. This paper introduces the first RoboFish prototype that comprises cost-effective 3D printed modules joined together with innovative magnetic coupling joints and a modular software framework. Initial testing shows that the preliminary working prototype is functional in terms of water-tightness, propulsion, body control and communication using acoustics, with visual localisation and mapping capability. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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12 pages, 856 KiB

Open AccessArticle

Unmanned Aircraft Systems Risk Assessment Based on SORA for First Responders and Disaster Management

by Paweł Janik, Maciej Zawistowski, Radosław Fellner and Grzegorz Zawistowski

Appl. Sci. 2021, 11(12), 5364; https://doi.org/10.3390/app11125364 - 09 Jun 2021

Cited by 17 | Viewed by 4083

Abstract

Worldwide, there is a significant increase in the use of unmanned aerial vehicles (UAVs) by emergency services. They offer a lot of possibilities during rescue operations. Such a wide application for various purposes and environments causes many threats related to their use. To [...] Read more.

Worldwide, there is a significant increase in the use of unmanned aerial vehicles (UAVs) by emergency services. They offer a lot of possibilities during rescue operations. Such a wide application for various purposes and environments causes many threats related to their use. To minimize the risks associated with conducting air operations with UAVs, the application of the SORA (Specific Operations Risk Assessment) methodology will be important. Due to its level of detail, it is a methodology adapted to civilian use. In this article, the authors’ team will try to develop guidelines and directions for adapting SORA to the requirements of the operational work of emergency services. Thus, the following article aims to present the most important risks related to conducting operations with the use of UAVs by first responders (FRs), and to show the sample risk analysis performed for this type of operation on the example of the ASSISTANCE project. The paper describes, on the one hand, possibilities offered by UAVs in crisis or disaster management and step-by-step Specific Operations Risk Assessment (SORA), and on the other hand, presents possible threats, consequences and methods of their mitigation during FR missions. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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17 pages, 1576 KiB

Open AccessArticle

Building Survivable Software Systems by Automatically Adapting to Sensor Changes

by Yuan Shi, Ang Li, T. K. Satish Kumar and Craig A. Knoblock

Appl. Sci. 2021, 11(11), 4808; https://doi.org/10.3390/app11114808 - 24 May 2021

Cited by 2 | Viewed by 1721

Abstract

Many software systems run on long-lifespan platforms that operate in diverse and dynamic environments. If these software systems could automatically adapt to hardware changes, it would significantly reduce the maintenance cost and enable rapid upgrade. In this paper, we study the problem of [...] Read more.

Many software systems run on long-lifespan platforms that operate in diverse and dynamic environments. If these software systems could automatically adapt to hardware changes, it would significantly reduce the maintenance cost and enable rapid upgrade. In this paper, we study the problem of how to automatically adapt to sensor changes, as an important step towards building such long-lived, survivable software systems. We address challenges in sensor adaptation when a set of sensors are replaced by new sensors. Our approach reconstructs sensor values of replaced sensors by preserving distributions of sensor values before and after the sensor change, thereby not warranting a change in higher-layer software. Compared to existing work, our approach has the following advantages: (a) ability to exploit new sensors without requiring an overlapping period of time between the new sensors and the old ones; (b) ability to provide an estimation of adaptation quality; and (c) ability to scale to a large number of sensors. Experiments on weather data and Unmanned Undersea Vehicle (UUV) data demonstrate that our approach can automatically adapt to sensor changes with 5.7% higher accuracy compared to baseline methods. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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16 pages, 4137 KiB

Open AccessArticle

Path Following and Obstacle Avoidance for Unmanned Aerial Vehicles Using a Virtual-Force-Based Guidance Law

by Xun Wang, Libing Cai, Longxing Kong, Binfeng Wang, Shaohua Huang and Chengdi Lin

Appl. Sci. 2021, 11(10), 4618; https://doi.org/10.3390/app11104618 - 18 May 2021

Cited by 3 | Viewed by 2044

Abstract

This paper presents a virtual-force-based guidance law (VFGL) for path following and obstacle avoidance in unmanned aerial vehicles. First, a virtual spring force and a virtual drag force are designed for straight-line following; then, the dynamic of the cross-track-error is equivalent to a [...] Read more.

This paper presents a virtual-force-based guidance law (VFGL) for path following and obstacle avoidance in unmanned aerial vehicles. First, a virtual spring force and a virtual drag force are designed for straight-line following; then, the dynamic of the cross-track-error is equivalent to a spring mass system, which is easy to tune to acquire stability and non-overshoot convergence. Secondly, an additional virtual centripetal force is designed to counteract the influence of the curvature of the planned path so that the guidance law can accurately track a curve with a time-varying curvature. Thirdly, an extra virtual repulsive force is designed directly according to the sensor inputs; the virtual repulsive force pushes the vehicle away to move around obstacles. The use of artificial physics means the guidance law is founded on solid physical theory and is computationally simple. The physical meanings of the parameters are definite, and the VFGL has a large parameter adaptation. These make the guidance law easy to tune in application. Both the numerical and hardware-in-the-loop simulation results demonstrated the effectiveness of the proposed guidance law for path following and obstacle avoidance in unmanned aerial vehicles. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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21 pages, 4130 KiB

Open AccessArticle

Roto-Translational Control of Spacecraft in Low Earth Orbit Using Environmental Forces and Torques

by Camilo Riano-Rios, Alberto Fedele and Riccardo Bevilacqua

Appl. Sci. 2021, 11(10), 4606; https://doi.org/10.3390/app11104606 - 18 May 2021

Cited by 2 | Viewed by 1718

Abstract

In this paper, relative orbit and attitude adaptive controllers are integrated to perform roto-translational maneuvers for CubeSats equipped with a Drag Maneuvering Device (DMD). The DMD enables the host CubeSat with modulation of aerodynamic forces/torques and gravity gradient torque. Adaptive controllers for independent [...] Read more.

In this paper, relative orbit and attitude adaptive controllers are integrated to perform roto-translational maneuvers for CubeSats equipped with a Drag Maneuvering Device (DMD). The DMD enables the host CubeSat with modulation of aerodynamic forces/torques and gravity gradient torque. Adaptive controllers for independent orbital and attitude maneuvers are revisited to account for traslational-attitude coupling while compensating for uncertainty in parameters such as atmospheric density, drag/lift coefficients, location of the Center of Mass (CoM) and inertia matrix. Uniformly ultimately bounded convergence of the attitude error and relative orbit states is guaranteed by Lyapunov-based stability analysis for the integrated roto-translational maneuver. A simulation example of an along-track formation maneuver between two CubeSats with simultaneous attitude control using only environmental forces and torques is presented to validate the controller. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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20 pages, 867 KiB

Open AccessArticle

Dynamic Maneuverability Analysis: A Preliminary Application on an Autonomous Underwater Reconfigurable Vehicle

by Edoardo Topini, Marco Pagliai and Benedetto Allotta

Appl. Sci. 2021, 11(10), 4469; https://doi.org/10.3390/app11104469 - 14 May 2021

Cited by 4 | Viewed by 1952

Abstract

Since the development of the first autonomous underwater vehicles, the demanded tasks for subsea operations have become more and more challenging as, for instance, intervention, maintenance and repair of seabed installations, in addition to surveys. As a result, the development of autonomous underwater [...] Read more.

Since the development of the first autonomous underwater vehicles, the demanded tasks for subsea operations have become more and more challenging as, for instance, intervention, maintenance and repair of seabed installations, in addition to surveys. As a result, the development of autonomous underwater reconfigurable vehicles (AURVs) with the capability of interacting with the surrounding environment and autonomously changing the configuration, according to the task at hand, can represent a real breakthrough in underwater system technologies. Driven by these considerations, an innovative AURV has been designed by the Department of Industrial Engineering of the University of Florence (named as UNIFI DIEF AURV), capable of efficiently reconfiguring its shape according to the task at hand. In particular, the UNIFI DIEF AURV has been provided with two extreme configurations: a slender (“survey”) configuration for long navigation tasks, and a stocky (“hovering”) configuration designed for challenging goals as intervention operations. In order to observe the several dynamic features for the two different configurations, a novel formulation for the dynamic maneuverability analysis (DMA) of an AURV, adapting Yoshikawa’s well-known manipulability theory for robotic arms, is proposed in this work. More specifically, we introduce a novel analysis which relates the vehicle body-fixed accelerations with the rotational speed of each thruster, taking into account also the AURV dynamic model for each configuration and the propulsion system. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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14 pages, 6312 KiB

Open AccessArticle

Multi-Sensor Fusion for Aerial Robots in Industrial GNSS-Denied Environments

by Paloma Carrasco, Francisco Cuesta, Rafael Caballero, Francisco J. Perez-Grau and Antidio Viguria

Appl. Sci. 2021, 11(9), 3921; https://doi.org/10.3390/app11093921 - 26 Apr 2021

Cited by 10 | Viewed by 1971

Abstract

The use of unmanned aerial robots has increased exponentially in recent years, and the relevance of industrial applications in environments with degraded satellite signals is rising. This article presents a solution for the 3D localization of aerial robots in such environments. In order [...] Read more.

The use of unmanned aerial robots has increased exponentially in recent years, and the relevance of industrial applications in environments with degraded satellite signals is rising. This article presents a solution for the 3D localization of aerial robots in such environments. In order to truly use these versatile platforms for added-value cases in these scenarios, a high level of reliability is required. Hence, the proposed solution is based on a probabilistic approach that makes use of a 3D laser scanner, radio sensors, a previously built map of the environment and input odometry, to obtain pose estimations that are computed onboard the aerial platform. Experimental results show the feasibility of the approach in terms of accuracy, robustness and computational efficiency. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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29 pages, 13988 KiB

Open AccessArticle

Online Learning Based Underwater Robotic Thruster Fault Detection

by Gaofei Xu, Wei Guo, Yang Zhao, Yue Zhou, Yinlong Zhang, Xinyu Liu, Gaopeng Xu and Guangwei Li

Appl. Sci. 2021, 11(8), 3586; https://doi.org/10.3390/app11083586 - 16 Apr 2021

Cited by 8 | Viewed by 1975

Abstract

This paper presents a novel online learning-based fault detection designed for underwater robotic thruster health monitoring. In the fault detection algorithm, we build a mathematical model between the control variable and the propeller speed by fitting collected online work status data to the [...] Read more.

This paper presents a novel online learning-based fault detection designed for underwater robotic thruster health monitoring. In the fault detection algorithm, we build a mathematical model between the control variable and the propeller speed by fitting collected online work status data to the model. To improve the accuracy of online modeling, a multi-center PSO algorithm with memory ability is utilized to optimize the modeling parameters. Additionally, a model online update mechanism is designed to accommodate the model to the change of thruster work status and sea environment. During the operation, propeller speed of the underwater robot is predicted through the online learning-based model, and the model residuals are used for thruster health monitoring. To avoid false alarm, an adaptive fault detection strategy is established based on model online update mechanism. The proposed method has been extensively evaluated using different underwater robotics, through a sea trial data simulation, a pool test fault detection experiment and a sea trial fault detection experiment. Compared with fixed model-based method, speed prediction MAE of the online learning model is at least 37.9% lower than that of the fixed model. The online learning-based method show no misdiagnosis in experiments, while the fixed model-based method is misdiagnosed. Experimental results show that the proposed method is competitive in terms of accuracy, adaptability, and robustness. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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24 pages, 4071 KiB

Open AccessArticle

Quasi-Passive Resistive Exosuit for Space Activities: Proof of Concept

by Christian Di Natali, Giorgia Chini, Massimo Totaro, Julio S. Lora-Millán, Eduardo Rocon, Lucia Beccai, Darwin G. Caldwell, Gianfranco Visentin and Jesús Ortiz

Appl. Sci. 2021, 11(8), 3576; https://doi.org/10.3390/app11083576 - 16 Apr 2021

Cited by 11 | Viewed by 3609

Abstract

The limits of space travel are continuously evolving, and this creates increasingly extreme challenges for the crew’s health that must be addressed by the scientific community. Long-term exposure to micro-gravity, during orbital flights, contributes to muscle strength degradation and increases bone density loss. [...] Read more.

The limits of space travel are continuously evolving, and this creates increasingly extreme challenges for the crew’s health that must be addressed by the scientific community. Long-term exposure to micro-gravity, during orbital flights, contributes to muscle strength degradation and increases bone density loss. In recent years, several exercise devices have been developed to counteract the negative health effects of zero-gravity on astronauts. However, the relatively large size of these devices, the need for a dedicated space and the exercise time-frame for each astronaut, does not make these devices the best choice for future long range exploration missions. This paper presents a quasi-passive exosuit to provide muscle training using a small, portable, proprioceptive device. The exosuit promotes continuous exercise, by resisting the user’s motion, during routine all-day activity. This study assesses the effectiveness of the resistive exosuit by evaluating its effects on muscular endurance during a terrestrial walking task. The experimental assessment on biceps femoris and vastus lateralis, shows a mean increase in muscular activation of about

97.8 %

during five repetitions of 3 min walking task at 3 km/h. The power frequency analysis shows an increase in muscular fatigue with a reduction of EMG median frequency of about

15.4 %

for the studied muscles. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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24 pages, 4945 KiB

Open AccessArticle

Stabilization of an Unconventional Large Airship When Hovering

by Naoufel Azouz, Mahmoud Khamlia, Jean Lerbet and Azgal Abichou

Appl. Sci. 2021, 11(8), 3551; https://doi.org/10.3390/app11083551 - 15 Apr 2021

Cited by 6 | Viewed by 2338

Abstract

In this paper, we present the stabilization of an unconventional unmanned airship above a loading and unloading area. The study concerns a quad-rotor flying wing airship. This airship is devoted to freight transport. However, during the loading and unloading phases, the airship is [...] Read more.

In this paper, we present the stabilization of an unconventional unmanned airship above a loading and unloading area. The study concerns a quad-rotor flying wing airship. This airship is devoted to freight transport. However, during the loading and unloading phases, the airship is very sensitive to squalls. In this context, we present in this paper the dynamic model of the airship, and we propose a strategy for controlling it under the effects of a gust of wind. A feedforward/feedback control law is proposed to stabilize the airship when hovering. As part of the control allocation, the non-linear equations between the control vectors and the response of the airship actuators are highlighted and solved analytically through energy optimization constraints. A comparison with classical numerical algorithms was performed and demonstrated the power and interest of our analytic algorithm. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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13 pages, 1504 KiB

Open AccessArticle

Time-Continuous Real-Time Trajectory Generation for Safe Autonomous Flight of a Quadrotor in Unknown Environment

by Yonghee Park, Woosung Kim and Hyungpil Moon

Appl. Sci. 2021, 11(7), 3238; https://doi.org/10.3390/app11073238 - 04 Apr 2021

Cited by 4 | Viewed by 2533

Abstract

In this paper, we present an efficient global and local replanning method for a quadrotor to complete a flight mission in a cluttered and unmapped environment. A minimum-snap global path planner generates a global trajectory that comprises some waypoints in a cluttered environment. [...] Read more.

In this paper, we present an efficient global and local replanning method for a quadrotor to complete a flight mission in a cluttered and unmapped environment. A minimum-snap global path planner generates a global trajectory that comprises some waypoints in a cluttered environment. When facing unexpected obstacles, our method modifies the global trajectory using geometrical planning and closed-form formulation for an analytical solution with 9th-order polynomial. The proposed method provides an analytical solution, not a numerical one, and it is computationally efficient without falling into a local minima problem. In a simulation, we show that the proposed method can fly a quadrotor faster than the numerical method in a cluttered environment. Furthermore, we show in experiments that the proposed method can provide safer and faster trajectory generation than the numerical method in a real environment. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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34 pages, 3035 KiB

Open AccessArticle

Geometric Reduced-Attitude Control of Fixed-Wing UAVs

by Erlend M. Coates and Thor I. Fossen

Appl. Sci. 2021, 11(7), 3147; https://doi.org/10.3390/app11073147 - 01 Apr 2021

Cited by 10 | Viewed by 3743

Abstract

This paper presents nonlinear, singularity-free autopilot designs for multivariable reduced-attitude control of fixed-wing aircraft. To control roll and pitch angles, we employ vector coordinates constrained to the unit two-sphere and that are independent of the yaw/heading angle. The angular velocity projected onto this [...] Read more.

This paper presents nonlinear, singularity-free autopilot designs for multivariable reduced-attitude control of fixed-wing aircraft. To control roll and pitch angles, we employ vector coordinates constrained to the unit two-sphere and that are independent of the yaw/heading angle. The angular velocity projected onto this vector is enforced to satisfy the coordinated-turn equation. We exploit model structure in the design and prove almost global asymptotic stability using Lyapunov-based tools. Slowly-varying aerodynamic disturbances are compensated for using adaptive backstepping. To emphasize the practical application of our result, we also establish the ultimate boundedness of the solutions under a simplified controller that only depends on rough estimates of the control-effectiveness matrix. The controller design can be used with state-of-the-art guidance systems for fixed-wing unmanned aerial vehicles (UAVs) and is implemented in the open-source autopilot ArduPilot for validation through realistic software-in-the-loop (SITL) simulations. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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23 pages, 1176 KiB

Open AccessArticle

Safety Analysis of a Certifiable Air Data System Based on Synthetic Sensors for Flow Angle Estimation

by Angelo Lerro and Manuela Battipede

Appl. Sci. 2021, 11(7), 3127; https://doi.org/10.3390/app11073127 - 01 Apr 2021

Cited by 8 | Viewed by 2765

Abstract

This work deals with the safety analysis of an air data system (ADS) partially based on synthetic sensors. The ADS is designed for the small aircraft transportation (SAT) community and is suitable for future unmanned aerial vehicles and urban air mobility applications. The [...] Read more.

This work deals with the safety analysis of an air data system (ADS) partially based on synthetic sensors. The ADS is designed for the small aircraft transportation (SAT) community and is suitable for future unmanned aerial vehicles and urban air mobility applications. The ADS’s main innovation is based on estimation of the flow angles (angle-of-attack and angle-of-sideslip) using synthetic sensors instead of classical vanes (or sensors), whereas pressure and temperature are directly measured with Pitot and temperature probes. As the air data system is a safety-critical system, safety analyses are performed and the results are compared with the safety objectives required by the aircraft integrator. The present paper introduces the common aeronautical procedures for system safety assessment applied to a safety critical system partially based on synthetic sensors. The mean time between failures of ADS’s sub-parts are estimated on a statistical basis in order to evaluate the failure rate of the ADS’s functions. The proposed safety analysis is also useful in identifying the most critical air data system parts and sub-parts. Possible technological gaps to be filled to achieve the airworthiness safety objectives with nonredundant architectures are also identified. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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12 pages, 531 KiB

Open AccessFeature PaperArticle

Safety-Aware Optimal Attitude Pointing for Low-Thrust Satellites

by Helen Henninger, James Biggs and Karl von Ellenrieder

Appl. Sci. 2021, 11(7), 3002; https://doi.org/10.3390/app11073002 - 27 Mar 2021

Cited by 1 | Viewed by 1451

Abstract

In geostationary orbit, long eclipses and the seasonal variations in the direction and intensity of the solar input can cause damage to sensitive equipment during attitude maneuvers, which may inadvertently point the equipment towards the Sun. The requirement that transmitting and receiving antennae [...] Read more.

In geostationary orbit, long eclipses and the seasonal variations in the direction and intensity of the solar input can cause damage to sensitive equipment during attitude maneuvers, which may inadvertently point the equipment towards the Sun. The requirement that transmitting and receiving antennae remain pointed towards the Earth creates further restrictions to pointing directions. The aim of the study is to construct a novel geometric and reinforcement-learning-based method to determine attitude guidance maneuvers that maintain the equipment in safe and operational orientations throughout an attitude maneuver. The attitude trajectory is computed numerically using the geometric framing of Pontryagin’s maximum principle applied to the vehicle kinematics using the global matrix Lie group representation on

S O (3)

, and the angular velocities are shaped using free parameters. The values of these free parameters are determined by a reinforcement learning algorithm to avoid the forbidden areas while maintaining the pointing in operational areas (modeled as subsets of the two-sphere of all possible pointing directions of a particular axis). The method is applied to a model geosynchronous satellite and demonstrated in a simulation. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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23 pages, 11476 KiB

Open AccessArticle

Bio-Inspired Morphing Tail for Flapping-Wings Aerial Robots Using Macro Fiber Composites

by Vicente Perez-Sanchez, Alejandro E. Gomez-Tamm, Emanuela Savastano, Begoña C. Arrue and Anibal Ollero

Appl. Sci. 2021, 11(7), 2930; https://doi.org/10.3390/app11072930 - 25 Mar 2021

Cited by 11 | Viewed by 2757

Abstract

The aim of this work is to present the development of a bio-inspired approach for a robotic tail using Macro Fiber Composites (MFC) as actuators. The use of this technology will allow achieving closer to the nature approach of the tail, aiming to [...] Read more.

The aim of this work is to present the development of a bio-inspired approach for a robotic tail using Macro Fiber Composites (MFC) as actuators. The use of this technology will allow achieving closer to the nature approach of the tail, aiming to mimic a bird tail behavior. The tail will change its shape, performing morphing, providing a new type of actuation methodology in flapping control systems. The work is intended as a first step for demonstrating the potential of these technologies for being applied in other parts of the aerials robotics systems. When compared with traditional actuation approaches, one key advantage that is given by the use of MFC is their ability to adapt to different flight conditions via geometric tailoring, imitating what birds do in nature. Theoretical explanations, design, and experimental validation of the developed concept using different methodologies will be presented in this paper. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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27 pages, 2498 KiB

Open AccessArticle

Dynamic Neural Network-Based Adaptive Tracking Control for an Autonomous Underwater Vehicle Subject to Modeling and Parametric Uncertainties

by Filiberto Muñoz, Jorge S. Cervantes-Rojas, Jose M. Valdovinos, Omar Sandre-Hernández, Sergio Salazar and Hugo Romero

Appl. Sci. 2021, 11(6), 2797; https://doi.org/10.3390/app11062797 - 21 Mar 2021

Cited by 18 | Viewed by 3000

Abstract

This research presents a way to improve the autonomous maneuvering capability of a four-degrees-of-freedom (4DOF) autonomous underwater vehicle (AUV) to perform trajectory tracking tasks in a disturbed underwater environment. This study considers four second-order input-affine nonlinear equations for the translational (x,y,z) and rotational [...] Read more.

This research presents a way to improve the autonomous maneuvering capability of a four-degrees-of-freedom (4DOF) autonomous underwater vehicle (AUV) to perform trajectory tracking tasks in a disturbed underwater environment. This study considers four second-order input-affine nonlinear equations for the translational (x,y,z) and rotational (heading) dynamics of a real AUV subject to hydrodynamic parameter uncertainties (added mass and damping coefficients), unknown damping dynamics, and external disturbances. We proposed an identification-control scheme for each dynamic named Dynamic Neural Control System (DNCS) as a combination of an adaptive neural controller based on nonparametric identification of the effect of unknown dynamics and external disturbances, and on parametric estimation of the added mass dependent input gain. Several numerical simulations validate the satisfactory performance of the proposed DNCS tracking reference trajectories in comparison with a conventional feedback controller with no adaptive compensation. Some graphics showing dynamic approximation of the lumped disturbance as well as estimation of the parametric uncertainty are depicted, validating effective operation of the proposed DNCS when the system is almost completely unknown. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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12 pages, 3684 KiB

Open AccessArticle

Preliminary Analysis of a Lightweight and Deployable Soft Robot for Space Applications

by Mario Troise, Matteo Gaidano, Pierpaolo Palmieri and Stefano Mauro

Appl. Sci. 2021, 11(6), 2558; https://doi.org/10.3390/app11062558 - 12 Mar 2021

Cited by 11 | Viewed by 3730

Abstract

The rising interest in soft robotics, combined to the increasing applications in the space industry, leads to the development of novel lightweight and deployable robotic systems, that could be easily contained in a relatively small package to be deployed when required. The main [...] Read more.

The rising interest in soft robotics, combined to the increasing applications in the space industry, leads to the development of novel lightweight and deployable robotic systems, that could be easily contained in a relatively small package to be deployed when required. The main challenges for soft robotic systems are the low force exertion and the control complexity. In this manuscript, a soft manipulator concept, having inflatable links, is introduced to face these issues. A prototype of the inflatable link is manufactured and statically characterized using a pseudo-rigid body model on varying inflation pressure. Moreover, the full robot model and algorithms for the load and pose estimation are presented. Finally, a control strategy, using inverse kinematics and an elastostatic approach, is developed. Experimental results provide input data for the control algorithm, and its validity domain is discussed on the basis of a simulation model. This preliminary analysis puts the basis of future advancements in building the robot prototype and developing dynamic models and robust control. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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16 pages, 17419 KiB

Open AccessFeature PaperArticle

Bio-Inspired Design of an Underwater Robot Exploiting Fin Undulation Propulsion

by Giovanni Bianchi, Simone Cinquemani and Ferruccio Resta

Appl. Sci. 2021, 11(6), 2556; https://doi.org/10.3390/app11062556 - 12 Mar 2021

Cited by 10 | Viewed by 3220

Abstract

Interest in autonomous underwater vehicles is constantly increasing following the emerging needs of underwater exploration and military purposes. Thus, several new propulsion mechanisms are studied and developed. Fish swimming is a promising source of inspiration because they outperform conventional propellers in terms of [...] Read more.

Interest in autonomous underwater vehicles is constantly increasing following the emerging needs of underwater exploration and military purposes. Thus, several new propulsion mechanisms are studied and developed. Fish swimming is a promising source of inspiration because they outperform conventional propellers in terms of energy efficiency and maneuvrability. Their advantages are not only due to the streamlined shape and their low-drag skin but also, above all, due to the particular fin motion, which makes thrust generation possible with small energy dissipation. This paper analyses the motion of batoid fishes that are considered highly efficient by biologists. Their motion is reproduced by different linkage mechanisms optimized to fit underwater robots. A bioinspired robot mimicking cownose ray locomotion is, then, designed and built. Numerical analysis of its dynamics allows us to measure the size of actuators and to estimate the robot behavior. Finally, the control algorithm that maintains the mechanism synchronization according to different strategies is described and some experimental results are presented. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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15 pages, 2725 KiB

Open AccessFeature PaperArticle

Finite-Horizon Kinetic Energy Optimization of a Redundant Space Manipulator

by Alessandro Tringali and Silvio Cocuzza

Appl. Sci. 2021, 11(5), 2346; https://doi.org/10.3390/app11052346 - 06 Mar 2021

Cited by 12 | Viewed by 1962

Abstract

The minimization of energy consumption is of the utmost importance in space robotics. For redundant manipulators tracking a desired end-effector trajectory, most of the proposed solutions are based on locally optimal inverse kinematics methods. On the one hand, these methods are suitable for [...] Read more.

The minimization of energy consumption is of the utmost importance in space robotics. For redundant manipulators tracking a desired end-effector trajectory, most of the proposed solutions are based on locally optimal inverse kinematics methods. On the one hand, these methods are suitable for real-time implementation; nevertheless, on the other hand, they often provide solutions quite far from the globally optimal one and, moreover, are prone to singularities. In this paper, a novel inverse kinematics method for redundant manipulators is presented, which overcomes the above mentioned issues and is suitable for real-time implementation. The proposed method is based on the optimization of the kinetic energy integral on a limited subset of future end-effector path points, making the manipulator joints to move in the direction of minimum kinetic energy. The proposed method is tested by simulation of a three degrees of freedom (DOF) planar manipulator in a number of test cases, and its performance is compared to the classical pseudoinverse solution and to a global optimal method. The proposed method outperforms the pseudoinverse-based one and proves to be able to avoid singularities. Furthermore, it provides a solution very close to the global optimal one with a much lower computational time, which is compatible for real-time implementation. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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18 pages, 4000 KiB

Open AccessArticle

On a New Type of Combined Solar–Thermal/Cold Gas Propulsion System Used for LEO Satellite’s Attitude Control

by Constantin Sandu, Valentin Silivestru, Grigore Cican, Horațiu Șerbescu, Traian Tipa, Andrei Totu and Andrei Radu

Appl. Sci. 2020, 10(20), 7197; https://doi.org/10.3390/app10207197 - 15 Oct 2020

Cited by 2 | Viewed by 2246

Abstract

This paper presents the development, construction and testing of a new type of solar–thermal propulsion system which can be used for low earth orbit (LEO) satellites. Currently, the vast majority of LEO satellites are fitted with a cold gas propulsion system. Although such [...] Read more.

This paper presents the development, construction and testing of a new type of solar–thermal propulsion system which can be used for low earth orbit (LEO) satellites. Currently, the vast majority of LEO satellites are fitted with a cold gas propulsion system. Although such a propulsion system is preferred, the service duration of an LEO satellite is limited by the amount of cold gas they carry onboard. In the case of the new type of solar–thermal propulsion system proposed in this paper, the cold gas is first transferred from the main tank in a cylindrical service tank/buffer tank which is placed in the focal line of a concave mirror. After the gas is heated by the solar light focused on the service tank by the concave mirror, it expands by opening the appropriate solenoid valve for the satellite’s attitude control. In this way the service duration of LEO satellite on orbit can increase by 2.5 times compared with a classic cold gas propulsion system. This is due to the propellant’s internal energy increase by the focused solar light. This paper also presents the results achieved by carrying out tests for the hot gas propulsion system in a controlled environment. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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28 pages, 468 KiB

Open AccessReview

Review of Propulsion System Design Strategies for Unmanned Aerial Vehicles

by Cinzia Amici, Federico Ceresoli, Marco Pasetti, Matteo Saponi, Monica Tiboni and Simone Zanoni

Appl. Sci. 2021, 11(11), 5209; https://doi.org/10.3390/app11115209 - 04 Jun 2021

Cited by 18 | Viewed by 5016

Abstract

The design of the propulsion system for Unmanned Aerial Vehicles (UAVs) demands an inclusive multidisciplinary approach from the earliest design phases, since every design choice strictly affects and is affected by the overall working conditions. This paper presents a review of the scientific [...] Read more.

The design of the propulsion system for Unmanned Aerial Vehicles (UAVs) demands an inclusive multidisciplinary approach from the earliest design phases, since every design choice strictly affects and is affected by the overall working conditions. This paper presents a review of the scientific literature focused on the design methods applied in defining and sizing the propulsion system of drones. The analysis, performed with a systematic approach, evaluated 123 papers according to two custom classification taxonomies, which investigated respectively the primary aim and specific content of the works. Finally, literature indications and hints were combined into an integrated framework for the functional design of the propulsion system of UAVs. The procedure aimed to support the designer in the preliminary selection of the propulsion candidates and the quick sizing of the supply system, during the first phases of the design process. According to the literature, design methods dramatically change depending on the expected applications and working conditions of UAVs, so that the detailed design of specific drone elements and propulsion components represents the focus of most of the papers in this field. Full article

(This article belongs to the Special Issue Advances in Aerial, Space, and Underwater Robotics)

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