# René BoelGhent University | UGhent

René Boel

## About

164

Publications

13,898

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3,044

Citations

Citations since 2016

Introduction

**Skills and Expertise**

Additional affiliations

September 1976 - present

## Publications

Publications (164)

This paper presents an analysis on the convergence to a steady state for the traffic dynamics in a network of signalized intersections. The links carrying the traffic from one intersection to another in the network are partitioned into a series of cells whose dynamics is modelled as a nonlinear cell transmission model. A microscopic convergence ana...

This paper is the first in a series of reports presenting a framework for the hierarchical design of feedback controllers for traffic lights in urban networks. The goal of the research is to develop an easy to understand methodology for designing model based feedback controllers that use the current state estimate in order to select the next switch...

The present paper describes how to use coordination between neighbouring intersections in order to improve the performance of urban traffic controllers. Both the local MPC (LMPC) introduced in the companion paper (Hao et al., 2018) and the coordinated MPC (CMPC) introduced in this paper use the urban cell transmission model (UCTM) (Hao et al., 2018...

This paper considers partial observation Markov decision processes. Besides the classical control decisions influencing the transition probabilities of the Markov process, we also consider control actions that can activate the sensors to provide more or less accurate information about the system state, explicitly including the cost of activating se...

This study proposes a novel data-based approach for estimating the parameters of a stochastic hybrid model describing the traffic flow in an urban traffic network with signalized intersections. The model represents the evolution of the traffic flow rate, measuring the number of vehicles passing a given location per time unit. This traffic flow rate...

This essay deals with the coordination of the control actions in a network of interacting components, where actuator values for each component are calculated by its local control agent (CA). If the local CAs act independently, then the interaction between different control loops often leads to instability of the network as a whole. Using hierarchic...

The purpose of this chapter is to describe the leader–follower approach for coordinating many interacting components of a large network. This leader–follower approach is suitable for systems with intermediate load, where only a few critically loaded components are having difficulties to achieve their local specifications. We assume that a superviso...

This paper considers control of networks modeled by a directional graph. We propose a leader-follower paradigm for coordinating local feedback controllers in a large network of interacting components, where most components -the followers -can handle local load without problems, but where a few heavily loaded components -the leaders -are close to sa...

Stable and efficient operation of a smart grid requires coordination of the actions of many independent decision makers or agents that must cooperate in globally balancing the demand for power to the partly unpredictable and uncontrollable supply. This paper proposes the use of the correlation coefficient between the renewable supply and the (contr...

This paper deals with the application of an anticipating and coordinating feedback control scheme in order to mitigate the long-term voltage instability of multi-area power systems. Each local area is uniquely controlled by a control agent (CA) selecting control values based on model predictive control (MPC) and is possibly operated by an independe...

Stable and efficient operation of a smart grid requires coordination of the actions of many independent decision makers or agents that must cooperate in globally balancing the demand for power to the partly unpredictable and uncontrollable supply. This paper proposes the use of the correlation coefficient between the renewable supply and the (contr...

This paper deals with a form of long-term voltage instability which can arise from uncoordinated control actions taken by interacting voltage controllers. An effective coordination paradigm, based on Model Predictive Control (MPC), is proposed in order to properly coordinate local control actions taken by Load Tap Changing transformers (LTCs). This...

Raw measurement data are too noisy to directly obtain queue and traffic flow estimates usable for feedback control of urban traffic. In this paper, we propose a recursive filter to estimate traffic state by combining the real-time measurements with a reduced model of expected traffic behavior. The latter is based on platoons rather than individual...

The intermittent and fluctuating nature of output power of renewable energy sources (RES) can lead to serious security concerns such as congestion in the transmission system. Incorporating storage devices with RES is technically an effective means to mitigate this concern by allowing fluctuating RES to be as stable as traditional power plants. Stor...

This lecture treats the problem of designing local control agents for cooperating components in a network of interacting dynamic systems. Each local control agent must ensure that all local specifications are met, but at the same time must ensure that the different components help each other in achieving good global behavior as well as good local b...

In this paper we propose an on-line diagnosis algorithm for Time Petri Nets (TPN). The plant observation is given by a subset of transitions and the faults are modeled by a subset of unobservable transitions. The plant behavior is derived on-line and the diagnosis is obtained checking whether or not some or all of the traces in the behaviour that o...

This paper proposes a coordination paradigm for properly coordinating local control actions, taken by many communicating control agents (CAs), in order to maintain multi-area power system voltages within acceptable bounds. The proposed control scheme is inspired by distributed model predictive control (DMPC), and relies on the communication of plan...

In this chapter we extend the results presented in Chapter 14 and Chapter 15 by assuming that the Petri Net models include also information on the time delay between satisfying an enabling condition (tokens entering a place) and executing a transition. We address the diagnosis problem for Time Petri Net models and illustrate how this task can be pe...

The automatic control of interacting autonomous vehicles (AVs) is one of the problems that engineers are currently trying to solve. The present paper deals with the design of local control laws governing the movement and collision avoidance of such groups of AVs, enforcing the safeness of the operations as well as task completions. This problem is...

Logical controllers used for Load Tap Changing transformers (LTCs) or CapacitorBanks (CBs), as well as thresholds reached by discrete logics such as Over eXcitationLimiter (OXL) of the synchronous generators introduce discrete events into continuousdynamics of the electrical power systems. The resulting dynamic behavior often involvesintrinsic inte...

We propose algorithms for the synthesis of state-feedback controllers with partial observation of infinite state discrete event systems modelled by Symbolic Transition Systems. We provide models of safe memoryless controllers both for potentially deadlocking ...

The paper proposes a new platoon based (PB) model of traffic behavior in an urban traffic network. By grouping the vehicles that travel closely together at approximately the same speed into a platoon the model provides an abstract representation of the dynamical evolution of the traffic state. This leads to efficient discrete event simulation tools...

Large-scale traffic systems require techniques that are able to 1) deal with high amounts of data and heterogenous data coming from different types of sensors, 2) provide robustness in the presence of sparse sensor data, 3) incorporate different models that can deal with various traffic regimes, and 4) cope with multimodal conditional probability d...

This two-part paper deals with the coordination of the control actions in a network of many interacting components, where each component is controlled by independent control agents. As a case study we consider voltage control in large electric power systems, where ever-increasing pressures from the liberalization and globalization of the electricit...

This paper proposes a particle filter (PF) state estimator, using a platoon based model for urban traffic networks. The urban traffic network model consists of signalized intersections (representing queues of vehicles competing for service) connected to each other through links with predefined receiving capacities and stochastic delays. Sensors det...

Over the past decades many voltage collapse incidents have occurred, caused by uncoordinated interactions of local controllers, following a major disturbance in electric power system operating closer and closer to their safety limits. Currently most voltage control schemes are rule-based and only rely on local measurements. However the availability...

The development of real-time traffic models is of paramount importance for the purposes of optimizing traffic flow. Inspired by the compositional model (CM) and the METANET model, this paper proposes an interval approach for macroscopic traffic modeling. We develop an interval CM (ICM) and an in- terval implementation of the METANET model (IMETANET...

This paper applies a particle filter (PF) state estimator to urban traffic networks. The traffic network consists of signalized intersections, the roads that link these intersections, and sensors that detect the passage time of vehicles. The traffic state X(t) specifies at each time time t the state of the traffic lights, the queue sizes at the int...

Clustering is an important approach in the analysis of biological data, and often a first step to identify interesting patterns of coexpression in gene expression data. Because of the high complexity and diversity of gene expression data, many genes cannot be easily assigned to a cluster, but even if the dissimilarity of these genes with all other...

Modeling and simulation of increasingly complex power systems is becoming more important for design, implementation and validation of power system on-line management. Current special-purpose tools are generally weak in the sense that they are mostly block-oriented and thus demand a huge amount of manual rewriting to get the equations into explicit...

Control in urban traffic networks constitutes an important and challenging research topic nowadays. In the literature, a lot of work can be found devoted to improving the performance of the traffic flow in such systems, by means of controlling the red-to-green switching times of traffic signals. Different techniques have been proposed and commercia...

Control in urban traffic networks constitutes an important and challenging research topic nowadays. In the literature, a lot of work can be found devoted to improving the performance of the traffic flow in such systems, by means of controlling the red-to-green switching times of traffic signals. Different techniques have been proposed and commercia...

Traffic systems are often highly populated discrete event systems that exhibit several modes of behavior such as free flow traffic, traffic jams, stop-and-go waves, etc. An appropriate closed loop control of the congested system is crucial in order to avoid undesirable behavior. This paper proposes a macroscopic model based on continuous Petri nets...

For a bounded Petri Net model the diagnosability property is usually checked via its regular language represented by the reachability graph RG. However, this is problematic because the computational complexity of the diagnosability test is polynomial in the cardinality of the state space of the model which is typically very large. This limitation c...

The demand for drives with high quality torque control has grown tremendously in a wide variety of applications. Direct torque control (DTC) for permanent magnet synchronous motors can provide this accurate and fast torque control. When applying DTC the change of the stator flux linkage vector is controlled. As such the estimation of the stator flu...

The demand for highly dynamic electrical drives, characterized by high quality torque control, in a wide variety of applications has grown tremendously during the past decades. Direct torque control (DTC) for permanent magnet synchronous motors (PMSM) can provide this accurate and fast torque control. When applying DTC the change of the stator flux...

Clustering is an important approach in the analysis of biological data, and often a first step to identify interesting patterns of coexpression in gene expression data. Because of the high complexity and diversity of gene expression data, many genes cannot be easily assigned to a cluster, but even if the dissimilarity of these genes with all other...

We propose a measure for the validation of clusterings of gene expression data. This measure is also useful to estimate missing gene expression levels, based on the similarity information contained in a given clustering. It is shown that this measure is an improvement over the figure of merit, an existing validation measure especially developed for...

How to control the activiation of an expensive observation channel of a stochastic system? The control objective is to reduce the conditional error variance of state estimation but a cost is to be paid for acquiring a reading of the channel. The optimal control law depends only on the conditional error variance and has to be determined computationa...

Modeling and simulation of increasingly complex power systems is becoming more important for design, implementation and validation of power system on-line management. Current special-purpose tools are generally weak in the sense that they are mostly block-oriented and thus demand a huge amount of manual rewriting to get the equations into explicit...

In an increasing number of applications highly dynamic electrical drives, characterized by high quality torque control, are demanded. Direct torque control (DTC) for AC machines, permanent magnet synchronous motors (PMSM) or induction machines, can provide this accurate and fast torque control. When applying DTC the change of the stator flux linkag...

This paper presents an on-line diagnosis algorithm for Petri nets where a priori probabilistic knowledge about the plant operation is available. We follow the method developed by Benveniste, Fabre, and Haar to assign probabilities to configurations in a net unfolding thus avoiding the need for randomizing all concurrent interleavings of transitions...

This paper presents an on-line diagnosis algorithm for Petri nets where a priori probabilistic knowledge about the plant operation is available. We follow the method developed by Benveniste, Fabre, and Haar to assign probabilities to configurations in a net unfolding thus avoiding the need for randomizing all concurrent interleavings of transitions...

Large traffic network systems require handling huge amounts of data, often distributed over a large geographical region in space and time. Centralised processing is not then the right choice in such cases. In this paper we develop a parallelised Gaus- sian Mixture Model filter (GMMF) for traffic networks aimed to: 1) work with high amounts of data...

This paper presents an on-line diagnosis algorithm for Petri nets where a priori probabilistic knowledge about the plant operation is available. We follow the method developed by Benveniste, Fabre, and Haar to assign probabilities to configurations in a net unfolding thus avoiding the need for randomizing all concurrent interleavings of transitions...

It is well known that the clusters produced by a clustering algorithm depend on the chosen initial centers. In this paper
we present a measure for the degree to which a given clustering algorithm depends on the choice of initial centers, for a
given data set. This measure is calculated for four well-known offline clustering algorithms (k-means Forg...

We consider a Petri Net model of the plant. The observation is given by a subset of transitions whose occurrence is always and immediately sensed by a monitoring agent. Other transitions not in this subset are silent (unobservable). Classical on-line monitoring techniques, which are based on the estimation of the current state of the plant and the...

Modelling and identification of synchronous machines has attracted much attention during the past decades. Although the standstill frequency response (SSFR) method has become standardized (IEEE Std. 115) it has some disadvantages (e.g. it is a time consuming method). To overcome these, the use of broadband excitation has been proposed in the litera...

This paper proposes an interval approach to vehicular traffic flow modeling. The developed interval compositional model (ICM) provides a natural way of predicting traffic flows without the assumption of uniform distribution of vehicles along the road. The model can be used for real-time prediction of traffic flows and can be part of road traffic su...

Modelling and identification of synchronous machines has attracted much attention during the past decades. Although the standstill frequency response (SSFR) method has become standardized (IEEE Std. 115) it has some disadvantages (e.g. it is a time consuming method). To overcome these, the use of multisine excitation has been proposed in the litera...

We describe an on-line probabilistic diagnosis algorithm for free choice Petri Nets. The plant observation is given by a subset of transitions whose occurrence is reported while the rest of transitions including faults are unobservable silent. We propose two notions for the probabilistic diagnosis, the likelihood that a fault must have happened pri...

On-line supervisory control of large discrete event systems is difficult due to the exponentially growing size of the state space to be enumerated in a naive analysis. This paper surveys several attempts to reduce the computational complexity, as investigated in some recent papers by the SYSTeMS group of Ghent University. Compositionality and distr...

This paper formulates the problem of real-time estimation of traffic state in freeway networks by means of the particle filtering framework. A particle filter (PF) is developed based on a recently proposed speed-extended cell-transmission model of freeway traffic. The freeway is considered as a network of components representing different freeway s...

The use of embedded Runge-Kutta methods for the time-domain simulation of a dynamic finite element model of a switched reluctance motor is discussed, along with the features of embedded Runge-Kutta methods for the numerical solution of this model. It is shown that step size control and interpolator polynomials can be used to take accurately into ac...

We consider parallelized particle filters for state tracking (estimation) of freeway traffic networks. Particle filters can accurately solve the state estimation problem for general nonlinear systems with non-Gaussian noises. However, this high accuracy may come at the cost of high computational demand. We present two parallelized particle filterin...

We describe an on-line probabilistic diagnosis algorithm for free choice Petri Nets. The plant observation is given by a subset of transitions whose occurrence is reported while the rest of transitions including faults are unobservable silent. We propose two notions for the probabilistic diagnosis, the likelihood that a fault must have happened pri...

In telephone networks the switching and connecting operations are performed by the exchanges. The Stored Program Control (SPC) exchanges which are nowadays installed are computer controlled. One of the problems with these exchanges is the severe performance degradation during periods in which the demand for service exceeds the design capacity. The...

Purpose - To provide a discrete-time nonlinear model for surface permanent-magnet synchronous machines (SPMSMs) in order to discuss the stability of such machines.
Design/methodology/approach - Through differencing the co-energy, obtained from a finite element method, the main flux path can be described by a complex reluctance. Furthermore, for a S...

This paper addresses the problem of freeway traffic flow estimation. The freeway is considered as a network of components representing different freeway stretches called segments. The evolution of the traffic in a segment is modelled as a dynamic stochastic system, influenced by states of neighbour segments. Measurements are received only at bounda...

This paper presents an on-line algorithm for fault diagnosis of time Petri net (TPN) models. The plant observation is given by a subset of transitions whose occurrence is always reported while the faults are represented by unobservable transitions. The model-based diagnosis uses the TPN model to derive the legal traces that obey the received observ...

We derive in this paper on-line algorithms for fault diagnosis of Time Petri Net (TPN) models. The plant observation is given by a subset of transi-tions while the faults are represented by unobserv-able transitions. The model-based diagnosis uses the TPN model to derive the legal traces that obey the received observation and then checks whether or...

Nowadays numerous techniques to model the behaviour of electrical drives are discussed in the literature. In many cases a linear magnetic network is proposed. This paper proposes a large-signal simulation model of an induction machine that takes into account the magnetizing-flux saturation. The model is given as a state-space model with nonlinear f...

In this paper a nonlinear model for AC machines is proposed that takes into account the magnetic saturation and magnetic interaction between both orthogonal magnetic axes. Furthermore, the model includes the presence of air-gap flux harmonic components caused by magnetic saturation and multiple-pole spatial saliencies. Such a model is used to descr...

Traffic flow on freeways is a non-linear, many-particle phenomenon, with complex interactions between vehicles. This paper presents a stochastic model of freeway traffic at a time scale and of a level of detail suitable for on-line estimation, routing and ramp metering control. The freeway is considered as a network of interconnected components, co...

Diffusions in manifolds with non-smooth boundaries (e.g. in R
+
r
Rn-n) often arise as approximations to queueing networks. We consider the following stochastic differential equation : where wt is a Brounian motion, l
t
i
the local time at {xi = 0} and m
t
i
a Brounian motion at the time scale l
t
i
.
We first prove existence of weak solutions to t...

This paper proposes an algorithm for the model based design of a distributed protocol for fault detection and diagnosis for very large systems. The overall process is modeled as different Time Petri Net (TPN) models (each one modeling a local process) that interact with each other via guarded transitions that becomes enabled only when certain condi...

In two earlier papers [1, 2] the use of diffusion processes with general boundary conditions was suggested as a method for analysing queueing networks. The distinguishing features compared to classical diffusion approximation were the delayed reflections in a random direction. This short paper first discusses advantages and disadvantages of these g...

One of the main difficulties of the diffusion approximation to queues is that it underestimates the probability of an empty queue. This is due to the use of instantaneous reflection at the boundary. In this paper the use of diffusion processes with delayed reflections is suggested. A survey of the available mathematical literature on this topic is...

In this paper we consider the case of a large plant comprising different local sites. At each site, a local diagnoser must provide the diagnosis of the site based on the local plant model (a Petri Net), the local observation and the information exchanged with its neighbors. The communication between the local diagnosers is not event-driven and the...