In this paper we suggest a method to control the chaotic behavior of the stepper motor into a per... more In this paper we suggest a method to control the chaotic behavior of the stepper motor into a periodic one. In fact, using the supply frequency as a bifurcation parameter, we show that as the frequency is increased beyond a critical value the motor steps become irregular and even chaotic hence it becomes unpractical to be controlled in open loop mode. To circumvent the problem we propose a slight perturbation to the frequency in order to regularize the steps for high frequencies. The approach consists in using several heuristic methods such as Practical Swarm Optimization (PSO), Genetic Algorithms (GA) and Ant Colony Optimization (ACO) to obtain the optimal switching instances which define the change in the supply state (polarization). The numerical simulations performed on a stepper model show that regularization of the motor steps can be achieved for a large range of power supply frequencies ranging from quasiperiodic behavior to chaotic behavior. , GA PSO J J and ACO J be the three global criteria of the three optimization algorithms given by the three following equations: 1 2 3 = + + GA GA GA GA J J J J PSO PSO PSO PSO J J J J (19) 1 2 3 = + + ACO ACO ACO ACO J J J J
14th International Conference on Sciences and Techniques of Automatic Control & Computer Engineering - STA'2013, 2013
ABSTRACT Sliding mode control (SMC) has been considered as an effective tool in different studies... more ABSTRACT Sliding mode control (SMC) has been considered as an effective tool in different studies for control systems. The robustness of SMC against the disturbances and model uncertainties makes the system stable. However, the chattering phenomenon degrades the system performances, it may even lead to instability. This paper deals with the second order sliding mode the twisting and super-twisting algorithm to solve the tracking control of underactuated manipulators. Further, comparison between controllers has been done. Simulation results are given to demonstrate the effectiveness of the proposed approaches.
International Journal of Automation and Computing, 2015
ABSTRACT In this paper, first-order and second-order sliding mode controllers for underactuated m... more ABSTRACT In this paper, first-order and second-order sliding mode controllers for underactuated manipulators are proposed. Sliding mode control (SMC) is considered as an effective tool in different studies for control systems. However, the associated chattering phenomenon degrades the system performance. To overcome this phenomenon and track a desired trajectory, a twisting, a super-twisting and a modified super-twisting algorithms are presented respectively. The stability analysis is performed using a Lyapunov function for the proposed controllers. Further, the four different controllers are compared with each other. As an illustration, an example of an inverted pendulum is considered. Simulation results are given to demonstrate the effectiveness of the proposed approaches.
2008 5th International Multi-Conference on Systems, Signals and Devices, 2008
Controlling an underactuated manipulator with less actuators than degree of freedom is a challeng... more Controlling an underactuated manipulator with less actuators than degree of freedom is a challenging problem, specifically when it is to force the underactuated manipulator to track a given trajectory or to be configurated at a specific position in the work space. This paper presents a cascade sliding mode tracking controller for set-point regulation of 2-DOF underactuated manipulators. This work builds on an observation that an underactuated manipulator can be treated as two subsystems. Consequently, a cascade sliding mode tracking controller can be designed as follows. First, a sliding mode surface is designed for both subsystems, this two sliding surfaces represent a first layer in the design architecture. A second layer sliding mode surface is then constructed based on the first layer sliding surface. The cascaded sliding mode controller is therefor deduced in terms of Lyapunov stability theorem. Robustness issues to bounded disturbances are then investigated. Simulation results on 2-DOF whiling pendulum are presented to demonstrate the effectiveness of the approach.
In this paper we suggest a method to control the chaotic behavior of the stepper motor into a per... more In this paper we suggest a method to control the chaotic behavior of the stepper motor into a periodic one. Using the supply frequency as a bifurcation parameter we show that as the frequency is increased beyond a critical value the motor steps become irregular and even chaotic hence it becomes unpractical to be controlled in open loop mode. To circumvent the problem we propose a slight perturbation to the frequency in order to regularize the steps for high frequencies. The approach consists in using a genetic algorithm to obtain the optimal switching instances which define the change in the supply state. The numerical simulations performed on a stepper model show that regularization of the motor steps can be achieved for a large range of power supply frequencies.
This paper deals with robust control problem of an electropneumatic system subjected to parameter... more This paper deals with robust control problem of an electropneumatic system subjected to parameters uncertainties and load disturbances. The control strategies are based on passivity control approaches. First, the nonlinear model of the electropneumatic system is presented. Then, a nonlinear control law is developed without depending on the mass of the carriage, to track desired position. Experimental results for various
Communications in Nonlinear Science and Numerical Simulation, 2015
In this paper, we are interested in the control of a chaotic hybrid system with an application to... more In this paper, we are interested in the control of a chaotic hybrid system with an application to Chua's system. It is known that chaotic attractors contain an infinite number of unstable periodic orbits (UPO) with different lengths, our idea consists in stabilizing a predetermined orbit of a given length by using an optimal control method. Our approach is to determine the switching instants from one subsystem to the other while minimizing the difference between two successive orbits. Should the switchings be state dependent, as is the case for the well known Chua's circuit, then our approach consists in perturbing the switching boundaries such that the system trajectory hits those boundaries at the specified instants. Numerical simulations illustrating the efficiency of the proposed method are presented. open loop control system. A chaotic macroeconomic growth cycle [30] is unpredictable and leads to difficulty in organizing long delay projects. The aforementioned examples indicate that rendering a chaotic system periodic is a worthy endeavor.
This work is aimed at looking into the determination of optimal neuro-feedback control for discre... more This work is aimed at looking into the determination of optimal neuro-feedback control for discrete time nonlinear systems. The basic idea consists in the use of two coupled neural networks to approximate the solution of the Hamilton-Jacobi-Bellman equation (HJB) and to obtain a robust feedback closedloop control law. The used learning algorithm is a modified version of the backpropagation one. As an illustration, a numerical nonlinear discrete time example is considered. Simulation results show the effectiveness of the proposed method.
2008 5th International Multi-Conference on Systems, Signals and Devices, 2008
... 3083, Sfax, Tunisia (2)Laboratoire d'Etude et de Commande Automatique des Processus (LEC... more ... 3083, Sfax, Tunisia (2)Laboratoire d'Etude et de Commande Automatique des Processus (LECAP) Ecole polytechnique de Tunisie Email: [email protected] houssem.jerbi@fss ... In a first step, an algorithm for analytical exact input-state linearizing control is formulated ...
ABSTRACT The aim of this paper concerns motion control and robust path tracking design for square... more ABSTRACT The aim of this paper concerns motion control and robust path tracking design for square MIMO systems. A path tracking approach using fractional differentiation is proposed, based on direct optimization of an I/O Davidson-Cole type transfer function. The main important property of this transfer function is that it does not present overshoot on its output and allows synthesis with only two parameters to obtain an optimal settling time. The SISO approach was presented in previous works. This paper presents an extension for square multivariable systems. Using MIMO-QFT robust synthesis methodology and taking into account the plant uncertainties, the fractional prefilters are deduced. This method specifically deals with the appropriate transformation of the MIMO system to the equivalent MISO system. The optimization of the two prefilter parameters is founded on the plant output error integral minimization, considering the actuators physical constraints and the tracking performance specifications. A numerical example is considered to indicate performances of the used procedure.
2008 2nd International Conference on Signals, Circuits and Systems, 2008
In this paper, we present a VSS-based tracking control for a fixed point regulation of 2-DOF unde... more In this paper, we present a VSS-based tracking control for a fixed point regulation of 2-DOF underactuated manipulators. The design approach is systematic and relies on the selection of appropriate choice of two sliding surface. The controller is designed for the both sliding surfaces are attractive. Lyapunov theory is used to study and demonstrate the stability of the system. Convergence
International Journal of Modelling Identification and Control, 2010
ABSTRACT This paper presents fuzzy logic controller (FLC) design using optimisation techniques. T... more ABSTRACT This paper presents fuzzy logic controller (FLC) design using optimisation techniques. The FLC has been developed and implemented for the motion of the robot from an initial position towards another desired position, taking into account the kinematic constraints. First, we have carried out a simulation of a fuzzy logic based controller which determines the speed values of each driving wheel, while the robot seeking the goal. Second, an optimisation of this controller has been realised using gradient method or genetic algorithms. Simulation and experimental results demonstrates the effectiveness of the proposed approach.
Signal-Image Technology and Internet-Based Systems, 2005
Texture segmentation via wavelet transform traditionally adopts textural features based approach.... more Texture segmentation via wavelet transform traditionally adopts textural features based approach. However, applying this method can lead to over- segmentation problems. To overcome this limitation, we propose a new scheme of texture segmentation. The proposed approach will be applied to remotely sensed images for vegetation extraction. The key idea is that we precede wavelet transform by a preliminary step for
Engineering Applications of Artificial Intelligence, Sep 1, 2002
This paper is aimed at looking into the automatic design and the size reduction of the rule base ... more This paper is aimed at looking into the automatic design and the size reduction of the rule base of fuzzy logic controllers. The first part is concerned with an automatic generation method of the fuzzy rule base. This is done by the use of an intelligent optimization method, and its implementation to the design of a fuzzy controller for robot manipulators. It is assumed that such system is known but ill-defined because of the inherent uncertainties associated with the model. Thus, an accurate mathematical model is not required, but a simplified one is acceptable. The second part treats the reduction of large scale fuzzy rule bases. Two approaches are used for this purpose: the boolean method and the decoupling approach giving a local control loop yielding smaller fuzzy controllers.The boolean approach is based on the equivalence between fuzzy preconditions and on boolean expressions. Using the fact that fuzzy sets are a generalization of classical subsets, we introduced some operations on fuzzy sets that are equivalent to those applied in the boolean logic approach.The paper then discusses the reduction of large scale fuzzy rule bases by the use of a decoupling approach, and its application to the case of an optimal fuzzy logic controller of a three-links robot manipulator using local PID controllers.
In this paper we suggest a method to control the chaotic behavior of the stepper motor into a per... more In this paper we suggest a method to control the chaotic behavior of the stepper motor into a periodic one. In fact, using the supply frequency as a bifurcation parameter, we show that as the frequency is increased beyond a critical value the motor steps become irregular and even chaotic hence it becomes unpractical to be controlled in open loop mode. To circumvent the problem we propose a slight perturbation to the frequency in order to regularize the steps for high frequencies. The approach consists in using several heuristic methods such as Practical Swarm Optimization (PSO), Genetic Algorithms (GA) and Ant Colony Optimization (ACO) to obtain the optimal switching instances which define the change in the supply state (polarization). The numerical simulations performed on a stepper model show that regularization of the motor steps can be achieved for a large range of power supply frequencies ranging from quasiperiodic behavior to chaotic behavior. , GA PSO J J and ACO J be the three global criteria of the three optimization algorithms given by the three following equations: 1 2 3 = + + GA GA GA GA J J J J PSO PSO PSO PSO J J J J (19) 1 2 3 = + + ACO ACO ACO ACO J J J J
14th International Conference on Sciences and Techniques of Automatic Control & Computer Engineering - STA'2013, 2013
ABSTRACT Sliding mode control (SMC) has been considered as an effective tool in different studies... more ABSTRACT Sliding mode control (SMC) has been considered as an effective tool in different studies for control systems. The robustness of SMC against the disturbances and model uncertainties makes the system stable. However, the chattering phenomenon degrades the system performances, it may even lead to instability. This paper deals with the second order sliding mode the twisting and super-twisting algorithm to solve the tracking control of underactuated manipulators. Further, comparison between controllers has been done. Simulation results are given to demonstrate the effectiveness of the proposed approaches.
International Journal of Automation and Computing, 2015
ABSTRACT In this paper, first-order and second-order sliding mode controllers for underactuated m... more ABSTRACT In this paper, first-order and second-order sliding mode controllers for underactuated manipulators are proposed. Sliding mode control (SMC) is considered as an effective tool in different studies for control systems. However, the associated chattering phenomenon degrades the system performance. To overcome this phenomenon and track a desired trajectory, a twisting, a super-twisting and a modified super-twisting algorithms are presented respectively. The stability analysis is performed using a Lyapunov function for the proposed controllers. Further, the four different controllers are compared with each other. As an illustration, an example of an inverted pendulum is considered. Simulation results are given to demonstrate the effectiveness of the proposed approaches.
2008 5th International Multi-Conference on Systems, Signals and Devices, 2008
Controlling an underactuated manipulator with less actuators than degree of freedom is a challeng... more Controlling an underactuated manipulator with less actuators than degree of freedom is a challenging problem, specifically when it is to force the underactuated manipulator to track a given trajectory or to be configurated at a specific position in the work space. This paper presents a cascade sliding mode tracking controller for set-point regulation of 2-DOF underactuated manipulators. This work builds on an observation that an underactuated manipulator can be treated as two subsystems. Consequently, a cascade sliding mode tracking controller can be designed as follows. First, a sliding mode surface is designed for both subsystems, this two sliding surfaces represent a first layer in the design architecture. A second layer sliding mode surface is then constructed based on the first layer sliding surface. The cascaded sliding mode controller is therefor deduced in terms of Lyapunov stability theorem. Robustness issues to bounded disturbances are then investigated. Simulation results on 2-DOF whiling pendulum are presented to demonstrate the effectiveness of the approach.
In this paper we suggest a method to control the chaotic behavior of the stepper motor into a per... more In this paper we suggest a method to control the chaotic behavior of the stepper motor into a periodic one. Using the supply frequency as a bifurcation parameter we show that as the frequency is increased beyond a critical value the motor steps become irregular and even chaotic hence it becomes unpractical to be controlled in open loop mode. To circumvent the problem we propose a slight perturbation to the frequency in order to regularize the steps for high frequencies. The approach consists in using a genetic algorithm to obtain the optimal switching instances which define the change in the supply state. The numerical simulations performed on a stepper model show that regularization of the motor steps can be achieved for a large range of power supply frequencies.
This paper deals with robust control problem of an electropneumatic system subjected to parameter... more This paper deals with robust control problem of an electropneumatic system subjected to parameters uncertainties and load disturbances. The control strategies are based on passivity control approaches. First, the nonlinear model of the electropneumatic system is presented. Then, a nonlinear control law is developed without depending on the mass of the carriage, to track desired position. Experimental results for various
Communications in Nonlinear Science and Numerical Simulation, 2015
In this paper, we are interested in the control of a chaotic hybrid system with an application to... more In this paper, we are interested in the control of a chaotic hybrid system with an application to Chua's system. It is known that chaotic attractors contain an infinite number of unstable periodic orbits (UPO) with different lengths, our idea consists in stabilizing a predetermined orbit of a given length by using an optimal control method. Our approach is to determine the switching instants from one subsystem to the other while minimizing the difference between two successive orbits. Should the switchings be state dependent, as is the case for the well known Chua's circuit, then our approach consists in perturbing the switching boundaries such that the system trajectory hits those boundaries at the specified instants. Numerical simulations illustrating the efficiency of the proposed method are presented. open loop control system. A chaotic macroeconomic growth cycle [30] is unpredictable and leads to difficulty in organizing long delay projects. The aforementioned examples indicate that rendering a chaotic system periodic is a worthy endeavor.
This work is aimed at looking into the determination of optimal neuro-feedback control for discre... more This work is aimed at looking into the determination of optimal neuro-feedback control for discrete time nonlinear systems. The basic idea consists in the use of two coupled neural networks to approximate the solution of the Hamilton-Jacobi-Bellman equation (HJB) and to obtain a robust feedback closedloop control law. The used learning algorithm is a modified version of the backpropagation one. As an illustration, a numerical nonlinear discrete time example is considered. Simulation results show the effectiveness of the proposed method.
2008 5th International Multi-Conference on Systems, Signals and Devices, 2008
... 3083, Sfax, Tunisia (2)Laboratoire d'Etude et de Commande Automatique des Processus (LEC... more ... 3083, Sfax, Tunisia (2)Laboratoire d'Etude et de Commande Automatique des Processus (LECAP) Ecole polytechnique de Tunisie Email: [email protected] houssem.jerbi@fss ... In a first step, an algorithm for analytical exact input-state linearizing control is formulated ...
ABSTRACT The aim of this paper concerns motion control and robust path tracking design for square... more ABSTRACT The aim of this paper concerns motion control and robust path tracking design for square MIMO systems. A path tracking approach using fractional differentiation is proposed, based on direct optimization of an I/O Davidson-Cole type transfer function. The main important property of this transfer function is that it does not present overshoot on its output and allows synthesis with only two parameters to obtain an optimal settling time. The SISO approach was presented in previous works. This paper presents an extension for square multivariable systems. Using MIMO-QFT robust synthesis methodology and taking into account the plant uncertainties, the fractional prefilters are deduced. This method specifically deals with the appropriate transformation of the MIMO system to the equivalent MISO system. The optimization of the two prefilter parameters is founded on the plant output error integral minimization, considering the actuators physical constraints and the tracking performance specifications. A numerical example is considered to indicate performances of the used procedure.
2008 2nd International Conference on Signals, Circuits and Systems, 2008
In this paper, we present a VSS-based tracking control for a fixed point regulation of 2-DOF unde... more In this paper, we present a VSS-based tracking control for a fixed point regulation of 2-DOF underactuated manipulators. The design approach is systematic and relies on the selection of appropriate choice of two sliding surface. The controller is designed for the both sliding surfaces are attractive. Lyapunov theory is used to study and demonstrate the stability of the system. Convergence
International Journal of Modelling Identification and Control, 2010
ABSTRACT This paper presents fuzzy logic controller (FLC) design using optimisation techniques. T... more ABSTRACT This paper presents fuzzy logic controller (FLC) design using optimisation techniques. The FLC has been developed and implemented for the motion of the robot from an initial position towards another desired position, taking into account the kinematic constraints. First, we have carried out a simulation of a fuzzy logic based controller which determines the speed values of each driving wheel, while the robot seeking the goal. Second, an optimisation of this controller has been realised using gradient method or genetic algorithms. Simulation and experimental results demonstrates the effectiveness of the proposed approach.
Signal-Image Technology and Internet-Based Systems, 2005
Texture segmentation via wavelet transform traditionally adopts textural features based approach.... more Texture segmentation via wavelet transform traditionally adopts textural features based approach. However, applying this method can lead to over- segmentation problems. To overcome this limitation, we propose a new scheme of texture segmentation. The proposed approach will be applied to remotely sensed images for vegetation extraction. The key idea is that we precede wavelet transform by a preliminary step for
Engineering Applications of Artificial Intelligence, Sep 1, 2002
This paper is aimed at looking into the automatic design and the size reduction of the rule base ... more This paper is aimed at looking into the automatic design and the size reduction of the rule base of fuzzy logic controllers. The first part is concerned with an automatic generation method of the fuzzy rule base. This is done by the use of an intelligent optimization method, and its implementation to the design of a fuzzy controller for robot manipulators. It is assumed that such system is known but ill-defined because of the inherent uncertainties associated with the model. Thus, an accurate mathematical model is not required, but a simplified one is acceptable. The second part treats the reduction of large scale fuzzy rule bases. Two approaches are used for this purpose: the boolean method and the decoupling approach giving a local control loop yielding smaller fuzzy controllers.The boolean approach is based on the equivalence between fuzzy preconditions and on boolean expressions. Using the fact that fuzzy sets are a generalization of classical subsets, we introduced some operations on fuzzy sets that are equivalent to those applied in the boolean logic approach.The paper then discusses the reduction of large scale fuzzy rule bases by the use of a decoupling approach, and its application to the case of an optimal fuzzy logic controller of a three-links robot manipulator using local PID controllers.
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Papers by Nabil Derbel