Abdellatif Reama

Technical communique: Stability analysis of neutral systems with mixed delays

The stability of neutral systems with mixed delays is studied in this paper. A new discretized Lyapunov functional method is proposed. The method in this paper is less conservative than the existing ones and the results are very close to the analytical results. In addition, this method allows the coefficient matrix of the neutral term to have time-varying uncertainties.

Some problems in the stability of networked-control systems with periodic scheduling

This article addresses three stability problems related to networked-control systems (NCSs) with periodic scheduling, where control systems may have multiple samplings in a hyperperiod (a hyperperiod is a periodically repeated scheduling sequence for all tasks in an NCS). As expected, the analysis of a system with multiple samplings is much richer than the case with single sampling. For example, a system with two samplings may be stable (unstable) even if it is unstable (stable) when sampled by either sampling. In this context, it is important to understand how network-induced delays and multiple samplings affect the systems stability. In this article, three particular stability problems involving constant and/or time-varying parameters are investigated, and the corresponding stability regions are derived. Numerical examples and various discussions complete the presentation.

Energy Optimal Real-Time Navigation System

The rapid development of Mobile Internet and Smart Devices and advent of a new generation of Intelligent Transportation Systems (ITS) increase information about present driving conditions and make its prediction possible. Real time traffic information systems (TIS) like SYTADIN help in route to destination planning and traffic state prediction. Energy-optimal routing for electric vehicles creates novel algorithmic challenges where the computation complexity and the quality of information on traffic state are the main issues. This complexity is induced by the possible negative values of edge energy as well as the variability of route and vehicle variables which render the standard algorithms unsuitable. In this paper we present an Energy Optimal Real Time Navigation System (EORTNS), implemented on Samsung Galaxy Tab, capable of calculating the route to destination based on information flow obtained from SYTADIN. As an application example we propose a real time energy management for a Hybrid Electrical Vehicle (HEV) composed of batteries and Super-Capacitors (SC). The EORTNS is not only capable of energy optimal route to destination calculation with respect to traffic state but also operates the On-Board power splitting between batteries and Super-Capacitors.

Real time implementation of backstepping controller in indirect field oriented control of induction motor drive

A novel structure of backstepping control has been proposed for indirect field oriented control of induction motor drive. Voltage and current signals are usually contaminated with high frequency switching noises due to SVPWM inverter. The proposed structure avoids real time integration and its associated drift problems, which in practice are the source of generation of unwanted noise. These problems are typical in the PI controllers used in conventional indirect vector control for speed and current regulation. By using the proposed backstepping controller, the system has a good load disturbance rejection capability, fast dynamic response and less parameters sensitivity. The effectiveness of this proposed control structure is verified by simulation as well as by experiment under critical operating conditions.

Stability analysis of networked control systems based on a switched control

Abstract This paper studies the stability of networked control systems with a switched control law. Both the cases of constant and time-varying sampling periods are considered and the stability intervals are obtained. It is seen that this method can lead to bigger stability intervals than the standard control law. In particular, some NCSs can be stabilized with an infinitely big sampling period. A sufficient condition for this case is presented.

Performance evaluation of the distributed implementation of a car suspension system

Abstract In a wide category of embedded systems, sensors, controllers and actuators are located in distant locations. To ensure the control functions, these components need to be interconnected. Usually, communication networks are chosen to support the required communication exchange. In the context of the automotive industry, the Controller Area Network (CAN) bus is yidely used because of its interesting properties. In theory, a CAN network can ensure real-time communications, when no transmission errors are detected. However, an incrpasing numher of applications are sharing this hus, generating jitter and delays on the exchanged messages, which can degrade the performance of control applications. In this paper, the distributed implementation of an active suspension controller is modelled in Simulink thanks to the use of the tool box TRUETIME. The network traffic is generated using the well-known SAE benchmark. Using this simulation model, the control performance of the active suspension system is studied as a function of the available network bandwidth

Real time energy management algorithm for hybrid electric vehicle

The rapid development of mobile Internet and smart devices and advent of new generation of Intelligent Transportation Systems (ITS) increase information about future driving conditions and makes on-board energy management of Hybrid Electrical Vehicle (HEV) realistic. In this paper we propose a real time energy management algorithm RTEMA for a HEV composed of batteries and Super-Capacitors (SC). We suppose that the On-board Dedicated Computer (ODC) has a permanent Internet connection and has the possibility to perform Google-Maps application queries to calculate 3D route to destination. Based on 3D route to destination and average speeds for each road segment the state of charge (SOC) for battery and SC at the end of each receding horizon are predicted. A cost function considering the efficiency of battery, SC, DC/DC converter and electric motor as well as the battery life cycles increase is presented and an optimization problem is formulated and resolved. As ODC for real-time communication and computation we use Samsung Galaxy Pad which is an Android smart device. Performance results in terms of energy optimization, increased battery life and computing time are given which show the practical usefulness of this approach and application. Such a system can be made available to potential users of HEV as well as to the Android community driver members who share information on the state of traffic flow via their Android mobile phones [30].

Nonlinear integral backstepping control for induction motors

A novel structure of nonlinear integral backstepping control has been proposed for induction motors. We can see clearly that the structure of the controller generated by the classical version of backstepping is composed of a proportional action, which was added a derivative action on errors. Such a structure makes the system sensitive to measurement noise. The lack of integration means also the appearance of a constant static error, caused mainly by non-zero mean disturbances. The solution to this problem is to design a new version of the backstepping with integral action. By using the proposed integral backstepping controller, the system has a better load disturbance rejection capability. The effectiveness of this proposed control structure is verified by simulation as well as by experiment under critical disturbance conditions.

Some remarks on robust stability of networked control systems

This paper focuses on the robust stability of networked control systems (NCSs), considering time-delay and sampling period simultaneously. Particular stability problems involving constant and/or time-varying parameters are investigated, and the corresponding stability regions are derived. The methods are based on searching an appropriate Lyapunov matrix and parameter-sweeping. It is shown that the obtained results are less conservative than the existing ones.

Optimal Power Management for Vehicle Hybrid Electric System using Look-ahead Route Information

Abstract For a vehicle hybrid electric (VHE) system powered by the batteries and supercapacitors (SC), a real-time optimal power management (OPM) algorithm is proposed based on the look-ahead route information in consideration of the complex traffic environment. At first, a configuration and modeling of the VHE system is addressed. Then, enlighten by the model predictive control (MPC), multiple route information including the traffic and the road terrain over a look-ahead horizon is utilized to predict the future states, and a cost function to minimize total energy loss of the VHE system is given. On above preliminaries, the dynamic programming (DP) algorithm is applied recursively over the look-ahead horizon to update the optimal power distribution between the battery and SC during the total route. Finally, the simulation results confirm that the computational time of OPM has been reduced significantly although a part of energy efficiency is sacrificed. Moreover, the behavior of OPM is similar to that of a skilful driver and thus appropriate be applied to the practical traffic environment.