[Show abstract][Hide abstract] ABSTRACT: The evaluation of the benefits of an Eco-Driving assistance system is carried out in the urban environment in presence of traffic lights. The traffic evolution is modeled macroscopically with the Urban Variable-Length Model  in a variable speed limits framework. Under the assumption of equal boundary flows, the vehicles in a road section dispose themselves according to well defined equilibrium conditions which are dependent on the traveling speed in the free-flow part of the section. Given certain initial traffic conditions, an optimal speed limit for the section can be found in order to drive the system to an efficient equilibrium state. Further analysis of the equilibrium conditions and the stability properties of the system is conducted in this work. The system is proved to be controllable, under the working hypotheses, and a controller is designed to simulate the response of the drivers compliant to the eco-speed advisory. A sub-optimal control strategy is finally proposed also in the case of unequal boundary flows.
53rd IEEE Conference on Decision and Control; 12/2014
[Show abstract][Hide abstract] ABSTRACT: The problem of traveling at maximum energy efficiency (Eco-Driving) is addressed for urban traffic networks at macroscopic level. The scope of this paper is the analysis of the steady-state behavior of the system, given certain boundary flows conditions fixed by traffic lights timings, and in presence of a traffic control policy based on variable speed limits. The formal study is carried out on a two-cells variable length model adapted to the urban setup from previous works on highway traffic . Informative traffic metrics, aimed at assessing traffic and vehicles performance in terms of traveling time, infrastructure utilization and energy consumption, are then defined and adapted to the new macroscopic traffic model. If congestion in a road section does not spill back or vanish, the system is stable and many different equilibrium points can be reached via variable speed limits. Efficient operation points and traffic conditions are identified as a trade-off between optimization of global traffic energy consumption, traveling time and infrastructure utilization.
[Show abstract][Hide abstract] ABSTRACT: We consider the problem of localizing the source of a diffusion process. The source is supposed to be isotropic, and several sensors, equipped on a vehicle moving without position information, provide pointwise measures of the quantity being emitted. The solution we propose is based on computing the gradient–and higher-order derivatives such as the Hessian–from Poisson integrals: in opposition to other solutions previously proposed, this computation does neither require specific knowledge of the solution of the diffusion process, nor the use of probing signals, but only exploits properties of the PDE describing the diffusion process. The theoretical results are illustrated by simulations.
[Show abstract][Hide abstract] ABSTRACT: We consider a group of autonomous communicating sensors, and our objective is to steer the group, with a low information exchange, towards the isotropic source of a diffusion process in steady-state. We suppose the graph describing the communication links between sensors to have a time-invariant ring-topology. Each sensor, which has no position information, takes pointwise measurements of the quantity of interest, and is able to measure the bearing angle with respect to its neighbours. We solve the source-localisation task via a gradient-ascent technique based on a distributed implementation of Poisson integral formula; our approach is based on a twofold control law, which is able to bring and keep the set of sensors on a circular equispaced formation while seeking the source.
[Show abstract][Hide abstract] ABSTRACT: This work addresses the problem of finding
energy-optimal velocity profiles for a vehicle in an urban traffic
network. Assuming communication between infrastructure and
vehicles (I2V) and a complete knowledge of the upcoming
traffic lights timings, a preliminary velocity pruning algorithm
is proposed in order to identify the feasible region a vehicle may
travel along in compliance with city speed limits. Then, a graph
discretizing approach is utilized for advanced selection, among
the feasible “green windows”, of the optimal ones in terms of
energy consumption. Finally, a velocity trajectory is advised,
which will be tracked by the driver-in-the-loop in order to
pass through the signalized intersections without stopping. The
proposed eco-driving assistance algorithm results are compared
to the optimal solution provided by the Dynamic Programming,
in order to prove not only the effectiveness but also its capability
to be employed online due to its low computational load.
52nd IEEE Conference on Decision and Control; 12/2013
[Show abstract][Hide abstract] ABSTRACT: Given the importance of continuous traffic flow forecasting in most of Intelligent Transportation Systems (ITS) applications, where every new traffic data become available in every few minutes or seconds, the main objective of this study is to perform a multi-step ahead traffic flow forecasting that can meet a trade-off between accuracy, low computational load, and limited memory capacity. To this aim, based on adaptive Kalman filtering theory, two forecasting approaches are proposed. We suggest solving a multi-step ahead prediction problem as a filtering one by considering pseudo-observations coming from the averaged historical flow or the output of other predictors in the literature. For taking into account the stochastic modeling of the process and the current measurements we resort to an adaptive scheme. The proposed forecasting methods are evaluated by using measurements of the Grenoble south ring.
[Show abstract][Hide abstract] ABSTRACT: An important issue in the trends of miniaturization
of systems-on-chips (SoCs) is to obtain a high energy efﬁciency.
This can be reached by dynamic voltage scaling (DVS) architec-
tures as the novel discrete Vdd-Hopping circuit. Generally, this
kind of systems present parameter uncertainties and delays. Like-
wise, current peaks and energy dissipation must be reduced. In this
paper, an optimal and robust saturated control law is proposed for
this Vdd-Hopping circuit via Lyapunov-Krasovskii theory that en-
sures asymptotic stability as well as system robustness with respect
to delay presence and parameter uncertainties. The closed-loop
system presents a regional stabilization due to the actuator sat-
uration. An estimation of an attraction domain is provided. This
controller also limits the current peaks and it provides an energy-
aware performance. The advantages achieved with this controller
are shown in simulation.
IEEE Transactions on Control Systems Technology 03/2013; 21(2):530. · 2.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Traffic forecasting is considered nowadays as one of the most important traffic management techniques on road networks. To provide suitable control strategies and advanced traveler information, which improve traffic performance, a continuous short-term prediction is a significant requirement. In this paper, we propose a new approach for travel time forecasting between two points of interest of a given highway divided in nodes and links. Since nodes and links have distinct characteristics, two different prediction methods are proposed. The resulting predicted travel time is then computed as the sum of predicted travel times in nodes with those in links. An adaptive Kalman filtering approach is considered for predicting sojourn time in nodes and flows at boundaries of links. Inside links, divided in cells for improving resolution, a deterministic observer is used for computing unmeasured densities. The performance of the proposed method is evaluated by using data of the Grenoble south ring, a case study of the NoE Hycon2.
[Show abstract][Hide abstract] ABSTRACT: Energy efficiency is one of the main issues in wireless Networked Control Systems. The control community has already shown large interest in the topics of intermittent control and event-based control, allowing to turn off the radio of the nodes, which is the main energy consumer, on longer time intervals than in the periodic case. While the existing literature only addresses policies using two radio-modes (Tx-Transmitting, and Sleep), this paper considers intermediate radio-modes, which consume more energy than the Sleep mode but have cheaper transition costs to the Transmitting mode. We propose an event-based radio-mode switching policy to perform a trade-off between energy saving and performance of the control application. To this end, we derive a switched model taking into account control and communication. We compute the optimal switching policy using Dynamic Programming and we illustrate the results in simulations.
[Show abstract][Hide abstract] ABSTRACT: This paper proposes an event-based scheme to control a networked control system and to manage the radio-modes of its smart sensor node. The smart node is battery driven and is in charge of sensing the system and computing the control law which is sent to the receiver using a wireless channel. To save energy and to limit the amount of communication with the receiver, the smart node combines two techniques: event-based control and radio-mode management. The control law and radio-mode switching policy are derived jointly in a predictive finite receding horizon optimization problem. We derive a Model Predictive Controller using Dynamic Programming and we prove the stability of the obtained control law using the Input-to-State Stability framework. The main contribution of this paper is to take into account several low consuming radio-modes, e.g. Idle and Sleep and the energy-transition costs between modes. Most of the existing literature only considers one mode when the radio is not transmitting, i.e., the scheduling problem. As illustrated via simulations, our proposal has the potential of significant energy savings.
Decision and Control (CDC), 2012 IEEE 51st Annual Conference on; 01/2012
[Show abstract][Hide abstract] ABSTRACT: Dynamic voltage scaling (DVS) is an important method in managing dynamically the system supply voltage for efficient power reduction. This approach is applied in very large scale integration (VLSI). A dc-dc converter is an electronic device which allows to vary the voltage and, thus, to implement DVS tech- nique. In this paper, a high-performancecontroller is presented for a novel discrete DVS converter. This controller is developed with the aim to deal with the unknown resistive component of the load as well as to minimize the dissipated energy and current peaks, what is very important in the field of microelectronics. Current peaks and power consumption are minimized by computing an optimal evolution for the voltage reference. Likewise, an adaptive controller is proposed to deal with the unknown load resistive parameter. Consequently, the obtained advanced controller can acquires a high consideration on electronic devices. IndexTerms—Adaptivecontrol, dynamic voltagescaling, energy aware, Lyapunov's methods, optimal control.
Circuits and Systems I: Regular Papers, IEEE Transactions on 12/2011; 58-I:2919-2930. · 2.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The paper presents several aspects of modeling, observation and control towards a new generation of Electrical Power Steering(EPS) systems. In particular we design an optimal control to reject oscillations of the steering column, then we device a new observer to estimate the internal state variables of the steering column, the driver applied torque (steering wheel torque), and the load torque (tire/ground contact friction). Finally, we also revisited the LuGre tire dynamic friction model by improving the transient behavior between the sticking phases and the dynamic ones. Simulation of the proposed control and observer are shown at the end of the paper using the improved LuGre-tire friction model.
Proceedings of the IEEE International Conference on Control Applications, CCA 2011, Denver, CO, USA, September 28-30, 2011; 09/2011
[Show abstract][Hide abstract] ABSTRACT: The travel time spent in traffic networks is one of the main concerns of the societies in developed countries. A major requirement for providing traffic control and services is the continuous prediction, for several minutes into the future. This paper focuses on an important ingredient necessary for the traffic forecasting which is the real-time traffic state estimation using only a limited amount of data. Simulation results illustrate the performances of the proposed state-estimation technique.
Proceedings of the American Control Conference 06/2011;
[Show abstract][Hide abstract] ABSTRACT: This paper deals with the control of a fleet of non-linear systems representing AUVs (autonomous underwater vehicles). The purpose is here to design a control law to stabilize the fleet to time-varying formations which are not only circular. A novel framework is proposed to express a general control law for a large class of formations. This is produced by applying a sequence of affine transformations such as translations, rotations and scalings. The paper also includes a cooperative control to distribute the agents along the formation which takes into account the communication constraints. The system was implemented in computer simulation, accessible through Web 1 .
Proceedings of the American Control Conference 06/2011;
[Show abstract][Hide abstract] ABSTRACT: This work deals with the source-seeking problem in which the task is to locate the source of some signal using a fleet of AUVs (autonomous underwater vehicles). The present paper proposes a distributed solution in which a group of vehicles uniformly distributed in a fixed circular formation, estimates the gradient direction of the signal propagation. The distributed algorithm takes into account the communication constraints and depends on direct signal measurements. Our approach is based on the previous results in formation control to stabilize the fleet in a circular formation with time-varying center and in a collaborative source-seeking algorithm. The results are supported through computer simulations.
Proceedings of the 5th International ICST Conference on Performance Evaluation Methodologies and Tools; 05/2011
[Show abstract][Hide abstract] ABSTRACT: In this paper, a novel control strategy for a nonlinear boost inverter is proposed. The idea is based on generating an autonomous oscillator that does not need an external reference signal. This aim is achieved by using energy shaping methodology with a suitable Hamiltonian function which defines the desired system behavior. A phase controller is added to the control law in order to achieve 180◦-synchronization between both parts of the circuit as well as synchronize the voltage output with a pre-specified signal, e.g. synchronization with the electrical grid. An adaptive control is designed for dealing with the common problem of unknown load. In order to analyze the stability of the full system, singular perturbation approach is used. The resulting control is tested by means of simulations.
Control Engineering Practice 01/2011; · 1.91 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In this paper we introduce an integration framework for Control/Communication/Computation (3C) co-design based on the motivating example of fleet control of Autonomous Underwater Vehicles (AUVs) supervised by an Autonomous Surface Vehicle (ASV). Specifically, we address the problem of almost sure stability of an unstable system with multiple observations over the packet erasure channel with emphasize on coding computational complexity. We look at the tradeoff between duty cycle for feedback channel use, coding computational complexity, and performance. We compare coding computational complexity and performance for two cases: a) No feedback channel at all, and b) Feedback channel all the time. It is shown that the strategy of using feedback channel results in a better performance.
[Show abstract][Hide abstract] ABSTRACT: A mathematical driver model is given in the spacial equation form, which takes into account the previewed information of the path. Optimal control method is considered for the ideal no time-delay case and Lyapunov-Krasovskii functional approach is applied to deal with drivers' reaction time-delay. For both cases, exponential stability is guaranteed for the closed loop system.
Proceedings of the IFAC Word Congress 2011. 01/2011;
[Show abstract][Hide abstract] ABSTRACT: The problem of controlling the congestion front in a single link road section is considered in this paper. For this purpose, we introduce a new variable-length two-cell lumped model composed of; one congested cell, and another in free flow. This model has the advantage of having few states while preserving the vehicle conservation property. This model is used as a basis to design a simple “best-effort” controller that regulates (at its best) the congestion front to some pre-specified value. The control law can be implemented using only information about the congestion front position.
[Show abstract][Hide abstract] ABSTRACT: This work proposes a novel control algorithm dedicated to multi-agent systems with nonlinear dynamics. The aim of this paper is for the agents to form a circular formation whose center is fixed and whose radius is given by a time-varying reference. The problem of uniform distribution of all the agents along the circle is also addressed under the assumption of limited communication range. This communication constraint is tackled by using a cooperative control scheme which includes the Laplacian matrix of the communication graph (distance-dependent). The multi-agent system is simulated with Matlab. Videos showing the simulations are accessible though Web.