Showing papers by "Mohamed Tadjine published in 2013"

Robust Fuzzy Backstepping Sliding Mode Controller For a Quadrotor Unmanned Aerial Vehicle

Abstract: The main purpose of this paper is to integrate fuzzy logic control and sliding mode control techniques based on backstepping approach to develop a robust fuzzy backstepping sliding mode controller (RFBSMC) for an under-actuated quadrotor UAV system under external disturbances and parameter uncertainties. First, a robust backstepping sliding mode control for quadrotor is introduced briefly. Moreover, a fuzzy logic inference mechanism is employed for implementing a fuzzy hitting control law to reduce the chattering phenomena on the conventional RBSMC. Lyapunov based stability analysis shows the main advantage of these control systems which are the trajectory tracking and the stability maintaining of the closed loop dynamics of quadrotor UAV even after occurrence of external disturbances and parameter uncertainties. The effectiveness of the complete system including the quadrotor, and the RFBSMC controller is demonstrated via some simulation results, and its advantages are indicated in comparison with the conventional RBSMC system.

Hybrid Fuzzy Sliding Mode Control of a DFIG Integrated into the Network

Abstract: This paper presents the study of a variable speed wind energy conversion system using a Doubly Fed Induction Generator (DFIG) based on a Fuzzy sliding mode control (FSMC) applied to achieve control of active and reactive powers exchanged between the stator of the DFIG and the grid to ensure a Maximum Power Point Tracking (MPPT) of a wind energy conversion system. However the principal drawback of the sliding mode, is the chattering effect which characterized by torque ripple, this phenomena is undesirable and harmful for the machines, it generates noises and additional forces of torsion on the machine shaft. In order to reduce the chattering effect, the Sign function of sliding mode controller’s discontinuous part is replaced by a fuzzy logic; we will have the fuzzy sliding mode controller (FSMC). The FSMC makes it possible to combine the performances of the two types of controllers (SMC and FLC) and eliminates the chattering effect. The proposed control algorithm is applied to a DFIG where the stator is directly connected to the grid and the rotor is connected to a three-level converter structure NPC to suppress low level harmonics, higher frequencies will be filtered out by the machine. Second goal of this paper is to extract a maximum of power; the rotor side converter is controlled by using a stator flux-oriented strategy. The decoupling created by the control between active and reactive stator power allows keeping the power factor close to unity. Simulation results show that the wind turbine can operate at its optimum energy for a wide range of wind speed. Both simulation and validation results show effectiveness of the proposed control strategy is in terms of power regulation. Moreover, the fuzzy sliding mode approach is arranged so as to reduce the chattering produced in the generated power that could lead to increased mechanical stress because of strong torque variations. DOI: http://dx.doi.org/10.11591/ijpeds.v3i4.4072

Control and Fault Diagnosis Based Sliding Mode Observer of a Multicellular Converter: Hybrid Approach

Abstract: In this article, the diagnosis of a three cell converter is developed. The hybrid nature of the system represented by the presence of continuous and discrete dynamics is taken into account in the control design. The idea is based on using a hybrid control and an observer-type sliding mode to generate residuals from the observation errors of the system. The simulation results are presented at the end to illustrate the performance of the proposed approach. K e y w o r d s: multicellular converter, diagnosis based-observer, hybrid observer, residual, cell fault sliding mode, hybrid dynamical systems

Improved direct torque control of induction motors using adaptive observer and sliding mode control

Abstract: This paper presents the synthesis of an adaptive observer which is used for the improvement of the direct torque control of induction motor drives. The observer detects stator flux components in two-phase stationary reference frame, rotor speed and stator resistance by measure of the stator terminal voltages and currents. The observer is adapted using a simple algorithm which does not imply a high computational load. Stability analysis based on Lyapunov theory is performed in order to guarantee the closed loop stability. Simulation tests under load disturbance and stator resistance variation are provided to evaluate the consistency and performance of the proposed control technique in the low and high speeds.

Quaternion-based global attitude tracking controller for a quadrotor UAV

Abstract: In this work, the problem of quaternion-based global attitude stabilization is addressed, using the Backstepping technique. The proposed controller is conceived to be consistent in order to prevent the ambiguity in relating a given attitude to its two corresponding quaternions. The set of the two antipodal equilibrium error quaternions are rendered attractive and asymptotically stable. The error quaternion is then attracted by the nearest equilibrium in the set. In order to escape from the invariant and non attractive undesirable manifold, defined by attitude errors of 180°, the rigid-body attitude dynamics is augmented by a time varying dynamics. Simulation results illustrate the efficiency of the proposed controller, for attitude stabilization or tracking, even in the presence of a centred Gaussian noise, on angular velocity measurements.

Super-Twisting Algorithm approach to control tumors growth

Abstract: This work is about computing the robust control for tumors growth. This control law is developed using the Super-Twisting Algorithm. It is based on the sliding modes approach, with appropriate choices for the control law expressions. As an improved version of the Twisting algorithm, it has been introduced in order to minimize the shattering phenomenon, to allow the outputs to converge in a reasonable amount of time. It also deals with the need of some data that are hard to obtain in practice. The mathematical model of the tumor, as we refer to it as the system, is based on the phases of the cell cycle, where three compartments are considered. The control law is computed and simulated using real data. The system responded in a robust way regarding the modeling and the measurements errors, and the cells concentrations decreased considerably, according to the simulations results.

Diagnosis of cage induction motors subject to unbalanced supply voltage conditions including space and time harmonics

Abstract: The paper describes an analytical method which is developed for the modeling of cage induction motors (IM) including space and time harmonics effects This model is used to predict the influence of these harmonics on the electromagnetic performances of IM drives in healthy condition and to extract significant signatures under faulty conditions such as unbalanced supply voltage The equations which describe the transient as well as steady state behavior including the computation of machine inductances are presented, basing on the calculation of the magnetic field distribution through the machine air-gap The proposed model is less complicated to be implemented for condition monitoring or control of IM drives The simulation results provide useful consequences about the characteristics of the IM under unbalanced voltage conditions including space and time harmonics effects It will be shown that the space and time harmonics influence significantly the harmonic content of the electromagnetic torque and stator currents which are used for condition monitoring of IM drives

The use of the principle of feedback scheduling for enhancing the real-time paraplegic knee response

Abstract: In this work we simulate the behavior of the knee movement in ideal case of a paraplegic subject in closed loop by implementing a PID controller. We are interested in the response of the knee angle by taking into account real-time constraints. First, we used the Ferrarin and Pedotti's model. Then, the knee FES application has been decomposed in three real-time tasks in such a way that two tasks execute the control and the third one calculates the parameters of control used by the two first tasks. The three tasks were executed by a real-time kernel employing Feedback Scheduling which is a sampling period selection for limited computing resources. As results, by satisfying the realtime constraints of the tasks and by reaching good processor utilization the knee response improved significantly.

Adaptive observation of stator flux and resistance for speed sensorless DTC controlled IM drives

Abstract: This paper presents the synthesis of an adaptive observer which is used for the improvement of the Direct Torque Control (DTC) of induction motor drives. The observer detects the stator flux components in the two-phase stationary reference frame, the rotor speed and the stator resistance by the measure of the stator terminal voltages and currents. The observer is adapted using a simple algorithm which does not imply a high computational load. Stability analysis based on Lyapunov theory is performed in order to guarantee the closed loop stability. Simulation tests under load disturbance and stator resistance variation are provided to evaluate the consistency and performance of the proposed control technique in the low and high speeds.

New observer-based UAV attitude controller with gyroscopic bias estimation

Abstract: This paper addresses the problem of global attitude control, in quaternion space for a small UAV equipped with a low cost IMU. The proposed controller is based on a new observer that estimates the true angular velocity from the biased measurements fed by a low cost IMU. The observer based controller is synthesized based on a single Lyapunov function and stability analysis shows that UAV attitude converges globally asymptotically towards the desired attitude trajectory. Simulation results including realistic robustness tests illustrate the effectiveness of the proposed controller.