Anis Messaoud

Supervision based on partial predictors for a multimodel generalised predictive control: experimental validation on a semi-batch reactor

The multimodel approach has become a major research topic during the last few decades and unlike many other advanced techniques, it has also been successfully applied in industry. This paper describes the application of a multimodel generalised predictive control (MGPC) based on a commutation algorithm to the problem of a semi-batch reactor control. The commutation is controlled by a set of partial predictors which constitute a supervisor. The experimental results show that the multimodel generalised predictive control based on supervisor leads to good performances in terms of precision and tracking, relatively to the case where the direct adaptive generalised predictive control (DAGPC), is applied.

Supervised Model Predictive Control for discrete-time nonlinear systems with time-varying delay

The present paper deals with a decoupled multimodel predictive control based on multi-observer for the control of discrete-time nonlinear systems with time-varying delay. For each local model, a controller based on partial predictor/observer is synthesized. A switching algorithm is established to yield the adequate partial controller ensuring the closed-loop desired performances. Simulation results are given to illustrate the significance of the proposed decoupled multimodel predictive control strategy.

Robust design of non-stationary sinusoidal unknown inputs multiobserver based on decoupled state multimodel

This paper deals with the design of robust non-stationary sinusoidal unknown inputmultiobserver for discrete-time nonlinear systems described by decoupled state multimodel. The particularity of this work resides in the fact that it provides a simultaneous state and non-stationary sinusoidal unknown inputs estimations. A new robust strategy allowing the minimization of the non-stationary sinusoidal unknown inputs and disturbances impact on the state estimation error will be developed.

Robust multiobserver design for discrete uncertain nonlinear systems with time-varying delay

In this paper, a robust multiobserver is proposed for the state estimation of discrete-time uncertain nonlinear systems with time-varying delay. The designed multiobserver is based on the decoupled multimodel approach. Unlike the classically used multimodel structures, the decoupled multimodel provides a flexibility of modelling. Indeed, the partial models’ structures can be adapted to the complexity of the system in each operating regime, thus the partial models can be with different dimensions. Delay-dependent sufficient conditions for the synthesis of a robust multiobserver against norm-bounded parametric uncertainties and in the presence of measurement noise are established in terms of linear matrix inequalities. A simulation example is given to illustrate the effectiveness of the designed multiobserver.

Multimodel repetitive–predictive control of nonlinear systems: rejection of unknown non-stationary sinusoidal disturbances

ABSTRACT In the present work, we propose a supervised multimodel repetitive–predictive control scheme for discrete-time nonlinear systems in order to reject unknown non-stationary sinusoidal disturbances and to track reference trajectory. The nonlinear system is described by the decoupled state multimodel. Also, a non-stationary sinusoidal unknown input multi-observer is used to estimate the state and the unknown non-stationary sinusoidal disturbances simultaneously. The estimate of the disturbances is exploited by the magnitude–phase-locked loop (MPLL) approach to reconstruct the accurate disturbance period used to develop a robust supervised multi-rejector. The proposed control strategy provides good closed-loop performance despite the changes of the disturbance characteristics. A simulation example is provided to illustrate the significance of the proposed multi-rejector.

Internal multimodel control for discrete nonlinear systems with time-delay

In this paper, an internal multimodel control scheme is proposed for the control of discrete nonlinear systems with time-delay. In this framework, a decoupled polynomial multimodel is proposed for the representation of the nonlinear system. The control scheme incorporates partial internal model controls where each partial controller is associated to a specified operating zone of the nonlinear system. The switching between these controllers is ensured by a supervisor that contains a set of local predictors. A simulation example is carried out to illustrate the significance of the proposed internal multimodel control scheme.

Robustness enhancement of proportional Q-integral multiobserver in the case of non-stationary sinusoidal unknown inputs

This paper deals with the robustness enhancement of proportional Q-integral multiobserver in the case of non-stationary sinusoidal unknown inputs. The multimodel approach is proposed in order to overcome the complexity problems of nonlinear systems. The proposed multiobserver uses the multi-integral strategy in order to provide a simultaneous estimation of the state and unknown inputs. A new robust strategy allowing the minimization of the non-stationary sinusoidal unknown inputs impact on the estimation error is developed. The significance of the proposed study is illustrated via a simulation example.

An online identification algorithm of unknown time-varying delay and internal multimodel control for discrete non-linear systems

ABSTRACT In this paper, an online algorithm is proposed for the identification of unknown time-varying input delay in the case of discrete non-linear systems described by decoupled multimodel. This method relies on the minimization of a performance index based on the error between the real system and the partial internal models outputs. In addition, a decoupled internal multimodel control is proposed for the compensation of discrete non-linear systems with time-varying delay. This control scheme incorporates partial internal model controls. Each partial controller is associated to a specified operating zone of the non-linear system. The switching between these controllers is ensured by a supervisor that contains a set of local predictors. A simulation example is carried out to illustrate the significance of the proposed time-varying delay identification algorithm and the proposed internal multimodel control scheme.