4,065 research outputs found

    Design and Implementation of a Range-Based Formation Controller for Marine Robots

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    There is considerable worldwide interest in the use of groups of autonomous marine vehicles to carry our challenging mission scenarios, of which marine habitat mapping of complex, non-structured environments is a representative example. Relative positioning and formation control becomes mandatory in many of the missions envisioned, which require the concerted operation of multiple marine vehicles carrying distinct, yet complementary sensor suites. However, the constraints placed by the underwater medium make it hard to both communicate and localise the vehicles, even in relation to each other, let alone maintain them in a formation. As a contribution to overcoming some of these problems, this paper deals with the problem of keeping an autonomous marine vehicle in a moving triangular formation with respect to two leader vehicles. Simple feedback laws are derived to drive a controlled vehicle to its intended position in the formation using acoustic ranges obtained to the leading vehicles with no knowledge of the formation path. The paper discusses the implementation of this solution in the MEDUSA class of autonomous marine vehicles operated by IST and describes the results of trials with these vehicles exchanging information and ranges over an acoustic network

    Dynamic Control of Mobile Multirobot Systems: The Cluster Space Formulation

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    The formation control technique called cluster space control promotes simplified specification and monitoring of the motion of mobile multirobot systems of limited size. Previous paper has established the conceptual foundation of this approach and has experimentally verified and validated its use for various systems implementing kinematic controllers. In this paper, we briefly review the definition of the cluster space framework and introduce a new cluster space dynamic model. This model represents the dynamics of the formation as a whole as a function of the dynamics of the member robots. Given this model, generalized cluster space forces can be applied to the formation, and a Jacobian transpose controller can be implemented to transform cluster space compensation forces into robot-level forces to be applied to the robots in the formation. Then, a nonlinear model-based partition controller is proposed. This controller cancels out the formation dynamics and effectively decouples the cluster space variables. Computer simulations and experimental results using three autonomous surface vessels and four land rovers show the effectiveness of the approach. Finally, sensitivity to errors in the estimation of cluster model parameters is analyzed.Fil: Mas, Ignacio Agustin. Instituto TecnolĂłgico de Buenos Aires; Argentina. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas; ArgentinaFil: Kitts, Christopher. Santa Clara University; Estados Unido

    Controlling rigid formations of mobile agents under inconsistent measurements

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    Despite the great success of using gradient-based controllers to stabilize rigid formations of autonomous agents in the past years, surprising yet intriguing undesirable collective motions have been reported recently when inconsistent measurements are used in the agents' local controllers. To make the existing gradient control robust against such measurement inconsistency, we exploit local estimators following the well known internal model principle for robust output regulation control. The new estimator-based gradient control is still distributed in nature and can be constructed systematically even when the number of agents in a rigid formation grows. We prove rigorously that the proposed control is able to guarantee exponential convergence and then demonstrate through robotic experiments and computer simulations that the reported inconsistency-induced orbits of collective movements are effectively eliminated.Comment: 10 page

    Multi-bot Easy Control Hierarchy

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    The goal of our project is to create a software architecture that makes it possible to easily control a multi-robot system, as well as seamlessly change control modes during operation. The different control schemes first include the ability to implement on-board and off-board controllers. Second, the commands can specify either actuator level, vehicle level, or fleet level behavior. Finally, motion can be specified by giving a waypoint and time constraint, a velocity and heading, or a throttle and angle. Our code is abstracted so that any type of robot - ranging from ones that use a differential drive set up, to three-wheeled holonomic platforms, to quadcopters - can be added to the system by simply writing drivers that interface with the hardware used and by implementing math packages that do the required calculations. Our team has successfully demonstrated piloting a single robots while switching between waypoint navigation and a joystick controller. In addition, we have demonstrated the synchronized control of two robots using joystick control. Future work includes implementing a more robust cluster control, including off-board functionality, and incorporating our architecture into different types of robots

    Cluster Control of Automated Surface Vessels

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    This research focuses on the design and control of a fleet of robotic kayaks, and presents experimental data regarding the functionality and performance of the system. One of the key technical challenges in fielding multi-robot systems for real-world applications is the coordination and relative motion control of the individual units. Coordinated formation control of the fleet is implemented through the use of the cluster space control architecture, which is a full-order controller that treats the fleet as a virtual, articulating, kinematic mechanism. The resulting system is capable of autonomous navigation utilizing a centralized controller, currently implemented via a shore-based computer that wirelessly receives ASV data and relays control commands. Using the cluster space control approach, these control commands allow a cluster supervisor to oversee a flexible and mobile formation formed by the ASV cluster. This paper includes an extended appendix which includes MatLab and Simulink code as well as two publications completed in the process of this research

    Generalized Method Of Designing Unmanned Remotely Operated Complexes Based On The System Approach

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    Self-propelled underwater systems belong to the effective means of marine robotics. The advantages of their use include the ability to perform underwater work in real time with high quality and without risk to the life of a human operator. At present, the design of such complexes is not formalized and is carried out separately for each of the components – a remotely operated vehicle, a tether-cable and cable winch, a cargo device and a control and energy device. As a result, the time spent on design increases and its quality decreases. The system approach to the design of remotely operated complexes ensures that the features of the interaction of the components of the complex are taken into account when performing its main operating modes. In this paper, the system interaction between the components of the complex is proposed to take into account in the form of decomposition of “underwater tasks (mission) – underwater technology of its implementation – underwater work on the selected technology – task for the executive mechanism of the complex” operations. With this approach, an information base is formed for the formation of a list of mechanisms of the complex, the technical appearance of its components is being formed, which is important for the early design stages. Operative, creative and engineering phases of the design of the complex are proposed. For each phase, a set of works has been formulated that cover all the components of the complex and use the author's existence equations for these components as a tool for system analysis of technical solutions.The perspective of the scientific task of the creative phase to create accurate information models of the functioning of the components of the complex and models to support the adoption of design decisions based on a systematic approach is shown.The obtained results form the theoretical basis for finding effective technical solutions in the early stages of designing remotely operated complexes and for automating the design with the assistance of modern applied computer research and design packages

    Comprehensive review on controller for leader-follower robotic system

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    985-1007This paper presents a comprehensive review of the leader-follower robotics system. The aim of this paper is to find and elaborate on the current trends in the swarm robotic system, leader-follower, and multi-agent system. Another part of this review will focus on finding the trend of controller utilized by previous researchers in the leader-follower system. The controller that is commonly applied by the researchers is mostly adaptive and non-linear controllers. The paper also explores the subject of study or system used during the research which normally employs multi-robot, multi-agent, space flying, reconfigurable system, multi-legs system or unmanned system. Another aspect of this paper concentrates on the topology employed by the researchers when they conducted simulation or experimental studies
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