Results 1  10
of
27
Optimal LQG control across packetdropping links
 Systems & Control Letters
, 2007
"... Abstract We examine two special cases of the problem of optimal Linear Quadratic Gaussian control of a system whose state is being measured by sensors that communicate with the controller over packetdropping links. We extend the LQG separation principle using a standard LQR statefeedback design, ..."
Abstract

Cited by 77 (7 self)
 Add to MetaCart
(Show Context)
Abstract We examine two special cases of the problem of optimal Linear Quadratic Gaussian control of a system whose state is being measured by sensors that communicate with the controller over packetdropping links. We extend the LQG separation principle using a standard LQR statefeedback design, along with an optimal algorithm for propagating and using the information across the unreliable link. Our design is optimal for any arbitrary packet drop pattern. Further, the solution is appealing from a practical point of view because it can be implemented as a small modification of an existing LQG control design.
Optimal dropout compensation in networked control systems
 in Proc. IEEE Conf. Decision Control
, 2003
"... This paper examines optimal compensation for dropped feedback measurements in a networked control system. A common policy for handling such lost data is to simply use the past data. This case was treated in [8]. This paper extends that prior work to cover a more general class of dropout compensation ..."
Abstract

Cited by 45 (3 self)
 Add to MetaCart
(Show Context)
This paper examines optimal compensation for dropped feedback measurements in a networked control system. A common policy for handling such lost data is to simply use the past data. This case was treated in [8]. This paper extends that prior work to cover a more general class of dropout compensation. The paper's principal result shows that determining the optimal dropout compensator can be posed as a constrained generalized regulator problem. An example compares the performance of a networked control system using the optimal dropout compensator against more commonly used heuristic dropout policies. The comparison shows that the optimal compensator works better than these heuristic policies. 1
Data Transmission over Networks for Estimation and Control
"... We consider the problem of controlling a linear time invariant process when the controller is located at a location remote from where the sensor measurements are being generated. The communication from the sensor to the controller is supported by a communication network with arbitrary topology compo ..."
Abstract

Cited by 45 (9 self)
 Add to MetaCart
(Show Context)
We consider the problem of controlling a linear time invariant process when the controller is located at a location remote from where the sensor measurements are being generated. The communication from the sensor to the controller is supported by a communication network with arbitrary topology composed of analog erasure channels. Using a separation principle, we prove that the optimal LQG controller consists of an LQ optimal regulator along with an estimator that estimates the state of the process across the communication network mentioned above. We then determine the optimal information processing strategy that should be followed by each node in the network so that the estimator is able to compute the best possible estimate in the minimum mean squared error sense. The algorithm is optimal for any packetdropping process and at every time step, even though it is recursive and hence requires a constant amount of memory, processing and transmission at every node in the network per time step. For the case when the packet drop processes are memoryless and independent across links, we analyze the stability properties and the performance of the closed loop system. The algorithm is an attempt to escape the more commonly used viewpoint of treating a network of communication links as a single endtoend link with the probability of successful transmission determined by some measure of the reliability of the network. I.
Overload management in sensoractuator networks used for spatiallydistributed control systems
 in SenSys
, 2003
"... abstract: Overload management policies avoid network congestion by actively dropping packets. This paper studies the effect that such data dropouts have on the performance of spatially distributed control systems. We formally relate the spatiallydistributed system’s performance (as measured by the ..."
Abstract

Cited by 15 (0 self)
 Add to MetaCart
(Show Context)
abstract: Overload management policies avoid network congestion by actively dropping packets. This paper studies the effect that such data dropouts have on the performance of spatially distributed control systems. We formally relate the spatiallydistributed system’s performance (as measured by the average output signal power) to the data dropout rate. This relationship is used to pose an optimization problem whose solution is a Markov chain characterizing a dropout process that maximizes control system performance subject to a specified lower bound on the dropout rate. We then use this Markov chain to formulate an overload management policy that enables nodes to enforce the ”optimal ” dropout process identified in our optimization problem. Simulation experiments are used to verify the paper’s claims. 1
On Stability in Presence of Analog Erasure Channels
 Mathematical Theory of Networks and Systems
, 2008
"... Abstract — Consider a discretetime networked control scheme, in which the controller has direct access to noisy measurements of the plant’s output, but the controller and the actuator are connected via a link that features Bernoulli erasure events. We determine necessary and sufficient conditions ..."
Abstract

Cited by 13 (3 self)
 Add to MetaCart
(Show Context)
Abstract — Consider a discretetime networked control scheme, in which the controller has direct access to noisy measurements of the plant’s output, but the controller and the actuator are connected via a link that features Bernoulli erasure events. We determine necessary and sufficient conditions for the stabilizability of an unstable linear and timeinvariant plant. We show that these conditions are identical for two types of actuators: • (Type I) Processing at the actuator has access to the plant’s model; • (Type II) Processing at the actuator uses a universal algorithm that does not depend on the model of the plant. We also identify cases where availability of acknowledgements over the controlleractuator channel is not required for stability. We also consider decentralized networked control structures, where two or more independent controllerlinkactuator assemblies have access to different measurements of the plant’s output. I.
On LQG Joint Optimal Scheduling and Control under Communication Constraints
, 2009
"... In this paper, we consider a discretetime stochastic system, where sensor measurements are sent over a network to the controller. The design objective is a nonclassical multicriterion optimization problem for finite horizon, where the cost function consists of the linear quadratic cost reflecting ..."
Abstract

Cited by 11 (3 self)
 Add to MetaCart
(Show Context)
In this paper, we consider a discretetime stochastic system, where sensor measurements are sent over a network to the controller. The design objective is a nonclassical multicriterion optimization problem for finite horizon, where the cost function consists of the linear quadratic cost reflecting the control performance and a communication cost penalizing information exchange between sensor and controller. It is shown that the joint optimization of scheduling and control can be separated into three subproblems: an optimal regulator problem, an estimation problem and an optimal scheduling problem. The obtained results are extended to TCPlike networks with random packet loss. In the proposed framework, we classify three classes of schedulers, a purely randomized, a deterministic and a statedependent scheme, and compare their performance by a numerical example.
Analysis of bird formations
 IEEE Conference on Decision and Control
, 2002
"... Birds in V formations are frequently observed and two main hypotheses have emerged in the biology/ornithology literature to explain this particular geometry: (i) it o®ers aerodynamic advantages and (ii) it is used to improve visual communication. Both explanations require a bird to track its pred ..."
Abstract

Cited by 10 (1 self)
 Add to MetaCart
(Show Context)
Birds in V formations are frequently observed and two main hypotheses have emerged in the biology/ornithology literature to explain this particular geometry: (i) it o®ers aerodynamic advantages and (ii) it is used to improve visual communication. Both explanations require a bird to track its predecessor. Observations of °ocks suggest that this task is di±cult for birds in large formations. In this paper, we explain this phenomenon using a simple bird model and systems theory. This result has implications for the coordinated control of unmanned aerial vehicles. In particular, predecessorfollowing is an inherently poor strategy for formation °ight. 1
On LQG Control Across a Stochastic packetdropping link
, 2005
"... In this paper, we consider the problem of optimal Linear Quadratic Gaussian control of a system in which communication between the sensor and the controller occurs across a packetdropping link. We first prove a separation principle that allows us to solve this problem using a standard LQR statef ..."
Abstract

Cited by 9 (3 self)
 Add to MetaCart
In this paper, we consider the problem of optimal Linear Quadratic Gaussian control of a system in which communication between the sensor and the controller occurs across a packetdropping link. We first prove a separation principle that allows us to solve this problem using a standard LQR statefeedback design, along with an optimal algorithm for propagating and using the information across the unreliable link. Then we present one such optimal algorithm, which consists of a Kalman filter at the sensor side of the link, and a switched linear filter at the controller side. Our design does not assume any statistical model of the packet drop events, and is thus optimal for any arbitrary packet drop pattern. Further, the solution is appealing from a practical point of view because it can be implemented as a small modification of an existing LQG control design.
Fault Diagnosis of Networked Control Systems
 Int. J. Appl. Math. Comput. Sci
, 2008
"... Networked Control Systems (NCSs) deal with feedback control systems with loops closed via data communication networks. Control over a network has many advantages compared with traditionally controlled systems, such as a lower implementation cost, reduced wiring, simpler installation and maintenance ..."
Abstract

Cited by 7 (2 self)
 Add to MetaCart
(Show Context)
Networked Control Systems (NCSs) deal with feedback control systems with loops closed via data communication networks. Control over a network has many advantages compared with traditionally controlled systems, such as a lower implementation cost, reduced wiring, simpler installation and maintenance and higher reliability. Nevertheless, the networkinduced delay, packet dropout, asynchronous behavior and other specificities of networks will degrade the performance of closedloop systems. In this context, it is necessary to develop a new theory for systems that operate in a distributed and asynchronous environment. Research on Fault Detection and Isolation (FDI) for NCSs has received increasing attention in recent years. This paper reviews the state of the art in this topic.
Radio leashing of an unmanned aircraft
 in AIAA’s Infotech@Aerospace Conference
, 2005
"... This paper introduces the Radio Leashing Problem and presents a control system to solve the problem for a single unmanned aircraft. The leashing problem as presented in this paper is to electronically tether an unmanned vehicle to one ore more radio nodes so that it may act as a communication repeat ..."
Abstract

Cited by 4 (3 self)
 Add to MetaCart
This paper introduces the Radio Leashing Problem and presents a control system to solve the problem for a single unmanned aircraft. The leashing problem as presented in this paper is to electronically tether an unmanned vehicle to one ore more radio nodes so that it may act as a communication repeater between them in a multihop network. The method proposed in this paper solves the leashing problem using only local measurements of network performance and assumes no knowledge of the node locations or on the RF propagation environment. This paper addresses two specific concepts that are not seen in literature: (i) the formulation of a control strategy based only upon received radio statistics, and (ii) utilizing the motion of a single aircraft to gain further information about the local RF environment. In this work, the signaltonoise ratio for each individual link is the only input into a highlevel control system. Due to the orbital motion of the aircraft, a gradient of the signaltonoise field can be measured, and is used to control the motion of an orbit center point as well as provide a directional estimate of the transmitting node’s location from the aircraft. Nomenclature