Cooperative Transport Research Articles

Adaptive control scheme for cooperative transport systems navigation under uncertainty

An adaptive robust control scheme for a cooperative transport system is proposed to tackle the challenges arising from parameter uncertainty, external interference, measurement errors, and other factors. The cooperative transport system consists of a leader automated ground vehicle, a baggage carrier, and a follower automated ground vehicle. Firstly, a mechanics-based independent dynamic model without constraints is established for each component within the system, and the coupling relationship between components is analyzed to design the constraint function. Secondly, to address inaccuracies in initial conditions, the trajectory errors in both their zero- and first-order forms are introduced. A closed-form dynamic model that is subject to constraints is then developed for the entire cooperative system, incorporating both structural and performance constraints. Thirdly, an innovative adaptive robust control scheme is introduced for mechanical systems facing uncertainty. An adaptive law is devised to estimate the bounds of uncertainty. The control is deterministic and can be mathematically expressed in a closed-form. Fourthly, a constrained optimization problem is formulated using the fuzzy information of uncertainty to choose an appropriate optimal gain kopt of the adaptive law. This is achieved by minimizing the combination of average fuzzy system performance and control effort. Finally, numerical simulations are conducted to verify the effectiveness and adaptability of the proposed control method. The performance of controlled cooperative transport system is both deterministically guaranteed and fuzzily optimized.

Designing Cooperative Ion Transport Pathway in Ultra‐Thin Solid‐State Electrolytes toward Practical Lithium Metal Batteries

AbstractSolid polymer electrolytes (SPEs) are promising for high‐energy‐density solid‐state Li metal batteries due to their decent flexibility, safety, and interfacial stability. However, their development was seriously hindered by the interfacial instability and limited conductivity, leading to inferior electrochemical performance. Herein, we proposed to design ultra‐thin solid‐state electrolyte with long‐range cooperative ion transport pathway to effectively increase the ionic conductivity and stability. The impregnation of PVDF−HFP inside pores of fluorinated covalent organic framework (CF3−COF) can disrupt its symmetry, rendering rapid ion transportation and inhibited anion immigration. The functional groups of CF3−COF can interact with PVDF−HFP to form fast Li+ transport channels, which enables the uniform and confined Li+ conduction within the electrolyte. The introduction of CF3−COF also enhances the mechanical strength and flexibility of SPEs, as well as ensures homogeneous Li deposition and inhibited dendrite growth. Hence, a remarkably high conductivity of 1.21×10−3 S cm−1 can be achieved. Finally, the ultra‐thin SPEs with an extremely long cycle life exceed 9000 h can be obtained while the NCM523/Li pouch cell demonstrates a high capacity of 760 mAh and 96 % capacity retention after cycling, holding great promises to be utilized for practical solid‐state Li metal batteries.

Distributed Neural Adaptive Impedance Control for Cooperative Manipulation With Unknown Objects.

Existing cooperative manipulation methods for multiple manipulator systems usually assume that the grasp matrix and the desired trajectory of each manipulator are known in advance. In this work, distributed neural adaptive impedance control (AIC) strategies integrating fully distributed observers are proposed to remove both limitations. Specifically, two fully distributed finite-time observers are designed to estimate the actual and ideal states of the reference point without using global information. The estimates of the grasp matrix and the desired trajectory of each end-effector (EE) are then obtained by kinematic constraints and the estimates of the reference point's states. At the controller development, a distributed adaptive impedance model is established to achieve an adaptive trade-off between tracking performance and compliance. Then, distributed neural network (NN)-based tracking control strategies are developed to asymptotically realize the desired adaptive impedance dynamics in the presence of uncertainties. Additionally, a virtual energy tank (EK) is employed to interact with the impedance system to correct the adaptive impedance laws for system passivity. A simulation for four mobile manipulators tightly cooperative transport an unknown object is carried out to demonstrate the established results.

Human–robot cooperative object transportation with intention-driven manipulation and trajectory guidance

Human–robot cooperative object transportation with intention-driven manipulation and trajectory guidance

Thermoelectric metadevice-assisted cooperative magnetic-free transverse energy transport

Thermoelectric metadevice-assisted cooperative magnetic-free transverse energy transport

Positive Reinforcement-Based Magnet Training Permits Social Housing in Catheterized Squirrel Monkeys

BackgroundNon-human primates play a critical role in neuroscience research. Though they are social animals, laboratory study requirements can sometimes require single housing and thereby prevent social housing. New MethodTo eliminate single housing and promote well-being within our squirrel monkey colony, we used positive reinforcement training in combination with magnetic/mechanical clasps and custom jackets to permit pair housing of catheterized squirrel monkeys used in behavioral studies. ResultsAdult Saimiri boliviensis boliviensis monkeys (n = 7) readily progressed through a six-stage training procedure for cooperative handling and transport from the home cage to the experimental testing rooms.Comparison with existing methods and conclusions: Given the evidence of isolation induced stress and neurobiological consequences in multiple species, and consistent with an increased regulatory emphasis on social housing of non-human primates, the methods presented herein provide a method for handling squirrel monkeys in behavioral studies that is compatible with social housing.

Robust Cooperative Transportation of a Cable-Suspended Payload by Multiple Quadrotors Featuring Cable-Reconfiguration Capabilities

Robust Cooperative Transportation of a Cable-Suspended Payload by Multiple Quadrotors Featuring Cable-Reconfiguration Capabilities

Designing Cooperative Ion Transport Pathway in Ultra-Thin Solid-State Electrolytes toward Practical Lithium Metal Batteries.

Solid polymer electrolytes (SPEs) are promising for high-energy-density solid-state Li metal batteries due to their decent flexibility, safety, and interfacial stability. However, their development was seriously hindered by the interfacial instability and limited conductivity, leading to inferior electrochemical performance. Herein, we proposed to design ultra-thin solid-state electrolyte with long-range cooperative ion transport pathway to effectively increase the ionic conductivity and stability. The impregnation of PVDF-HFP inside pores of fluorinated covalent organic framework (CF3-COF) can disrupt its symmetry, rendering rapid ion transportation and inhibited anion imigration. The functional groups of CF3-COF can interact with PVDF-HFP to form fast Li+ transport channels, which enables the uniform and confined Li+ conduction within the electrolyte. The introduction of CF3-COF also enhances the mechanical strength and flexibility of SPEs, as well as ensures homogeneous Li deposition and inhibited dendrite growth. Hence, a remarkably high conductivity of 1.21×10-3 S cm-1 can be achieved. Finally, the ultra-thin SPEs with an extremely long cycle life exceed 9000 h can be obtained (the longest cycle life reported until now) while the NCM523/Li pouch cell demonstrates a high capacity of 760 mAh and 96% capacity retention after cycling, holding great promises to be utilized for practical solid-state Li metal batteries.

Cooperative Drone Transportation of a Cable-Suspended Load: Dynamics and Control

The cooperative transportation of a cable-suspended load by two unmanned rotorcraft is analyzed. Initially, the equations describing a system composed of three point masses and two rigid cables are derived. The model is then linearized about the hovering condition, and analytical expressions are derived to describe the eigenstructure of the open-loop system. Thanks to the specific parameterization of the problem, the different dynamic modes are outlined and discussed within an analytical framework. A novel controller is designed to enable the UAVs in the formation to perform trajectory tracking, maintain formation geometry, and stabilize payload swing simultaneously. A preliminary investigation of closed-loop stability is conducted using a linear approach. Validation is performed in a realistic simulation scenario where two drones are modeled as rigid bodies under the effect of external disturbances and rotor-generated forces and moments, as obtained by Blade Element Theory. The proposed method demonstrates relative simplicity and significantly improves the flying qualities of delivery operations while minimizing hazardous payload oscillations and reducing energy demand.

Advancements in Cooperative Mobile Robots Control Strategies for Large-Scale Material Transport

This paper explores groundbreaking advancements in control strategies for cooperative mobile robots used in large-scale material transport, a critical aspect of modern industrial, manufacturing, logistics, and construction sectors. It delves into the development of sophisticated systems that enable seamless coordination among multiple mobile robot systems. The research presents a novel hierarchical finite state automaton for dynamic mission adaptation and a null space-based control scheme for precise task execution and enhanced system resilience. The introduction of Mecanum wheels facilitates flexible movement and manipulation of materials, thereby increasing operational efficiency and safety. Cutting-edge sensory technology, including LiDAR, and the implementation of the Robot Operating System are highlighted for their roles in enhancing autonomous navigation and intelligent operation. Additionally, the paper discusses the impact of centralized and decentralized control methods in ensuring safe, cooperative object transport. The findings contribute to the vision of Industry 4.0 by promoting the integration of automation and robotic cooperation in complex environments and present a foundational blueprint for further research. Challenges for future work such as scalability, communication efficiency, collision avoidance, and energy efficiency are also considered, underscoring the need for ongoing development of robust and scalable robotic systems to address modern transport challenges.

A decoupled solution to heterogeneous multi-formation planning and coordination for object transportation

Multi-robot formations have numerous applications, such as cooperative object transportation in intelligent warehouses. In this context, robots are tasked with delivering objects in formation while avoiding intra- and inter-formation collisions. This necessitates the development of solutions for multi-robot task allocation, formation generation, rigid formation route planning, and formation coordination. In this paper, we present a cooperative formation object transportation system for heterogeneous multi-robot systems which captures robot dynamics and avoids inter-formation collisions. Accounting for heterogeneous formations expands the applicability of the proposed robotic transport system. For formation generation, we propose an approach based on conflict-based search, which integrates high-level path planning with low-level trajectory optimisation. For heterogeneous formation planning, we present a two-stage iterative trajectory optimisation framework which adheres to the kinematic constraints of our heterogeneous multi-robot system while retaining formation rigidity. For multi-formation coordination, we use a loosely-coupled algorithm which can guarantee collision-free and deadlock-free formation navigation under minimal assumptions. We demonstrate the efficacy of our approach in simulation.

Stochastic Initial States Randomization Method for Robust Knowledge Transfer in Multi-Agent Reinforcement Learning

Reinforcement learning, which are also studied in the field of defense, face the problem of sample efficiency, which requires a large amount of data to train. Transfer learning has been introduced to address this problem, but its effectiveness is sometimes marginal because the model does not effectively leverage prior knowledge. In this study, we propose a stochastic initial state randomization(SISR) method to enable robust knowledge transfer that promote generalized and sufficient knowledge transfer. We developed a simulation environment involving a cooperative robot transportation task. Experimental results show that successful tasks are achieved when SISR is applied, while tasks fail when SISR is not applied. We also analyzed how the amount of state information collected by the agents changes with the application of SISR.

Leaderless consensus decision-making determines cooperative transport direction in weaver ants.

Animal groups need to achieve and maintain consensus to minimize conflict among individuals and prevent group fragmentation. An excellent example of a consensus challenge is cooperative transport, where multiple individuals cooperate to move a large item together. This behaviour, regularly displayed by ants and humans only, requires individuals to agree on which direction to move in. Unlike humans, ants cannot use verbal communication but most likely rely on private information and/or mechanical forces sensed through the carried item to coordinate their behaviour. Here, we investigated how groups of weaver ants achieve consensus during cooperative transport using a tethered-object protocol, where ants had to transport a prey item that was tethered in place with a thin string. This protocol allows the decoupling of the movement of informed ants from that of uninformed individuals. We showed that weaver ants pool together the opinions of all group members to increase their navigational accuracy. We confirmed this result using a symmetry-breaking task, in which we challenged ants with navigating an open-ended corridor. Weaver ants are the first reported ant species to use a 'wisdom-of-the-crowd' strategy for cooperative transport, demonstrating that consensus mechanisms may differ according to the ecology of each species.

Semi-decentralized Lyapunov-based formation control of multiple omnidirectional mobile robots

<p>This paper introduces an advanced formation control algorithm based on a Lyapunov approach for coordinating multiple omnidirectional mobile robots in collaborative object transport tasks. The semi-decentralized strategy ensures that the robots maintain a predefined geometric formation, crucial for stability during material transportation, and dynamically adapt to avoid collisions using onboard sensors. Experimental with a physical robot simulator demonstrates successful maintenance of line and triangle formations achieving an average side length maintenance of 1.00 meters with minimal deviation. Quantitative analysis across 30 experimental runs reveals consistent performance, with a maximum side length fluctuation of only 2 centimeters, validating the effectiveness of maintaining formation within a multi-robot system (MRS) framework. The Lyapunov-based approach proves to be an efficient method for cooperative object transport, achieving consistent performance with minimal deviation.</p>

Optimal Containment Control of a Quadrotor Team With Active Leaders via Reinforcement Learning.

This article proposes an optimal controller for a team of underactuated quadrotors with multiple active leaders in containment control tasks. The quadrotor dynamics are underactuated, nonlinear, uncertain, and subject to external disturbances. The active team leaders have control inputs to enhance the maneuverability of the containment system. The proposed controller consists of a position control law to guarantee the achievement of position containment and an attitude control law to regulate the rotational motion, which are learned via off-policy reinforcement learning using historical data from quadrotor trajectories. The closed-loop system stability can be guaranteed by theoretical analysis. Simulation results of cooperative transportation missions with multiple active leaders demonstrate the effectiveness of the proposed controller.

Design of New BLE GAP Roles for Vehicular Communications.

Bluetooth Low Energy (BLE) is a prominent short-range wireless communication protocol widely extended for communications and sensor systems in consumer electronics and industrial applications, ranging from manufacturing to retail and healthcare. The BLE protocol provides four generic access profile (GAP) roles when it is used in its low-energy version, i.e., ver. 4 and beyond. GAP roles control connections and allow BLE devices to interoperate each other. They are defined by the Bluetooth special interest group (SIG) and are primarily oriented to connect peripherals wirelessly to smartphones, laptops, and desktops. Consequently, the existing GAP roles have characteristics that do not fit well with vehicular communications in cooperative intelligent transport systems (C-ITS), where low-latency communications in high-density environments with stringent security demands are required. This work addresses this gap by developing two new GAP roles, defined at the application layer to meet the specific requirements of vehicular communications, and by providing a service application programming interface (API) for developers of vehicle-to-everything (V2X) applications. We have named this new approach ITS-BLE. These GAP roles are intended to facilitate BLE-based solutions for real-world scenarios on roads, such as detecting road traffic signs or exchanging information at toll booths. We have developed a prototype able to work indistinctly as a unidirectional or bidirectional communication device, depending on the use case. To solve security risks in the exchange of personal data, BLE data packets, here called packet data units (PDU), are encrypted or signed to guarantee either privacy when sharing sensitive data or authenticity when avoiding spoofing, respectively. Measurements taken and their later evaluation demonstrated the feasibility of a V2X BLE network consisting of picocells with a radius of about 200 m.

Metal ionic liquid-based hybrid membranes for ammonia separation through moderate interaction sites and cooperative transport channels

The combination ionic liquids (ILs) with membranes is a potential method for direct NH3 separation. In particular, ILs can modulate the interactions with NH3 and construct pathways in membranes for preferential NH3 transport, which is expected to overcome the trade-off effect and achieve a desirable separation performance. In this work, four metal ILs (MILs) with different metal centres and hydrogen bond donating ability, including [2-Mim][Li(NTf2)2], [Eim][Li(NTf2)2], [Bmim]2[Co(NCS)4], and [Bim]2[Co(NCS)4], were incorporated into sulfonated block copolymers to prepare MIL-based hybrid membranes for NH3 separation. The investigation of structure–performance relationships suggested that the interaction sites and transport channels could be tuned by the MIL type, which greatly affects the NH3 separation performance of the membranes. The Nexar/2-Mim-Li-10 membrane exhibits NH3 permeability of 735.6 Barrer with NH3/N2 selectivity of 844.5 and NH3/H2 selectivity of 154.7, which is higher than other MIL-based hybrid membranes owing to self-assembled transport channels and moderate complexation. Increasing the MIL content and feed pressure significantly improved NH3 separation performance.

Formation Planning for Tethered Multirotor UAV Cooperative Transportation With Unknown Payload and Cable Length

This study investigates the formation planning problem of tethered multirotor unmanned aerial vehicle (UAV) cooperative transportation with unknown payload and cable length. Normally, the transportation formation and trajectory are given in advance or designed based on the coupled system model. It is challenging to dynamically generate flexible formations in response to changing environments when the payload and cable length are unknown. This paper proposes an online formation planning method for multirotor UAVs. First, by analyzing the tension on cables, we propose some formation criteria and further construct a corresponding performance function of optimization. Then, desired trajectories/formations that can reduce the cost functions are generated by using the admittance model. Next, an estimation-based formation tracking control is designed, which ensures that multirotor UAVs follow the desired trajectories/formations. Finally, numerical simulations and experiments are conducted to demonstrate the effectiveness of the proposed method. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This paper is motivated by the formation planning problem of tethered multirotor UAV cooperative transportation. In industry and production applications, a team of multirotor UAVs has a larger load capacity than a single one. Nevertheless, the formation planning of the tethered cooperative transportation is challenging, especially when the payload and cable length are unknown. Rather than give a predefined formation or trajectory, this paper suggests an online formation planning method for multirotor UAVs in case of unknown payload and cable length. The method is implemented through the following three parts: 1) By analyzing the tension on cables, we propose some formation criteria and further construct a corresponding performance function of optimization. 2) By using the admittance model, we generate desired trajectories/formations that can minimize the proposed cost function. 3) By estimating cable tension, we design formation tracking control laws for multirotor UAVs to follow the desired trajectories/formations. The proposed formation planning method does not rely on the knowledge of the payload and length of cables, which makes it can be easily applied to extensive industry, production, and military practice. Finally, numerical simulations and experiments are conducted to demonstrate the feasibility of the proposed method.

Embedded technique-based formation control of multiple wheeled mobile robots with application to cooperative transportation

The cooperative transportation problem for multiple wheeled mobile robots (WMRs) via formation control is investigated in this paper. A formation control algorithm based on an embedded technique is proposed for cooperative transportation of a shared object using n-WMRs. Instead of relying on the conventional design philosophy directly based on formation errors, the proposed algorithm is divided into two parts by considering the communication topology and WMRs’ dynamics “separately”. The first part involves a distributed signal generator that generates desired trajectories for the WMRs based on their initial positions, the formation vector, and the desired trajectory of the object. The second part consists of tracking controllers to enable the WMRs to track their desired trajectories. The proposed algorithm is distributed and differs from the existing cooperative transportation algorithms, as it eliminates the requirement for all WMRs to know the object’s position. Moreover, it exhibits remarkable compatibility and features a concise modular design. With the proposed algorithm, WMRs achieve formation in finite time. Theoretical proof supports the effectiveness of the proposed algorithm, which is further validated through several conducted experiments.

Human-Centric Digitization in Montenegro: Progress through 17 Years of National Independence and Future Trends

Montenegro restored its national independence in 2006, and in the 17 years since then, the country has made significant progress in digital transformation, which is especially important for its accession to the European Union. In this paper, this period of 17 years of Montenegrin digital transformation is reviewed. The work aims to provide comprehensive coverage of the digitization processes across all relevant sectors, including healthcare, education, telecommunications and internet, personal and public transportation, tourism, agriculture, energy and sustainability, and public administration. The human-centric nature of digitization is emphasized where relevant, as well as related future trends. This paper also highlights barriers and limitations, such as the lack of consideration for cooperative intelligent transportation systems in national strategies, and user-related issues in digital public administration.