Autonomous underwater vehicles (AUVs) are submersible underwater vehicles controlled by onboard computers. AUV formation is a cooperative control which focuses on controlling multiple AUVs to move in a group while executing tasks. In contrast to a single AUV, multi-AUV formation represents higher efficiency and better stability for many applications, such as oil and gas industries, hydrographic surveys, and military missions, etc. To achieve better formation, there are several key factors, including AUV performance, formation control, and communication capability. However, most studies in the field of AUV formation mainly focus on formation control methods. We observe that the research of communication capability and AUV performance of multiple AUV formation is still in an early stage. It is beneficial to researchers to present a comprehensive survey of the state of the art of AUV formation research and development. In this paper, we study AUV, formation control, and underwater acoustic communication capability in detail. We propose a classification framework with three dimensions, including AUV performance, formation control, and communication capability. This framework provides a comprehensive classification method for future AUV formation research. It also can be used to compare different methods and help engineers choose suitable formation methods for various applications. Moreover, our survey discusses formation architecture with communication constraints and we identify some common misconceptions and questionable research for formation control related to communication.

A Survey of Autonomous Underwater Vehicle Formation: Performance, Formation Control, and Communication Capability

Methods, systems, and devices for leaving evidence of a contract on a blockchain with a simple method while having agreements made among the involved parties, maintaining the mode of one electronic signature per transaction, and maintaining credibility Transactions of an issuing-party terminal, an agreeing-party terminal, and an agreeing-party terminal involved in contract agreement are linked as a chain, and the agreeing-party terminal at the end generates a transaction directed to the issuing-party terminal who has issued the contract Each of these terminals previously generates a key pair for encryption of the contract and transmits the encryption key to a terminal which is its transaction sender Then, this sender terminal encrypts a contract to be included in a transaction of the user of the sender terminal using the encryption key of the receiver of the transaction

Contract Agreement Method, Agreement Verification Method, Contract Agreement System, Agreement Verification Device, Contract Agreement Device, Contract Agreement Program and Agreement Verification Program

Towards structure-independent stabilization for uncertain underactuated Euler–Lagrange systems

This article investigates the control problem for leader-following (LF) vehicle platoons with a constant-spacing policy, where the information of the leader is broadcast to each follower via vehicular ad hoc networks (VANETs) subject to varied communication ranges. According to the connectivity status between the leader and each follower, platoon control is modeled as a switched platoon control system with a connectivity-status-matrix-dependent controller. By using switched system theory, a series of sufficient conditions are obtained as a criteria for the stability analysis and control synthesis of the LF platoon. Based on the obtained conditions, a useful platoon control algorithm is proposed. For each obtained connectivity-status-matrix-dependent controller, the string stability and a zero steady-state spacing error can be guaranteed by additional conditions. Numerical simulations and experiments with laboratory-scale Arduino cars are conducted to verify the effectiveness and practicability of the proposed algorithm.

Control of Leader-Following Vehicle Platoons With Varied Communication Range

Recently proposed adaptive platooning strategies for connected automated vehicles are able to address uncertain parameters of the vehicles in the platoon (uncertain driveline time constants), but are limited to acyclic interaction like look-ahead interaction. This restrains from augmenting platooning protocols with synchronized merging maneuvers, where cyclic communication is needed and creates algebraic loops that require well posedness of the inputs. We propose an adaptive protocol for synchronized merging in the cyclic communication scenario. The protocol exploits a set of adaptive control strategies, designed to cope with uncertain driveline time constants. Well-posedness of the control inputs is proven in a distributed way (using information from neighboring vehicles) in spite of uncertainty and cyclic communication. The proposed strategy is shown in a benchmark merging scenario.

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Cyclic Communication in Adaptive Strategies to Platooning: The Case of Synchronized Merging

Adaptive hierarchical formation control for uncertain Euler–Lagrange systems using distributed inverse dynamics

https://hal.archives-ouvertes.fr/hal-01945760/document

Platooning merging maneuvers in the presence of parametric uncertainty

This paper addresses the problem of leader–follower synchronization of uncertain Euler–Lagrange systems under input constraints. The problem is solved in a distributed model reference adaptive control framework that includes positive μ-modification to address input constraints. The proposed design has the distinguishing features of updating the gains to synchronize the uncertain systems and of providing stable adaptation in the presence of input saturation. By using a matching condition assumption, a distributed inverse dynamics architecture is adopted to guarantee convergence to common dynamics. The design is studied analytically, and its performance is validated in simulation using spacecraft dynamics.

https://www.mdpi.com/2226-4310/7/9/127/pdf

Leader–Follower Synchronization of Uncertain Euler–Lagrange Dynamics with Input Constraints

https://hal.archives-ouvertes.fr/hal-01945733/document

Adaptive state-feedback synchronization with distributed input : The cyclic case

This work provides a multi-agent extension of output-feedback model reference adaptive control (MRAC), designed to synchronize a network of heterogeneous uncertain agents. The implementation of this scheme is based on multi-agent matching conditions. The practical advantage of the proposed MRAC is the possibility of handling the case of the unknown dynamics of the agents only by using the output and the control input of its neighbors. In addition, it is reasonable to consider the case when the communication topology is time-varying. In this work, the time-varying communication leads to a switching control structure that depends on the number of the predecessor of the agents. By using the switching control structure to handle the time-varying topologies, we show that synchronization can be achieved. The multi-agent adaptive switching controller is first analyzed, and numerical simulations based on formation control of simplifier quadcopter dynamics are provided.

Muhammad Ridho Rosa

Papers

Adaptive hierarchical formation control for uncertain Euler–Lagrange systems using distributed inverse dynamics

Platooning merging maneuvers in the presence of parametric uncertainty

Leader–Follower Synchronization of Uncertain Euler–Lagrange Dynamics with Input Constraints

Adaptive state-feedback synchronization with distributed input : The cyclic case

Adaptive Synchronization for Heterogeneous Multi-Agent Systems with Switching Topologies