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Zhang, Fumin

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Author: Egerstedt, Magnus B. ×

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Now showing 1 - 9 of 9
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Intruder Capturing Game on a Topological Map Assisted by Information Networks

2011-12 , Kim, Jonghoek , Maxon, Sean , Egerstedt, Magnus B. , Zhang, Fumin

Intruder capturing games on a topological map of a workspace with obstacles are investigated. Assuming that a searcher can access the position of any intruder utilizing information networks, we provide theoretical upper bounds for the minimum number of searchers required to capture all intruders on a Voronoi graph. Intruder capturing algorithms are proposed and demonstrated through an online computer game.

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An exploration strategy by constructing Voronoi Diagrams with provable completeness

2009-12 , Kim, Jonghoek , Zhang, Fumin , Egerstedt, Magnus B.

We present novel exploration algorithms and a control law that enable the construction of Voronoi diagrams over unknown areas using a single autonomous vehicle equipped with range sensors. Our control law and exploration algorithms are provably complete. The control law uses range measurements to enable tracking Voronoi edges between two obstacles. Exploration algorithms make decisions at vertices of the Voronoi diagram to expand the explored area until a complete Voronoi diagram is constructed in finite time. MATLAB simulation results are provided to demonstrate the effectiveness of both the control law and the exploration algorithms.

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Simultaneous Cooperative Exploration and Networking Based on Voronoi Diagrams

2009 , Kim, Jonghoek , Zhang, Fumin , Egerstedt, Magnus B.

We develop a strategy that enables multiple intelligent vehicles to cooperatively explore complex territories. Every vehicle deploys communication devices and expands an information network while constructing a topological map based on Voronoi diagrams. As the information network weaved by each vehicle grows, intersections eventually happen so that the topological maps are shared. This allows for distributed vehicles to share information with other vehicles that have also deployed communication devices. Our exploration algorithms are provably complete under mild technical assumptions. A performance analysis of the algorithms shows that in a bounded workspace, the time spent to complete the exploration decreases as the number of vehicles increases. We further provide an analytical formula for this relationship. Time efficiency of the algorithms is demonstrated in MATLAB simulation.

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Battery Level Estimation of Mobile Agents Under Communication Constraints

2010-06 , Kim, Jonghoek , Zhang, Fumin , Egerstedt, Magnus B.

Consider a team of mobile agents monitoring large areas, e.g. in the ocean or the atmosphere, with limited sensing resources. Only the leader transmits information to other agents, and the leader has a role to monitor battery levels of all other agents. Every now and then, the leader commands all other agents to move toward or away from the leader with speeds proportional to their battery levels. The leader then simultaneously estimates the battery levels of all other agents from measurements of the relative distances between the leader and other agents. We propose a nonlinear system model that integrates a particle motion model and a dynamic battery model that has demonstrated high accuracy in battery capacity prediction. The extended Kalman filter (EKF) is applied to this nonlinear model to estimate the battery level of each agent. We improve the EKF so that, in addition to gain optimization embedded in the EKF, the motions of agents are controlled to minimize estimation error. Simulation results are presented to demonstrate effectiveness of the proposed method.

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Simultaneous Cooperative Exploration and Networking based on Voronoi Diagrams

2009-10 , Kim, Jonghoek , Zhang, Fumin , Egerstedt, Magnus B.

We develop a strategy that enables multiple intelligent vehicles to cooperatively explore complex and dangerous territories. Every vehicle drops communication devices and expands an information network while constructing a topological map based on the Voronoi diagram. As the information network weaved by each vehicle grows, intersections eventually happen so that the networks are shared. This allows for distributed vehicles to share information with other vehicles that have also dropped communication devices. Our exploration algorithms are provably complete under mild technical assumptions. A performance analysis of the algorithms shows that in a bounded workspace, the time spent to complete the exploration decreases in proportion to the number of vehicles employed. The algorithms are demonstrated in simulation.

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Curve Tracking Control for Autonomous Vehicles with Rigidly Mounted Range Sensors

2009 , Kim, Jonghoek , Zhang, Fumin , Egerstedt, Magnus B.

In this paper, we present feedback control laws for an autonomous vehicle with rigidly mounted range sensors to track a desired curve. In particular, we consider a vehicle that has a group of rays around two center rays that are perpendicular to the velocity of the vehicle. Under such a sensor configuration, singularities are bound to occur in the curve tracking feedback control law when tracking concave curves. To overcome this singularity, we derive a hybrid strategy of switching between control laws when the vehicle gets close to singularities. Rigorous proof and extensive simulation results verify the validity of the proposed feedback control law.

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A provably complete exploration strategy by constructing Voronoi diagrams

2010 , Kim, Jonghoek , Zhang, Fumin , Egerstedt, Magnus B.

We present novel exploration algorithms and a control law that enables the construction of Voronoi diagrams over unknown areas using a single vehicle equipped with range sensors. The control law uses range measurements to make the vehicle track Voronoi edges between obstacles. The exploration algorithms make decisions at vertices in the Voronoi diagram to expand the explored area until a complete Voronoi diagram is constructed in finite time. Our exploration algorithms are provably complete, and the convergence of the control law is guaranteed. Simulations and experimental results are provided to demonstrate the effectiveness of both the control law and the exploration algorithms.

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Curve Tracking Control for Autonomous Vehicles with Rigidly Mounted Range Sensors

2009-09 , Kim, Jonghoek , Zhang, Fumin , Egerstedt, Magnus B.

In this paper, we present feedback control laws for an autonomous vehicle with rigidly mounted range sensors to track a desired curve. In particular, we consider a vehicle that has a group of rays around two center rays that are perpendicular to the velocity of the vehicle. Under such a sensor configuration, singularities are bound to occur in the curve tracking feedback control law when tracking concave curves. To overcome this singularity, we derive a hybrid strategy of switching between control laws when the vehicle gets close to singularities. Rigorous proof and extensive simulation results verify the validity of the proposed feedback control law.

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Curve Tracking for Autonomous Vehicles with Rigidly Mounted Range Sensors

2008-12 , Kim, Jonghoek , Zhang, Fumin , Egerstedt, Magnus B.

In this paper, we present a feedback control law to make an autonomous vehicle with rigidly mounted range sensors track a desired curve. In particular, we consider a vehicle which has two range sensors that emit rays perpendicular to the velocity of the vehicle. Under such a sensor configuration, singularities are bound to occur in the feedback control law. Thus, to overcome this, we derive a hybrid strategy of switching between control laws close to the singularity.

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