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Robotics and Automation, IEEE Transactions on

Issue 5 • Date Oct. 2002

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Displaying Results 1 - 17 of 17
  • Guest editorial advances in multirobot systems

    Publication Year: 2002 , Page(s): 655 - 661
    Cited by:  Papers (122)
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    Freely Available from IEEE
  • A control Lyapunov function approach to multiagent coordination

    Publication Year: 2002 , Page(s): 847 - 851
    Cited by:  Papers (134)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (397 KB) |  | HTML iconHTML  

    In this paper, the multiagent coordination problem is studied. This problem is addressed for a class of robots for which control Lyapunov functions can be found. The main result is a suite of theorems about formation maintenance, task completion time, and formation velocity. It is also shown how to moderate the requirement that, for each individual robot, there exists a control Lyapunov function. An example is provided that illustrates the soundness of the method. View full abstract»

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  • Performance of a distributed robotic system using shared communications channels

    Publication Year: 2002 , Page(s): 713 - 727
    Cited by:  Papers (40)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1333 KB) |  | HTML iconHTML  

    We have designed and built a set of miniature robots called Scouts and have developed a distributed software system to control them. This paper addresses the fundamental choices we made in the design of the control software, describes experimental results in a surveillance task, and analyzes the factors that affect robot performance. Space and power limitations on the Scouts severely restrict the computational power of their on-board computers, requiring a proxy-processing scheme in which the robots depend on remote computers for their computing needs. While this allows the robots to be autonomous, the fact that robots' behaviors are executed remotely introduces an additional complication-sensor data and motion commands have to be exchanged using wireless communications channels. Communications channels cannot always be shared, thus requiring the robots to obtain exclusive access to them. We present experimental results on a surveillance task in which multiple robots patrol an area and watch for motion. We discuss how the limited communications bandwidth affects robot performance in accomplishing the task, and analyze how performance depends on the number of robots that share the bandwidth. View full abstract»

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  • Probabilistic pursuit-evasion games: theory, implementation, and experimental evaluation

    Publication Year: 2002 , Page(s): 662 - 669
    Cited by:  Papers (143)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1099 KB)  

    We consider the problem of having a team of unmanned aerial vehicles (UAVs) and unmanned ground vehicles (UGVs) pursue a second team of evaders while concurrently building a map in an unknown environment. We cast the problem in a probabilistic game theoretical framework, and consider two computationally feasible greedy pursuit policies: local-mar and global-max. To implement this scenario on real UAVs and UGVs, we propose a distributed hierarchical hybrid system architecture which emphasizes the autonomy of each agent, yet allows for coordinated team efforts. We describe the implementation of the architecture on a fleet of UAVs and UGVs, detailing components such as high-level pursuit policy computation, map building and interagent communication, and low-level navigation, sensing, and control. We present both simulation and experimental results of real pursuit-evasion games involving our fleet of UAVs and UGVs, and evaluate the pursuit policies relating expected capture times to the speed and intelligence of the evaders and the sensing capabilities of the pursuers. View full abstract»

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  • Hormone-inspired adaptive communication and distributed control for CONRO self-reconfigurable robots

    Publication Year: 2002 , Page(s): 700 - 712
    Cited by:  Papers (85)
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    Presents a biologically inspired approach to two basic problems in modular self-reconfigurable robots: adaptive communication in self-reconfigurable and dynamic networks, and distributed collaboration between the physically coupled modules to accomplish global effects such as locomotion and reconfiguration. Inspired by the biological concept of hormone, the paper develops the adaptive communication (AC) protocol that enables modules continuously to discover changes in their local topology, and the adaptive distributed control (ADC) protocol that allows modules to use hormone-like messages in collaborating their actions to accomplish locomotion and self-reconfiguration. These protocols are implemented and evaluated, and experiments in the CONRO self-reconfigurable robot and in a Newtonian simulation environment have shown that the protocols are robust and scaleable when configurations change dynamically and unexpectedly, and they can support online reconfiguration, module-level behavior shifting, and locomotion. The paper also discusses the implication of the hormone-inspired approach for distributed multiple robots and self-reconfigurable systems in general. View full abstract»

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  • Cooperative probabilistic state estimation for vision-based autonomous mobile robots

    Publication Year: 2002 , Page(s): 670 - 684
    Cited by:  Papers (32)
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    With the services that autonomous robots are to provide becoming more demanding, the states that the robots have to estimate become more complex. In this paper, we develop and analyze a probabilistic, vision-based state estimation method for individual autonomous robots. This method enables a team of mobile robots to estimate their joint positions in a known environment and track the positions of autonomously moving objects. The state estimators of different robots cooperate to increase the accuracy and reliability of the estimation process. This cooperation between the robots enables them to track temporarily occluded objects and to faster recover their position after they have lost track of it. The method is empirically validated based on experiments with a team of physical robots. View full abstract»

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  • Distributed multirobot localization

    Publication Year: 2002 , Page(s): 781 - 795
    Cited by:  Papers (181)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (921 KB) |  | HTML iconHTML  

    In this paper, we present a new approach to the problem of simultaneously localizing a group of mobile robots capable of sensing one another. Each of the robots collects sensor data regarding its own motion and shares this information with the rest of the team during the update cycles. A single estimator, in the form of a Kalman filter, processes the available positioning information from all the members of the team and produces a pose estimate for every one of them. The equations for this centralized estimator can be written in a decentralized form, therefore allowing this single Kalman filter to be decomposed into a number of smaller communicating filters. Each of these filters processes the sensor data collected by its host robot. Exchange of information between the individual filters is necessary only when two robots detect each other and measure their relative pose. The resulting decentralized estimation schema, which we call collective localization, constitutes a unique means for fusing measurements collected from a variety of sensors with minimal communication and processing requirements. The distributed localization algorithm is applied to a group of three robots and the improvement in localization accuracy is presented. Finally, a comparison to the equivalent decentralized information filter is provided. View full abstract»

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  • Decentralized control of cooperative robotic vehicles: theory and application

    Publication Year: 2002 , Page(s): 852 - 864
    Cited by:  Papers (68)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1113 KB)  

    Describes how decentralized control theory can be used to analyze the control of multiple cooperative robotic vehicles. Models of cooperation are discussed and related to the input/output reachability, structural observability, and controllability of the entire system. Whereas decentralized control research in the past has concentrated on using decentralized controllers to partition complex physically interconnected systems, this work uses decentralized methods to connect otherwise independent nontouching robotic vehicles so that they behave in a stable, coordinated fashion. A vector Liapunov method is used to prove stability of two examples: the controlled motion of multiple vehicles along a line and the controlled motion of multiple vehicles in formation. Also presented are three applications of this theory: controlling a formation, guarding a perimeter, and surrounding a facility. View full abstract»

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  • A general algorithm for robot formations using local sensing and minimal communication

    Publication Year: 2002 , Page(s): 837 - 846
    Cited by:  Papers (134)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (633 KB)  

    We study the problem of achieving global behavior in a group of distributed robots using only local sensing and minimal communication, in the context of formations. The goal is to have N mobile robots establish and maintain some predetermined geometric shape. We report results from extensive simulation experiments, and 40+ experiments with four physical robots, showing the viability of our approach. The key idea is that each robot keeps a single friend at a desired angle θ, using some appropriate sensor. By panning the sensor by θ degrees, the goal for all formations becomes simply to center the friend in the sensor's field of view. We also present a general analytical measure for evaluating formations and apply it to the position data from both simulation and physical robot experiments. We used two lasers to track the physical robots to obtain ground truth validation data. View full abstract»

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  • A vision-based formation control framework

    Publication Year: 2002 , Page(s): 813 - 825
    Cited by:  Papers (339)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1142 KB)  

    We describe a framework for cooperative control of a group of nonholonomic mobile robots that allows us to build complex systems from simple controllers and estimators. The resultant modular approach is attractive because of the potential for reusability. Our approach to composition also guarantees stability and convergence in a wide range of tasks. There are two key features in our approach: 1) a paradigm for switching between simple decentralized controllers that allows for changes in formation; 2) the use of information from a single type of sensor, an omnidirectional camera, for all our controllers. We describe estimators that abstract the sensory information at different levels, enabling both decentralized and centralized cooperative control. Our results include numerical simulations and experiments using a testbed consisting of three nonholonomic robots. View full abstract»

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  • Cooperative transport by multiple mobile robots in unknown static environments associated with real-time task assignment

    Publication Year: 2002 , Page(s): 769 - 780
    Cited by:  Papers (42)  |  Patents (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1054 KB) |  | HTML iconHTML  

    This paper deals with a task-assignment architecture for cooperative transport by multiple mobile robots in an unknown static environment. The architecture should satisfy three features: deal with a variety of tasks in time and space, deal with a large number of tasks compared with the number of robots, and decide the behavior in real time. The authors propose the following approach: we consider the unit of task (task instance) as the job that should be done in a short time by one robot. Based on the environmental information, task instances are dynamically generated using task templates. The priority of task instances is evaluated dynamically based on the number of robots and the configuration in the workspace. In addition, we avoid generating too many task instances by suppressing object motion. The main part of the architecture consists of two real-time planners: a priority-based task-assignment planner solved by using the linear programming method, and motion planners based on short-time estimation. The effectiveness of the proposed architecture is verified by a cooperative transport simulation in an unknown environment. View full abstract»

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  • Sold!: auction methods for multirobot coordination

    Publication Year: 2002 , Page(s): 758 - 768
    Cited by:  Papers (243)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (677 KB)  

    The key to utilizing the potential of multirobot systems is cooperation. How can we achieve cooperation in systems composed of failure-prone autonomous robots operating in noisy, dynamic environments? We present a method of dynamic task allocation for groups of such robots. We implemented and tested an auction-based task allocation system which we call MURDOCH, built upon a principled, resource centric, publish/subscribe communication model. A variant of the Contract Net Protocol, MURDOCH produces a distributed approximation to a global optimum of resource usage. We validated MURDOCH in two very different domains: a tightly coupled multirobot physical manipulation task and a loosely coupled multirobot experiment in long-term autonomy. The primary contribution of the paper is to show empirically that distributed negotiation mechanisms such as MURDOCH are viable and effective for coordinating physical multirobot systems. View full abstract»

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  • CS Freiburg: coordinating robots for successful soccer playing

    Publication Year: 2002 , Page(s): 685 - 699
    Cited by:  Papers (48)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2565 KB) |  | HTML iconHTML  

    Robotic soccer is a challenging research domain because many different research areas have to be addressed in order to create a successful team of robot players. The paper presents the CS Freiburg team, the winner in the middle-size league at RoboCup 1998, 2000, and 2001. The paper focuses on multiagent coordination for both perception and action. The contributions of the paper are new methods for tracking ball and players observed by multiple robots, team coordination methods for strategic team formation and dynamic role assignment; a rich set of basic skills allowing robots to respond to a large range of situations in an appropriate way, and an action-selection method based on behavior networks, as well as a method to learn the skills and their selection. As demonstrated by evaluations of the different methods and by the success of the team, these methods permit the creation of a multirobot group which is able to play soccer successfully. In addition, the developed methods promise to advance the state of the art in the multirobot field. View full abstract»

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  • Human-supervised multiple mobile robot system

    Publication Year: 2002 , Page(s): 728 - 743
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2426 KB) |  | HTML iconHTML  

    In order that robots may achieve tasks in unknown environments, research focusing on the following three points must be conducted: (1) design of commands from the operator to the robots; (2) environmental recognition to show the operator information about the remote work area where robots are working; and (3) interface between a system and the operator and information display of the work area for the operator. For (1), the focus is on the operation of the multiple robots by a single operator. For (2), the problem is divided into two parts; object recognition and self-positioning. As for (3), a graphical user interface is implemented. The operator mainly uses a mouse to input commands, and the operator watches a virtual environment to monitor remote working areas. The virtual environment is constructed with the environment information acquired by the method described in (2) above. After the problems mentioned above are solved, our system will provide a flexible command and monitoring structure and an operator would be able to command the robots appropriately. These are the main advantages of the method we are proposing. We verified the effectiveness of the proposed methods in experiments. View full abstract»

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  • LOST: localization-space trails for robot teams

    Publication Year: 2002 , Page(s): 796 - 812
    Cited by:  Papers (16)  |  Patents (4)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1015 KB)  

    We describe localization-space trails (LOST), a method that enables a team of robots to navigate between places of interest in an initially unknown environment using a trail of landmarks. The landmarks are not physical; they are waypoint coordinates generated online by each robot and shared with teammates. Waypoints are specified in each robot's local coordinate system, and contain references to features in the world that are relevant to the team's task and common to all robots. Using these task-level references, robots can share waypoints without maintaining a global coordinate system. The method is tested in a series of real-world multirobot experiments. The results demonstrate that the method: 1) copes with accumulating odometry error; 2) is robust to the failure of individual robots; 3) converges to the best route discovered by any robot in the team. In one experiment, a team of four autonomous mobile robots performs a resource transportation task in our uninstrumented office building. Despite significant divergence of their local coordinate systems, the robots are able to share waypoints, forming and following a common trail between two predetermined locations for more than three hours, traveling a total of 8.2 km (5.1 miles) before running out of power. Designed to scale to large populations, LOST is fully distributed, with low costs in processing, memory, and bandwidth. It combines metric data about the position of features in the world with instructions on how to get from one place to another; producing something between a map and a plan. View full abstract»

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  • Emotion-based control of cooperating heterogeneous mobile robots

    Publication Year: 2002 , Page(s): 744 - 757
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (740 KB) |  | HTML iconHTML  

    Previous experiences show that it is possible for agents such as robots cooperating asynchronously on a sequential task to enter deadlock, where one robot does not fulfil its obligations in a timely manner due to hardware or planning failure, unanticipated delays, etc. Our approach uses a formal multilevel hierarchy of emotions where emotions both modify active behaviors at the sensory-motor level and change the set of active behaviors at the schematic level. The resulting implementation of a team of heterogeneous robots using a hybrid deliberative/reactive architecture produced the desired emergent societal behavior. Data collected at two different public venues illustrate how a dependent agent selects new behaviors (e.g., stop serving, move to intercept the refiner) to compensate for delays from a subordinate agent (e.g., blocked by the audience). The subordinate also modifies the intensity of its active behaviors in response to feedback from the dependent agent. The agents communicate asynchronously through knowledge query and manipulation language via wireless Ethernet. View full abstract»

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  • Distributed surveillance and reconnaissance using multiple autonomous ATVs: CyberScout

    Publication Year: 2002 , Page(s): 826 - 836
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (675 KB) |  | HTML iconHTML  

    The objective of the CyberScout project is to develop an autonomous surveillance and reconnaissance system using a network of all-terrain vehicles. We focus on two facets of this system: 1) vision for surveillance and 2) autonomous navigation and dynamic path planning. In the area of vision-based surveillance, we have developed robust, efficient algorithms to detect, classify, and track moving objects of interest (person, people, or vehicle) with a static camera. Adaptation through feedback from the classifier and tracker allow the detector to use grayscale imagery, but perform as well as prior color-based detectors. We have extended the detector using scene mosaicing to detect and index moving objects when the camera is panning or tilting. The classification algorithm performs well with coarse inputs, has unparalleled rejection capabilities, and can flag novel moving objects. The tracking algorithm achieves highly accurate (96%) frame-to-frame correspondence for multiple moving objects in cluttered scenes by determining the discriminant relevance of object features. We have also developed a novel mission coordination architecture, CPAD (Checkpoint/Priority/Action Database), which performs path planning via checkpoint and dynamic priority assignment, using statistical estimates of the environment's motion structure. The motion structure is used to make both preplanning and reactive behaviors more efficient by applying global context. This approach is more computationally efficient than centralized approaches and exploits robot cooperation in dynamic environments better than decoupled approaches. View full abstract»

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Aims & Scope

This Transactions ceased production in 2004. The current retitled publications areIEEE Transactions on Automation Science and Engineering and IEEE Transactions on Robotics.

Full Aims & Scope