Azita Dabiri

Distributed LPV state-feedback control with application to motorway ramp metering

In this paper, we develop a distributed state-feedback controller synthesis algorithm for a discrete-time LPV system that is composed of the interconnection of several sub-systems each scheduled by its own parameters. A set of LMI conditions are derived for robust ℒ2-gain performance of such a system in the framework of multiplier-based LPV synthesis. The results have been oriented to be applied in traffic flow control in motorways by ramp metering. First, with the use of a proper transformation, the nonlinear traffic flow model has been represented as the interconnection of LPV subsystems. Then the developed synthesis results have been used to design a gain-scheduled distributed state-feedback controller that keeps the density of all segments around a desired value by the use of ramp metering.

Distributed LPV State-Feedback Control Under Control Input Saturation

Developed in this note is a scheduled state-feedback controller synthesis method for discrete-time Linear Parameter Varying (LPV) systems subjected to control input saturation constraints. The static state-feedback gain is scheduled with an exact replica of the parameter matrix. The saturation effect is modeled by introducing time-varying parameters as functions of the control inputs, which are also used to schedule the controller. The synthesis method is then specialized to distributed state-feedback by imposing a particular structure on the feedback gain matrix. An explicit formula is also derived for the computation of the distributed control input from a nonlinear equation. The viability of the proposed method is tested in a simulation environment, for a ramp meter traffic flow control problem.

Incident Parameter Scheduled Freeway Traffic Control - a Ramp Meter Approach

A novel model based local ramp metering method is presented in the paper by means of incident scheduled freeway traffic control solution. First, second order macroscopic freeway model is used with appropriate incident parametrization to describe eventual and unattended traffic variation caused by off-nominal traffic conditions (e.g. accidents). These traffic anomalies are captured by adequate model parameters, i.e. incident parameters that can be on-line estimated. The paper is motivated by incident scheduled ramp-meter solution to encounter real-time incident parameter information. The main idea is to use local freeway control solution triggered by available incident parameter values. The proposed approach is local in the sense of considering only non-coordinated ramp meter solution, first. Furthermore, we apply locally optimal (linearized) control solution to satisfy throughput maximization objective. The formal controller synthesis involves parameters to correct, compensate the effect of incidents. The proposed method is evaluated and compared to other existing approach by using simulation environment.

Distributed Ramp Metering—A Constrained Discharge Flow Maximization Approach

Considered in this paper is a novel model-based, coordinated ramp metering strategy. It aims at maximizing the discharge flow in motorway networks by minimizing the divergence of the traffic density from its critical value caused by unknown demand flow. The suggested synthesis algorithm casts the traffic control objective into the form of an induced

Distributed dynamic output feedback control for discrete-time linear parameter varying systems

\mathcal {L}_{2}

Freeway traffic incident reconstruction – A bi-parameter approach

-norm minimization problem. Hence, we aim at rejecting the effect of disturbance on the overall network performance output while the ramp input flow is subjected to constraints. With such a problem formulation, it is not required to know the disturbance input in order to find the proper control input. Without any central decision unit (traffic control center), ramp meters coordinate by sharing their local variables with solely their neighbor units (upstream and downstream) to achieve the global performance goal. Under some network symmetry conditions, a compositionally inexpensive distributed flow control method is suggested to address scalability issues. The method is implemented in simulation environment and compared with other control algorithms in two comprehensive case studies.

Incident parameter estimation

Proposed in this note, is a method for scheduled distributed dynamic output feedback controller design. The underlying large-scale system is assumed to be the interconnection of Linear Parameter Varying (LPV) discrete time sub-systems. Following the concept of Integral Quadratic Constraints, robust LPV controller is developed aiming at ℓ2 norm minimisation. The interconnection of the controller has been selected to be identical to the spacial distribution of the sub-systems to secure the level of sparsity in communication topology. By using agent-wise full block multipliers in the design phase, distributed output feedback controller design framework is obtained by the sequential use of elimination and dualization lemmas. In order to show the benefits of the suggested methodology, numerical simulation tests are carried out to control the traffic flow in a motorway segment by means of on-ramp input flow gating.