Hassane Abouaïssa

Flatness based control of traffic flow

This paper is concerned with the traffic flow control using the concept of flatness. The proposed approach exploits the bond-graphs formalism in the macroscopic modeling of the traffic flow. The main advantage is that it allows to strongly simplify the analysis techniques, offering a physical comprehension of the dynamical behavior of the studied system. Indeed, the obtained model is on the form of space discretized continuous lumped parameters. Starting from the mathematical equations deduced directly from the bond-graph model, we propose a flatness based control algorithm in order to regulate the flow at the mainline section of road. The same method can be used to develop isolated and coordinated ramp metering algorithms

On ramp metering: Towards a better understanding of ALINEA via model-free control

ABSTRACT ALINEA, which was introduced almost 30 years ago, remains certainly the most well-known feedback loop for ramp metering control. A theoretical proof of its efficiency at least when the traffic conditions are rather mild is given here, perhaps for the first time. It relies on tools stemming from the new model-free control and the corresponding ‘intelligent’ proportional controllers. Several computer experiments confirm our theoretical investigations.

Fast Parametric Estimation for Macroscopic Traffic Flow Model

The main traffic parameters such as the critical density and the free flow speed of a motorway segments are subject to changes over time due to traffic conditions (traffic composition, incidents, . . . ) and environmental factors (dense fog, strong wind, snow, . . . ). As such parameters have an impact on the performance of the traffic control strategies, they must be estimated on-line. Our approach, which is of algebraic flavor and avoids asymptotic and statistical techniques, yields fast implementable formulae in closed form. Some convincing computer simulations are provided.

MACRO-MICRO SIMULATION OF TRAFFIC FLOW

Abstract This paper presents the recent progress in the development of the hybrid concept for the traffic simulation. The main objective is to couple two traffic representation models with different scale levels. The first allows a global traffic representation providing the possibility to simulate a large network. The second model focuses on the individual interactions of vehicles and allows then to understand the phenomena of the microscopic point of view. The paper shows that the proposed approach is generic allowing the cohabitation of various macroscopic models with the microscopic model developed using the agent paradigm. It presents also some simulation results that illustrate the relevance of the elaborated approach.

High order sliding mode control for real-time ramp metering

We propose the application of the High Order Sliding Mode Control (HOSMC) and the concept of differentially flat systems in order to solve the ramp metering problem. The main characteristic of differential flatness is that, the whole system behavior is described by the trajectory of a so called “flat output” and a number of its successive time-derivatives. This leads to a simple design of trajectories without integration of any differential equation. On the other hand, HOSMC is known to be a robust control method appropriate for uncertain systems. The effectiveness of the proposed approach is demonstrated via some simulation results from a case study and enable to foresee several very promising further developments for ramp metering and integrated traffic flow control.

Sliding Mode Control and Flatness-Based Concept for Real-Time Ramp Metering

Abstract The aim of this paper is to present an application of a sliding mode control (SMC) and flatness-based concept to real-time ramp metering. Such application is a novel attempt in the field of traffic control. Differentially flat concept provides simple algorithms to generate optimal trajectories, without integration of any differential equation. On the other hand, SMC is known to be a robust control method appropriate for uncertain systems such that the traffic ones. The proposed approach is based on the well-known space discrete first order macroscopic model. A simple case study shows very promising results for further works including traffic control for more complex motorway network.

Traffic network ramp metering based on High Order Sliding Mode and flatness approaches: A case study

Freeway traffic control is achieved using High Order Sliding Mode Control (HOSMC) and the concept of differentially flat systems. The main objective of this paper, which follows the work in [22] is to evaluate the impact of the traffic ramp metering on the freeway network using real field data of the French motorway A6.

Distributed model predictive control of freeway traffic networks: A serial partially cooperative approach

In this paper, a new distributed model predictive control (MPC) scheme for freeway traffic control is proposed. It is aimed at reducing the communication efforts and the computation times in a large network. This new algorithm can coordinate a large number of on-ramps throughout a freeway network in a partially cooperative scheme. The communication is performed between neighboring on-ramps in a special serial fashion and with three different proposed cooperative schemes. The computation time is much less than that of existing distributed MPC approaches in the literature, while achieving a performance close to the one of the centralized MPC method. To evaluate the performance of the proposed partially cooperative schemes, a freeway network case study is selected and the problem of coordination between several on-ramps is solved using different methods from a centralized approach to a fully decentralized one. The obtained results show a significant decrease in the total computation time with respect to the centralized and fully cooperative schemes, while maintaining a close distance to the optimal objective function obtained from the centralized case. Furthermore, the performance of the proposed partially cooperative MPC method is evaluated in the case of incidents in the network.

Energy saving for building heating via a simple and efficient model-free control design: First steps with computer simulations

The model-based control of building heating systems for energy saving encounters severe physical, mathematical and calibration difficulties in the numerous attempts that has been published until now. This topic is addressed here via a new model-free control setting, where the need of any mathematical description disappears. Several convincing computer simulations are presented. Comparisons with classic PI controllers and flatness-based predictive control are provided.

State reconstructor for real-time freeway ramp metering

The work presented in this paper aims to solve the problem of isolated ramp metering in the case of unavailable (not measured) traffic state variables (density and mean speed). A state reconstructor is then proposed and a systematic approach is developed for real time freeway ramp metering. The state reconstructor is developed using a second order sliding mode observer, while the control algorithm is based on the concept of differential flatness. Numerical simulations demonstrate the relevance of the provided algorithm for both state reconstructor and control of freeway networks.