Robotics

17 pages, 10027 KiB

Open AccessArticle

Assembly Modes and Workspace Analysis of a 3-RRR Planar Manipulator

by Florentin Buium, Ioan Doroftei and Stelian Alaci

Robotics 2025, 14(2), 16; https://doi.org/10.3390/robotics14020016 - 31 Jan 2025

This paper examines the influence of the eight assembling modes of the 3-RRR planar manipulator on its workspace. The workspace is analyzed considering both first-type and second-type singularities. Understanding these issues is crucial in the process of designing such manipulators to avoid unfavorable [...] Read more.

This paper examines the influence of the eight assembling modes of the 3-RRR planar manipulator on its workspace. The workspace is analyzed considering both first-type and second-type singularities. Understanding these issues is crucial in the process of designing such manipulators to avoid unfavorable cases. Additionally, a modular platform concept, suitable for experimental testing and informed by the numerical results presented here, is proposed. The outcomes of the experimental tests will be addressed in future work. Full article

(This article belongs to the Special Issue Selected Papers from MEDER 2024: Advances in Mechanism Design for Robotics)

22 pages, 7750 KiB

Open AccessArticle

Haptic Guidance System for Teleoperation Based on Trajectory Similarity

by Hikaru Nagano, Tomoki Nishino, Yuichi Tazaki and Yasuyoshi Yokokohji

Robotics 2025, 14(2), 15; https://doi.org/10.3390/robotics14020015 - 30 Jan 2025

Abstract

Teleoperation technology enables remote control of machines, but often requires complex manoeuvres that pose significant challenges for operators. To mitigate these challenges, assistive systems have been developed to support teleoperation. This study presents a teleoperation guidance system that provides assistive force feedback to [...] Read more.

Teleoperation technology enables remote control of machines, but often requires complex manoeuvres that pose significant challenges for operators. To mitigate these challenges, assistive systems have been developed to support teleoperation. This study presents a teleoperation guidance system that provides assistive force feedback to help operators align more accurately with desired trajectories. Two key issues remain: (1) the lack of a flexible, real-time approach to defining desired trajectories and calculating assistive forces, and (2) uncertainty about the effects of forward motion assistance within the assistive forces. To address these issues, we propose a novel approach that captures the posture trajectory of the local control interface, statistically generates a reference trajectory, and incorporates forward motion as an adjustable parameter. In Experiment 1, which involved simulating an object transfer task, the proposed method significantly reduced the operator’s workload compared to conventional techniques, especially in dynamic target scenarios. Experiment 2, which involved more complex paths, showed that assistive forces with　forward assistance significantly improved manoeuvring performance. Full article

(This article belongs to the Special Issue Robot Teleoperation Integrating with Augmented Reality)

31 pages, 1489 KiB

Open AccessArticle

Quantum-Inspired Sliding-Mode Control to Enhance the Precision and Energy Efficiency of an Articulated Industrial Robotic Arm

by Mehdi Fazilat and Nadjet Zioui

Robotics 2025, 14(2), 14; https://doi.org/10.3390/robotics14020014 - 29 Jan 2025

Abstract

Maintaining precise and robust control in robotic systems, particularly those with nonlinear dynamics and external disturbances, is a significant challenge in robotics. Sliding-mode control (SMC) is a widely used technique to tackle these issues; however, it is plagued by chattering and computational complexity, [...] Read more.

Maintaining precise and robust control in robotic systems, particularly those with nonlinear dynamics and external disturbances, is a significant challenge in robotics. Sliding-mode control (SMC) is a widely used technique to tackle these issues; however, it is plagued by chattering and computational complexity, which limit its effectiveness in high-precision environments. This study aims to develop and assess a quantum-inspired sliding-mode control (QSMC) strategy to enhance the SMC’s robustness, precision, and computational efficiency, specifically in controlling a six-jointed articulated robotic arm. The methodology involves creating a comprehensive kinematic and dynamic model of the robot, followed by implementing both classic SMC and the proposed Q-SMC in a comparative way. The simulation results confirm that the Q-SMC method outperforms the classic SMC, particularly in reducing chattering, improving tracking accuracy, and decreasing energy consumption by approximately 3.79%. These findings suggest that the Q-SMC technique provides a promising alternative to classical control methods, with potential applications in tasks requiring high precision and efficient robotic manipulations. Full article

(This article belongs to the Special Issue Adaptive and Nonlinear Control of Robotics)

17 pages, 3461 KiB

Open AccessArticle

Real-Time Registration of 3D Underwater Sonar Scans

by António Ferreira, José Almeida, Aníbal Matos and Eduardo Silva

Robotics 2025, 14(2), 13; https://doi.org/10.3390/robotics14020013 - 29 Jan 2025

Abstract

Due to space and energy restrictions, lightweight autonomous underwater vehicles (AUVs) are usually fitted with low-power processing units, which limits the ability to run demanding applications in real time during the mission. However, several robotic perception tasks reveal a parallel nature, where the [...] Read more.

Due to space and energy restrictions, lightweight autonomous underwater vehicles (AUVs) are usually fitted with low-power processing units, which limits the ability to run demanding applications in real time during the mission. However, several robotic perception tasks reveal a parallel nature, where the same processing routine is applied for multiple independent inputs. In such cases, leveraging parallel execution by offloading tasks to a GPU can greatly enhance processing speed. This article presents a collection of generic matrix manipulation kernels, which can be combined to develop parallelized perception applications. Taking advantage of those building blocks, we report a parallel implementation for the 3DupIC algorithm—a probabilistic scan matching method for sonar scan registration. Tests demonstrate the algorithm’s real-time performance, enabling 3D sonar scan matching to be executed in real time onboard the EVA AUV. Full article

(This article belongs to the Special Issue Localization and 3D Mapping of Intelligent Robotics)

21 pages, 10181 KiB

Open AccessArticle

Development of a Rehabilitation Apparatus for Frozen Shoulder Enabling Total Motion of Shoulder Complex

by Xiao Sun, Koji Makino, Daichi Kurita, Hiromi Kaneko, Kazuyoshi Ishida and Hidetsugu Terada

Robotics 2025, 14(2), 12; https://doi.org/10.3390/robotics14020012 - 29 Jan 2025

Abstract

This article describes an apparatus developed by the authors as a substitution for physical therapists regarding mechanical movements in the rehabilitation of frozen shoulder. In particular, the performance of this apparatus is improved in comparison with existing methods in terms of the following [...] Read more.

This article describes an apparatus developed by the authors as a substitution for physical therapists regarding mechanical movements in the rehabilitation of frozen shoulder. In particular, the performance of this apparatus is improved in comparison with existing methods in terms of the following two major points: (1) realization of individual rehabilitation for the patient’s scapula by an innovative parallel–serial hybrid linkage design and supporting parts that can fix and move the patient’s scapula; and (2) the addition of a “teaching” and “playback” mode to enable the apparatus to record the motion of rehabilitation, allowing it to be customized for each patient by physical therapists and reproduce the recorded motion accurately, thus freeing physical therapists from repetitive rehabilitation routines. With the introduction of the whole system, experimental results are shown and discussed to verify and evaluate the performance of the developed apparatus. Full article

(This article belongs to the Special Issue Selected Papers from MEDER 2024: Advances in Mechanism Design for Robotics)

19 pages, 3390 KiB

Open AccessArticle

Tension-Aware Motion Planning for Tethered Robots

by Rogério R. Lima and Guilherme A. S. Pereira

Robotics 2025, 14(2), 11; https://doi.org/10.3390/robotics14020011 - 28 Jan 2025

Abstract

This paper presents a path-planning approach for tethered robots. The proposed planner finds paths that minimize the tether tension due to tether–obstacle and tether–floor interaction. The method assumes that the tether is managed externally by a tether management system and pulled by the [...] Read more.

This paper presents a path-planning approach for tethered robots. The proposed planner finds paths that minimize the tether tension due to tether–obstacle and tether–floor interaction. The method assumes that the tether is managed externally by a tether management system and pulled by the robot. The planner is initially formulated for ground robots in a 2D environment and then extended for 3D scenarios, where it can be applied to tethered aerial and underwater vehicles. The proposed approach assumes a taut tether between two consecutive contact points and knowledge of the coefficient of friction of the obstacles present in the environment. The method first computes the visibility graph of the environment, in which each node represents a vertex of an obstacle. Then, a second graph, named the tension-aware graph, is built so that the tether–environment interaction, formulated in terms of tension, is computed and used as the cost of the edges. A graph search algorithm (e.g., Dijkstra) is then used to compute a path with minimum tension, which can help the tethered robot reach longer distances by minimizing the tension required to drag the tether along the way. This paper presents simulations and a real-world experiment that illustrate the characteristics of the method. Full article

(This article belongs to the Special Issue Autonomous Robotics for Exploration)

27 pages, 12074 KiB

Open AccessArticle

Near Time-Optimal Trajectories with ISO Standard Constraints for Human–Robot Collaboration in Fabric Co-Transportation

by Renat Kermenov, Alessandro Di Biase, Ilaria Pellicani, Sauro Longhi and Andrea Bonci

Robotics 2025, 14(2), 10; https://doi.org/10.3390/robotics14020010 - 27 Jan 2025

Abstract

Enabling robots to work safely close to humans requires both adherence to safety standards and the development of appropriate strategies to plan and control robot movements in accordance with human movements. Collaboration between humans and robots in a shared environment is a joint [...] Read more.

Enabling robots to work safely close to humans requires both adherence to safety standards and the development of appropriate strategies to plan and control robot movements in accordance with human movements. Collaboration between humans and robots in a shared environment is a joint activity aimed at completing specific tasks, requiring coordination, synchronisation, and sometimes physical contact, in which each party contributes its own skills and resources. Among the most challenging tasks of human–robot cooperation is the co-transport of deformable materials such as fabrics. This paper proposes a method for generating the trajectory of a collaborative manipulator. The method is designed for the co-transport of materials such as fabrics. It combines a near time-optimal control strategy that ensures responsiveness in following human actions while simultaneously guaranteeing compliance with the safety limits imposed by current regulations. The combination of these two elements results in a viable co-transport solution which preserves the safety of human operators. This is achieved by constraining the path of the robot trajectory with prescribed velocities and accelerations while simultaneously ensuring a near time-optimal control strategy. In short, the robot movement is generated in such a way as to ensure both the tracking of humans in the co-transportation task and compliance with safety limits. As a first attempt to adopt the proposed approach to integrate time-optimal strategies into human–robot interaction, the simulations and preliminary experimental result obtained are promising. Full article

(This article belongs to the Section Industrial Robots and Automation)

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26 pages, 656 KiB

Open AccessReview

Agricultural Robotics: A Technical Review Addressing Challenges in Sustainable Crop Production

by Maria Spagnuolo, Giuseppe Todde, Maria Caria, Nicola Furnitto, Giampaolo Schillaci and Sabina I. G. Failla

Robotics 2025, 14(2), 9; https://doi.org/10.3390/robotics14020009 - 23 Jan 2025

Abstract

The adoption of agricultural robots is revolutionizing the agricultural sector, offering innovative solutions to optimize production and reduce environmental impact. This review examines the main functions and applications of agricultural robots, with a focus on the crops handled and the technologies employed. The [...] Read more.

The adoption of agricultural robots is revolutionizing the agricultural sector, offering innovative solutions to optimize production and reduce environmental impact. This review examines the main functions and applications of agricultural robots, with a focus on the crops handled and the technologies employed. The study analyzes the current state of the art regarding the market trend of agricultural robots used in field and greenhouse operations. Several solutions are emerging, some already implemented and others still in the prototype or project stage. These solutions are beginning to spread, though they may still seem far from widespread field application, particularly given the peculiarities and heterogeneity of the global agricultural landscape. In the face of the many benefits associated with the use of agricultural robots, even today some technical bottlenecks and costs limit their widespread use by farmers. The review provides a fairly comprehensive and up-to-date overview of current trends in agricultural automation, suggesting new areas of research to improve the efficiency and adaptability of robotic systems to different types of crops and environments. Full article

(This article belongs to the Section Agricultural and Field Robotics)

27 pages, 4409 KiB

Open AccessArticle

Design of a Novel Bio-Inspired Three Degrees of Freedom (3DOF) Spherical Robotic Manipulator and Its Application in Human–Robot Interactions

by Suleyman Soltanov and Rodney Roberts

Robotics 2025, 14(2), 8; https://doi.org/10.3390/robotics14020008 - 22 Jan 2025

Abstract

Studying the interactions between biological organisms and their environment provides engineers with valuable insights for developing complex mechanical systems and fostering the creation of novel technological innovations. In this study, we introduce a novel bio-inspired three degrees of freedom (DOF) spherical robotic manipulator [...] Read more.

Studying the interactions between biological organisms and their environment provides engineers with valuable insights for developing complex mechanical systems and fostering the creation of novel technological innovations. In this study, we introduce a novel bio-inspired three degrees of freedom (DOF) spherical robotic manipulator (SRM), designed to emulate the biomechanical properties observed in nature. The design utilizes the transformation of spherical Complex Spatial Kinematic Pairs (CSKPs) to synthesize bio-inspired robotic manipulators. Additionally, the use of screw theory and the Levenberg–Marquardt algorithm for kinematic parameter computation supports further advancements in human–robot interactions and simplifies control processes. The platform directly transmits motion from the motors to replicate the ball-and-socket mobility of biological joints, minimizing mechanical losses, and optimizing energy efficiency for superior spatial mobility. The proposed 3DOF SRM provides advantages including an expanded workspace, enhanced dexterity, and a lightweight, compact design. Experimental validation, conducted through SolidWorks, MATLAB, Python, and Arduino, demonstrates the versatility and broad application potential of the novel bio-inspired 3DOF SRM, positioning it as a robust solution for a wide range of robotic applications. Full article

(This article belongs to the Section Humanoid and Human Robotics)

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Graphical abstract

22 pages, 6085 KiB

Open AccessArticle

A Sliding Mode Approach to Vector Field Path Following for a Fixed-Wing UAV

by Luca Pugi, Lorenzo Franchi, Samuele Favilli and Giuseppe Mattei

Robotics 2025, 14(1), 7; https://doi.org/10.3390/robotics14010007 - 9 Jan 2025

Abstract

Unmanned aerial vehicle (UAV) technology has recently experienced increasing development, leading to the creation of a wide variety of autonomous solutions. In this paper, a guidance strategy for straight and orbital paths following fixed-wing small UAVs is presented. The proposed guidance algorithm is [...] Read more.

Unmanned aerial vehicle (UAV) technology has recently experienced increasing development, leading to the creation of a wide variety of autonomous solutions. In this paper, a guidance strategy for straight and orbital paths following fixed-wing small UAVs is presented. The proposed guidance algorithm is based on a reference vector field as desired, with 16 courses for the UAV to follow. A sliding mode approach is implemented to improve the robustness and effectiveness, and the asymptotic convergence of the aircraft to the desired trajectory in the presence of constant wind disturbances is proved according to Lyapunov. The algorithm exploits the banking dynamics and generates reference signals for the inner-loop aileron control. A MATLAB&Simulink^® simulation environment is used to verify the performance and robustness of the compared guidance algorithms. This high-fidelity model considers the six-degrees-of-freedom (DoF) whole-flight dynamics of the UAV and it is based on experimental flight test data to implement the aerodynamic behavior. Full article

(This article belongs to the Section Aerospace Robotics and Autonomous Systems)

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23 pages, 5366 KiB

Open AccessArticle

Evaluation of the Cyber-Physical System State Under Destructive Impact Conditions Based on a Comprehensive Analysis of Parameters

by Anton Mogilny, Elena Basan and Alexey Nekrasov

Robotics 2025, 14(1), 6; https://doi.org/10.3390/robotics14010006 - 8 Jan 2025

Abstract

This manuscript proposes a method for analyzing the stability of the behavior of a cyber-physical system (CPS) under conditions of potential destructive impact, considering the tasks it performs, which does not require labeled sets of abnormal data. The considered CPS has an autonomous [...] Read more.

This manuscript proposes a method for analyzing the stability of the behavior of a cyber-physical system (CPS) under conditions of potential destructive impact, considering the tasks it performs, which does not require labeled sets of abnormal data. The considered CPS has an autonomous decision-making system. The method was formalized in terms of the Markov decision-making process. Proposed metrics for assessing CPS behavior based on changes in its parameters were defined. They allowed classifying the operating mode into three classes: normal, abnormal, and uncertain. Evaluation results prove the efficiency of the proposed method. Despite the proposed method being tested on an unmanned vehicle (UV), it can also be applied to other CPSs, primarily to autonomous mobile robots (AMRs). Full article

(This article belongs to the Special Issue UAV Systems and Swarm Robotics)

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26 pages, 34170 KiB

Open AccessArticle

Navigating ALICE: Advancements in Deployable Docking and Precision Detection for AUV Operations

by Yevgeni Gutnik, Nir Zagdanski, Sharon Farber, Tali Treibitz and Morel Groper

Robotics 2025, 14(1), 5; https://doi.org/10.3390/robotics14010005 - 31 Dec 2024

Abstract

Autonomous Underwater Vehicles (AUVs) operate independently using onboard batteries and data storage, necessitating periodic recovery for battery recharging and data transfer. Traditional surface-based launch and recovery (L&R) operations pose significant risks to personnel and equipment, particularly in adverse weather conditions. Subsurface docking stations [...] Read more.

Autonomous Underwater Vehicles (AUVs) operate independently using onboard batteries and data storage, necessitating periodic recovery for battery recharging and data transfer. Traditional surface-based launch and recovery (L&R) operations pose significant risks to personnel and equipment, particularly in adverse weather conditions. Subsurface docking stations provide a safer alternative but often involve complex fixed installations and costly acoustic positioning systems. This work introduces a comprehensive docking solution featuring the following two key innovations: (1) a novel deployable docking station (DDS) designed for rapid deployment from vessels of opportunity, operating without active acoustic transmitters; and (2) an innovative sensor fusion approach that combines the AUV’s onboard forward-looking sonar and camera data. The DDS comprises a semi-submersible protective frame and a subsurface, heave-compensated docking component equipped with backlit visual markers, an electromagnetic (EM) beacon, and an EM lifting device. This adaptable design is suitable for temporary installations and in acoustically sensitive or covert operations. The positioning and guidance system employs a multi-sensor approach, integrating range and azimuth data from the sonar with elevation data from the vision camera to achieve precise 3D positioning and robust navigation in varying underwater conditions. This paper details the design considerations and integration of the AUV system and the docking station, highlighting their innovative features. The proposed method was validated through software-in-the-loop simulations, controlled seawater pool experiments, and preliminary open-sea trials, including several docking attempts. While further sea trials are planned, current results demonstrate the potential of this solution to enhance AUV operational capabilities in challenging underwater environments while reducing deployment complexity and operational costs. Full article

(This article belongs to the Special Issue Navigation Systems of Autonomous Underwater and Surface Vehicles)

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15 pages, 2425 KiB

Open AccessArticle

Online Self-Supervised Learning for Accurate Pick Assembly Operation Optimization

by Sergio Valdés, Marco Ojer and Xiao Lin

Robotics 2025, 14(1), 4; https://doi.org/10.3390/robotics14010004 - 30 Dec 2024

Abstract

The demand for flexible automation in manufacturing has increased, incorporating vision-guided systems for object grasping. However, a key challenge is in-hand error, where discrepancies between the actual and estimated positions of an object in the robot’s gripper impact not only the grasp but [...] Read more.

The demand for flexible automation in manufacturing has increased, incorporating vision-guided systems for object grasping. However, a key challenge is in-hand error, where discrepancies between the actual and estimated positions of an object in the robot’s gripper impact not only the grasp but also subsequent assembly stages. Corrective strategies used to compensate for misalignment can increase cycle times or rely on pre-labeled datasets, offline training, and validation processes, delaying deployment and limiting adaptability in dynamic industrial environments. Our main contribution is an online self-supervised learning method that automates data collection, training, and evaluation in real time, eliminating the need for offline processes. Building on this, our system collects real-time data during each assembly cycle, using corrective strategies to adjust the data and autonomously labeling them via a self-supervised approach. It then builds and evaluates multiple regression models through an auto machine learning implementation. The system selects the best-performing model to correct the misalignment and dynamically chooses between corrective strategies and the learned model, optimizing the cycle times and improving the performance during the cycle, without halting the production process. Our experiments show a significant reduction in the cycle time while maintaining the performance. Full article

(This article belongs to the Section Industrial Robots and Automation)

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18 pages, 1226 KiB

Open AccessArticle

Quadrotor Trajectory Planning with Tetrahedron Partitions and B-Splines in Unknown and Dynamic Environments

by Jiayu Men and Jesús Requena Carrión

Robotics 2025, 14(1), 3; https://doi.org/10.3390/robotics14010003 - 30 Dec 2024

Abstract

Trajectory planning is a key task in unmanned aerial vehicle navigation systems. Although trajectory planning in the presence of obstacles is a well-understood problem, unknown and dynamic environments still present significant challenges. In this paper, we present a trajectory planning method for unknown [...] Read more.

Trajectory planning is a key task in unmanned aerial vehicle navigation systems. Although trajectory planning in the presence of obstacles is a well-understood problem, unknown and dynamic environments still present significant challenges. In this paper, we present a trajectory planning method for unknown and dynamic environments that explicitly incorporates the uncertainty about the environment. Assuming that the position of obstacles and their instantaneous movement are available, our method represents the environment uncertainty as a dynamic map that indicates the probability that a region might be occupied by an obstacle in the future. The proposed method first divides the free space into non-overlapping tetrahedral partitions using Delaunay triangulation. Then, a topo-graph that describes the topology of the free space and incorporates the uncertainty of the environment is created. Using this topo-graph, an initial path and a safe flight corridor are obtained. The initial safe flight corridor provides a sequence of control points that we use to optimize clamped B-spline trajectories by formulating a quadratic programming problem with safety and smoothness constraints. Using computer simulations, we show that our algorithm can successfully find a collision-free and uncertainty-aware trajectory in an unknown and dynamic environment. Furthermore, our method can reduce the computational burden caused by moving obstacles during trajectory replanning. Full article

(This article belongs to the Special Issue UAV Systems and Swarm Robotics)

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15 pages, 5191 KiB

Open AccessArticle

Determining the Proper Force Parameters for Robotized Pipetting Devices Used in Automated Polymerase Chain Reaction (PCR)

by Melania-Olivia Sandu, Valentin Ciupe, Corina-Mihaela Gruescu, Robert Kristof, Carmen Sticlaru and Elida-Gabriela Tulcan

Robotics 2025, 14(1), 2; https://doi.org/10.3390/robotics14010002 - 28 Dec 2024

Abstract

This study aims to provide a set of experimentally determined forces needed for gripping operations related to a robotically manipulated microliter manual pipette. The experiments are conducted within the scope of automated sample processing for polymerase chain reaction (PCR) analysis in small-sized to [...] Read more.

This study aims to provide a set of experimentally determined forces needed for gripping operations related to a robotically manipulated microliter manual pipette. The experiments are conducted within the scope of automated sample processing for polymerase chain reaction (PCR) analysis in small-sized to medium-sized laboratories where dedicated automated equipment is absent and where procedures are carried out manually. Automation is justified by the requirement for increased efficiency and to eliminate possible errors generated by lab technicians. The test system comprises an industrial robot; a dedicated custom gripper assembly necessary for the pipette; pipetting tips; and mechanical holders for tubes with chemical substances and genetic material. The selected approach is to measure forces using the robot’s built-in force–torque sensor while controlling and limiting the pipette’s gripping force and the robot’s pushing force. Because the manipulation of different materials requires the attachment and discarding of tips to and from the pipette, the operator’s perceived tip release force is also considered. Full article

(This article belongs to the Special Issue Selected Papers from MEDER 2024: Advances in Mechanism Design for Robotics)

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18 pages, 11046 KiB

Open AccessArticle

Inverse and Forward Kinematics and CAD-Based Simulation of a 5-DOF Delta-Type Parallel Robot with Actuation Redundancy

by Pavel Laryushkin, Anton Antonov, Alexey Fomin and Oxana Fomina

Robotics 2025, 14(1), 1; https://doi.org/10.3390/robotics14010001 - 27 Dec 2024

Abstract

This article introduces a novel modification of a Delta-type parallel robot. The robot has five degrees of freedom and provides its end-effector with a 3T2R motion pattern (three translational and two rotational degrees of freedom). The fifth degree of freedom (rotation) is kinematically [...] Read more.

This article introduces a novel modification of a Delta-type parallel robot. The robot has five degrees of freedom and provides its end-effector with a 3T2R motion pattern (three translational and two rotational degrees of freedom). The fifth degree of freedom (rotation) is kinematically decoupled from the other four motions, and it is controlled by two drives. Thus, the proposed robot has a redundant actuation. In this article, we present an algorithm to solve the inverse kinematics of this robot and apply it to a path modeling example of a spiral-like trajectory. Numerical simulations illustrate the algorithm and show how the actuated coordinates change along the considered trajectory. Forward kinematics follows next, and an approach is introduced to determine all end-effector configurations for the specified displacements in the actuated joints. A numerical example presents four assembly modes of the robot corresponding to four real solutions of the forward kinematic problem. Finally, this article demonstrates a computer-aided design and analysis of the proposed robot: we describe a procedure for analyzing inverse kinematics and calculating actuation torques. This study forms the basis for the future manufacturing and experimental analysis of a robot prototype. Full article

(This article belongs to the Section Industrial Robots and Automation)

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28 pages, 1413 KiB

Open AccessReview

A Comprehensive Review of Control Challenges and Methods in End-Effector Upper-Limb Rehabilitation Robots

by Dalia M. Mahfouz, Omar M. Shehata, Elsayed I. Morgan and Filippo Arrichiello

Robotics 2024, 13(12), 181; https://doi.org/10.3390/robotics13120181 - 18 Dec 2024

Abstract

In the last decades, there has been an increasing number of human patients who suffer from upper-limb disorders limiting their motor abilities. One of the possible solutions that gained extensive research interest is the development of robot-aided rehabilitation training setups, including either end-effector [...] Read more.

In the last decades, there has been an increasing number of human patients who suffer from upper-limb disorders limiting their motor abilities. One of the possible solutions that gained extensive research interest is the development of robot-aided rehabilitation training setups, including either end-effector or exoskeleton robots, which showed various advantages compared to traditional manual rehabilitation therapy. One of the main challenges of these systems is to control the robot’s motion to track a desirable rehabilitation training trajectory while being affected by either voluntary or involuntary human forces depending on the patient’s recovery state. Several previous studies have been targeting exoskeleton robotic systems focusing on their structure, clinical features, and control methods, with limited review on end-effector-based robotic rehabilitation systems. In this regard, an overview of the most common end-effector robotic devices used for upper-limb rehabilitation is provided in this paper, describing their mechanical structure, features, clinical application, commercialization, advantages, and shortcomings. Additionally, a comprehensive review on possible control methods applied to end-effector rehabilitation exploitation is presented. These control methods are categorized as conventional, robust, intelligent, and most importantly, adaptive controllers implemented to serve for diverse rehabilitation control modes, addressing their development, implementation, findings, and possible drawbacks. Full article

(This article belongs to the Special Issue Neurorehabilitation Robotics: Recent Trends and Novel Applications)

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17 pages, 1570 KiB

Open AccessArticle

Backstepping-Based Nonsingular Terminal Sliding Mode Control for Finite-Time Trajectory Tracking of a Skid-Steer Mobile Robot

by Mulugeta Debebe Teji, Ting Zou and Dinku Seyoum Zeleke

Robotics 2024, 13(12), 180; https://doi.org/10.3390/robotics13120180 - 16 Dec 2024

Abstract

Skid-steer mobile robots (SSMRs) are ubiquitous in indoor and outdoor applications. Their accurate trajectory tracking control is quite challenging due to the uncertainties arising from the complex behavior of frictional force, external disturbances, and fluctuations in the instantaneous center of rotation (ICR) during [...] Read more.

Skid-steer mobile robots (SSMRs) are ubiquitous in indoor and outdoor applications. Their accurate trajectory tracking control is quite challenging due to the uncertainties arising from the complex behavior of frictional force, external disturbances, and fluctuations in the instantaneous center of rotation (ICR) during turning maneuvers. These uncertainties directly disturb velocities, hindering the robot from tracking the velocity command. This paper proposes a nonsingular terminal sliding mode control (NTSMC) based on backstepping for a four-wheel SSMR to cope with the aforementioned challenges. The strategy seeks to mitigate the impacts of external disturbances and model uncertainties by developing an adaptive law to estimate the integrated lumped outcome. The finite time stability of the closed-loop system is proven using Lyapunov’s theory. The designed NTSMC input is continuous and avoids noticeable chattering. It was noted in the simulation analysis that the proposed control strategy is strongly robust against disturbance and modeling uncertainties, demonstrating effective trajectory tracking performance in the presence of disturbance and modeling uncertainties. Full article

(This article belongs to the Special Issue Navigation Systems of Autonomous Underwater and Surface Vehicles)

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15 pages, 1709 KiB

Open AccessArticle

An Aircraft-Manipulator System for Virtual Flight Testing of Longitudinal Flight Dynamics

by Ademayowa A. Ishola, James F. Whidborne and Gilbert Tang

Robotics 2024, 13(12), 179; https://doi.org/10.3390/robotics13120179 - 15 Dec 2024

Abstract

A virtual flight test is the process of flying an aircraft model inside a wind tunnel in a manner that replicates free-flight. In this paper, a 3-DOF aircraft-manipulator system is proposed that can be used for longitudinal dynamics virtual flight tests. The system [...] Read more.

A virtual flight test is the process of flying an aircraft model inside a wind tunnel in a manner that replicates free-flight. In this paper, a 3-DOF aircraft-manipulator system is proposed that can be used for longitudinal dynamics virtual flight tests. The system consists of a two rotational degrees-of-freedom manipulator arm with an aircraft wind tunnel model attached to the third joint. This aircraft-manipulator system is constrained to operate for only the longitudinal motion of the aircraft. Thus, the manipulator controls the surge and heave of the aircraft whilst the pitch is free to rotate and can be actively controlled by means of an all-moving tailplane of the aircraft if required. In this initial study, a flight dynamics model of the aircraft is used to obtain dynamic response trajectories of the aircraft in free-flight. A model of the coupled aircraft-manipulator system developed using the Euler method is presented, and PID controllers are used to control the manipulator so that the aircraft follows the free-flight trajectory (with respect to the air). The inverse kinematics are used to produce the reference joint angles for the manipulator. The system is simulated in MATLAB/Simulink and a virtual flight test trajectory is compared with a free-flight test trajectory, demonstrating the potential of the proposed system for virtual flight tests. Full article

(This article belongs to the Special Issue Adaptive and Nonlinear Control of Robotics)

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