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Formations with a Mission: Stable Coordination of Vehicle Group Maneuvers
, 2002
"... In this paper we present a stable coordination strategy for vehicle formation missions that involve group translation, rotation, expansion and contraction. The underlying coordination framework uses arti cial potentials and virtual leaders. Symmetry in the framework is exploited to partially decoup ..."
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Cited by 83 (11 self)
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In this paper we present a stable coordination strategy for vehicle formation missions that involve group translation, rotation, expansion and contraction. The underlying coordination framework uses arti cial potentials and virtual leaders. Symmetry in the framework is exploited to partially decouple the mission control problem into a formation management subproblem and a maneuver management subproblem. The designed dynamics of the virtual leaders play a key role in both subproblems: the direction of motion of the virtual leaders is designed to satisfy the mission while the speed of the virtual leaders is designed to ensure stability and convergence properties of the formation. The latter is guaranteed by regulating the virtual leader speed according to a feedback measurement of an appropriate formation error function. The coordination strategy is illustrated in the context of adaptive gradient climbing missions.
Vehicle Networks for Gradient Descent in a Sampled Environment
- PROC. 41ST IEEE CONF. DECISION AND CONTROL
, 2002
"... Fish in a school efficiently find the densest source of food by individually responding not only to local environmental stimuli but also to the behavior of nearest neighbors. It is of great interest to enable a network of autonomous vehicles to function similarly as an intelligent sensor array capab ..."
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Cited by 77 (9 self)
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Fish in a school efficiently find the densest source of food by individually responding not only to local environmental stimuli but also to the behavior of nearest neighbors. It is of great interest to enable a network of autonomous vehicles to function similarly as an intelligent sensor array capable of climbing or descending gradients of some spatially distributed signal. We formulate and study a coordinated control strategy for a group of autonomous vehicles to descend or climb an environmental gradient using measurements of the environment together with relative position measurements of nearest neighbors. Each vehicle is driven by an estimate of the local environmental gradient together with control forces, derived from artificial potentials, that maintain uniformity in group geometry.
Model-Based Feedback Control of Autonomous Underwater Gliders
, 2001
"... We describe the development of feedback control for autonomous underwater gliders. Feedback is introduced to make the glider motion robust to disturbances and uncertainty. Our focus is on buoyancy-propelled, fixed-wing gliders with attitude controlled by means of active internal mass redistribution. ..."
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Cited by 42 (10 self)
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We describe the development of feedback control for autonomous underwater gliders. Feedback is introduced to make the glider motion robust to disturbances and uncertainty. Our focus is on buoyancy-propelled, fixed-wing gliders with attitude controlled by means of active internal mass redistribution. We derive a nonlinear dynamic model of a nominal glider complete with hydrodynamic forces and coupling between the vehicle and the movable internal mass. We use this model to study stability and controllability of glide paths and to derive feedback control laws. For our analysis, we restrict to motion in the vertical plane and consider linear control laws. For illustration, we apply our methodology to a model of our own laboratory-scale underwater glider.
Underwater glider dynamics and control
- in Proc. 12th Int. Symposium on Unmanned Untethered Submersible Tech
, 2001
"... We present a linear controller and observer de-sign for autonomous underwater gliders based on a model of glider dynamics that we have derived. Our focus is on buoyancy-propelled, xed-wing gliders with attitude controlled by means of internal mass distribution. In cases when some states cannot be d ..."
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Cited by 10 (4 self)
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We present a linear controller and observer de-sign for autonomous underwater gliders based on a model of glider dynamics that we have derived. Our focus is on buoyancy-propelled, xed-wing gliders with attitude controlled by means of internal mass distribution. In cases when some states cannot be directly measured, such as with oceangoing gliders, the design of an observer oers possible improve-ments over current glider control methods. 1
Cooperative Vehicle Control, Feature Tracking and Ocean Sampling
- PRINCETON UNIVERSITY
, 2005
"... This dissertation concerns the development of a feedback control framework for coordinat-ing multiple, sensor-equipped, autonomous vehicles into mobile sensing arrays to perform adaptive sampling of observed fields. The use of feedback is central; it maintains the array, i.e. regulates formation pos ..."
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Cited by 3 (1 self)
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This dissertation concerns the development of a feedback control framework for coordinat-ing multiple, sensor-equipped, autonomous vehicles into mobile sensing arrays to perform adaptive sampling of observed fields. The use of feedback is central; it maintains the array, i.e. regulates formation position, orientation, and shape, and directs the array to perform its sampling mission in response to measurements taken by each vehicle. Specifically, we address how to perform autonomous gradient tracking and feature detection in an unknown field such as temperature or salinity in the ocean. Artificial potentials and virtual bodies are used to coordinate the autonomous vehicles, modelled as point masses (with unit mass). The virtual bodies consist of linked, moving reference points called virtual leaders. Artificial potentials couple the dynamics of the vehicles and the virtual bodies. The dynamics of the virtual body are then prescribed allowing the virtual body, and thus the vehicle group, to perform maneuvers that include translation, rotation and contraction/expansion, while ensuring that the formation error remains bounded. This methodology is called the Virtual Body and Artificial Potential
Development of a power system and analysis of inertial system calibration for a small autonomous underwater vehicle
- Master’s thesis, Virginia Tech, 2004. Jessica Luan Chapter 6. Conclusions and Future Work 47
"... Compared to large vehicles acting individually, platoons of small, inex-pensive autonomous underwater vehicles have the potential to perform some missions that are commonly conducted by larger vehicles faster, more effi-ciently, and at a reduced operational cost. This thesis describes the power syst ..."
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Cited by 3 (0 self)
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Compared to large vehicles acting individually, platoons of small, inex-pensive autonomous underwater vehicles have the potential to perform some missions that are commonly conducted by larger vehicles faster, more effi-ciently, and at a reduced operational cost. This thesis describes the power system of a small, inexpensive autonomous underwater vehicle developed by the Autonomous Systems Controls Laboratory at Virginia Tech. Reduction in vehicle size and cost reduces the accuracy of navigational sensors, leading to the need for autonomous calibration. Several models of navigational sensors are discussed, and the extended Kalman filter is used to form an observer for each, which are simulated and analyzed. Acknowledgments I would not be where I am today without the love and support of my future wife, Melissa. I know that it is a daunting and often thankless task to keep me down to earth and focused, but she accomplishes it with patience and
