Observer Based Adaptive Neuro-Sliding Mode Control for MIMO Nonlinear Systems

Slim Frikha,Mohamed Djemel,Nabil Derbel 제어·로봇·시스템학회 2010 International Journal of Control, Automation, and Vol.8 No.2

In this paper, a stable adaptive neural sliding mode controller is developed for a class of multivariable uncertain nonlinear systems. For these systems not all state variables are available for measurements. By designing a state observer, adaptive neural systems, which are used to model unknown functions, can be constructed using the state estimations. Based on Lyapunov stability theorem, the proposed adaptive neural control system can guarantee the stability of the whole closed loop system and obtain good tracking performances. Adaptive laws are proposed to adjust the free parameters of the neural models. Simulation results illustrate the design procedure and demonstrate the tracking performances of the proposed controller.

A New Adaptive Neuro-sliding Mode Control for Gantry Crane

Slim Frikha,Mohamed Djemel,Nabil Derbel 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.2

This paper presents a new adaptive neuro-sliding mode control for gantry crane as varying rope length. This control method derived from combining the sliding surfaces of three subsystem of the gantry crane (trolley position, rope length, anti-swing) to draw out two system sliding surfaces: the trolley position with the anti-swing and the rope length and the anti-swing. On the based of the sliding mode control principle, drawn out the equivalent controller and the switching controller for gantry crane. But due to the uncertain parameters-nonlinear model of gantry crane with the bound disturbances, combining the neural approximate method, defined the neural controller and the compensation controller for the difference between the equivalent controller and the neural controller for two system control inputs: trolley position and rope length. The adaptive control laws for these controllers were deduced from Lyapunov’s stable criteria to asymptotically stabilize the sliding surfaces. Simulation studies are performed to illustrate the effectiveness of the proposed control.

Bit Error Probability of Noncoherent M-ary Orthogonal Modulation over Generalized Fading Channels

Simon, Marvin K.,Alouini, Mohamed-Slim The Korean Institute of Communications and Informa 1999 Journal of communications and networks Vol.1 No.2

Using a method recently reported in the literature for analyzing the bit error probability (BEP) performance of noncoherent Mary orthogonal signals with square-law combining in the presence of independent and identically distributed Nakagami-m faded paths, we are able to reformulate this method so as to apply to a generalized fading channel in which the fading in each path need not be identically distributed nor even distributed ac-cording to the same family of distribution. The method leads to exact expressions for the BEP in the form of a finite-range integral whose integrand involves the moment generating function of the combined signal-to-noise ratio and which can therefore be readily evaluated numerically. The mathematical formalism is illustrated by applying the method to some selected numerical examples of interest showing the impact of the multipath intensity profile (MIP) as well as the fading correlation profile (FCP) on the BEP performance of M-ary orthogonal signal over Nakagami-m fading channels. Thses numerical results show that both MIP and FCP induce a non-negligible degradition in the BEP and have therefore to be taken into account for the accurate prediction of the performance of such systems.

Simplified model to study the dynamic behaviour of a bolted joint and its self loosening

Olfa Ksentini,Bertrand Combes,Mohamed Slim Abbes,Alain Daidié,Mohamed Haddar 국제구조공학회 2015 Structural Engineering and Mechanics, An Int'l Jou Vol.55 No.3

Bolted joints are essential elements of mechanical structures and metal constructions. Although their static behaviour is fairly well known, their dynamic behaviour due to shocks and vibrations has been less studied, because of the large size of the finite element models needed for a detailed simulation. This work presents four different simplified models suitable for studying the dynamic behaviour of an elementary bolted joint. Three of them include contact elements to allow sliding of the screw head and the nut on the assembled parts, and the last one allows rotation between screw and nut. A penalty approach based on the Coulomb friction model is used to model contact. The results show that these models effectively represent the dynamic behaviour, with different accuracy depending on the model details. The last model simulates the self loosening of a bolt subjected to transversal vibrations.

Codebook-Based Interference Alignment for Uplink MIMO Interference Channels

이현호,박기홍,고영채,Mohamed-Slim Alouini 한국통신학회 2014 Journal of communications and networks Vol.16 No.1

In this paper, we propose a codebook-based interferencealignment (IA) scheme in the constant multiple-input multipleoutput(MIMO) interference channel especially for the uplink scenario. In our proposed scheme, we assume cooperation among basestations (BSs) through reliable backhaul links so that global channelknowledge is available for all BSs, which enables BS to computethe transmit precoder and inform its quantized index to theassociated user via limited rate feedback link.We present an upperbound on the rate loss of the proposed scheme and derive the scalinglaw of the feedback load tomaintain a constant rate loss relativeto IA with perfect channel knowledge. Considering the impact ofoverhead due to training, cooperation, and feedback, we addressthe effective degrees of freedom (DOF) of the proposed scheme andderive the maximization of the effective DOF. From simulation results,we verify our analysis on the scaling law to preserve the multiplexinggain and confirm that the proposed scheme is more effectivethan the conventional IA scheme in terms of the effective DOF.

Co‑simulation Improvement for Uncertain Flexible Robot Arm

Lilia Zouari,Mossaad Ben Ayed,Slim Chtourou,Shaya Abdullah Alshaya,Mohamed Abid 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.1

Flexible robot arm driven by Brushless DC Motor (BDCM) under uncertainties represents one of the most complex and heterogeneous system. Indeed, the verifcation phase becomes a great challenge for designers. Avoid and predict risks accurately at earlier stage represents the main purpose of the Computer-Aided Design (CAD) feld. This paper treats the case of robotics system for tracking trajectory problem and attempts to improve the verifcation phase by identifying the most suitable co-simulation technique. For the system analyzed in this paper, the fexible robot arm driven by Brushless DC actuator is verifed using the Model In the Loop (MIL) technique, the Software In the Loop (SIL) technique and CODIS+technique. Each one verifes the system according to a particular abstraction level. The performance of each technique is determined by measuring the accuracy and time simulation. Experimental results have revealed that CODIS+is the most adequate technique for fexible robot arm, outperforming MIL and SIL by 4–5 times.

An MGF-Based Unified Framework to Determine the Joint Statistics of Partial Sums of Ordered i.n.d. Random Variables

Nam, Sung Sik,Yang, Hong-Chuan,Alouini, Mohamed-Slim,Kim, Dong In Institute of Electrical and Electronics Engineers 2014 IEEE transactions on signal processing Vol. No.

<P>The joint statistics of partial sums of ordered random variables (RVs) are often needed for the accurate performance characterization of a wide variety of wireless communication systems. A unified analytical framework to determine the joint statistics of partial sums of ordered independent and identically distributed (i.i.d.) random variables was recently presented. However, the identical distribution assumption may not be valid in several real-world applications. With this motivation in mind, we consider in this paper the more general case in which the random variables are independent but not necessarily identically distributed (i.n.d.). More specifically, we extend the previous analysis and introduce a new more general unified analytical framework to determine the joint statistics of partial sums of ordered i.n.d. RVs. Our mathematical formalism is illustrated with an application on the exact performance analysis of the capture probability of generalized selection combining (GSC)-based RAKE receivers operating over frequency-selective fading channels with a non-uniform power delay profile.</P>

Performance analysis of joint switched diversity and adaptive modulation

Haewoon Nam,Young-chai Ko,Alouini, Mohamed-slim IEEE 2008 IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS Vol.7 No.10

<P>In this paper, a simple and practical system based on a switched diversity scheme with adaptive modulation is presented. This system provides a reduced number of channel estimation while offering the optimum spectral efficiency given by a selection diversity system. In addition, the switching threshold is easily manipulated so as to make an efficient use of the tradeoff between spectral efficiency and channel estimation overhead. An extension of switched diversity into a multiuser scheduling is later also considered. This switch-based multiuser access scheme results in a lower average feedback load than that for the optimal selection-based multiuser scheme. Numerical results show that we can obtain a trade-off between spectral efficiency and the feedback load by choosing the switching threshold appropriately.</P>

Performance Analysis of Two-Way Amplify and Forward Relaying with Adaptive Modulation over Multiple Relay Network

Kyu-Sung Hwang,Young-Chai Ko,Alouini, Mohamed-Slim IEEE 2011 IEEE TRANSACTIONS ON COMMUNICATIONS Vol.59 No.2

<P>In this letter, we propose two-way amplify-and-forward relaying in conjunction with adaptive modulation in order to improve spectral efficiency of relayed communication systems while monitoring the required error performance. We also consider a multiple relay network where only the best relay node is utilized so that the diversity order increases while maintaining a low complexity of implementation as the number of relays increases. Based on the best relay selection criterion, we offer an upper bound on the signal-to-noise ratio to keep the performance analysis tractable. Our numerical examples show that the proposed system offers a considerable gain in spectral efficiency while satisfying the error rate requirements.</P>

Outage Performance of Opportunistic Two-Way Amplify-and-Forward Relaying with Outdated Channel State Information

Kyu-Sung Hwang,MinChul Ju,Alouini, Mohamed-Slim IEEE 2013 IEEE TRANSACTIONS ON COMMUNICATIONS Vol.61 No.9

<P>In this paper, we study the outage performance of an amplify-and-forward (AF)-based two-way relaying (TWR) system with multiple relays where a single relay selection is performed based on outdated channel state information (CSI). Specifically, we propose a single relay selection scheme in AF-based TWR system under outdated CSI conditions. With this policy, we offer a statistical analysis of the signal-to-noise ratio per hop and analyze the outage probability with asymmetric outage thresholds based on CSI-assisted AF protocol. Additionally, we provide the exact and asymptotic expressions based on the provided statistical/joint statistical analyses of a dual-hop AF transmission. Finally, we verify our analytical results with some selected computer-based simulation results.</P>