International Journal of Digital Signals and Smart Systems (22 papers in press)
Identification and removal of different categories of noises from magnetic resonance image using hybrid partial differential equation based filter
by Ram Bharos Yadav, Subodh Srivastava, Rajeev Srivastava
Abstract: In this paper, automatically identify various types of noise present into the MRI and filters them by choosing an appropriate filter. The different categories of noises during the acquisition of MR image may be generally corrupted due to external or internal causes. The external causes lead to an additive noise pattern which follows a Gaussian distribution (pdf). Causes of internal noise in MR image are basically the intrinsic noise that is generated during the acquisition process. Normally intrinsic noise in MR image follows the Rician distribution (pdf). The proposed filter gets adapted for the removal of specific types of noise based on SNR values of image data. The performance analysis and comparative study of the proposed method with other standard methods is presented for Brain Web dataset at varying noise levels in terms of PSNR, MSE, SSIM, and CP. From the simulation results, it is observed that the proposed framework with CD based prior is performing better in comparison to other priors.
Keywords: Gaussian; Rician noise reduction; 2D MR images; Gaussian’s; Rician’s probability distribution function.
Shaping the future design and manufacturing of a composite rotor blade for multi-megawatt wind turbines
by Brahim Attaf
Abstract: Given that wind energy is a key solution in fighting against global warming emissions arising from human activities, the interest for developing more powerful wind turbines has become nowadays a challenging area to research and innovation for the wind-turbine industry worldwide. As the electric power supplied by the wind turbine is directly related to the size of its blades: the larger the size of blades the more energy is captured, new design and manufacturing strategies of these critical components, using advanced fibre-reinforced composites such as carbon nanotubes (CNTs) and resin transfer moulding (RTM) process, have become a major focus for manufacturers and competitors of wind turbines. In this perspective, the outcomes presented in this paper can be exploited by the modern wind turbine industry with the aim of developing reliable, efficient and cost-effective rotor blades that are capable to withstand, without adverse effects, severe static and/or dynamic loading to which they may be exposed during their lifetime. As part of long-term strategic plans, CNTs offer the required criteria to help researchers design and manufacture 200 m rotor blades for 50 MW turbines.
Keywords: wind energy; composite blade; nanomaterials; carbon nanotubes; CNTs; closed moulding; sustainable development; renewable energy.
Development of Monitoring Algorithm for Controlling a Biped Robot: Norm Bounded Uncertainties System Based
by Imen Dakhli, Elyes Maherzi, Mongi Besbes
Abstract: It is well known that the biped walking gait is represented as a steady periodic gait. Investigation of such passive natural motion leads to different strategies of control; these strategies require a sharp mathematical model of the walking dynamics. One of the most used models is the Kajitas one.
In this paper, we present an algorithm of controllers design used for the stabilization of biped robots gait. Using the kajitas model as a reference, we include a Norm bounded uncertainties to ensure a more realistic numerical model. The modified model allows us to include constraints on both inputs, outputs and states.
The synthesis of the dynamic controller relies on the use of predictive control theory (MPC) and the resolution of a convex optimization problem with Linear Matrix Inequalities (LMI) at every sampling period. The generated control law allows a real-time walking robot even in rough ground or unknown environment.
Keywords: Dynamic controller; predictive control; uncertainties; linear matrix inequality (LMI); biped robot; walking stability.
Robust DC-Motor Speed Control Using a Fractional Adaptive PI Regulator
by Khatir Khettab, Yassine Bensafia, Samir Ladaci
Abstract: Conventional Adaptive PI controller is one of the most widely used controllers in industry, but the recent advancement in fractional calculus has introduced applications of fractional order calculus in control theory. One of the prime applications of fractional calculus is fractional adaptive PI controller and it has received a considerable attention in academic studies and in industrial applications. Fractional order Adaptive PI controller is an advancement of classical integer order adaptive PI controller. In many a cases fractional order adaptive PI controller has outperformed classical integer order adaptive PI controller. Particularly for the problem of controlling the speed of DC-motors, it is very important use a suitable and efficient controller as any small change can lead to instability of the closed loop system. This research paper, studies the control aspect of fractional order controller in speed control of DC-motor.
Keywords: Adaptive Control; fractional order control; fractional order integral; output feedback; fractional PI control.
Policy Iteration and Coupled Riccati Solutions for Dynamic Graphical Games
by Mohammed I. Abouheaf, Magdi S. Mahmoud
Abstract: A novel online adaptive learning technique is developed to solve the dynamic graphical games in real-time. The players or agents exchange the information on a communication graph. Hamiltonian mechanics are used to derive the constrained minimum conditions for the graphical game. Novel coupled Riccati equations are developed for this type of games. Convergence of the adaptive learning technique is studied given the graph topology. Nash equilibrium solution for the graphical game is found by solving the underlying Hamilton-Jacobi-Bellman equations. Actor-Critic neural network structures are used to implement the adaptive learning solution using local information available to the players.
Keywords: Dynamic Games; Optimal Control; Game Theory; Cooperative Control.
A State Space I/O Map to Transform Nonlinear Systems into an Observable Form
by Hamrouni Lotfi
Abstract: This paper deals with the problematic of state-space realization of input-output (i/o) nonlinear systems. For that, we propose a general method that can be used to verify the realizability of i/o models and provides the equivalent state-space model when it is possible. The main advantage of the proposed approach is the use of graphic map to design the state space model without analytic analysis. The resulted state-space model is identified using a special class of modular feed-forward neural networks that embeds the state vector of the model. New results are also proposed using a realizable non-recurrent i/o subclass that is adapted to Matlab identification procedure. This approach is applied on some examples and proved its efficiency.
Keywords: state-space realization; nonlinear systems; modular neural networks.
A Review on fault-tolerant control for vehicle dynamics
by Mohamed Riad Boukhari, Ahmed Chaibet, Moussa Boukhnifer, Sébastien Glaser
Abstract: The more growing complexity in conception of nowadays systems, has increase the risks of malfonctions caused by abnormalities which may degrade the system performance, and even make it unstable leading to threaten severly its safety. To overcome the risks of these abnormalities, an effective fault-tolerant control strategy should be carried out. In recent years, several techniques have been studied mostly in theoretical topic with some application tests around a variety of engineering systems. This manuscript gives a state of the art in the field of fault-tolerant control outlining what has been done and giving future issues for application to the domain of vehicle dynamics.
Keywords: Fault-Tolerant Control; Fault Diagnosis; Robust Control; Analytical Redundancy; Vehicle Dynamics.
Power Control of a variable speed wind turbine based on Direct Torque Control of a Permanent Magnet Synchronous Generator
by Marwa Ayadi, Fatma Ben Salem, Nabil Derbel
Abstract: This paper focus is on the problem of controlling power generation in variable-speed wind turbine (VS-WT). The aim is tornmaximize the extracted power at below rated wind speed and to regulate the extracted power when operating at above rated windrnspeed. In this work, the torque control is used to extract the maximum of power whereas above rated wind speed pitch control isrnapplied. For variable pitch control, two types of controllers has been proposed: the first is a PI controller and the second is slidingrnmode controller based on two approach for chattering reduction: the introduction of a boundary layer and the developing of arnsecond order sliding mode approach. Simulation results show that the second order sliding mode control has better performancesrnsuch as strong ability for eliminating chattering, fast response and good robustness to parameter variations.
Keywords: Wind turbine; PMSG; torque control; pitch control; Sliding Mode Control.
Tracking Control of Mobile Manipulator Robot Based on Adaptive Backstepping Approach
by Abdelkrim Brahmi, Maarouf Saad, Guy Gauthier, Wen-Hong Zhu, Jawhar Ghommam
Abstract: This paper presents a tracking control of non-holonomic mobile manipulator robot using an adaptive backstepping control scheme based on the virtual decomposition control (VDC). The proposed control scheme was implemented on a three degrees of freedom manipulator arm mounted on a two degrees of freedom mobile platform subject to non-holonomic constraints to track a predefined workspace trajectory. The inverse kinematics algorithm is used to calculate the desired joint space trajectory. In the known decentralized control scheme, the mobile manipulator robot is divided into two subsystems including the manipulator arm and the mobile platform. In the proposed work, if the mobile manipulator has N degree of freedom, then it will be decomposed virtually into N subsystems. This simplifies both the control and the dynamic parameters adaptation. The validation of the developed controller is proved in real time implementation. The experimental results show the effectiveness of the proposed control schemes based on the backstepping combined with the VDC approach.
Keywords: Virtual decomposition control; adaptive backstepping control; centralized/decentralized control.
Nonlinear controllability of an underactuated two-link manipulator
by Chenzi Huang, Klaus Röbenack, Carsten Knoll
Abstract: In this contribution we show the global controllability of an underactuated two-link manipulator model using the characteristic of the system's drift vector field and weak Poisson stability. The main idea is to proof the general possibility to let the system return to its starting equilibrium point even though the state space is not compact. After this analysis a control method based on the controllability property of the system is suggested. More precisely, we concatenate flows of vector fields of the system to generate appropriate constant input values. This method is especially useful for underactuated systems which fail to meet the so-called Brockett-condition.
Keywords: Nonlinear controllability; underactuated mechanical systems; two-link
manipulator; weakly positive Poisson stability; drift vector field; Poincaré's recurrence theorem; piecewise constant input; finite horizon control.
On the fast Motion Control of R/W Head Track Following in Hard-Disc-Drives
by Manel Taktak-Meziou, Jawhar Ghommam, Nabil Derbel
Abstract: The main objective of this study is to address the track-following problem of a Read/Write (R/W) head of a Hard-Disk-Drive (HDD) servo-system in presence of external disturbances. Sliding mode algorithms ranging from classical approach (SMC) to Adaptive Continuous Twisting Algorithm (ACTA) are therefore developed to control the R/W head tip. Such a comparative study, as has never been conducted before on such a system, aims to highlight the efficiency of the Sliding Mode Control algorithms to achieve good tracking performances despite the presence of disturbances. A Continuous Twisting Algorithm (CTA) is proved to ensure finite time convergence of the system to the desired trajectory by adjusting the controller gains when the upper bound of derivative of the perturbation exists and it is well known. Then, in order to relax the constraint of knowing that bound, the ACTA control approach based on an adaptive gain is introduced. Simulation studies are presented.
Keywords: Nonlinear systems; hard-disc-drives; high precision motion; Sliding Mode Control (SMC); Adaptive control.rn.
Third order sliding mode control of a medical robot for tele-echography
by Amina Jribi
Abstract: This paper deals with the control problem of robotic manipulators, which are always subject to nonlinear uncertainties. In particular, a dynamic system with fast actuators is exposed to many disrupting risks, generally induced by the presence of parametric uncertainties and unmoderated dynamics. So the dynamic model becomes highly nonlinear, which requires the use of a robust stabilizing control. In this context, we propose a solution based on the third order Sliding Mode Control (SMC) approach, in order to ensure a performant trajectory tracking motion control for a medical task. The proposed controller is expected to remove the standard sliding mode restrictions, to provide for a higher accuracy and robustness in realization with respect to the current existence of imperfections. Simulation results confirm the effectiveness of the proposed third order SMC design with respect to disturbances, mainly affecting control systems.
Keywords: Trajectory tracking; third order sliding mode controller; manipulator robots; medical task; disturbances.
Robust Fault Detection and Accommodation for Stochastic Systems based on Adaptive Threshold
by Marwa Houiji, Rim Hamdaoui, Mohamed Aoun
Abstract: This paper treats the problem of sensor and actuator fault detection and accommodation for a linear stochastic systems subjected to unknown disturbances. A bank of Augmented Robust Three stage Kalman filters (ARThSKF) is adapted to estimate both the state and the fault as well as to generate the residuals. Besides this paper presents the evaluation of the residuals with Bayes test of binary hypothesis test for fault detection to adaptive threshold compared with fixed threshold. This test allows the detection of low magnitude faults as fast as possible with a minimum risk of errors, which reduces the probability of non detection and false alarm probability. Moreover, the result given by the fault detection and diagnosis part are then used by the Fault Accommodation (FA) that tolerates the faults and compensates its effects on the system behaviour.
Keywords: Fault Detection; Sensor and actuator failures; Stochastic Systems; Detection delay,
Adaptive Threshold; Fault accommodation.
Robust Fault Detection Based on Bond Graph UIO Observer
by Ghada Saoudi
Abstract: Motivated by recent concerns in building a totally graphical unknown
input observer (UIO), a bond graph approach to design an UIO observer for
linear systems with unknown inputs is reevaluated in this paper. By using the
Bond graph methodology and the geometric theory as the main tools, a simple
and systematic design procedure is depicted. Compared with the classical UIO
design, the built observer is a none other than the famous Luenberger observer
but with higher freedom degree that ensures the decoupling of the disturbance
and the estimation error. In the past, it was believed that the method is valid for
control purpose. Here, a new result is obtained, namely that the method is valid
also for robust fault detection purpose. On the other hand, the method is found
with no previous simulation results. In this paper, a proof with simulations results
on an electromechanical system will show the performance of the approach.
Keywords: Unknown Input Observer; Bond Graph; Geometric Approach; Robust Fault detection.
A Speed Sensor Fault Tolerant Control for Electrical Vehicle System
by Moussa Boukhnifer
Abstract: In this paper, we propose an experimental study for hybrid voting algorithm based on observer and robust control design for two mechanical sensor faults. The proposed strategy is applied for the induction motor speed drive of electrical vehicle powertrain. To adopt the best performance method for electrical vehicle application, we illustrate the effectiveness of the hybrid voting algorithm approach with the New European Driving Cycle (NEDC) speed profile. The experimental results demonstrate the effectiveness of the proposed Input/Output FTC architecture.
Keywords: Fault Tolerant Control; Induction Motor; Electric Vehicle; Sliding Mode; Voting Algorithm.
Sensor fault detection in nonlinear system using threshold estimation
by NORA KACIMI
Abstract: In this paper, an advanced study of fault diagnosis by using real data signal system. This study is online and fast application for fault diagnosis sensors. The diagnosis involves respectively two steps: fault detection and fault localization. An online fault detection approach for an experimental three tanks system is developed. This approach is based on real time signal and statistical analysis. We used the standard deviation and the mean value of several independent experimental repeated in the normal state and under the same conditions for estimating threshold of fault detection. Then, the acquisition of signal data test in real time is used to validate this threshold estimation. Also, in this research work, a proposed technique of fault detection is implemented and validated experimentally in prototype of three tanks laboratory.
Keywords: Fault detection,statistical analysis,adaptive threshold,fault sensor,three tanks system.
Adaptive Neural Super Twisting Controller Based on Terminal Sliding Mode and Time Delay Estimation Method for Robotic Manipulator.
by Amar Rezoug, Mustapha Hamerlain
Abstract: In this paper a robust control approach based on sliding mode theory and artificial neural network technique was proposed for trajectory tracking mode of n-DOF robot manipulator. Time delay estimation method and Nonsingular terminal sliding mode control were used to design the nominal control part of the sliding mode control without any knowledge about the robot model. Super twisting algorithm was designed using radial based function neural networks to replace the discontinuous control part. In order to test the effectiveness of the proposed approach, it was applied to 2-DOF robotic manipulator and compared with a classical approach.
Keywords: Terminal Sliding Mode; neural networks; Super Twisting; Time Delay Estimation.
CONTROLLING SCHEMES IN DIGITAL LOAD SIDE TRANSMISSION SYSTEM FOR INTELLIGENT LIGHTING
by T. Yuvaraja, K. Ramya, Mathudevan V
Abstract: This manuscript deals with the DLT compatible control devices in intelligent lighting systems with high output power in the designed converter. The presented methodology deals with two-wire bound power line communication. The presented topology works without a neutral wire connection and is hence applicable to all typical house installations lacking a neutral wire at the light switch lead-out and is an excellent solution for providing continuous operation of a DLT control device with WiFi, even if half waves of mains are missing or short blackouts of several half waves. DLT control devices can be embedded in a smart home environment, which is a unique feature enabled by the proposed power supply concept.
Keywords: Light Emitting Diode; Digital Load Transmission; Low Current.
Fast detection control for fault-tolerant converter back-to-back with redundancy leg supplying an induction motor drives
by Khaled Sahraoui, Bachir GAOUI, Lakhdar MOKRANI, Kelthoum BELARBI
Abstract: The purpose of this paper is the study of fault tolerant control with pulse large modulation (PWM) AC-DC-AC converter for supplying a three-phase rotor field oriented induction motor. The back to back converter is supplied with three-phase network and composed of a PWM rectifier and a voltage source inverter. Fault tolerant topology of AC-DC-AC converter with redundancy have been studied and associated with affective and fast method of fault detection and compensation to guarantee the continuity of service, in the presence of an open circuit failure possibility on the level of one of their legs. Although of the presence of open circuit on the level of the converter legs, the obtained simulation results show that the proposed method has the ability to maintain the good performance of the drive.
Keywords: Asynchrouns machine; Converter with redundant leg; Field oriented control; Service Continuity; sigma-delta PWM; Three-phase AC-DC-AC converter.
Iris recognition: using a Statistical Models of Shape and Spatial Relation for effective segmentation
by Houda Khmila
Abstract: This paper presents a new segmentation method based both on Active Shape Model (ASM) and spatial distance model to segment iris structures. The extracted iris is normalized by Daugmans Rubber Sheet model. Then the feature are extracted by the 1D Log Gabor Filter, afterwards The Hamming distance is used to compare the binary codes stored previously. The evaluation experiments are performed on a set of 300 right iris images from 41 persons of CASIA-IrisV4 database. We obtain a correct recognition rate of 100%. The experimental results have shown that the performance of the proposed approach is encouraging
Keywords: Biometrics; iris recognition; segmentation; ASM+D; identification.
Control Design and Sensors Fault Tolerant for Vehicle Dynamics
by Naoufal El Youssfi, Mohammed Oudghiri, Rachid El Bachtiri
Abstract: This paper presents a control approach based on the state feedback estimated by the observer. It also offers a method of detection and isolation of sensor defects (FDI), which is based on a bank of observers in order to apply a fault tolerant control strategy (FTC) to the lateral and roll dynamics of the vehicle represented by the fuzzy model of Takagi-Sugeno (TS). This approach makes it possible to preserve the stability of the vehicle despite the presence of sensor defects; based on the Lyapunov approach, the observer and controller designs were formulated as linear matrix inequalities (LMI); the simulation results clearly show the importance and effectiveness of the proposed strategy.
Keywords: Takagi Sugeno (TS) Fuzzy model; observer bank; controller; LMI; FTC; FDI; vehicle lateral dynamics.
Massively Parallel Hybrid Algorithm on Embedded Graphics Processing Unit for Unmanned Aerial Vehicle Path Planning
by Vincent Roberge
Abstract: To operate autonomously, military unmanned aerial vehicles (UAVs) must be equipped with a path planning module capable of calculating feasible trajectories. This is a highly complex and non-linear optimization problem that challenges state of the art methods. In this paper, we present a massively parallel hybrid algorithm to solve the path planning problem for fixed-wing military UAVs. The proposed solution combines the strengths of the genetic algorithm and the particle swarm optimization and allows for the calculation of quasi-optimal paths in realistic 3D environments. To reduce the execution time, the proposed algorithm is parallelized on the NVIDIA Jetson TX1 embedded graphics processing unit (GPU). By exploiting the parallel architecture of the GPU, the runtime is reduced by a factor of 23.6x to just 4.3 seconds while requiring only 10 Watts, making it an excellent solution for on-board path planning. The proposed system is tested in a simulation using 18 scenarios on 6 different terrains.
Keywords: hybrid metaheuristic; genetic algorithm; graphics processing units; NVIDIA Jetson TX1; particle swarm optimization; path planning; parallel computing; unmanned aerial vehicle