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Zhang,
Fumin
Zhang,
Fumin
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ItemAn exploration strategy by constructing Voronoi Diagrams with provable completeness(Georgia Institute of Technology, 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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ItemSimultaneous Cooperative Exploration and Networking based on Voronoi Diagrams(Georgia Institute of Technology, 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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ItemCurve Tracking Control for Autonomous Vehicles with Rigidly Mounted Range Sensors(Georgia Institute of Technology, 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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ItemSimultaneous Cooperative Exploration and Networking Based on Voronoi Diagrams(Georgia Institute of Technology, 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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ItemCurve Tracking Control for Autonomous Vehicles with Rigidly Mounted Range Sensors(Georgia Institute of Technology, 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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ItemTask Scheduling for Control Oriented Requirements for Cyber-Physical Systems(Georgia Institute of Technology, 2008-12) Zhang, Fumin ; Szwaykowska, Klementyna ; Wolf, Wayne ; Mooney, Vincent John, IIIThe wide applications of cyber-physical systems (CPS) call for effective design strategies that optimize the performance of both computing units and physical plants. We study the task scheduling problem for a class of CPS whose behaviors are regulated by feedback control laws. We codesign the control law and the task scheduling algorithm for predictable performance and power consumption for both the computing and the physical systems. We use a typical example, multiple inverted pendulums controlled by one processor, to illustrate our method.
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ItemCurve Tracking for Autonomous Vehicles with Rigidly Mounted Range Sensors(Georgia Institute of Technology, 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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ItemControl of coordinated patterns for ocean sampling(Georgia Institute of Technology, 2007) Zhang, Fumin ; Fratantoni, David M. ; Paley, Derek A. ; Lund, John M. ; Leonard, Naomi EhrichA class of underwater vehicles are modelled as Newtonian particles for navigation and control. We show a general method that controls cooperative Newtonian particles to generate patterns on closed smooth curves. These patterns are chosen for good sampling performance using mobile sensor networks. We measure the spacing between neighbouring particles by the relative curve phase along the curve. The distance between a particle and the desired curve is measured using an orbit function. The orbit value and the relative curve phase are then used as feedback to control motion of each particle. From an arbitrary initial configuration, the particles converge asymptotically to form an invariant pattern on the desired curves. We describe application of this method to control underwater gliders in a field experiment in Buzzards Bay, MA in March 2006.