Nicanor Quijano | Universidad de los Andes (Colombia) (original) (raw)
Papers by Nicanor Quijano
2015 IEEE 2nd Colombian Conference on Automatic Control (CCAC), 2015
... DRAFT Emergence of Scale Free Networks from Ideal Free Distributions (2006). Download: http:/... more ... DRAFT Emergence of Scale Free Networks from Ideal Free Distributions (2006). Download: http://www.ece.osu.edu/~finkej/Publications_files/ CACHED: Download as a PDF. by Jorge Finke , Nicanor Quijano , Kevin M. Passino. ...
American Control Conference, 2008, Jan 1, 2008
The integration of physical systems with distributed embedded computing and communication devices... more The integration of physical systems with distributed embedded computing and communication devices offers advantages on reliability, efficiency, and maintenance. At the same time, these embedded computers are susceptible to cyber-attacks that can harm the performance of the physical system, or even drive the system to an unsafe state; therefore, it is necessary to deploy security mechanisms that are able to automatically detect, isolate, and respond to potential attacks. Detection and isolation mechanisms have been widely studied for different types of attacks; however, automatic response to attacks has attracted considerably less attention. Our goal in this paper is to identify trends and recent results on how to respond and reconfigure a system under attack, and to identify limitations and open problems. We have found two main types of attack protection: i) preventive, which identifies the vulnerabilities in a control system and then increases its resiliency by modifying either control parameters or the redundancy of devices; ii) reactive, which responds as soon as the attack is detected (e.g., modifying the non-compromised controller actions).
Recent work has studied the impact caused by attackers that compromise pricing signals used in th... more Recent work has studied the impact caused by attackers that compromise pricing signals used in the emerging retail electricity market and send false prices to a subset of consumers. In this paper, we extend previous work by considering a more realistic adversary model that is not arbitrarily tied
to scaling and delay attacks, but that can generate any arbitrary pricing signal and show how to keep the problem tractable with a new analysis based on sensitivity functions. In addition, we
extend previous work by proposing countermeasures to mitigate the negative impact of these attacks. Countermeasures include selecting parameters of the controller, designing robust control
algorithms, and by detecting anomalies in the behavior of the system.
Accepted to the 53th Conference on Decision and Control, 2014
The consensus algorithm can represent many problems in cooperative behavior, and has been widely ... more The consensus algorithm can represent many problems in cooperative behavior, and has been widely used in engineering and social sciences. In this work, we prove that the consensus model where the information that each agent receives from its neighbors has time-varying asynchronous delays and sampling, converges to an agreement independent of these communication constraints. This independence is useful in the context of ``data minimization,'' which is one of the principles for privacy. As a practical example, we show how this independence can be used for microgrids with a consensus-based secondary control scheme where participants have incentives to share their states to ensure frequency synchronization, while at the same time minimizing the amount of data shared to preserve their privacy. We then propose two data sharing algorithms: 1) periodic sampling, and 2) discretionary sampling, and study their privacy as well as their performance. We show that even when a discretionary sampling scheme ``lies'' to their neighbors in order to preserve their privacy, the consensus algorithm performs almost as well as with periodic sampling.
In proceeding of the Conference on Decision and Control (CDC 2013), 2013
Motivated by the increasing interest in networked multi-agent systems and the wide number of appl... more Motivated by the increasing interest in networked multi-agent systems and the wide number of applications in distributed control of smart grids, we address the problem of synchronization of microgrids. Two topologies are considered: the physical topology that relates the interconnection of distributed generators and loads, and the communication topology, which describes the information flow of the power system measurements. We propose a control strategy based on the information flow and we show that there exists a strong relationship between both topologies in order to achieve synchronization. As a matter of fact, we show that our results can be extended when isolated group of nodes are taken into account, and they can be connected or disconnected to the main grid. Finally, the effects of time-varying sampling are analyzed using some average passivity conditions, and sampling-time independence is demonstrated with the proposed controller.
n proceeding of the American Control Conference 2014, 2014
The Kuramoto oscillator has been widely studied because it can model biological, social, chemical... more The Kuramoto oscillator has been widely studied because it can model biological, social, chemical, and engineering problems. Conditions for frequency synchronization of a network of Kuramoto oscillators have
been well established, but it depends on the connectivity of the network and on the natural frequencies. However, some applications requires that oscillators oscillate to a desired frequency even when the network topology is
disconnected. In this work we propose a consensus-based control strategy that forces the network to follow a virtual agent with constant frequency. Besides, we consider that the control input is constrained and we establish the limits of the set of inputs that assure frequency tracking. The results are extended to the smart grid case, where the nodes of a power network are modeled as Kuramoto oscillators that synchronize to a desired frequency using the injection/absorbsion of power according to a consensus based control. We show that our results are feasible when isolated group of nodes are taken into account, and they can be connected or disconnected to the main grid. Finally, the effects of time-varying sampling are analyzed and sampling period independence is demonstrated.
In proceedings of the 2013 European Control Conference
Motivated by the increasing interest in networked multi-agent systems and the wide number of appl... more Motivated by the increasing interest in networked multi-agent systems and the wide number of applications in decentralized distributed control of smart grids, we address the problem of synchronization when each node (e.g., a microgrid, a distributed generator) is modeled as a linear-time continuous system whose output measurements are sent through communication links. However, the inclusion of a communication infrastructure adds new challenges to control strategies and some problems may arise such as time delays, packet losses, sampling period, just to name a few. In this work, we consider that data is sampled with homogeneous sampling periods. Then, using the novel concept of average passivity, we define the conditions for synchronizability when all nodes are identical and unstable dynamics are present. Additionally, results are extended to the case of non-uniform agents, and some simulations of synchronization in smart grids are introduced.
In proceeding of: IEEE IX Latin American Robotics Symposium and IEEE Colombian Conference on Automatic Control, 2011
Networked Control Systems (NCS) has been one of the main research areas in the last few years, du... more Networked Control Systems (NCS) has been one of the main research areas in the last few years, due to the benefits of the insertion of a communication network in distributed systems, and the widely area of applications such as tele-operations, robotics, UAVs, power systems, among others, and new growing areas like smart grids and Cyber-Physiscal Systems. This paper surveys the main aspects on performance analysis and controllers design that take into account the problems that arise when the control feedback loop is closed over a communication network. At the end, an example of a NCS implementation using the simulation tool TrueTime is introduced, and some recent results and possible future directions are presented.
In proceeding of: 3rd IFAC Workshop on Distributed Estimation and Control in Networked Systems, 2012
Many control problems can be considered as resource allocation problems, where the main objective... more Many control problems can be considered as resource allocation problems, where the main objective is to allocate an amount of resources (e.g., voltage, power) among some distributed elements. However, the inclusion of communication networks adds new challenges to these kind of problems and new control strategies must be developed. This work presents an evolutionary strategy that can be used in dynamical resource allocation control problems, where sensors and actuators signals are transmitted through a communication network. We show that this strategy is independent of the delays using some passivity based analysis and an application in smart grids generation dispatch is illustrated. However, the performance of the controlled system may be degraded with the inclusion of the time delays. Hence, an observer for nonlinear delayed systems is implemented in order to improve the performance of the RD technique.
53Rd Ieee Conference on Decision and Control, Dec 15, 2014
ABSTRACT The consensus algorithm can represent many problems in cooperative behavior, and has bee... more ABSTRACT The consensus algorithm can represent many problems in cooperative behavior, and has been widely used in engineering and social sciences. In this work, we prove that the consensus model where the information that each agent receives from its neighbors has time-varying asynchronous delays and sampling, converges to an agreement independent of these communication constraints. This property is useful in the context of ``data minimization,'' which is one of the principles for privacy. As a practical example, we show how the independence of sampling rate can be used for microgrids with a consensus-based secondary control scheme where participants have incentives to share their states to ensure frequency synchronization, while at the same time minimizing the amount of data shared to preserve their privacy. We then propose two data sharing algorithms: 1) periodic sampling, and 2) discretionary sampling, and study their privacy as well as their performance. We show that even when a discretionary sampling scheme ``lies'' to their neighbors in order to preserve their privacy, the consensus algorithm performs almost as well as with periodic sampling.
2012 IEEE 51st IEEE Conference on Decision and Control (CDC), 2012
ABSTRACT We present a novel scheme of a deterministic continuous extremum seeking control based o... more ABSTRACT We present a novel scheme of a deterministic continuous extremum seeking control based on evolutionary game theory (EGT), which allows the optimization in real-time of non-modeled multivariable dynamic systems under inequality and equality constraints. Unlike traditional extremum seeking controllers, which use classical Euclidean gradient-based optimization methods, the scheme proposed is based on the Shahshahani Gradient, which emerges in some evolutionary games. The notion of maximal in the plant and its stability properties are correlated with the concepts of Nash equilibrium and evolutionarily stable states (ESS). The implementation of the algorithm is illustrated via simulation.
53rd IEEE Conference on Decision and Control, 2014
Motivated by the increasing interest in networked multi-agent systems and the wide number of appl... more Motivated by the increasing interest in networked multi-agent systems and the wide number of applications in decentralized distributed control of smart grids, we address the problem of synchronization when each node (e.g., a microgrid, a distributed generator) is modeled as a linear-time continuous system whose output measurements are sent through communication links. However, the inclusion of a communication infrastructure adds new challenges to control strategies and some problems may arise such as time delays, packet losses, sampling period, just to name a few. In this work, we consider that data is sampled with homogeneous sampling periods. Then, using the concept of average passivity, we define the conditions for synchronizability when all nodes are identical and unstable dynamics are present. Additionally, results are extended to the case of non-uniform agents, and some simulations of synchronization in smart grids are introduced. Synchronization involves intrinsically a communication aspect between agents, which is commonly described using graph theory. However, these communications between agents cannot be considered as instantaneous or ideal in real applications, due to the fact that agents are spatially distributed and information exchange has to be done using communication networks [6]. In particular, for synchronization of dynamic networks, several works have included communication limitations. In [7], the effects of time-delays in the communication between agents are considered, and in [8], some conditions for synchronization are introduced when random packet losses are induced. On the other hand, in [9] [10] sampled-measurements have been addressed using This work has been supported by CIFI 2011, Facultad de Ingeniería, Universidad de los Andes, and Proyecto SILICE 3, Colciencias-Codensa. J. Giraldo and N. Quijano are with
2015 IEEE 2nd Colombian Conference on Automatic Control (CCAC), 2015
... DRAFT Emergence of Scale Free Networks from Ideal Free Distributions (2006). Download: http:/... more ... DRAFT Emergence of Scale Free Networks from Ideal Free Distributions (2006). Download: http://www.ece.osu.edu/~finkej/Publications_files/ CACHED: Download as a PDF. by Jorge Finke , Nicanor Quijano , Kevin M. Passino. ...
American Control Conference, 2008, Jan 1, 2008
The integration of physical systems with distributed embedded computing and communication devices... more The integration of physical systems with distributed embedded computing and communication devices offers advantages on reliability, efficiency, and maintenance. At the same time, these embedded computers are susceptible to cyber-attacks that can harm the performance of the physical system, or even drive the system to an unsafe state; therefore, it is necessary to deploy security mechanisms that are able to automatically detect, isolate, and respond to potential attacks. Detection and isolation mechanisms have been widely studied for different types of attacks; however, automatic response to attacks has attracted considerably less attention. Our goal in this paper is to identify trends and recent results on how to respond and reconfigure a system under attack, and to identify limitations and open problems. We have found two main types of attack protection: i) preventive, which identifies the vulnerabilities in a control system and then increases its resiliency by modifying either control parameters or the redundancy of devices; ii) reactive, which responds as soon as the attack is detected (e.g., modifying the non-compromised controller actions).
Recent work has studied the impact caused by attackers that compromise pricing signals used in th... more Recent work has studied the impact caused by attackers that compromise pricing signals used in the emerging retail electricity market and send false prices to a subset of consumers. In this paper, we extend previous work by considering a more realistic adversary model that is not arbitrarily tied
to scaling and delay attacks, but that can generate any arbitrary pricing signal and show how to keep the problem tractable with a new analysis based on sensitivity functions. In addition, we
extend previous work by proposing countermeasures to mitigate the negative impact of these attacks. Countermeasures include selecting parameters of the controller, designing robust control
algorithms, and by detecting anomalies in the behavior of the system.
Accepted to the 53th Conference on Decision and Control, 2014
The consensus algorithm can represent many problems in cooperative behavior, and has been widely ... more The consensus algorithm can represent many problems in cooperative behavior, and has been widely used in engineering and social sciences. In this work, we prove that the consensus model where the information that each agent receives from its neighbors has time-varying asynchronous delays and sampling, converges to an agreement independent of these communication constraints. This independence is useful in the context of ``data minimization,'' which is one of the principles for privacy. As a practical example, we show how this independence can be used for microgrids with a consensus-based secondary control scheme where participants have incentives to share their states to ensure frequency synchronization, while at the same time minimizing the amount of data shared to preserve their privacy. We then propose two data sharing algorithms: 1) periodic sampling, and 2) discretionary sampling, and study their privacy as well as their performance. We show that even when a discretionary sampling scheme ``lies'' to their neighbors in order to preserve their privacy, the consensus algorithm performs almost as well as with periodic sampling.
In proceeding of the Conference on Decision and Control (CDC 2013), 2013
Motivated by the increasing interest in networked multi-agent systems and the wide number of appl... more Motivated by the increasing interest in networked multi-agent systems and the wide number of applications in distributed control of smart grids, we address the problem of synchronization of microgrids. Two topologies are considered: the physical topology that relates the interconnection of distributed generators and loads, and the communication topology, which describes the information flow of the power system measurements. We propose a control strategy based on the information flow and we show that there exists a strong relationship between both topologies in order to achieve synchronization. As a matter of fact, we show that our results can be extended when isolated group of nodes are taken into account, and they can be connected or disconnected to the main grid. Finally, the effects of time-varying sampling are analyzed using some average passivity conditions, and sampling-time independence is demonstrated with the proposed controller.
n proceeding of the American Control Conference 2014, 2014
The Kuramoto oscillator has been widely studied because it can model biological, social, chemical... more The Kuramoto oscillator has been widely studied because it can model biological, social, chemical, and engineering problems. Conditions for frequency synchronization of a network of Kuramoto oscillators have
been well established, but it depends on the connectivity of the network and on the natural frequencies. However, some applications requires that oscillators oscillate to a desired frequency even when the network topology is
disconnected. In this work we propose a consensus-based control strategy that forces the network to follow a virtual agent with constant frequency. Besides, we consider that the control input is constrained and we establish the limits of the set of inputs that assure frequency tracking. The results are extended to the smart grid case, where the nodes of a power network are modeled as Kuramoto oscillators that synchronize to a desired frequency using the injection/absorbsion of power according to a consensus based control. We show that our results are feasible when isolated group of nodes are taken into account, and they can be connected or disconnected to the main grid. Finally, the effects of time-varying sampling are analyzed and sampling period independence is demonstrated.
In proceedings of the 2013 European Control Conference
Motivated by the increasing interest in networked multi-agent systems and the wide number of appl... more Motivated by the increasing interest in networked multi-agent systems and the wide number of applications in decentralized distributed control of smart grids, we address the problem of synchronization when each node (e.g., a microgrid, a distributed generator) is modeled as a linear-time continuous system whose output measurements are sent through communication links. However, the inclusion of a communication infrastructure adds new challenges to control strategies and some problems may arise such as time delays, packet losses, sampling period, just to name a few. In this work, we consider that data is sampled with homogeneous sampling periods. Then, using the novel concept of average passivity, we define the conditions for synchronizability when all nodes are identical and unstable dynamics are present. Additionally, results are extended to the case of non-uniform agents, and some simulations of synchronization in smart grids are introduced.
In proceeding of: IEEE IX Latin American Robotics Symposium and IEEE Colombian Conference on Automatic Control, 2011
Networked Control Systems (NCS) has been one of the main research areas in the last few years, du... more Networked Control Systems (NCS) has been one of the main research areas in the last few years, due to the benefits of the insertion of a communication network in distributed systems, and the widely area of applications such as tele-operations, robotics, UAVs, power systems, among others, and new growing areas like smart grids and Cyber-Physiscal Systems. This paper surveys the main aspects on performance analysis and controllers design that take into account the problems that arise when the control feedback loop is closed over a communication network. At the end, an example of a NCS implementation using the simulation tool TrueTime is introduced, and some recent results and possible future directions are presented.
In proceeding of: 3rd IFAC Workshop on Distributed Estimation and Control in Networked Systems, 2012
Many control problems can be considered as resource allocation problems, where the main objective... more Many control problems can be considered as resource allocation problems, where the main objective is to allocate an amount of resources (e.g., voltage, power) among some distributed elements. However, the inclusion of communication networks adds new challenges to these kind of problems and new control strategies must be developed. This work presents an evolutionary strategy that can be used in dynamical resource allocation control problems, where sensors and actuators signals are transmitted through a communication network. We show that this strategy is independent of the delays using some passivity based analysis and an application in smart grids generation dispatch is illustrated. However, the performance of the controlled system may be degraded with the inclusion of the time delays. Hence, an observer for nonlinear delayed systems is implemented in order to improve the performance of the RD technique.
53Rd Ieee Conference on Decision and Control, Dec 15, 2014
ABSTRACT The consensus algorithm can represent many problems in cooperative behavior, and has bee... more ABSTRACT The consensus algorithm can represent many problems in cooperative behavior, and has been widely used in engineering and social sciences. In this work, we prove that the consensus model where the information that each agent receives from its neighbors has time-varying asynchronous delays and sampling, converges to an agreement independent of these communication constraints. This property is useful in the context of ``data minimization,'' which is one of the principles for privacy. As a practical example, we show how the independence of sampling rate can be used for microgrids with a consensus-based secondary control scheme where participants have incentives to share their states to ensure frequency synchronization, while at the same time minimizing the amount of data shared to preserve their privacy. We then propose two data sharing algorithms: 1) periodic sampling, and 2) discretionary sampling, and study their privacy as well as their performance. We show that even when a discretionary sampling scheme ``lies'' to their neighbors in order to preserve their privacy, the consensus algorithm performs almost as well as with periodic sampling.
2012 IEEE 51st IEEE Conference on Decision and Control (CDC), 2012
ABSTRACT We present a novel scheme of a deterministic continuous extremum seeking control based o... more ABSTRACT We present a novel scheme of a deterministic continuous extremum seeking control based on evolutionary game theory (EGT), which allows the optimization in real-time of non-modeled multivariable dynamic systems under inequality and equality constraints. Unlike traditional extremum seeking controllers, which use classical Euclidean gradient-based optimization methods, the scheme proposed is based on the Shahshahani Gradient, which emerges in some evolutionary games. The notion of maximal in the plant and its stability properties are correlated with the concepts of Nash equilibrium and evolutionarily stable states (ESS). The implementation of the algorithm is illustrated via simulation.
53rd IEEE Conference on Decision and Control, 2014
Motivated by the increasing interest in networked multi-agent systems and the wide number of appl... more Motivated by the increasing interest in networked multi-agent systems and the wide number of applications in decentralized distributed control of smart grids, we address the problem of synchronization when each node (e.g., a microgrid, a distributed generator) is modeled as a linear-time continuous system whose output measurements are sent through communication links. However, the inclusion of a communication infrastructure adds new challenges to control strategies and some problems may arise such as time delays, packet losses, sampling period, just to name a few. In this work, we consider that data is sampled with homogeneous sampling periods. Then, using the concept of average passivity, we define the conditions for synchronizability when all nodes are identical and unstable dynamics are present. Additionally, results are extended to the case of non-uniform agents, and some simulations of synchronization in smart grids are introduced. Synchronization involves intrinsically a communication aspect between agents, which is commonly described using graph theory. However, these communications between agents cannot be considered as instantaneous or ideal in real applications, due to the fact that agents are spatially distributed and information exchange has to be done using communication networks [6]. In particular, for synchronization of dynamic networks, several works have included communication limitations. In [7], the effects of time-delays in the communication between agents are considered, and in [8], some conditions for synchronization are introduced when random packet losses are induced. On the other hand, in [9] [10] sampled-measurements have been addressed using This work has been supported by CIFI 2011, Facultad de Ingeniería, Universidad de los Andes, and Proyecto SILICE 3, Colciencias-Codensa. J. Giraldo and N. Quijano are with
12th IFAC Symposium on Control in Transportation Systems (2009), Sep 2, 2009
Green time allocation scheduling for a single road traffic intersection is a dynamic resource all... more Green time allocation scheduling for a single road traffic intersection is a dynamic resource allocation problem. In nature, a similar problem is found when animals need to allocate themselves across habitats. For instance, honeybees allocate more animals where there are more resources, when they are foraging for food. Based on these foraging ideas, we introduce a novel adaptive traffic light control strategy. The analogies between the two problems are discussed, and the proposed algorithm is compared with an optimal fixed-time controller. This bioinspired algorithm solves the green time allocation problem without the use of traffic models. This makes the solution feasible for a large-scale network. We also show on simulations, how an equilibrium state is reached under saturation and no saturation conditions.
Urban Traffic Control and Simulation: Literature Review, May 2009
Las condiciones actuales de la movilidad en Colombia generan interrogantes acerca de qué tan apro... more Las condiciones actuales de la movilidad en Colombia generan interrogantes acerca de qué tan apropiadas son las estrategias de control de tráfico aplicadas en las redes urbanas del país. Con esto en mente, se plantea una revisión de las estrategias de control y plataformas de simulación de sistemas de tráfico más utilizadas en Colombia y en otras partes del mundo; con el propósito de caracterizar el nivel de desarrollo del país en el estudio e implementación de estrategias de control de tráfico urbano y, posteriormente, formular propuestas orientadas hacia la mejora de la movilidad urbana en el país.
Proceedings of the VIII Congreso Asociación Colombiana de Automática (ACA), Apr 1, 2009
"Se presenta un algoritmo bioinspirado en el forrajeo social para control de tráfico urbano. El a... more "Se presenta un algoritmo bioinspirado en el forrajeo social para control de tráfico urbano. El algoritmo busca solucionar el problema de asignación de tiempos de verde en una intersección sencilla. Primero, se presentan los resultados obtenidos utilizando el algoritmo evolutivo para una intersección particular. Luego, se plantea un modelo haciendo uso de los replicator dynamics para modelar el comportamiento del algoritmo evolutivo y de un modelo inspirado en flujo de fluidos para modelar el comportamiento del tráfico. Finalmente, se analizan las trayectorias del sistema controlado y se comparan con los resultados obtenidos con el algoritmo bioispirado.
"
Colombian IEEE workshop of robotics and automation, Aug 13, 2008
Se presenta un algoritmo de control para tráfico urbano basado en un modelo biológico de forraje ... more Se presenta un algoritmo de control para tráfico urbano basado en un modelo biológico de forraje social. La asignación de tiempos en los sistemas de control de tráfico tiene una gran similitud con el problema de asignación de abejas obreras en varios hábitats. Se analizan las analog ́ıas entre los dos problemas y se plantea un ejemplo que da solución a la asignación de tiempos de fase para una intersección sencilla, y se comprueba la emergencia de un “ideal free distribution” (IFD) en escenarios de saturación y no saturación de la intersección.
Proceedings of the 2015 American Control Conference (ACC)
We investigate the invariance properties of a class of switched systems in which the value of a s... more We investigate the invariance properties of a class
of switched systems in which the value of a switching signal
determines the current mode of operation (among a finite
number of them) and, for each fixed mode, its dynamics
are described by a Differential-Algebraic Equation (DAE).
Motivated by the lack of invariance principles for such systems,
we develop such principles for switched DAE systems under
arbitrary and dwell-time switching. By obtaining a hybrid
system model that describes the switched DAE system, we
build from invariance results for hybrid systems and generate
invariance principles for such switched systems. Examples are
included to illustrate the results.
We investigate the invariance properties of a class of switched systems where the value of a swit... more We investigate the invariance properties of a class of switched systems
where the value of a switching signal determines the current mode of operation
(among a finite number of them) and, for each fixed mode, its dynamics are described
by a Differential Algebraic Equation (DAE). Motivated by the lack of
invariance principles of switched DAE systems, we develop such principles for
switched DAE systems under arbitrary and dwell-time switching. By obtaining
a hybrid system model that describes the switched DAE system, we build from
invariance results for hybrid systems the invariance principles for such switched
systems. Examples are included to illustrate the results.