Forthcoming articles

 


International Journal of Modelling, Identification and Control

 

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International Journal of Modelling, Identification and Control (71 papers in press)

 

Regular Issues

 

  • Designing Route Guidance Strategy with Travellers Stochastic Compliance: A Bi-level Optimal Control Procedure
    by Wei-li Sun, Ling-long Hu, Ping Li, Hui Wang 
    Keywords: .

  • Robust Q-parameterisation control for nonlinear magnetic bearing systems with imbalance based on TSK fuzzy model   Order a copy of this article
    by Mohamed Fekry, Abdelfatah M. Mohamed, Mohamed Fanni 
    Abstract: This paper presents a methodology for designing a robust gain scheduled Takagi-Sugeno-Kang (TSK) fuzzy Q-parameterisation controller for nonlinear magnetic bearing systems subjected to imbalanced sinusoidal disturbance. First, the mathematical model of nonlinear magnetic bearing is presented. Second, a set of Q-parameterisation observer based stabilising controllers is obtained, based on linearisation of the nonlinear system at different operating points. Third, the structure that combines the Q-parameterisation observer based controller (OBC) with TSK fuzzy modelling to overcome the model nonlinearity and expand the operating envelop is explained. Fourth, the proposed controller is applied to a nonlinear magnetic bearing system. Finally, the simulation results are presented. The results clearly show that the proposed controller is able to merge the intelligence of fuzzy systems with robustness of Q-parameterisation control to extend the operating range up to more than 80% of the gap length and reject imbalanced sinusoidal disturbances at different operating speeds.
    Keywords: distribution control; robust control; robust stability; fuzzy supervision; Q-parameterisation; magnetic bearings.

  • A sentiment analysis approach based on exploiting Chinese linguistic features and classification   Order a copy of this article
    by Kai Gao, Shu Su, Dan-yang Li, Shan-shan Zhang, Jiu-shuo Wang 
    Abstract: This paper proposes a novel approach to exploiting linguistic features and SVMperf algorithm based semantic classification, and this approach is applied into sentiment analysis. It uses the dependency relationship to do the linguistic feature extraction. This paper adopts χ2 (chi-square) and Pointwise Mutual Information (PMI) metrics for feature selection. Furthermore, as for the approach on sentiment analysis, this paper uses the SVMperf algorithm to implement the alternative structural formulation of the SVM optimisation problem for classification. E-commerce datasets are used to evaluate the experiment performance. Experiment results show the feasibility of the approach. Existing problems and further works are also presented.
    Keywords: sentiment analysis; linguistic feature; SVMperf; classification.

  • Adaptive Neural Networks for AC Voltage Sensorless Control of Three-Phase PWM Rectifiers
    by Adel RAHOUI, Hamid SEDIKI, Ali BECHOUCHE, Djaffar OULD ABDESLAM 
    Abstract: In this paper, a new adaptive grid voltages estimator for AC voltage sensorless control of three-phase pulse-width modulation (PWM) rectifier is proposed. The proposed method is based on a simple adaptive neural network (ANN) to estimate online the grid voltages. The main advantage of this method is its simplicity and it requires low computational cost. The ANN estimator is inserted in voltage-oriented control (VOC) to perform an AC voltage sensorless control scheme. During the startup process, the proposed ANN estimator is also used for estimating initial values of the grid voltages. For accurate estimation, adaptive neural filters (ANFs)-based pre-filtering stage of the input voltages and AC-line currents is added. Experimental tests are carried out to verify the feasibility and robustness of the proposed ANN estimator. Experimental results show good performances of the proposed AC voltage sensorless control scheme in normal and severe grid voltage conditions.
    Keywords: Adaptive neural network (ANN), Adaptive neural filter (ANF), pulse-width modulation (PWM) rectifier, diode rectifier, grid voltages estimation, voltage-oriented control (VOC), sensorless control, startup process, experimental verification, stability

  • Time Delay Finite Time Control of Unified Power Flow Controller for Power Flow Reference Tracking
    by Amar HAMACHE, Mohand Outahar BENSIDHOUM, Hachemi CHEKIREB 
    Abstract: This paper presents a Time Delay Finite Time Controller (TDFTC) applied to a unified power flow controller (UPFC) to achieve rapid and finite time reference signal tracking of power flow in presence of plant uncertainties. The TDFTC is a nonlinear control based on the time delay disturbance estimator and the Lyapunov's stability theory to estimate the disturbances and cancel them. The TDFTC overcomes the drawback of traditional linear PI control, which is typically tuned for one specific operating condition and reduces chattering by using lower design gains. In this paper, first a state space complete dynamic model of UPFC is established based on Kirchhoff’s equations and (d-q) transformation and then TDFTC law is developed for the UPFC system. The proposed control is validated via a detailed simulation on a two bus system. Simulation results show power, effectiveness, robustness and accuracy of the proposed controller.
    Keywords: Power Flow; Unified Power Flow Controller; Time Delay Estimation; Finite Time Control; Lyapunov Function

  • Complete Synchronization of Supply Chain System Using Adaptive Integral Sliding Mode Control Method
    by Hamed Tirandaz 
    Abstract: In this paper, synchronization problem of supply chain chaotic system is carried out with active and adaptive integral sliding mode controlling method. Active integral sliding mode synchronization is performed for two identical supply chain systems by assuming that all parameters of the systems are known. When the internal and external distortion parameters of the system are considered unknown, an appropriate feedback controller is developed based on the adaptive integral sliding mode control mechanismrnto synchronize two identical supply chain chaotic systems and to estimate the unknown parameters of the systems. The stability evaluation of the synchronization methods are performed by the Lyapunov stability theorem. In addition, the performance evaluation of the designed controllers and the theoretical analysis are verified by some illustrative numerical simulations. Simulation results indicate excellent convergence from both speed and accuracy points of view.
    Keywords: Supply chain system, Integral sliding mode control, Active control, Adaptive control

  • Enhanced receding horizon optimal performance for online tuning of PID controller parameters   Order a copy of this article
    by Shaoyuan Li, Yongling Wu, Kang Li 
    Abstract: In this paper, a new online Proportional-Integral-Derivative (PID) controller parameter optimisation method is proposed by incorporating the philosophy of the model predictive control (MPC) algorithm. The future system predictive output and control sequence are first written as a function of the controller parameters. Then the PID controller design is realised through optimising the cost function under the constraints on the system input and output. The MPC-based PID online tuning easily handles the constraints and time delay. Simulation results in three situations, changing the control weight, adding constraints on the overshoot, and control signal and changing the reference value, confirm that the proposed method is capable of producing good tracking performance with low energy consumption and short settling time.
    Keywords: online parameter optimisation; PID controller; model predictive control; tracking performance; control energy.

  • Estimation of the order and the memory of Volterra model from input/output observations   Order a copy of this article
    by Safa Chouchane, Kais Bouzrara, Hassani Messaoud 
    Abstract: This paper proposes a new method to estimate, from input/output measurements, the structure parameters (order and memory) of Volterra models used for describing nonlinear systems. For each structure parameter (order and memory), the identification method is based on the definition, for increasing values of such parameters, of a specific matrix the components of which are lagged inputs and lagged outputs. This matrix becomes singular once the parameter value exceeds its exact value. The proposed method is tested in numerical examples, then it is used to model a chemical reactor. The results are successful.
    Keywords: nonlinear system; Volterra model; structure estimation; determinant ratio.

  • Prescribed performance control for MDF continuous hot pressing hydraulic system   Order a copy of this article
    by Liangkuan Zhu, Zibo Wang, Xiaodong Shao, Yaqiu Liu 
    Abstract: In this paper, a prescribed performance control scheme is proposed for a medium density fibreboard (MDF) continuous hot pressing hydraulic system. The performance issues regarding transient and steady state behaviours are explicitly considered in the control design and analysis. First, a special error transformation is introduced into the first subsystem to transform original system with performance constraints into an equivalent 'output constrained' one to achieve prescribed performance guarantees. Subsequently, based on an appropriately designed barrier Lyapunov function (BLF), a controller is designed to stabilise the transformed system. Meanwhile, the novel error transformation effectively facilitates the control law derivation. It is proven that the proposed controller is capable of guaranteeing the satisfaction of the specific constraints on the transformed error and hence the prescribed performance specifications on the position tracking error, as well as the bounds of all closed-loop signals. In particular, in the second step of the controller design, a first-order filter is used in conjunction with the traditional backstepping control to eliminate the differential term expansion caused by the derivative of virtual control input. Finally, numerical simulation results are presented to authenticate and validate the effectiveness of the proposed control scheme.
    Keywords: medium density fibreboard; hydraulic system; guaranteed transient performance; barrier Lyapunov function; backstepping control; first-order filter.

  • Self-adaptative multi-kernel algorithm for switched linear systems identification   Order a copy of this article
    by Lamaa Sellami 
    Abstract: This paper deals with the identification problem of switched linear systems based on a measurement dataset. The great challenge of this problem lies in the dataset available for identification. Indeed, this set is a mixture of observations generated by a finite set of different linear submodels that interchange between each other with an unknown and unavailable switching dynamics. To overcome this problem, we developed an identification approach that consists of determining simultaneously a linear regression function that models each submodel and a switching signal estimation via a self-adaptive clustering algorithm. The regression function is identified based on the multi-kernel Support Regression Vector (SVR) approach. This identification approach consists of decomposing the regression vector into several blocks and assigning a kernel function to each block. However, the switching signal estimate is provided by an unsupervised classification algorithm with self-adaptive capacities. According to a similarity measure, this identification process is achieved through three main stages: classes creation (with an initialisation procedure), online classes adaptation and classes fusion. To evaluate the performance of the proposed method we include some simulation results.
    Keywords: switched linear systems; system identification; multi-kernel support regression; machine learning.

  • Intensity-curvature highlight of human brain magnetic resonance imaging vasculature   Order a copy of this article
    by Carlo Ciulla, Ustijana Rechkoska Shikoska, Dimitar Veljanovski, Filip A. Risteski 
    Abstract: This paper uses the concept of intensity-curvature to highlight human brain vasculature imaged through Magnetic Resonance Imaging (MRI). Two model functions are fitted to the MRI data. The model functions are: (i) the bivariate cubic polynomial (B32D), and (ii) the bivariate cubic Lagrange polynomial (G42D). The sum of all of the second order partial derivatives with respect to the independent variables of the model function is calculated and is called classic-curvature. The classic-curvature is therefore a function of the independent variables and it can be calculated at the origin (0, 0) of the pixel coordinate system and also at any intra-pixel coordinate (x, y). The antiderivative of the product between the classic-curvature calculated at (0, 0) and the image pixel intensity is called intensity-curvature term (ICT) before interpolation. The antiderivative of the product between the classic-curvature calculated at (x, y) and the model function is called intensity-curvature term (ICT) after interpolation. When the two intensity-curvature terms are calculated on a pixel-by-pixel basis across the image, they become two additional images. Through the use of the aforementioned ICT images, it is possible to highlight and filter the human brain vasculature imaged with MRI. Moreover, the inverse Fourier transformation of the difference between the k-space of the MRI and the k-space of the ICT provides vessel identification. In essence, this research presents evidence that MRI images of the human brain can be studied through two additional domains: the intensity-curvature terms.
    Keywords: bivariate cubic polynomial model; bivariate cubic Lagrange polynomial model; intensity-curvature term before interpolation; intensity-curvature term after interpolation; magnetic resonance imaging; k-space; human brain; vasculature.

  • Stabilisation of a class of non-minimum phase switched nonlinear systems based on backstepping method   Order a copy of this article
    by Arwa Abdelkrim, Khalil Jouili, Naceur Benhadj Braiek 
    Abstract: This paper addresses the formalism of the input-output feedback linearisation applied to a certain class of switched nonlinear systems, where each mode may be a non-minimum phase, to design state feedback controllers and a switching law based on multi-Lyapunov functions. The performed developments are largely based on a backstepping approach and multiple Lyapunov functions. The state feedback controllers and the switching law are developed to stabilise the transitions between the stability regions associated with each mode with non-minimum phase. Finally, simulation results of a non-minimum phase continuously stirred tank reactor show the effectiveness of the method.
    Keywords: backstepping; stabilisation; switched nonlinear systems; non-minimum phase; multiple Lyapunov functions; input–output feedback linearisation.

  • Adaptive decentralised sliding mode controller and observer for asynchronous nonlinear large scale systems with backlash   Order a copy of this article
    by Ahmad Taher Azar, Fernando E. Serrano 
    Abstract: In this article an adaptive decentralised sliding mode controller and observer for asynchronous nonlinear large scale systems with backlash are proposed. In the literature, only the synchronous case for input nonlinearities such as dead-zone and saturation are found. In this article, the asynchronous case for systems with backlash is studied considering the backlash effect. Owing to the complexity of the backlash nonlinearity, an adaptive decentralised controller is proposed because of the capability of this strategy to deal with uncertainties and to improve the system performance when this nonlinearity is found. Additionally, a decentralised sliding mode observer is proposed in order to estimate the states of the system.
    Keywords: decentralised control; switched systems; sliding mode control; asynchronous control.

  • D-stability of parameter-dependent linear systems including discretization by Taylor series expansion and search in a scalar parameter.
    by Marco Aurelio Leandro, karl Kienitz 
    Abstract: This work addresses the allocation of the closed-loop poles of a discretized system from a continuous-time one with varying parameters, aiming at its control through a computer. It proposes a sufficient condition for an allocating state feedback with parameter-dependent gain. The condition is veri ed through a feasibility test of a set of Linear Matrix Inequalities (LMIs), based on the existence of a homogeneous polynomially parameter-dependent Lyapunov function of arbitrary degree. The main contribution of this work is the guarantee of the continuous-time system's stability and simultaneously the allocation of the closed-loop poles of the discretized system in a D-stable region. In order to allow this, the discretized model is formed by homogeneous polynomial matrices of arbitrary degree, augmented by an additive norm-bounded term, which represents the discretization residual error. Numerical examples show a larger number of feasible cases associated to the proposed condition in comparison with the condition based on a parameter-independent gain.
    Keywords: Robust control; D-stability; discrete-time linear systems; parameter-dependent state feedback; linear matrix inequalities.

  • A novel four-dimensional conservative chaotic system without linear term, its analysis and adaptive control via integral sliding mode control   Order a copy of this article
    by Sundarapandian Vaidyanathan 
    Abstract: In this work, a novel conservative four-dimensional chaotic system without linear term is proposed. The fundamental qualitative properties of the novel chaotic system are described with details of volume-preserving property, equilibrium points, symmetry, Lyapunov exponents and Kaplan-Yorke dimension. We show that the novel four-dimensional chaotic system has two planes and one line of equilibrium points. Next, an adaptive integral sliding mode controller is designed to stabilise the novel chaotic system with an unknown system parameter. Moreover, an adaptive integral sliding mode controller is designed to achieve global chaos synchronisation of the identical novel chaotic systems with an unknown system parameter. The adaptive control mechanism helps the control design by estimating the unknown parameter. Numerical simulations using MATLAB are shown to illustrate all the main results derived in this work.
    Keywords: chaos; chaotic systems; novel system; adaptive control; sliding mode control; chaos synchronisation.

  • Feedback control of bilinear distributed parameter system by input-output linearization
    by Nouara HABRACHE, Ahmed MAIDI, Jean-Pierre Corriou 
    Abstract: In this paper, a control law that enforces the tracking of a boundary controlled output for a bilinear distributed parameter system is developed in the framework of geometric control. The dynamic behavior of the system is described by two weakly coupled linear hyperbolic partial differential equations. The stability of the resulting closed-loop system is investigated based on eigenvalues of the spatial operator of a weakly coupled system of balance equations. It is shown that, under some reasonable assumptions, the stability condition is related to the choice of the tuning parameter of the control law. The performance of the developed control law is demonstrated, through numerical simulation, in the case of a co-current heat exchanger. The control objective is to control the outlet cold fluid temperature by manipulating its velocity. Both tracking and disturbance rejection problems are considered.
    Keywords: partial differential equation; bilinear distributed parameter system; geometric control; characteristic index; exponential stability; co-current heat exchanger

  • Whole body motion generation of 18-DOF biped robot on flat surface during single support phase and double support phase   Order a copy of this article
    by Ravi Kumar Mandava, Pandu Ranga Vundavilli 
    Abstract: The present work explains the dynamically balanced gait generation of a 18-DOF biped robot on a flat surface during both double support phase (DSP) and single support phase (SSP). To generate the said gaits, cubic polynomial trajectories are assumed to be followed by the swing foot and wrist end of the hand. Further, the hip joint is assumed to follow a straight line and cubic polynomial trajectories in the sagittal and frontal planes, respectively. A closed form solution methodology based on inverse kinematics is used for determining the joint angles made by various links of the biped robot. Once the gait related to upper and lower limbs of the two-legged robot is generated, the balance of the generated gait is decided by finding the position of zero moment point (ZMP). Moreover, LagrangeEuler formulation is used for calculating the dynamics of the biped robot. Further, the effectiveness of the developed algorithm in terms of generating dynamically balanced gaits on a flat surface has been verified in computer simulations. Further, the generated gait has been tested on a real biped robot.
    Keywords: biped robot; single support phase; double support phase; dynamic balance margin.

  • A chattering-free adaptive second-order non-singular fast terminal sliding mode control scheme for a class of nonlinear uncertain systems   Order a copy of this article
    by Beibei Zhang, Dongya Zhao 
    Abstract: In this paper, an adaptive second-order non-singular fast terminal sliding mode (SONFTSM) control scheme is proposed so as to achieve finite-time stability with chattering-free control inputs for a class of nonlinear uncertain systems. Instead of the traditional control input in primitive sliding mode switching control design, the real control input is the time integration of the designed derivation of control input with discontinuous terms, such that the chattering phenomenon can be reduced. An integral terminal sliding mode (ITSM) and a non-singular fast terminal sliding mode (NFTSM) are applied into the equivalent control design such that finite-time convergence of system states can be guaranteed when it moves on a sliding surface. Then, an adaptive method are used to estimate the unknown upper bound of the lumped uncertainty caused by modelling error and external disturbance. The stability analysis of closed-loop system can be demonstrated by constructing a Lyapunov candidate function. Finally, the simulation results verify the effectiveness of the proposed control scheme.
    Keywords: non-singular fast terminal sliding mode; integral terminal sliding mode; adaptive method; Lyapunov candidate function; nonlinear uncertain systems.

  • Fault diagnosis and model predictive fault-tolerant control for stochastic distribution collaborative systems   Order a copy of this article
    by Yunfeng Kang, Ling Zhao, Lina Yao 
    Abstract: This paper presents a fault-tolerant control scheme for a class of stochastic distribution collaborative control systems, which are composed of two subsystems connected in series to complete the target. The output of the whole system is the output probability density function (PDF) of the second subsystem. To diagnose the fault in the first subsystem, an adaptive diagnostic observer and linear matrix inequality (LMI) technique are used to obtain the adaptive tuning law to estimate the fault. When a fault occurs, the fault itself cannot be compensated in the first subsystem, and a model predictive controller is designed in the second subsystem to compensate the fault, making the post-fault output PDF still track the desired PDF as closely as possible. A simulated example is given and desired results have been obtained.
    Keywords: stochastic distribution collaborative control systems; fault diagnosis; fault-tolerant control; model predictive control; linear matrix inequality.

  • Bolt quality testing research using weighted fusion algorithm based on correlation function   Order a copy of this article
    by Xiaoyun Sun, Hui Xing, Guang Han, Jiulong Cheng, Yongbang Yuan, Jianpeng Bian, Haiqing Zheng, Mingming Wang 
    Abstract: Bolt length is an important factor for the quality evaluation of anchors. Because of the harsh detection environment and the interference caused by instruments, bolt testing signal contains a lot of noise, which makes it difficult to analyse and predict the parameters of anchor bolts accurately. In this paper, a non-destructive method based on information fusion of pseudo random signals is presented for bolt quality testing. After pseudo-random signals are generated by multiple sources, a weighted fusion algorithm based on correlation function is proposed for fusion processing. Compared with the D-S fusion algorithm and average weighted approach, the correlation fusion is verified to have higher accuracy and better retention of frequency characteristic. Finally, this proposed approach is proved to be more suitable for random signal fusion.
    Keywords: anchor bolt; non-destructive testing; D-S fusion algorithm; Weighted fusion based on correlation function.

  • A new type-2 fuzzy modelling and identification for electrophysiological signals: a comparison between PSO, BBO, FA and GA approaches   Order a copy of this article
    by Mohammed Assam Ouali, Mouna Ghanai, Kheireddine Chafaa 
    Abstract: In this investigation, a novel type-2 fuzzy model for electrophysiological signals is presented. It is based on interval type-2 fuzzy systems. The proposed method can deal with the curve fitting and computational time problems of type-2 fuzzy systems. This approach will significantly reduce the number of type-2 fuzzy rules and simultaneously preserve the fitting quality. The proposed model comprises a parallel interconnection of two type-2 sub-fuzzy models. The first sub-fuzzy model is the primary model, which represents an ordinary model with a low resolution for the electrophysiological signal under consideration. To overcome the resolution quality problem and obtain a model with higher resolution, we introduce a second fuzzy sub-model called the error model, which represents a model for error modelling between the primary model and the real signal. The error model represents uncertainty in the primary model; this uncertainty is minimised by a simple subtraction of the error model output from the primary model output, resulting in a parallel interconnection between the two submodels; thus, a unique, entire final model possessing higher resolution is realised. The model's representation and identification are implemented by using type-2 fuzzy autoregressive (T2FAR) and type-2 fuzzy autoregressive moving average (T2FARMA) models. Identification is achieved by innovative metaheuristic optimisation algorithms, such as firefly and biogeography-based optimisation. The effectiveness of the method is evaluated through testing on generated synthetic ECG and also on real ECG signals taken from the MIT-BIH database. In addition, a detailed comparative study with several benchmark methods is given. Intensive computer experimentations confirm that the proposed method can significantly improve convergence, resolution and computational time.
    Keywords: electrophysiological signals; electrocardiogram; time series fitting; type-2 fuzzy logic; metaheuristics algorithms.

  • Model-based sliding functions design for sliding mode robot control   Order a copy of this article
    by Charles Fallaha, Maarouf Saad 
    Abstract: This paper introduces a novel manifold design for sliding mode control, applicable to second-order mechanical systems in which nonlinear dynamics can be formalised into that of robotic manipulators. The new approach shows that model-based sliding manifold design substantially simplifies the torque control law, which ultimately becomes linear in terms of joint angles and rates. Additionally, this approach allows the decoupling of the chattering effect on the torque inputs on each axis. A new property related to the gravity term is introduced, and is used for stability analysis and model validation. Simulation results compare the introduced approach with the conventional linear manifold design, and demonstrate that the new approach reduces transient constraints on torque input, and is more robust to matched uncertainties for low inertia robots.
    Keywords: sliding mode control; nonlinear control; robot control; nonlinear sliding manifolds; chattering.

  • High-performance torque controller design for AC driving 4WD electric vehicle in two timescales   Order a copy of this article
    by Bin Li, Zhijun Fu 
    Abstract: In this paper, a novel torque control method of AC induction motor in two timescales is proposed for 4WD electric vehicles. A two-timescale sliding-mode control (SMC) observer and a SMC controller are synthesised to ensure high-performance torque control. Two timescales are considered based on the natural timescale separation present in the AC induction motor driving system, i.e., rotor flux and speed corresponding to the slow dynamics, and the stator current corresponding to the fast dynamics. The convergence property of the controller is considered when performing the observer design rather than the conventional control method, in which the controller and observer are designed separately. Moreover, the more advanced space vector modulation (SVM) technology instead of the sinusoidal pulse width modulation (SPWM) method used in the conventional SMC is also introduced in the proposed method to achieve minimum torque ripple. The effectiveness of the proposed torque control method is illustrated through acting on a 4WD electric vehicle. Simulation results illustrate the improved performance compared with the conventional SMC method
    Keywords: torque control; 4WD; two timescales; electric vehicle; AC induction motor.

  • Command filter-based adaptive neural control for permanent magnet synchronous motor stochastic nonlinear systems with input saturation   Order a copy of this article
    by Yuxi Han, Jinpeng Yu, Zhen Liu, Lin Zhao 
    Abstract: For solving the problems of stochastic disturbance and input saturation in permanent magnet synchronous motors (PMSMs) drive systems, a command filter-based adaptive neural control method is proposed in this paper. Firstly, the neural networks technique is used to approximate unknown nonlinear functions. Then, the command filtered controller is constructed to avoid the "explosion of complexity" inherent in the classic backstepping control, and the error compensation mechanism is introduced to reduce the error caused by command filter. Moreover, the adaptive backstepping method is used to design controllers to ensure that all signals are bounded in the closed-loop systems. Finally, the effectiveness of the approach is certified by the given simulation results.
    Keywords: adaptive neural control; backstepping; PMSMs; command filter; stochastic nonlinear systems.

  • A Non-Linear Coupled-Variables Model for Mass Transfer Modes in MIG-MAG Processes with Experimental Validation
    by Paulo Evald, Jusoan Mór, Rodrigo Azzolin, Silvia Botelho 
    Abstract: Welding processes have relevant importance in many areas of industry, especially in the manufacturing area. The choice of mass transfer mode, to weld metal plates, depends on workpiece structure and its sensibility to the heat input and necessity for material deposition rate. Then, aiming the mass transfer modes in MIG-MAG (Metal Inert Gas - Metal Active Gas) processes utilising pure CO2 as shielding gas, the objective of this paper is present a detailed mathematical modelling for globular and short-circuit transfer modes. The proposed models comprehend a large set of process dynamics, approximating the simulated dynamics very closely to the physical process, which give a high level of credibility for the models. Furthermore, simulations and experimental data are presented to corroborate the validation of both models.
    Keywords: Non-linear systems; Time-varying systems; Coupled-parameters systems; Uncertain systems; Gas metal arc welding process.

  • Robust flux observer and robust block controller design for interior permanent magnet synchronous motor under demagnetisation fault   Order a copy of this article
    by Sajjad Shoja-Majidabad, Yashar Zafari 
    Abstract: This paper deals with rotor flux-linkage estimation in interior permanent magnet synchronous motors. In most applications, the rotor flux is considered as a known constant. However, sharp transients, high loads and high temperatures may cause demagnetisation, which has dominant impact on the interior permanent magnet synchronous motor performance. As a result, estimating the rotor flux-linkage can be helpful to detect and manage demagnetisation fault. To estimate the rotor flux-linkage, a novel integral terminal sliding mode observer is proposed. This fast and robust observer uses stator currents as state variables which can tolerate well against motor uncertainties. This observer can be used to detect or alarm demagnetisation fault for practical applications. However, to keep the motor performance during the demagnetisation fault, a sliding mode block control strategy is proposed for the interior permanent magnet synchronous motor for the first time. The suggested robust controller is composed of a speed control loop (outer-loop) and two stator currents control loops (inner-loops). Owing to rotor saliency, maximum torque per ampere technique is applied for the designed control strategy to provide a reference current. Practical stability of the proposed observer and controller is achieved properly. Finally, comprehensive simulations are carried out to show the effectiveness of the proposed observer and controllers.
    Keywords: interior permanent magnet synchronous motor; integral terminal sliding mode observer; sliding mode block control; maximum torque per ampere; demagnetisation fault.

  • MLNMF: multi-label learning based on non-negative matrix factorisation   Order a copy of this article
    by Yu Han, Cheng Shao, ShouTao Yang, WeiWei Deng 
    Abstract: Multi-label learning deals with the problem where each instance is associated with a set of labels. The task is to predict the label sets of unseen instances through training the instances with known label sets. Existing approaches make predictions by learning from the distribution of multi-label instances. However, the direct relevance between features and labels has often been overlooked in the literature. In this paper, a multi-label learning approach named MLNMF is presented, which is derived from the traditional non-negative matrix factorisation algorithm. In detail, first we propose to generate a label probability predict model (LPPM) using the NMF method to capture the direct relevance between features and labels. Then, we exploit the decision stump method to generate a classifier for each label. The proposed method is a first-order approach that assumes that each label is independent from the others. Compared with the existing approaches for multi-label learning, the proposed approach is advantageous and is able to explore the direct correlation between features and labels, and the the operating efficiency is much higher than that of other algorithms. The experimental results on a total of nine benchmark datasets illustrate the competitiveness of MLNMF against some well established multi-label learning algorithms.
    Keywords: machine learning; multi-label learning; non-negative matrix factorisation.

  • Nonlinear modelling of leader-follower UAV close formation flight with dynamic inversion-based control   Order a copy of this article
    by Johnson Yohannan 
    Abstract: The nonlinear dynamic inversion (DI) control techniques are used in leader-follower UAV dynamics modelling considering new input variables in the present paper. Three separate DI controllers are developed for holding the velocity, heading and flight path angles of both UAVs in a synchronous manner. A numerical simulation is performed at the end for validating this formation control mission of multiple UAVs. The quantitative estimation of reduction in follower drag while in close formation flight is also calculated along with the controller design.
    Keywords: dynamic inversion;close formation flight; leader-follower; UAV; induced drag; non-linear control; heading angle; flight path angle; aerodynamic derivatives; up-wash.

  • Robust speed control design for electric motors using the Kharitonov theorem and genetic algorithms: an experimental study   Order a copy of this article
    by Ashraf Saleem, Hisham Soliman, Serein Al-Ratrout, Mahmoud Masoud 
    Abstract: Electric motor drives are subjected to severe oscillations that might cause motor shaft fatigue and consequent breakdown during system operation. In this paper, a design of robust proportional integral (PI) controller for induction motor (IM) drives is presented. Uncertainties due to different load conditions of the drive system are modelled by a transfer function with interval coefficients. Instead of stabilising an infinite number of polynomials, the Kharitonov theorem is used to design a robust controller by simultaneous stabilisation of only four polynomials. The controller parameters are optimised so that the maximum eigenvalue among the four polynomials is pushed to the left in the complex plane. This is accomplished using Genetic Algorithm (GA) optimisation to achieve the maximum possible rapidity of the system. The proposed controller is tested experimentally using the Hardware-in-the-Loop (HIL) technique. The simulation and experimental results show the validity and effectiveness of the proposed controller as compared to the auto-tuned PID control at different loading conditions.
    Keywords: robust digital control; induction motors; Kharitonov theorem; system identification; model-based control.

  • Identification of rock bolt quality based on improved probabilistic neural network   Order a copy of this article
    by Weiguo Di, Mingming Wang, Xiaoyun Sun, Fengning Kang, Hui Xing, Haiqing Zheng, Jianpeng Bian 
    Abstract: Anchoring technology is widely used in slope, tunnel and underground engineering. However, the rock bolt quality is still a hot problem which is difficult to solve. Considering the shortcoming of pull-out testing, defect identification in a non-destructive way is necessary. In this paper, the signal
    Keywords: rock bolt; nondestructive testing; wavelet packet; probabilistic neural network; particle swarm optimisation.

  • Identification of multi-delay systems using orthogonal hybrid functions in state space environment   Order a copy of this article
    by Srimanti Roychoudhury, Anish Deb 
    Abstract: In this paper, a set of orthogonal hybrid functions (HF) is used for identification of non-homogeneous as well as homogeneous multi-delay systems. The HF set works with function samples and reconstructs a function in a piecewise linear manner. This reduces mean integral square error (MISE) and also computational burden, compared with other methods such as Walsh analysis and block pulse analysis. The presented technique uses a simple algorithm for time-delay system identification. After building up the theory, numerical examples are treated to identify both first- and second-order delay systems. The results obtained are highly reliable to prove the validity of the proposal.
    Keywords: orthogonal hybrid functions; multi-delay systems; state space; system identification.

  • Performance comparison between ultra-local model control, integral sliding mode control and PID control for a coupled tanks system   Order a copy of this article
    by Hajer Thabet, Mounir Ayadi, Frédéric Rotella 
    Abstract: This paper deals with the comparison of robust control approaches for the level water control of a coupled tanks system. A new ultra-local model control (ULMC) approach leading to an adaptive controller is proposed. The parameter identification of the ultra-local model is based on algebraic derivation techniques. The main advantages of this control strategy are its simplicity and robustness. A comparison study with the integral sliding mode control (ISMC) approach is carried out. The perfect knowledge of the output variable degree, which is a standard assumption for sliding modes, is assumed here. The comparison of the simulation results for the proposed adaptive controller with the ISMC controller and the classical PID controller has a better performance in the presence of external perturbations and parameter uncertainties.
    Keywords: ultra-local model control; adaptive PID controller; integral sliding mode control; robustness; coupled tanks system.

  • Modelling of the effect of interface morphology on hydrogen diffusion in a clad plate   Order a copy of this article
    by Muming Hao, Wenchun Jiang, Yucai Zhang, Yun Luo 
    Abstract: Clad plate has been widely used to fabricate the pressure vessels, but a lot of cracks have been found around the interface between the base metal and clad metal at the hydrogen-contained environment. This study examines the hydrogen diffusion in a clad metal. A finite element model is built to simulate the hydrogen diffusion in a clad plate during the shutdown, and the effect of interface morphology has been studied. It is shown that the hydrogen is diffused to the interface and the peak hydrogen concentration is shown in the interface of the clad metal side. The wave interface has a smaller hydrogen concentration than the straight line interface. With increased wavelength and amplitude, the hydrogen concentration is decreased. The hydrogen concentration is increased as the clad metal thickness decreases. When the base metal thickness is increased, the hydrogen concentration is increased.
    Keywords: clad plate; hydrogen diffusion; interfaces.

  • A new three-dimensional chaotic system with a cloud-shaped curve of equilibrium points, its circuit implementation and sound encryption   Order a copy of this article
    by Sundarapandian Vaidyanathan, Aceng Sambas, Sezgin Kacar, Unal Cavusoglu 
    Abstract: In the chaos literature, significant attention has been paid to chaotic systems with uncountable equilibrium points, such as chaotic systems with line equilibrium, curve equilibrium, etc. This paper reports a novel chaotic system with a cloud-shaped curve of equilibrium points with symmetry properties. A new control law for completely synchronising the new chaotic system with the cloud-shaped equilibrium curve has been established via adaptive integral sliding mode control. Also, an electronic circuit implementation of the theoretical system is designed to check its feasibility. As an engineering application, new results are derived for sound encryption with the new chaotic system.
    Keywords: chaos; chaotic systems; chaos synchronisation; sliding mode control; circuit implementation; chaos based encryption; sound encryption.

  • Accelerated model predictive controller for artificial pancreas   Order a copy of this article
    by Mohamed El Hachimi, Abdelhakim Ballouk, Ilyas Khelafa, Abdenasser Baghdad 
    Abstract: This work is a contribution to the Artificial Pancreas (AP) development by introducing new techniques of control based on an acceleration of reference tracking by using a variable penalisation of the cost function instead of fixed and arbitrary penalisation. Two new functions of the weighting factors are introduced in the formulation of the control algorithm. This method allows a rapid rejection of meal disturbance, a reduction of glucose peak and a complete avoidance of hypoglycemia. The developed controller performances are evaluated by the in silico test, which is equivalent to animal test using the UVa/Padova simulator.
    Keywords: artificial pancreas; reference tracking; weighting factors; control algorithm;rndisturbance; hypoglycaemia.

  • Surface reconstruction algorithm based on local data features   Order a copy of this article
    by Zhang Kun, Qiao Shiquan, Gao Kai 
    Abstract: With the development of reverse engineering devices, the point cloud data, as a common and important form, is applied to the surface reconstruction domain, especially during the non-contact measurement. The 3D scanner is the popular instrument for non-contact measurement as well as point data collection. However, the raw point data is so large, scattered and unordered, the representations of point cloud and reconstruction surface are critical contents in reverse engineering system. This paper provides a new method to describe the point cloud data and proposes the GeoSurface algorithm to complete the surface reconstruction. Firstly, we redefine the the point cloud according to set theory. Secondly, based on the estimation of point cloud feature, the rule of neighbour relationship of data can be deduced. According to this rule, we adopt the KD-tree algorithm to complete data organisation, and improve its searching approach. In addition, the GeoSurface algorithm is proposed in this paper. In this algorithm, the curvature and normal vector are used to estimate local surface features. The GeoSurface algorithm uses an iterative technique to mesh the surface and uses the depth of the KD-tree to control the parameters in the algorithm. Lastly, by using the existing experimental equipment, we verify the GeoSurface algorithm. We adopt three datasets in the experiment, which are collected from the Stanford 3D scanning repository and the 3D laser operated by our lab. The experimental results show the GeoSurface algorithm is an effective algorithm and achieves better results in running time and quality of surface reconstruction compared with greedy and Poisson reconstruction algorithm.
    Keywords: point cloud; geometrical features; set theory; surface reconstruction; reverse engineering.

  • Multi-model approach for 2-DOF control of a non-linear CSTR process   Order a copy of this article
    by Dipti Tamboli, Rajan Chile 
    Abstract: This paper proposes a novel approach to examine the performance of a non-linear Continuous Stirred Tank Reactor (CSTR) at large set point changes where a single model adaptive controller falls short. The efficient closed-loop performance is achieved through multiple models accompanied with a bank of pole placement controllers. To select the best controller at a particular operating point, several multi-model techniques based on different scheduling variables have been adapted. To avoid the multiple switching and discontinuity in switching, the global control signal is calculated by assigning certain weight to each controller. The advantages of proposed method are a satisfactory performance at an unstable operating point as well as at large set point changes with reduced number of models. The effectiveness of the scheme is evaluated and demonstrated through simulation results at different scenarios to achieve 2-DOF control. The comparative study between various techniques shows the superiority of gain scheduler designed on the reference signal for set point tracking and disturbance rejection to tackle the non-linearities of CSTR.
    Keywords: CSTR; RLS; pole placement; multiple models; gain scheduler.

  • Parameter identification and optimisation for a class of fractional-order chaotic system with time delay   Order a copy of this article
    by Xiao Li, Fucai Liu 
    Abstract: The fractional-order chaotic systems have more complex dynamic characteristics than the integer-order chaotic systems, which can more reflect the physical properties of the actual system and more practical values, whereas it is difficult to control the synchronisation for fractional chaotic systems. Chaotic system identification is the basis of chaos control and performance analysis. In order to identify the parameters of the chaotic systems with time delay, a novel particle swarm optimisation with increasing inertia weight is proposed, and then the issue is settled by solving an optimisation problem. The identification of parameters mainly includes the system order, the time delay parameter, and the coefficient parameters. An estimation-correction algorithm based on linear interpolation method is used to solve the fractional-order delay differential equation. The Mackey-Glass chaotic system is conducted and comparisons with other two widely used particle swarm optimisations and the differential evolution algorithm indicate the effectiveness of the proposed method, the improvement in identification accuracy as well as convergence speed.
    Keywords: parameter identification; fractional order; particle swarm optimisation; chaotic system; time delay.

  • Dynamic model of bottom-blown oxygen copper smelting process   Order a copy of this article
    by Bin Wang, Zhuo Wang, Yang Jia, Haibin Yu 
    Abstract: The bottom-blown oxygen copper smelting technology is a new copper concentrate smelting technology. However, in the actual production, it is difficult to measure some key parameters online, such as the matte grade, slag Fe/SiO2, melt temperature, total level, and matte level. A dynamic model is established to predict these parameters online, and is verified using actual production data. The results show that the predicted data and measured data are close, which indicates that the model could effectively predict these key parameters online and be applied to the actual production.
    Keywords: bottom-blown oxygen copper smelting process; dynamic model; mass balance; energy balance.

  • Numerical analysis of H-infinity filter for system parameter identification   Order a copy of this article
    by Vassilios Tsachouridis 
    Abstract: The numerical analysis of the H-infinity filter algorithm for system parameter identification is addressed in this paper. After presenting the filter under study and the convergence characteristics of the algorithm, a first order perturbation analysis is conducted. More specifically, norm-wise bounds are derived for the sensitivities, condition numbers, forward errors, backward errors and rounding errors of the iterative computational operations of the algorithm. Consequently, numerical stability and accuracy rules can be potentially composed as measures of algorithmic reliability and dynamical numerical performance. For exploring the impact of incorporating the specific algorithm dynamics in the numerical analysis, a similar framework is presented for the computed solutions, irrespective of the used algorithm. The paper further exploits the application of the synthesised numerical analysis framework to parameter identification of linear state space systems. Finally some numerical examples are given for demonstration purposes.
    Keywords: H-infinity filter; numerical algorithms; error analysis; perturbation analysis.

  • Wiener model of pressure management for water distribution network   Order a copy of this article
    by Shaoyuan Li, Dongming Liu, Jing Wu 
    Abstract: In this paper, a Wiener model is established to express the nonlinear dynamic pressure management mechanism of water distribution network (WDN). The studied topology of WDN is pumped into a closed system with pressure control. The hydraulic element tank plays a key role, and the pressure management model can be divided into two parts according to the feature of the tank being the only dynamic hydraulic component in the whole WDN: the linear dynamic module is to reflect the relationship between the volume (or level) and the flow of inflow/outflow of the tank, and nonlinear static module is to reflect the relationship between the outflows of the tanks and the heads of the terminal consumed nodes, and the linear dynamic block is followed by the static nonlinear block. Moreover, the Wiener model established is compared with the real model in Environmental Protection Agency Network (EPANET), where same consumer heads of the same water distribution network are applied. The theoretical data calculated by the Wiener model are compared with the real data generated by EPANET to show the effectiveness of our proposed modelling method, where three difference scenarios are tested, that is, a WDN with weekday water demands, a WDN including holiday water demands, and a WDN with the consideration of pipeline ages. It can be found that the running situations of the Wiener model are similar to those of actual operation in all of the three cases, which shows that the Wiener model of WDN we established in this paper is computationally efficient and highly accurate.
    Keywords: water distribution network; water pressure management; Wiener model; linear dynamic; nonlinear static.

  • Mathematical modelling and backstepping adaptive sliding mode control for multi-stage hydraulic cylinder   Order a copy of this article
    by Feng Jiangtao, Gao Qinhe, Guan Wenliang, He Zhenxin 
    Abstract: Multi-stage hydraulic cylinders are widely used in large scale erecting devices. They can provide a longer stroke from an initial package than single stage cylinders. They are divided into telescopic type and synchronous type. However, their structure is complicated. In order to get the characteristics of a multi-stage hydraulic cylinder, a motion model was established based on the node chamber method. The LuGre friction model was improved considering the lubricant film. The contact force model was optimised using the equivalent damping model of the hysteresis factor. Simulations of the erection process driven by telescopic and synchronous hydraulic cylinders were completed. A backstepping adaptive sliding mode controller was designed for the cylinder. The proposed controller has a better performance than the PID controller and ordinary sliding mode controller. The chattering has been reduced by using the saturation function instead of the sign function.
    Keywords: telescopic cylinder; synchronous cylinder; erection mechanism; backstepping sliding mode control.

  • New autonomous scheme of iterative learning control for online implementation   Order a copy of this article
    by Leila Noueili 
    Abstract: The purpose of this paper concerns the design and the implementation of a new autonomous iterative learning control (ILC) scheme for uncertain systems and disturbance rejection. The realization of a real time implementation of three control algorithms applied to a Resistor-Capacitor (RC) circuit is presented. The controller design is characterised as an online control problem. The first is the widely used ILC algorithm (ILC-1), which provides perfect tracking error, and the second ILC (ILC-2) algorithm uses the optimisation based on minimisation of a quadratic criterion in the control error and the input signal. Offline ILC cannot provide a perfect tracking error in every situation. Most noteworthy, non-repeating disturbances and noise degrade ILC performance. The focus is the design and the implementation of a new online autonomous control scheme combining two phases: online error learning and control procedure implementation applied to a Resistor-Capacitor (RC) circuit via the Arduino-Uno microcontroller, which is an advancement in the embedded technology that combines low cost, low consumption, as well as a great performance. The autonomous ILC scheme provides an excellent tradeoff between accuracy, disturbance rejection, response time, low overshoot, stability and robustness. The online ILC controller is presented here as a new approach to compensate the disturbances. The results obtained with the proposed control system and the described methodology to learn from previous errors and signal control inputs to improve the current input control, make it a very suitable solution for this application. It is important to note that fast tracking and high accuracy are achieved as illustrated in the control responses in both ILC-1 and ILC-2 compared with the proportional-integrator controller. Furthermore, the experimental results show the effectiveness of the proposed method.
    Keywords: proportional ILC; optimal ILC; Arduino-Uno microcontroller; real time implementation.

  • Time-varying leader-following consensus of high order multi-agent systems   Order a copy of this article
    by Ali Ranjbar, Reza Ghasemi, Ali Akramizadeh 
    Abstract: In this paper, a time-varying leader-following consensus of multi-agent systems under fixed, connected and undirected communication topology is presented. In the proposed method, the dynamics of each agent, including the followers and their corresponding leader, is a linear nth order system. Also, the communication topology between the leader and its neighbours depends on bounded and time-varying functions, assumed to be remained connected as time passes. To tackle this problem, a set of time-varying distributed control laws for each follower agent is designed, based on algebraic graph theory, the algebraic Riccati equation and the Lyapunov direct method. Simulation results indicate the effectiveness of the proposed method and show that convergence to consensus is achieved in a finite time via time-varying distributed control laws.
    Keywords: leader-following consensus; multi-agent systems; time-varying topology; linear agent.

  • Modelling and performance analysis of designed energy-efficient EHA under gravity loads   Order a copy of this article
    by Lijing Dong, Hao Yan, Lijun Feng, Qifan Tan 
    Abstract: Electro-Hydrostatic Actuators (EHA) are highly resembled hydraulic actuators. For specific applications under gravity loads, an innovative structure of EHA using double variable pump and accumulators with designated pressures specified is proposed. The motor speed and the pump displacement can be adjusted synchronously to provide the necessary flow. Consequently, inherent nonlinearity of the two inputs in a multiplication form is involved. Based on analysis of the working principle of the designed EHA, the nonlinear mathematical model precisely describing the multiplication of two coupled inputs is established. The designed EHA balances part of the gravity loads with accumulators, overwhelmingly inducing the energy consumption. Through analysing with reliable and professional hydraulic simulation tool AMESim, the energy-saving performance is demonstrated quantitatively.
    Keywords: electro-hydrostatic actuators; energy efficient; gravity heavy loads; mathematical modelling.

  • Online fault detection for networked control system with unknown network-induced delays   Order a copy of this article
    by Mingming Wang, Xiaoyun Sun, Hui Xing, Haiqing Zheng 
    Abstract: This paper focuses on the online fault detection problem for networked control systems with unknown network-induced delays. In the study, a fault detection model was established for the impact of the unknown network-induced delay. Based on the model, the fault detection filter was constructed, and then the corresponding fault detection problem was converted to an optimisation problem. Finally, a numerical simulation shows that the proposed online fault detection algorithm is not only sensitive to the fault, but also robust to the unknown disturbance caused by the delays.
    Keywords: fault detection; networked control system; network-induced delay.

  • Pedestrian indoor navigation using foot-mounted IMU with multi-sensor data fusion   Order a copy of this article
    by Shengkai Liu, Tingli Su, Binbin Wang, Shiyu Peng, Xuebo Jin, Yuting Bai, Chao Dou 
    Abstract: As a widely used indoor navigation technology, the inertial measurement unit (IMU) based methond has caught considerate research interest. However, owing to the significant and inherent drift of the sensors, it is difficult to get the accuracy trajectory for pedestrian movement estimation. In this paper, a foot-mounted IMU system was used to improve the accuracy of pedestrian trajectory, by fusing information from the multiple sensors. With the Kalman filter combined with the zero-velocity update method, a reasonably accurate pedestrian trajectory was then obtained. Furthermore, some adjustable parameters were introduced to better correct the estimation of position and velocity. The effectiveness of the proposed method was well verified through the indoor experiments, and the long track performance was also tested in a runway verification.
    Keywords: IMU; trajectory tracking; multi-sensor data fusion; Kalman filter; zero-velocity update.

  • On exponential stabilisation for descriptor time-delay systems with nonlinear input via SMC   Order a copy of this article
    by Shuqin Wang, Zhen Liu, Cunchen Gao 
    Abstract: The problem of exponential stabilisation for a class of uncertain descriptor time-delay systems (DTS) is investigated, where both nonlinear input and external disturbance are involved. A novel sliding mode control (SMC) scheme is developed to achieve a stable uncertain system. A delay-free linear sliding surface is first introduced for control design of the DTS. A new adaptive controller is designed to ensure the state trajectories globally converge onto the sliding surface. Furthermore, the considered sliding mode dynamics (SMDs) are derived via equivalent control of the SMC, once the system is in the sliding mode, the proposed criterion can guarantee the SMDs to be exponentially admissible and passive. Finally, the effectiveness of the proposed scheme is verified via an example.
    Keywords: descriptor time-delay systems;exponential stability;nonlinear input;sliding mode control.

  • Improved heuristic algorithm for modern industrial production Scheduling   Order a copy of this article
    by Jiang Yongqing, P.A.N. Fucheng 
    Abstract: Scheduling is one of the core links of modern industrial production. Scheduling needs to be designed according to the characteristics of the production line. In order to optimise the problem of workshop scheduling, the service-oriented programming idea is adopted, with advanced technology to optimise the system development of a mixed flow shop. The system is designed for applications in a distributed network environment. In this paper, an improved heuristic industrial production scheduling method is proposed to solve the scheduling system problem with multiple scheduling tasks, multiple processes, multiple stations, multiple constraints and multiple rules. This method specifies the processing equipment, start time and completion time for each process of the production task. The application method shows that the proposed method can improve the automation and intelligence level of the scheduling process, improve the use rate of equipment and other production resources, and give full play to the enterprise production capacity.
    Keywords: production management; modern industry; heuristic; scheduling.

  • Solvability for nonlinear fractional q-difference equations with nonlocal conditions   Order a copy of this article
    by Jufang Wang, Changlong Yu, Yanping Guo 
    Abstract: In this paper, we study a class of nonlinear fractional q-difference equations boundary value problems. We obtain the existence and uniqueness of positive solutions for this problem by Banach's contraction mapping principle and Krasnoselskii's fixed point theorem on cone. Finally, we give two examples to illuminate the use of the main results.
    Keywords: fractional $q$-difference equations; positive solutions; boundary value problem; fixed point theorem.
    DOI: 10.1504/IJMIC.2017.10011098
     
  • Robust Adaptive Sliding Mode Control Technique for Combination Synchronization of Non-Identical Time Delay Chaotic Systems
    by Shikha , Ayub Khan 
    Abstract: This manuscript presents the methodology in which robust adaptive sliding mode control technique is used for implementing combination synchronization of non-identical time-delay chaotic systems. To justify this introduced methodology modified Lorenz chaotic time delay system and Genesio time delay system are used. The stability condition for the error dynamics is analysed using Lyapunov stability theory and detailed mathematical theory. Numerical simulations are carried out to demonstrate the efficiency of the proposed approach that support the analytical results.
    Keywords: Time delay chaotic system, combination synchronization, robust adaptive sliding mode control, Lyapunov stability theory

  • Towards a Unified Stability Analysis of Continuous-Time T-S Model Based Fuzzy Control Systems
    by Weicun Zhang 
    Abstract: This paper is intended to develop a unified stability analysis framework for a general closed-loop continuous-time T-S model based fuzzy control (TSFC) system, which consists of the parallel distributed compensation (PDC) controller and the real plant instead of the T-S fuzzy model. Plant to be controlled may be linear time-invariant, linear parameter jump, or nonlinear time-varying systems. As an alternative to Lyapunov function based approach, virtual equivalent system (VES) approach is introduced. The stability of a TSFC system is identical to that of the corresponding VES.
    Keywords: T-S Model based Fuzzy control; Stability; Virtual equivalent system

  • Robust mixed performance for uncertain Takagi-Sugeno fuzzy time-delay systems with linear fractional perturbations
    by Chang-Hua Lien, Sundarapandian Vaidyanathan, Ker-Wei Yu, Hao-Chin Chang 
    Abstract: The robust mixed H2/Hinf. performance for Takagi-Sugeno (T-S) fuzzy systems with time delay and linear fractional perturbations is considered in this paper. Some delay-dependent conditions have been proposed to guarantee the mixed performance of uncertain fuzzy time-delay systems. The LMI optimization approach is used to find the minimization of performance measure. Some numerical simulations are illustrated to show the significant improvement over some previous results.
    Keywords: mixed H2/Hinf. performance; Takagi-Sugeno fuzzy systems; time delay; linear fractional perturbations.

  • Monitoring the lack of grease condition of rolling bearing using acoustic emission
    by Kaiqiang Wang, Xiaoqin Liu, Xing Wu, Zhenjun Zhu 
    Abstract: Bearings are the vital parts of machines, and their condition is often critical to the operation or process. Lubricant such as grease can present a film between the bearing surfaces and minimizes the friction and wear. Lack of lubricant may lead to ineffective performance or malfunction of the bearing. Therefore, in order to avoid unexpected breakdowns, reliable lubrication monitoring techniques are demanded. Acoustic Emission (AE) technology can detect the friction between moving parts in the machines. The object of the paper is to evaluate the grease amount in the rolling element bearing with AE signals. Four parameters of AE are studied, including event count rate, ring count per event, energy rate, and RMS. The first three parameters are derived from AE parameter analysis, and RMS is calculated directly on the continuously sampled signal. Eight amounts of the grease in the same bearing are tested respectively. Experiments on grease consumption with running time are also carried out. According to the results, RMS, Energy rate can be used to estimate the remaining amount of the lubricant. The method is also verified by field tests on articulated industrial robots.
    Keywords: acoustic emission; lack of lubricant; rolling bearings; condition monitoring.

  • Iterative Linear Quadratic Regulator (iLQR) Control for Quadrotors Leader-Follower Formation Flight
    by wesam Jasim, Dongbing Gu 
    Abstract: This paper presents an iterative linear quadratic regulator optimal control technique to solve the problem of quadrotors leader-follower formation. The dynamic motion equations are represented based on unit quaternion representation and include some modelled aerodynamical effects as a nonlinear part. Simulation results prove the ability and effectiveness of iLQR controller to successfully track different paths by the leader and maintain the relative distance between the leader and the follower by the follower. It also shows that iLQR controller outperforms LQR controller in terms of fast convergence and tracking errors.
    Keywords: iLQR Controller; LQR Controller; Optimal Control; Leader-Follower Formation; Unit Quaternion; UAV Quadrotors

  • Adaptive Backstepping Control of Multi-Mobile Manipulators Handling a Rigid Object in Coordination
    by Abdelkrim Brahmi, Maarouf Saad, Guy Gauthier, Wen-Hong Zhu, Jawhar Ghommam 
    Abstract: This paper presents an adaptive backstepping control scheme applied torna group of mobile manipulator robots transporting a rigid object in coordination. All the dynamic parameters of the robotic system, including the handled object and the mobile manipulators, are assumed to be unknown but constant. The problem of uncertain parameters is resolved by using the virtual decomposition approach (VDC). This approach was originally applied to multiple manipulator robot systems. In this paper, the VDC approach is combined with backstepping control to ensure a good position tracking. The controller developed in this work ensures that the position error in the workspace converges to zero, and that the internal force error is bounded. The global stability of the entire system is proven based on the appropriate choice of Lyapunov function using virtual stability of each subsystem, based on the principle of the virtual work. An experimental validation is carried out for two mobile manipulators moving a rigid object in order to show the effectiveness of the proposed approach.
    Keywords: Backstepping Control; Adaptive Control; Virtual decompositionrnApproach; Multiple mobile manipulator robots.

  • Kinematic Calibration for Industrial Robots Using Articulated Arm Coordinate Machines
    by Guanbin Gao 
    Abstract: To improve the position accuracy of industrial robots, a novel kinematic model and calibration method using articulated arm coordinate machines (AACMM) is proposed in this paper. The end of the industrial robot (the active arm) is connected to the probe of an AACMM (the passive arm), thus forming a closed kinematic chain. Therefore, the position of the industrial robot’s end can be derived from the AACMM after coordinate transformation. The coordinate systems of the double arms were established, based on which the mapping of the joint angles and the position of the end were derived as well as the nominal value of the kinematic parameters of the industrial robot. A two-step search method was presented for kinematic parameter identification of the industrial robot. The first step is to use genetic algorithm (GA) performing the global search. The result obtained in the first step is used as the initial solution of tabu search algorithm (TSA) in the second step to perform local search in a small range, and then the identified kinematic parameters can be reached. The identified kinematic parameters were used to compensate the errors of the nominal kinematic parameters in the controller of the industrial robot. Experiments were conducted to verify the calibration method, which show that after calibration, the average position errors of the industrial robot were decreased from 5.2944mm, 3.1068mm and 2.8433mm to 0.2137mm, 0.2385mm and 0.2032mm in x, y and z directions, respectively.
    Keywords: kinematic calibration; parameter identification; industrial robot; genetic-tabu search algorithm; articulated arm coordinate measuring machine

Special Issue on: ICMIC 2015 Sliding Mode Control, Theory and Application

  • Distributed second order sliding mode control for networked robots synchronisation: theory and experimental results   Order a copy of this article
    by Yassine Bouteraa, Nabil Derbel 
    Abstract: The paper focuses on synchronisation and trajectory tracking problems. The main goal of the distributed strategy is to produce and maintain a common behaviour using only local information interactions. A combination of a trajectory tracking theory and a cross-coupling algorithms have been used to solve synchronisation problems for a group of Lagrangian systems. A robust control law based on a modified high order sliding mode concept is developed. In the control architecture, the increment of the control responsible for the robustness of the proposed approach is not proportional to the sign of the sliding surface, but it is proportional to the integral of a sign function. The Lyapunov-based approach has been used to establish the multi-robot systems asymptotic stability. Experimental results are provided to demonstrate the performance of the proposed control schemes.
    Keywords: Second order sliding mode control; synchronization problems; trajectrory tracking.

  • Discrete time quasi-sliding mode control of nonlinear uncertain systems   Order a copy of this article
    by Ibtissem Bsili, Jalel Ghabi, Hassani Messaoud 
    Abstract: The control of nonlinear uncertain systems is still an open area of research, and sliding mode control (SMC) is one of the robust and effective methods to cope with uncertain conditions. In this paper, a new SMC algorithm for a class of discrete-time nonlinear uncertain systems is proposed. By using an estimator of uncertainties and external disturbances, the proposed algorithm ensures the stability of the closed loop system as well as the reference tracking. The controller is designed using the above technique and completely insensitive to the parametric uncertainty and the external disturbances. Simulations are carried out on a numerical example and a bioreactor benchmark and the yielded results confirm the effectiveness of our proposition.
    Keywords: discrete time quasi-sliding mode control; nonlinear systems; uncertain systems; estimator; a bioreactor benchmark.

  • Finite frequency observer design for T-S fuzzy systems with unknown inputs: an LMI approach   Order a copy of this article
    by Chibani Ali, Chadli Mohammed, Benhadj Braiek Naceur 
    Abstract: This papers investigates the problem of $H_{\infty}$ filtering for T-S fuzzy systems with unknown inputs. The frequency ranges of these external signals are assumed to be known beforehand and to belong in the low frequency band. The observer is designed in the low frequency domain such that the effects of the unknown inputs are attenuated to a specified level $\gamma$ by means of an $H_{\infty}$ performance norm. By exploiting the Generalized Kalman-Yakubovich-Popov (GKYP) lemma and the Lyapunov method, sufficient design conditions are derived in Linear Matrix Inequality (LMI) formulations for both continuous-time and discrete-time T-S fuzzy models. Finally, an illustrative example is introduced to provide the effectiveness of the proposed approach.
    Keywords: fuzzy models; unknown inputs observer; finite frequency domain; LMI.

  • A novel sliding mode controller scheme for a class of nonlinear uncertain systems   Order a copy of this article
    by Jalel Ghabi 
    Abstract: This paper considers a continuous sliding mode control for a class of nonlinear systems with uncertainties, including both parameter variations and external disturbances. Under the framework of sliding mode and using the upper bounds of the uncertainties, the proposed controller is derived to guarantee the stability of overall closed-loop systems and ensure robustness against modelling errors, parameter uncertainties and external disturbances. As for chattering elimination in sliding mode control, a boundary layer around the sliding surface is used and the continuous control is applied within the boundary. Moreover, an extended schema of a higher-order sliding mode controller is developed as another solution to avoid the problem of chattering effect. Simulation results demonstrate the efficacy of the proposed control methodology to stabilise an inverted pendulum, which is a standard nonlinear benchmark system. Although, the applicability of the proposed algorithm aims to be extended, via suitable modifications, to the case of multivariable nonlinear systems with uncertainties of more general type, covering a wide class of processes.
    Keywords: nonlinear systems; uncertainty; sliding mode control; stability; robustness; inverted pendulum; higher-order sliding mode.

  • Terminal sliding mode control based MPPT for a photovoltaic system with Uncertainties   Order a copy of this article
    by Wajdi Saad, Anis Sellami 
    Abstract: Over the past few decades, the world demand for energy has risen steadily, forcing the world communities to look for alternative sources. Photovoltaic (PV) is seen as the most appropriate solution for this demand. In this context, this paper presents a robust terminal sliding mode control (RTSMC) method for maximum power tracking of stand-alone PV systems. The design method provides good robustness proprieties face to the system uncertainties and change of environment conditions. Starting from the mathematical dependence between the open-circuit voltage (Voc) and the optimal operating voltage (Vop), an MPPT design method is given. To eliminate the tracking voltage error, a RTSMC method is introduced thereafter. A pulse width modulator (PWM) is used to maintain the switching frequency constant. Compared with the P&O algorithm, the proposed methodology reduces the oscillations around the maximum power point and provides better performance proprieties. Also, the simulation results prove the robustness qualities of the TSMC-MPPT design method.
    Keywords: terminal sliding mode control; robust control; MPPT; photovoltaic system.

  • Faults reconstruction for output time-delay systems: sliding mode observer approach   Order a copy of this article
    by Houaida Cherni, Iskander Boulaabi, Anis Sellami, Fayçel Ben Hmida 
    Abstract: This paper addresses actuator and sensor faults reconstruction based on a new Sliding Mode Observer (SMO) for output time-delay systems. Therefore, using the Lyapunov-Krasovskii functional, the stability of the estimation error dynamics is guaranteed. Also, the Linear Matrix Inequality (LMIs) technique is applied to express the observer synthesis. After that, the proposed SMO is used to obtain actuator and sensor faults reconstruction. To show the validity and the applicability of the proposed approaches, a numerical example is provided.
    Keywords: sliding mode observer; actuator fault reconstruction; sensor fault reconstruction; time-delay systems; LMI technique.

Special Issue on: ICEE2015 Signals and System Modelling, Design and Simulation

  • Design and real time implementation of hybrid fractional order controller for grid connected wind energy conversion system   Order a copy of this article
    by Antar Beddar, Hacen Bouzekri 
    Abstract: This paper focuses on designing and real time implementation of Hybrid Fractional Order Controller (HFC) for a grid-connected variable speed Wind Energy Conversion System (WECS). The HFC was integrated to current vector control and Direct Current Control (DCC) to guarantee maximum power extraction and ensuring unity power factor of the grid side. The proposed HFC employs a conventional PI controller, a Fractional Order PI controller (FO-PI), and a Switching Algorithm (SA). The parameters of the HFC were calculated using frequency method then adjusted by employing a PSO algorithm. To evaluate the performance of the proposed controller, an experimental test bench has been built in laboratory using dSPACE1104 card. The WECS contains a wind turbine emulator and Permanent Magnet Synchronous Generator (PMSG) feed a nonlinear load and been connected to the grid via back-to-back converters. The experimental results demonstrate the superiority of the proposed controller over integer order controllers in steady and transient states by realizing maximum power extraction and improving the grid-side power factor.
    Keywords: wind turbine emulator; PMSG; hybrid fractional controller; dSPACE1104; PSO algorithm; grid connected.

  • A comparative study between methods of detection and localization of open-circuit faults in a three phase voltage inverter fed induction motor   Order a copy of this article
    by Cherif Bilal Djamal Eddine, Bendiabdellah Azeddine, Bendjebbar Mokhtar, Telli Abderrahim 
    Abstract: This paper focuses on the techniques of detection and localisation of open-circuit faults in a three-phase voltage source inverter-fed induction motor. The paper starts by presenting the impact of an inverter IGBT open-circuit fault on the induction machine performance. A comparative study is then carried out between three different detection techniques: the mean value of the currents method, the measurement of the current drop method, and the Parks vectors method. The comparison is to assess each technique in terms of its performance that is the time detection rapidity and localisation ability as well as in terms of hardware, that is the number of current sensors required for IGBT open-circuit fault detection. To validate these methods, a test-rig is developed in our diagnostic group laboratory that consists of the realisation of a two-level voltage source inverter controlled by a DSPACE-1104 Card to generate the PWM vector control for the induction motor. The obtained simulation and experimental results illustrate well the detection effectiveness of each technique as well as the comparison study merits.
    Keywords: detection; localisation; open circuit; two-level inverter; DSPACE; induction motor.

  • PCB-planar transformers equivalent circuit model identification using genetic algorithm   Order a copy of this article
    by Aymen Ammouri, Tarek Ben Salah, Ferid Kourda 
    Abstract: Planar passive components are interesting solutions for the design of integrated power converters. Models of planar magnetic devices are still not available in simulator tools. Therefore, there is a limitation during the design process of integrated power systems. In this paper, an equivalent circuit model for planar transformers is developed. The modelling of a planar transformers parasitic, such as its winding loss, magnetising inductance, leakage inductance or parasitic capacitance, have individually been investigated. The magnetising inductance remains a complex parameter to model, particularly when the problem of corner sections effects is taken into account. Skin and proximity effects in primary and secondary windings are modelled by a ladder R-L network. The ladder parameters are identified by a minimising function between experimental and simulation results using the genetic algorithm. During the validation process, three typical winding arrangements of the planar transformer have been investigated. The planar transformer model has been favorably evaluated by comparison and validation with experimental data and 3D finite element method. It is found that simulation results and data measurements are in close agreement with a planar transformer model.
    Keywords: PCB planar transformer; interleaving; leakage inductance; parasitic capacitance; winding loss; finite element methods; genetic algorithm.

  • An interactive design strategy for fractional order PI controllers in LabVIEW   Order a copy of this article
    by Ali Yüce, Furkan Nur Deniz, Nusret Tan, Derek P. Atherton 
    Abstract: This paper presents an interactive design for a fractional order PI (FOPI) controller based on Inverse Fourier Transform Method (IFTM) in accordance with the stability region of a closed loop control system in LabVIEW, which is a powerful graphical program. A Stability Boundary Locus (SBL) method is used to obtain the stability region, including all stabilising FOPI controller parameters in the (Kp, Ki) plane. The time response of the closed loop control system with FOPI controller is then obtained by IFTM, using the stabilising controller parameters selected from the stability region. Changing the selected fractional order controller parameters in the stability region, users can observe the step response of the system interactively.
    Keywords: fractional order PI controller; inverse Fourier transform method; stability boundary locus method; interactive design.

  • Robust fuzzy sliding mode control for air supply on PEM fuel cell system   Order a copy of this article
    by Zakaria Baroud, Atallah Benalia, Carlos Ocampo-Martinez 
    Abstract: In this paper, an adaptive fuzzy sliding mode controller is employed for air supply on Proton Exchange Membrane Fuel Cell (PEMFC) systems. The control objective is to adjust the oxygen excess ratio at a given setpoint in order to prevent oxygen starvation and damage to the fuel-cell stack. The proposed control scheme consists of two parts: a sliding mode controller (SMC) and fuzzy logic controller (FLC) with an adjustable gain factor. The SMC is used to calculate the equivalent control law and the FLC is used to approximate the control hitting law. The performance of the proposed control strategy is analysed through simulations for different load variations. The results indicated that the adaptive fuzzy sliding mode controller (AFSMC) is excellent in terms of stability and several key performance indices, such as the Integral Squared Error (ISE), the Integral Absolute Error (IAE) and the Integral Time-weighted Absolute Error (ITAE), as well as the settling and rise time for the closed-loop control system.
    Keywords: PEM fuel cell system; oxygen starvation; sliding mode control; fuzzy logic control; stability analysis.

  • Hilbert Huang transform and pattern recognition to detect defects in induction motor   Order a copy of this article
    by Nassima Hamdad, Kamal Hammouche 
    Abstract: In this paper, a new time-frequency analysis technique called Hilbert Huang transform is applied to detect bars and ring defects in an induction motor. A pattern recognition method called support vector machine is used to classify the different operating modes of the motor (healthy and/or defective). The aim of this study is to improve the classification results obtained using the Fourier transform (as frequency analysis technique) and temporal signals.
    Keywords: Hilbert Huang transform; empirical mode decomposition; intrinsic mode functions; Fourier transform; fault diagnostic; support vector machine; induction motor.

  • Investigation of radio channel model in indoor environment at 60 GHz   Order a copy of this article
    by Tarik Zarrouk, Moussa El Yahyaoui, Ali El Moussati, Ahmed El Oualkadi 
    Abstract: This paper proposes a modelling approach of 60 GHz channel model and evaluates the performance of the IEEE 802.15.3c system. We have used the actual 60 GHz High Speed Interface Orthogonal Frequency Division Multiplexing (HSI-OFDM) system model of the IEEE 802.15.3c standard with the realistic 60 GHz channel model based on the Triple-S and Valenzuela (TSV) model. In this work, we aim to investigate the effect of small and large scale fading in indoor environment under Line-Of-Sight (LOS) and No-LOS (NLOS) scenarios. The performance is evaluated in terms of the Error Vector Magnitude (EVM) in function of the distance and Signal Noise Ratio (SNR). This investigation is done by using a co-simulation technique between MATLAB and ADS software. The simulation results show that the TSV channel model presents better performance than the Friis equation in indoor environment and under LOS and NLOS scenarios.
    Keywords: 60 GHz; IEEE 802.15.3c; TSV; EVM; small-scale fading; large-scale fading.

  • On lambda-matrices and their applications in MIMO control systems design   Order a copy of this article
    by Belkacem Bekhiti, Abdelhakim Dahimene, Bachir Nail, Kamel Hariche 
    Abstract: In the present paper we have introduced new control design algorithms based on the theory of matrix polynomials. The first procedure is called block decoupling control, which is based on the spectral factors of the denominator of the right matrix fraction description. The advantages of this control are the non-interacted behaviour, simplicity in control design and low order controller is obtained due to the cancellation property of the proposed algorithm. The second control algorithm is the whole set of latent-structure assignments via the approaches of block root placement. The procedure is developed even if the system is not block transformable. A process is done with the aid of conversion between state space and matrix fraction description. The last method is defined as a MIMO PID controller design via the placement of block roots with the help of Diophantine equation resolution, the latter systematic procedure retains both regulation and tracking objectives with small gains and minimum error.
    Keywords: block roots; spectral factors; right matrix fraction description; MIMO PID; Diophantine equation.
    DOI: 10.1504/IJMIC.2017.10008337