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31
Decentralized, Adaptive Coverage Control for Networked Robots
, 2007
"... A decentralized, adaptive control law is presented to drive a network of mobile robots to an optimal sensing configuration. The control law is adaptive in that it uses sensor measurements to learn an approximation of the distribution of sensory information in the environment. It is decentralized in ..."
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Cited by 44 (7 self)
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A decentralized, adaptive control law is presented to drive a network of mobile robots to an optimal sensing configuration. The control law is adaptive in that it uses sensor measurements to learn an approximation of the distribution of sensory information in the environment. It is decentralized in that it requires only information local to each robot. The controller is then improved upon by implementing a consensus algorithm in parallel with the learning algorithm, greatly increasing parameter convergence rates. Convergence and consensus of parameters is proven. Finally, several variations on the learning algorithm are explored with a discussion of their stability in closed loop. The controller with and without parameter consensus is demonstrated in numerical simulations. These techniques are suggestive of broader applications of adaptive control methodologies to decentralized control problems in unknown dynamical environments. 1
Distributed control of robotic networks: a mathematical approach to motion coordination algorithms
, 2009
"... (i) You are allowed to freely download, share, print, or photocopy this document. (ii) You are not allowed to modify, sell, or claim authorship of any part of this document. (iii) We thank you for any feedback information, including errors, suggestions, evaluations, and teaching or research uses. 2 ..."
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Cited by 41 (1 self)
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(i) You are allowed to freely download, share, print, or photocopy this document. (ii) You are not allowed to modify, sell, or claim authorship of any part of this document. (iii) We thank you for any feedback information, including errors, suggestions, evaluations, and teaching or research uses. 2 “Distributed Control of Robotic Networks ” by F. Bullo, J. Cortés and S. Martínez
A ladybug exploration strategy for distributed adaptive coverage control
- Proceedings of the International Conference on Robotics an Automation (ICRA 08
, 2008
"... Abstract — A control strategy inspired by the hunting tactics of ladybugs is presented to simultaneously achieve sensor coverage and exploration of an area with a group of networked robots. The controller is distributed in that it requires only information local to each robot, and adaptive in that i ..."
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Cited by 25 (6 self)
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Abstract — A control strategy inspired by the hunting tactics of ladybugs is presented to simultaneously achieve sensor coverage and exploration of an area with a group of networked robots. The controller is distributed in that it requires only information local to each robot, and adaptive in that it modifies its behavior based on information in the environment. The ladybug controller is developed as a modification to a basic coverage control law, first for the non-adaptive case, then for the adaptive case. Stability is proven for both cases with a Lyapunov-type proof. Results of numerical simulations are presented. I.
Coordinating construction of truss structures using distributed equal-mass partitioning
- in Proc. of the 14th International Symposium on Robotics Research, Lucern
, 2009
"... Abstract This paper presents a decentralized algorithm for the coordinated assembly of 3D objects that consist of multiple types of parts, using a networked team of robots. We describe the algorithm and analyze its stability and adaptation properties. We instantiate the algorithm to building truss-l ..."
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Cited by 15 (3 self)
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Abstract This paper presents a decentralized algorithm for the coordinated assembly of 3D objects that consist of multiple types of parts, using a networked team of robots. We describe the algorithm and analyze its stability and adaptation properties. We instantiate the algorithm to building truss-like objects using rods and connectors. We implement the algorithm in simulation and show results for constructing 2D and 3D parts. Finally, we discuss briefly preliminary hardware results. 1
Consensus learning for distributed coverage control
- in Proc. of ICRA
, 2008
"... Abstract — A decentralized controller is presented that causes a network of robots to converge to a near optimal sensing configuration, while simultaneously learning the distribution of sensory information in the environment. A consensus (or flocking) term is introduced in the learning law to allow ..."
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Cited by 11 (3 self)
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Abstract — A decentralized controller is presented that causes a network of robots to converge to a near optimal sensing configuration, while simultaneously learning the distribution of sensory information in the environment. A consensus (or flocking) term is introduced in the learning law to allow sharing of parameters among neighbors, greatly increasing learning convergence rates. Convergence and consensus is proven using a Lyapunov-type proof. The controller with parameter consensus is shown to perform better than the basic controller in numerical simulations. I.
Analysis and Implementation of Distributed algorithms for multi-robot Systems
, 2008
"... Distributed algorithms for multi-robot systems rely on network communications to share information. However, the motion of the robots changes the network topology, which affects the information presented to the algorithm. For an algorithm to produce accurate output, robots need to communicate rapidl ..."
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Cited by 11 (3 self)
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Distributed algorithms for multi-robot systems rely on network communications to share information. However, the motion of the robots changes the network topology, which affects the information presented to the algorithm. For an algorithm to produce accurate output, robots need to communicate rapidly enough to keep the network topology correlated to their physical configuration. Infrequent communications will cause most multirobot distributed algorithms to produce less accurate results, and cause some algorithms to stop working altogether. The central theme of this work is that algorithm accuracy, communications bandwidth, and physical robot speed are related. This thesis has three main contributions: First, I develop a prototypical multi-robot application and computational model, propose a set of complexity metrics to evaluate distributed algorithm performance on multi-robot systems, and introduce the idea of the robot speed ratio, a dimensionless measure of robot speed relative to message speed in networks that rely on multi-hop communication. The robot speed ratio captures key relationships
Distributed coverage and exploration in unknown non-convex environments
- In Proceedings of DARS 2010
, 2010
"... Summary. We consider the problem of multi-robot exploration and coverage in unknown non-convex environments. The contributions of the work include (1) the presentation of a distributed algorithm that computes the generalized Voronoi tessellation of non-convex environments (using a discrete represen ..."
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Cited by 9 (1 self)
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Summary. We consider the problem of multi-robot exploration and coverage in unknown non-convex environments. The contributions of the work include (1) the presentation of a distributed algorithm that computes the generalized Voronoi tessellation of non-convex environments (using a discrete representation) in real-time for use in feedback control laws; and (2) the extension of this method to entropy-based metrics that allow for cooperative coverage control in unknown non-convex environments. Simulation results demonstrate the application of the control methodology for cooperative exploration and coverage in an office environment.
A.: Dynamic team hierarchies in communicationlimited multi-robot exploration
- In: Proceedings of the IEEE International Workshop on Safety, Security and Rescue Robotics (SSRR
, 2010
"... Abstract — In the near future, groups of autonomous robots using wireless communication will be used for a wide variety of tasks. In many such applications, communication may be unreliable and communication ranges difficult to predict. While most current approaches to this problem strive to keep tea ..."
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Cited by 8 (3 self)
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Abstract — In the near future, groups of autonomous robots using wireless communication will be used for a wide variety of tasks. In many such applications, communication may be unreliable and communication ranges difficult to predict. While most current approaches to this problem strive to keep team members within range of one another, we propose an approach in which navigation and exploration beyond range limits is explicitly planned for. Robots may either explore or relay known information, and the team hierarchy corresponds to a tree. As the exploration effort unfolds, robots swap roles within this tree to improve the efficiency of exploration. Since robots reactively adjust to communication availability, the resulting behaviour is robust to limited communication. This makes it particularly suitable for applications such as robotic search and rescue, where environments are likely to contain significant interference and unexpected communication ranges.
1 Stochastic Modeling of the Expected Time to Search for an Intermittent Signal Source Under a Limited Sensing Range
"... Abstract—A mobile robot is deployed to search for a stationary target that intermittently emits short duration signals. The searching mission is accomplished as soon as the robot receives a signal from the target. However, the robot cannot perceive the signal unless the target is within its limited ..."
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Cited by 7 (3 self)
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Abstract—A mobile robot is deployed to search for a stationary target that intermittently emits short duration signals. The searching mission is accomplished as soon as the robot receives a signal from the target. However, the robot cannot perceive the signal unless the target is within its limited sensing range. Therefore, the time to search the target is inherently random and hence unknown despite its importance in many searching and rescue applications. Here we propose the expected searching time (EST) as a metric to evaluate different robot motion plans under different robot configurations. We derive a closed form solution for computing the EST. To illustrate the EST model, we present two case studies. In the first case, we analyze two common motion plans: a slap method and a random walk. The EST analysis shows that the slap method is asymptotically faster than the random walk when the searching space size increases. In the second case, we compare a team of n low-cost equallyconfigured robots with a super robot that has the sensing range equal to that of the summation of the n robots. The EST analysis shows that the low-cost robot team takes Θ(1/n) time and the super robot takes Θ(1 / √ n) time as n → ∞. In both cases, our EST model successfully demonstrates its ability in assessing the searching performance. The analytical results are also confirmed in simulation. I.
A Gradient Optimization Approach to Adaptive multi-robot control
, 2009
"... This thesis proposes a unified approach for controlling a group of robots to reach a goal configuration in a decentralized fashion. As a motivating example, robots are controlled to spread out over an environment to provide sensor coverage. This example gives rise to a cost function that is shown to ..."
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Cited by 7 (2 self)
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This thesis proposes a unified approach for controlling a group of robots to reach a goal configuration in a decentralized fashion. As a motivating example, robots are controlled to spread out over an environment to provide sensor coverage. This example gives rise to a cost function that is shown to be of a surprisingly general nature. By changing a single free parameter, the cost function captures a variety of different multi-robot objectives which were previously seen as unrelated. Stable, distributed controllers are generated by taking the gradient of this cost function. Two fundamental classes of multi-robot behaviors are delineated based on the convexity of the underlying cost function. Convex cost functions lead to consensus (all robots move to the same position), while any other behavior requires a nonconvex cost function. The multi-robot controllers are then augmented with a stable on-line learning mechanism to adapt to unknown features in the environment. In a sensor cover-age application, this allows robots to learn where in the environment they are most needed, and to aggregate in those areas. The learning mechanism uses communica-