International Journal of Automation and Control (50 papers in press)
Improved Reaching Law Based Sliding Mode Controller for Free Flight Autopilot System
by Devika K B, Susy Thomas
Abstract: This paper addresses the suitability of Sliding Mode Control (SMC) as a control strategy for a highly sophisticated aerospace application, viz., free flight autopilot system.When used for any practical application, chattering which is an inherent limitation of SMC have to be mitigated adequately. Reaching law approaches for SMC design are being investigated so as to identify an appropriate strategy that can ensure chattering free operation for free flight autopilot system. It is found that many of the reaching law based SMC methodology leads to shortened sliding mode phase, slow system response and/or unbounded control action. Hence, each of the existing conventional reaching law methods, viz., Constant Rate Reaching Law (CRRL), Constant plus Proportional Rate Reaching Law (CPRRL) and Power Rate Reaching Law (PRRL) are investigated not only for their efficacy in providing chattering free operation but also for sufficient sliding mode motion (hence robustness), fast response and bounded control action. Simultaneous assurance of all these four attributeswould provide confident operation of free flight system. From simulation analysis it is observed that the conventional reaching laws fail in achieving these attributes concurrently. In this context, the authors propose an improved reaching law, viz., Power Rate Exponential Reaching law (PRERL) so as to satisfy all the aforesaid desired properties. The performance of free flight modes of operation when controlled by PRERL based SMC controller is validated through simulation studies.
Keywords: Air traffic control; Chattering reduction; Free flight; Reaching Law; Sliding mode control.
Non-fragile H Controller for Combustion Process in Rocket Motors
by Yubin Wu, Hexin Zhang
Abstract: The aim of this paper is to analyze the problem of robust non-fragile H∞ controller for the combustion process in liquid propellant rocket motors chamber. Based on the delay decomposition approach, the whole delay interval is divided into two equidistant subintervals and a new Lyapunov-Krasovskii functional (LKF) which contains some triple-integral terms and augment terms is introduced on each interval. By using L-K stability theorem, integral inequality method together with free weighting matrix approach, a new delay-dependent bounded real lemma (BRL) is formulated. Then, by applying the BRL, non-fragile H∞ controller is formulated in terms of linear matrix inequalities (LMI), where no any parameter needs to be turned and apt to realization. Finally, simulation results are given to illustrate that the designed controller has good robust and non-fragile performance.
Keywords: rocket motors; combustion; Lyapunov-Krasovskii functional (LKF); delay-decomposition; non-fragile H∞ controller.
DEVELOPMENT OF CONTROL STRATEGIES OF A MULTI-WHEELED COMBAT VEHICLE
by Moustafa El-Gindy
Abstract: This work develops a vehicle dynamics controller for vehicle stability, maneuverability and turning circle reduction for an 8 x 8 heavy combat vehicle utilising both torque vectoring and third and fourth axle steering. The proposed control scheme is composed of two distinct controllers, each with their own range of operation based on vehicle speed. A feedforward zero side slip (ZSS) controller actuates the third and fourth axle steering angles. It is used for maneuvering at speeds of 30 kph and below and for turning circle reduction. A two degrees of freedom (DOF) linear parameter varying (LPV) H∞ controller that monitors steering wheel angle and yaw rate error and uses both the rear axle steering and torque vectoring to enhance vehicle stability and maneuverability at speeds above 40 kph. Gaussian distribution functions are used to switch from one controller to the other. The proposed control scheme is evaluated by running simulations using a validated computer simulation (TruckSim) full vehicle model in co-simulation with the controller and developed electric powertrain in Simulink. The proposed control system is able to greatly improve vehicle stability and maneuverability. A turning circle reduction of 30% is obtained using the ZSS feedforward method.
Keywords: Torque vectoring; rear wheel steering; H∞; linear parameter-varying; vehicle dynamics control; stability control; multi-wheeled combat vehicle; direct yaw moment control.
Optimal path planning for an autonomous articulated vehicle with two trailers
by Amr Mohamed, Jing Ren, Haoxiang Lang, Moustafa El-Gindy
Abstract: This paper proposed an optimal path planning algorithm for an autonomous vehicle with two trailers in autonomous navigation. The proposed algorithm is based on the combination of artificial potential field method (APF) and optimal control theory. A linear two-degree-of-freedom vehicle model with both lateral and yaw motion is derived and simulated in MATLAB environment. The optimal control theory is applied to generate an optimal free-obstacle path of the robotic vehicle from a starting point to the goal location. The obstacle-avoidance technique is mathematically modelled using a potential function based on the proposed sigmoid function. The constructed potential field model can achieve an accurate analytic description of objects in three dimensions. Moreover, the proposed model of potential field requires very modest computation at run time. The APF includes both the attractive (the target) and repulsive (the obstacles) potential fields that will control the steering angle of the vehicle so that it can reach to its target location. Several simulations are carried out to check the fidelity of the proposed technique. The illustrated results demonstrate the generated optimal path of autonomous vehicles with consideration of vehicle dynamics constraints, obstacle avoidance and collision free criteria in reaching the goal location.
Keywords: path planning; autonomous vehicle; vehicle with two trailer; artificial potential field; optimal control theory.
Fuzzy Logic-Based PI Controller Design and Implementation of Shape Memory Alloy Actuator
by Yasser Hassan, Ahmed Abouelsoud, Ahmed Fathelbab
Abstract: In this paper, a new implementation method is proposed for shape memory alloy (SMA) model which is used to design and control SMA based linear actuator. This implementation method is based on strain-driven approach rather than stress-driven approach found in the literature. This approach removes problems associated with model implementation of SMA actuator. An algorithm reminiscence to the return mapping algorithm is used to implement the strain-driven SMA model. A dynamic system that describes the characteristics of one-way bias force based SMA actuator is simulated using this implementation approach. An adaptive fuzzy logic based PI controller is designed to tune PI controller gains. The proposed controller shows superior response over existing controllers of SMA wire actuators found in the literature in terms of zero steady state error, no overshoot and reduced hysteresis.
Keywords: Shape Memory Alloy (SMA) actuators; stress-driven approach; strain-driven approach; and Adaptive Fuzzy logic PI controller.
Robust Cooperative Adaptive Cruise Control Design and Implementation for Connected Vehicles
by Mark Trudgen, Rebecca Miller, Javad Mohammadpour Velni
Abstract: Cooperative adaptive cruise control (CACC) is a developing technology that achieves reduced inter-vehicle distance following in order to increase roadway capacity. CACC provides much lower headway values than adaptive cruise control (ACC) or human drivers can; however, this relies on real-time acceleration data, which inherently has inexact timing. In order to implement a string stable CACC platoon following scheme, meaning that disturbances are attenuated down the stream of the platoon of vehicles, while also overcoming the inherent challenges of wireless communication and uncertain internal model parameters, we design an H1 controller that is robust to all aforementioned uncertainties. We implement this controller on a laboratory-scale test bed with an anti-windup compensation scheme and particularly show that the controller design is able to account for communication shortcomings.
Keywords: Cooperative adaptive cruise control; Robust H1 control; antirnwindup; loop shaping; platoon following; wireless communication; cyberrnphysical systems.
The Research on Digital and Intelligent Management System for Large Castings Based on Internet+
by Qinglin Chang, Hongyuan Fan, Li Hou, Hongjun Chen, Yang Duan, Peng Cai, Lan Luo
Abstract: In this paper the status and demands of casting production for large wind power and nuclear power companies was taken as the background. This paper aimed at problems in large casting companies such as various products but in small batch, low data utilization rate, complex management structure, slow data collection and transmission speed, inconsistent exchange of current software information and so on, to target the integration of equipment, process, software, production, project management, supply chain and customer management. The model using the top-down and taking current software/system into consideration was adopted, and the usage requirement of casting enterprise is analyzed in this paper. A casting system management platform based on Internet+ was obtained, of which the frame for sub function, system and module to realize it was divided. Research on data storage model and interaction pattern was conducted to provide reference for the development and implementation of information and intelligent platform for casting enterprises.
Keywords: Casting; Informationization; Management System; Internet+.
Two Degree of Freedom PID Controller in Time Delay System using Hybrid Controller Model
by G. Kannan, G. Saravanakumar, M. Saraswathi
Abstract: In the paper, a hybrid method based Two Degree of Freedom (2-DOF) PID controller is proposed for tuning the time delay system. The hybrid technique is the combination of Fuzzy Logic Controller (FLC) and Gravitational Search Algorithm (GSA). Here, the GSA is utilized for generating the logic rules of FLC. The 2-DOF Proportional Integral and Derivative (PID) controller ensures highly efficient disturbance rejection and reliable performance. Here, tuning of a 2-DOF PID controller with a time delay system design that achieves a high performance for a wide range. For the automatic tuning process, the parameters of time delays system is predicted and tuned optimally in the short period of time. The first order time delay system is tuned and the stability parameters such as small overshoot, settling time and rising time has been achieved. From the results, it is noted that, proposed controller provides enhanced results for the reference tracking and disturbance rejection operations. The effectiveness and feasibility of the proposed technique is demonstrated through the MATLAB/simulink platform, and the performance is tested and compared with the existing controller tuning methods such as FLC technique with Genetic algorithm (GA) and Artificial Neural Network (ANN) techniques.
Keywords: FLC; 2-DOF PID controller; GSA; ANN and time delay system.
A New Approach in Three-Axis Satellite Stabilization Using Redundant Thruster in Elliptical Orbit
by Mahdi Fakoor, Alireza Satterzadeh, Majid Bakhtiari
Abstract: Three-axis attitude stabilization of a satellite in a LEO elliptical orbit, with respect to the effects of applied disturbances such as eccentricity, gravity gradient, solar radiation pressure and aerodynamic loads is presented by applying three reaction wheel actuators. A new attitude stabilization method is investigated by considering failure in one or more reaction wheels. In this approach, in the absence of reaction wheels, control torques are generated by employing a two rotational degree of freedom redundant thruster which is mounted on a gimbal mechanism. If any failure happens in reaction wheels, redundant thruster will be added to the system by gimbal mechanism as an input controlling actuator. Controller algorithm based on dynamic and kinematic equations of the satellites motion is developed in the presence of mentioned disturbances. Considering the variable satellite model in different situations, neuro-fuzzy controller is employed. For training the intelligent neuro-fuzzy controller, PID controller is utilized. Numerical simulations show that, the recommend control method have acceptable results in the presence of disturbances, and supplementing of a thruster actuator as redundancy, could increase the space mission reliability. In the proposed scenario any fault in the operation of reaction wheels, will be compensated by redundant gimbal mounted thruster. So, satellite stabilization can be accomplished at desirable attitude.
Keywords: Satellite; Attitude Control Subsystem (ACS); Neuro-Fuzzy; PID Controller; Reaction Wheel; Elliptical Orbit.
Complete Synchronization of Non-Identical Fractional Order Hyperchaotic Systems Using Active Control
by Shikha Singh, Muzaffar Ahmad Bhat
Abstract: This manuscript investigates the complete synchronization of non-identical fractionalorder hyperchaotic system via active control technique. The hyperchaotic fractional order Chen system is taken as master system and a new fractional order hyperchaotic system is taken as a slave system. The controllers are constructed using active control technique to ensure the complete synchronization between master and slave system. Simulations results show that our scheme can not make the two systems synchronized, but also let them remain chaotic states.
Keywords: Fractional order hyperchaotic system; active control; stability; synchronization.
Extension of operating air-gap in Electromagnetic Levitation System by using Intelligent Controllers
by Subrata Banerjee
Abstract: Electromagnetic levitation system (EMLS) is inherently unstable and strongly non-linear in nature. The parameters of EMLS undergo considerable variation with change in air-gap. This makes the design and implementation of robust controllers is difficult. This paper deals with intelligent controllers utilizing Gravitational Search Algorithm (GSA) based piecewise linear control and GSA based fuzzy control scheme to extend the range of operating air-gap for an EMLS. Extensive simulation has been carried out for the tuning of controller parameters and it is found the GSA based technique produces improved performance. Robust design of controllers for different zones is confirmed by Kharitonov/Nyquist enclosure. The controllers are tested in a small-scale system in the laboratory confirming the usefulness of the proposed technique. Such systems are useful for magnetic levitation (maglev) based applications those need to operate in a large operating air-gap.
Keywords: Electromagnetic levitation; DC-DC power converters; PWM; Fuzzy control; GSA; Piecewise linear control; Robust Control.
Literature Survey for Autonomous Vehicles: Sensor Fusion, Computer Vision, System Identification and Fault Tolerance
by Amr Mohamed, Jing Ren, Moustafa El-Gindy, Haoxiang Lang, A.N. Ouda
Abstract: Autonomous vehicle technologies are receiving more and more attention with increasing demands for autonomy and performance for both civilian and military purposes. In our previous paper Mohamed et al (2016), the recent developments in autonomous vehicles in the fields of advanced control, perception and motion planning techniques is surveyed. In this paper, the state of research with respect to autonomous vehicles from a number of different perspectives will be described. Among the many factors that affect the performance of these autonomous systems is the capability to integrate data and knowledge from different sensors, both of which are essential. In addition, advanced perception techniques, within the environment, and the capability to locate obstacles and targets are necessary in order to properly operate these systems. Moreover, autonomous vehicles can achieve reliable levels of performance by determining the faults and enabling the system to operate with these faults in mind. In order to achieve fault tolerance, often it is required to determine the mathematical model of the dynamic system by analysing the measured input and output signals of the system. This paper will briefly survey the recent developments in the field of autonomous vehicles from the perspectives of sensor fusion, computer vision, system identification and fault tolerance.
Keywords: Autonomous vehicles; sensor fusion; computer vision; system identification; fault tolerance.
A Mixed-method for order reduction of linear time invariant systems using Big Bang-Big Crunch and Eigen spectrum Algorithm
by Akhilesh Gupta, Deepak Kumar, Paulson Samuel
Abstract: In this article, a novel mixed approach is presented for order reduction of complex higher order linear time invariant systems by merging the attributes of Big bang-Big crunch (BB-BC) optimization and Eigen spectrum algorithm. The cosmological theory based BB-BC optimization has the advantage of numerical simplicity with relatively fewer control parameters which makes this algorithm easier to implement.BB-BC optimization technique is based on the generation of random points in first step and contraction of these to a typical point in following step by the center of mass or minimal cost approach. On the other hand, Eigen permutation is based on the retention of dominant poles with simultaneous cluster formation of remaining real and complex poles which guarantee the stability of resulting reduced order model for a stable original model. In the proposed approach, denominator polynomial of the reduced order model (ROM) is determined by the Eigen permutation approach whereas the minimization of the fitness function,i.e.integral square error (ISE) by the BB-BC algorithm approach is adopted for the computation of numerator polynomial coefficients. The effectiveness of the proposed approach over well-known methods is validated with the help of numerical examples by the comparison of transient parameters and performance indices.
Keywords: Big bang-big crunch; Eigen spectrum; ISE; ITSE; IAE; ITAE; MOR; Reduced order model.
PSO Based Parameter Estimation and PID Controller Tuning For 2-DOF Non-linear Twin Rotor MIMO System
by Roshni Maiti, Kaushik Das Sharma, Gautam Sarkar
Abstract: The present paper proposes a control methodology for a non-linear multi-input multi-output (MIMO) system that combines a stochastic optimization and proportional-integral-differential (PID) control scheme. This methodology is demonstrated through a laboratory scale helicopter setup commonly known as the twin rotor MIMO system (TRMS). The objective is to design a stochastically optimal / near optimal control law that can simultaneously stabilize the TRMS with considerable cross-couplings and provide satisfactory tracking performance to reach a desired position. The proposed control methodology utilizes two PID controllers independently employed for the two rotors of TRMS. A PSO based parameter estimation technique has been utilized in this paper to estimate the parameters of the nonlinear TRMS laboratory setup. The nonlinear TRMS model with estimated parameters is employed to tune the PID gains by means of PSO in an off-line manner and then implemented in real-life experimentations. The proposed realization of PID control strategy is implemented for both simulation and real-life experimentations and their results demonstrate the usefulness of the proposed methodology.
Keywords: Multi-input multi-output (MIMO) system; twin rotor MIMO system (TRMS); proportional-integral-derivative (PID) controller; parameter estimation.
A linear algebra controller based on reduced order models applied to trajectory tracking for mobile robots: An experimental validation
by Leonardo Guevara Guevara, Oscar Camacho, Andres Rosales, Javier Guevara, Gustavo Scaglia
Abstract: A Linear Algebra Controller (LACr) based on an empirical linear model of the system is presented in this paper. The controller design is based on a First Order Plus Dead Time (FOPDT) model and can be tuned using the characteristic parameters obtained from the reaction curve. In previous studies, the versatility of this proposed controller was tested by simulations, proving be an alternative to control many kinds of processes. In this paper, the proposed controller is implemented for trajectory tracking using a real mobile robot platform. The performance results are compared against a PI controller using the ISE performance index to measure it.
Keywords: numerical method controller; linear algebra; reduced order models; characteristic parameters; pioneer 3-DX; mobile robot; trajectory tracking.
Control of Continuous-Time Chaotic (Hyperchaotic) Systems: F-M Synchronization
by Adel Ouannas, Ahmad Taher Azar, Toufik Ziar
Abstract: In this paper, a new type of chaos synchronization between differentrndimensional chaotic systems is proposed. The novel scheme is called F-Mrnsynchronization, since it combines the inverse generalized synchronization withrnthe matrix projective synchronization. In particular, the proposed approachrnenables F-M synchronization to be achieved between n-dimensional masterrnsystem and m-dimensional slave system in different dimensions. The technique,rnwhich exploits nonlinear controllers, stability property of integer-order linearrncontinuous-time dynamical systems and Lyapunov stability theory, proves to berneffective in achieving the F-M synchronization. Finally, simulation results arernreported, with the aim to illustrate the capabilities of the novel scheme proposed
Keywords: Chaotic systems; Different dimensions; Matrix projectivernsynchronization; nonlinear controllers; Inverse generalized synchronization.
Derivative Adaptive Predictive Control for a Tempering Process
by DANIEL VIUDEZ-MOREIRAS
Abstract: The modeling threshold problem made hard the Adaptive Predictive (AP/ADEX) controllers implementation in processes that, due to their dynamics behavior, require a control period below a certain value. However, a new concept named Guidance System for derivative control (GS), originally developed for the aerospace sector, overcomes this problem. This paper presents the first industrial application from this new concept, applied to an illustrative industrial tempering process, characterized by a multivariable, highly non-linear and time-varying dynamics. Thus, the new design is based on Adaptive Predictive Expert (ADEX) control, and extended with a new concept, the Guidance Block, required to overcome the ADEX methodology restrictions when it has to be applied with reduced control periods in order to deal satisfactorily with high disturbances and non-linear dynamics. This paper also presents a comparison between the new control system and the conventional control system (LCS), previously implemented in this industry and based on PID methodology, showing the benefits of implementing the new system.
Keywords: Optimized Adaptive Control; Predictive Control; Adaptive Predictive Control; Derivative Control; Guidance System; Process Control; Tempering Process.
CDM Based Two Degree of Freedom PI Controller Tuning Rules for Stable and Unstable FOPTD Processes and Pure Integrating Processes with Time Delay
by Somasundaram S, Benjanarasuth T
Abstract: This work proposes the Coefficient Diagram Method (CDM) based two degree of freedom Proportional Integral (CDM-PI) controller tuning rules for stable and unstable First Order Plus Time Delay (FOPTD) processes and Pure Integrating Processes with Time Delay (PIPTD). To derive the tuning rules, a general First Order Plus Time Delay (FOPTD) model, the first order Taylor denominator approximation technique and the pole allocation strategy named CDM is used. The tuning rules derived here are novel and they relate the controller parameters to the process model parameters directly. The performance of the CDM-PI controller utilizing the proposed tuning rules is tested with numerical examples of stable, unstable and pure integrating processes with time delay models. The test results indicate that the proposed tuning rules yield promising results over the other PI controllers. Performance measures confirm the effectiveness of the proposed tuning method.
Keywords: CDM-PI; Two degree of freedom; Tuning rules; Process models; Performance measures.
Modified PSO based Non-Linear Controllers Applied to a DC-DC Converter
by Hadjer Abderrezek, Ameur Aissa, M.N. Harmas
Abstract: Control of dc/dc Buck converter is a complex task due to the nonlinearity inherent in the converter and introduced by the external changes. A robust synergetic controller for the control of dc/dc Buck converter is described in this study. An adaptive terminal synergetic control is developed based on robust synergetic control theory and terminal attractor techniques. The method estimates the boundary of parameter uncertainty and external disturbance by adaptive law. The idea behind this strategy is to use the terminal synergetic control (TSYC) approach to assure finite time convergence of the output voltage error to the equilibrium point, and integrate an adaptive law to handle uncertainties is provided resulting in enhancing robustness as well as a better transient performance compared to the conventional control. In addition, Modified PSO algorithms will be used to optimize controllers parameters using an ITAE criterion. The results show and demonstrate the effectiveness and feasibility of the proposed approach.
Keywords: synergetic control; terminal; TSYC; Adaptive; ATSYC; particle swarm optimization; PSO; Lyapunov; finite time; MPSO.
Parabolic Angle-based Anti-sway Control for Container Cranes with Limited Dynamic Loads
by Kamal Khandakji, Victor Busher, Lubov Melnikova
Abstract: A novel anti-sway control system for cranes is proposed. The proposed method is based on the formation of a predetermined angle of deviation as a piecewise-continuous parabolic function, the second derivative of which does not experience discontinuity, and its third derivative is a rectangular pulse of certain variable-sign amplitude, which eliminates the mechanical stress in the crane construction and kinematic gears. The proposed method provides damping of the oscillations of the suspended load during its horizontal motion (in two orthogonal coordinates) and hoisting/lowering. The control method is invariant to the mechanism/payload mass ratio, lift height and hoisting speed.
Keywords: Anti-sway system; motion control; oscillations damping; container crane.
An algorithm to diagnose manufacturing hybrid systems
by Omaima BENATIA, Fouad BELMAJDOUB
Abstract: We propose in this paper a new method for diagnosing manufacturing hybrid systems. We are inspired by two methods: one is based on continuous Petri nets and the other is based on discrete Petri nets. The combination of these two methods will be based on hybrid Petri nets. Our approach is proposed in the form of an algorithm that treats the different steps to diagnose a manufacturing hybrid system whose discrete part controls the continuous part. We consider that the set of fault classes is partitioned into two subsets: continuous fault classes and discrete fault classes.
Keywords: Diagnosis; manufacturing hybrid systems; discrete Petri nets; continuous Petri nets; hybrid Petri nets; fault classes; continuous fault classes; discrete fault classes.
Resonance Compensation in Dual-stage Hard Disk Drive Servo System
by Md. Arifur Rahman, Alamgir Hossain, Md. Raju Ahmed
Abstract: This paper presents a simulation analysis of resonance compensation in dual-stage actuator system. To enhance the speed and precision, piezoelectric micro-actuator made form PZT (Lead-Zirconium-Titanium) is used as the secondary actuator in dual-stage hard disk drive (HDD) where a voice coil motor (VCM) is used as the primary actuator. Both VCM actuator and PZT micro-actuator (MA) have the problem of mechanical resonance. Conventional approach is to use a pre-compensator notch filter for each actuator to suppress the resonance. Since this method is based on inversion technique, it needs a very accurately identified plant model which is always difficult to obtain. On the other hand, a simple controller in the feedback path is a good solution for suppressing the resonance which does not require a very precise plant model. With the proper design of dual-stage controller, it is possible to bypass VCM actuator's resonance uncertainty by PZT micro-actuator in the high-frequency band. However, the resonance of the micro-actuator is detrimental to the stability of the dual-stage servo control loop. Therefore, proper design of resonance compensator of PZT loop is needed with the consideration of PZT actuator's resonance uncertainty. This paper presents a feedback resonant controller designed in simple way to suppress the resonant modes of PZT micro-actuator actuator in a dual-stage HDD servo system. The design is based on an integrated approach where M-norm minimization and mixed passivity, negative-imaginary, small-gain theorem are used. This approach results in a robust stable controller which provides better performance over the conventional notch filter. Simulation results substantiate the effectiveness of the proposed controller.
Keywords: Dual-stage HDD; VCM actuator; PZT micro-actuator; Resonant controller.
Designing dynamic fractional terminal sliding mode controller for a class of nonlinear system with uncertainties
by Arash Pourhashemi, Amin Ramezani, Mahdi Siahi
Abstract: In this paper, a novel terminal sliding manifold is introduced. Then, based on new sliding surface, we proposed two new fast converging robust controllers. The first controller is a fractional terminal sliding mode controller for a class of fractional order chaotic system in order to decrease singularity problem as well increasing fast convergence. Stability analysis of the system have been proved by Lyapunov stability theorem. The second one is the fractional dynamic terminal sliding mode controller for a class of fractional second order chaotic system so as to reduce chattering problem. For each, numerical simulations have been done to show the applicability and effectiveness of the proposals.
Keywords: Fractional Calculous; Terminal Sliding Mode Control; Dynamic Sliding Mode Control; Stabilization.
Development of New Cable-driven Minimally Invasive Surgical Robot
by Longwang Yue, Kong Fah Tee, Baoguo Liu, Tengfei Feng
Abstract: Operation intuitiveness and force feedback are two main problems of MIS robots. In order to solve these problems, a new type of robot-assisted MIS system has been proposed. Focusing on the cable-driven MIS robot, which is a core component of the system, the following steps in developing the underlying theory have been conducted. Firstly, the driving cable layout, motion mapping and symmetrical decoupling structures of all types of MIS robot joints are analyzed. Secondly, the mathematical formulation of the cable-driven layout of each joint based on the crossing number is derived. Finally, as an example of a cable-driven MIS robot, the kinematic analysis of the symmetrical spatial intersecting joints is developed based on D-H method and the crossing number. The results show that the cable driven symmetrical intersecting joints could improve the operation intuitiveness and realize direct force feedback.
Keywords: Minimally Invasive Surgery (MIS); Robot Design; Intuitive Operation; Cable-driven; Force Feedback; Cross Number; Specula Symmetry Mapping; Central Symmetry Mapping.
A Hardware / Software Architecture Dedicated to Model Predictive Control Law and Implemented into an FPGA Platform
by Sirine TELMOUDI BRINI, Badreddine Bouzouita, Faouzi Bouani
Abstract: Model Predictive Control (MPC) is an optimization-based strategy for high-performance control engineering practice and real-time applications. It has been widely used for slow dynamic process. This method needs to solve online a Quadratic Programming (QP) problem at each sample time to find optimal control sequence. However, the computational load for this control strategy is very high and is often restrictive for proper implementation. This means that an appropriate technology and a design approach should be applied. In this paper, a new optimized MPC architecture is presented, to meet the high sampling frequency demand of real-time control applications for a gradient-based QP solver to implement linear MPC on a Field-Programmable Gate Array (FPGA) platform with a fixed 20-MHz clock, which allows obtaining high-quality performances (in control quality, speed and hardware utilization). This MPC implementation achieves comparable results to those obtained with an AMD Turiom (Tm) II Dual core 2.2 GHz, which offers a promising platform to expand the field of the application of this technique to control embedded systems. This work is the first that has used this technique of conception thanks to the benefits of used chip components. However, this approach requires a manual programming of the high-level C/C ++ code in opposition to the other presented approaches, which automatically generates the code. The efficiency of the proposed approach is completed with real time control of the water level of a single tank system running on a Nanoboard 3000XN FPGA chip using a conception environment (Altium Designer), while comparing between the MPC and PID controllers.
Keywords: FPGA; predictive control; quadratic optimization problem; PID controller; Altium Designer; MPC.
A FPGA-based state space controller
by Ananthan T
Abstract: Many years digital controllers have been implemented using microprocessors, microcontrollers, digital signal processors etc. Recently, field programmable gate arrays (FPGA) is found to be an alternative because of its reconfigurability, high processing speed and the reduced cost of computation. Comparatively the performance of FPGA is appreciable in implementing controllers which involves intensive matrix computations. In this context, this paper presents the implementation of State Space Controller (SSC) on FPGA. It is one of the widely used controllers to obtain the desired response of dynamic systems in diverse fields of engineering. SSC contains an observer to estimate the system unknown states variables. Matrix multiplications involved in this estimation take most of the computation time of the controller. In order to make SSC much more competent for controlling fast dynamic systems, a new FPGA based parallel architecture is proposed. The reduction in computation time with optimal hardware resources is achieved by developing an efficient Multistage Matrix Multiplication algorithm (MMM). In addition, the proposed architecture has a high throughput. The performance of FPGA-based SSC is validated by implementing it in an inverted pendulum control system in Matlab Simulnk environment using electronic design automation (EDA) simulator. The design is mapped on xilinx virtex-5 FPGA device with a maximum frequency of 449.438MHz. Application specific integrated circuit (ASIC) implementation of SSC is also carried out using Cadence RTL compiler.
Keywords: FPGA; state feedback control; Parallel architecture ASIC.
Nominal Model Selection and Guidance Computer Design for Antitank Guided Missile
by A.N. Ouda, Gamal El-Sheikh, Yehia Elhalwagy, Mahmoud Ashry
Abstract: The great developments in applied mathematics and computational capabilities facilitate the design and implementation of robust control. In addition, the huge developments in nanotechnology and its availability in civilian level with less cost, size and weight attract many of the researchers all over the world towards embedded systems especially the embedded flight control. Among the real applications are the guided missiles especially the antitank guided missile systems which are commanded to the line of sight (CLOS) against ground and short-range targets. The present work is concerned with improving the performance of an antitank guided missile system belonging to the first generation via robust synthesis of guidance systems. The selection of nominal model is required to design the guidance computer for the system. This paper is devoted to the quantitative analysis to select a nominal plant which used to design a guidance computer that has a successful flight path trajectory against different types of uncertainties. The design and analysis necessitates somehow accurate model with different uncertainties for the system. The flight path is evaluated considering the HIL environment.
Keywords: Missile; Command guidance systems; Robust control; Guidance; nominal model; Autopilot design.
Intelligent Proportional-Integral Sliding Mode Control of Wind Turbine Systems Based Particle Swarm Optimization
by Salma Aboulem, El-mahjoub Boufounas, Ismail Boumhidi
Abstract: This paper presents a robust intelligent proportional-integral sliding mode controller for a variable speed wind turbine (VSWT). The main objective of the controller is to optimize the energy captured from the wind, and minimize the mechanical stress in the system. In order to guarantee the wind power capture optimization without any chattering problems, this study propose to combine the sliding mode control (SMC), proportional integral (PI) control and particle swarm optimization (PSO) algorithm. The PSO technique with efficient global search is used to optimize the PI and SMC parameters simultaneously to control the system trajectories to a sliding manifold that determines the system performance. The stability of the system using this controller is shown by the Lyapunov theory. The simulation results of the proposed PSO-PI based SMC (PSOPISMC) method are compared with the PSO-I based SMC (PSO-ISMC) and the conventional PSO based SMC (PSO-SMC). The comparison results reveal that the proposed controller is more effective in reducing the tracking error and chattering. In addition, the controller shows more robustness against uncertainties and faster transient response of the system with reduced steady state error.
Keywords: sliding mode control; PI sliding surface; particle swarm optimization; variable-speed wind turbine.
A new three-dimensional chaotic system: Its adaptive control and circuit design
by Sundarapandian Vaidyanathan, Oumate Alhadji Abba, Gambo Betchewe, Mohamadou Alidou
Abstract: A new three-dimensional chaotic system with two nonlinearities is proposed in
this research work. Specifically, the two nonlinearities considered in the construction of the new chaotic system are a quadratic nonlinearity and a quartic nonlinearity. A systematic study of the three-dimensional chaotic system has been made including phase portraits, dissipativity, rest points and their stability, Lyapunov chaos exponents, Kaplan-Yorke fractal dimension, etc. As main control results, we design feedback control laws using adaptive control theory to achieve global stabilisation of the new chaotic system and also global synchronisation of identical chaotic systems with unknown parameters. Finally, an electronic circuit design of the new chaotic system using Electronic Work Bench (EWB) is described in detail to confirm the feasibility of the theoretical chaotic model.
Keywords: Chaos; chaos control; chaos synchronisation; adaptive control; circuit design.
Robust Observer-based Synchronization of Chaotic Oscillators with Structural Perturbations and Input Nonlinearity
by KAMMOGNE SOUP TEWA Alain, Ahmad Taher Azar, Hilaire Bertrand Fotsin, Romanic Kengne
Abstract: This paper presents a generalized robust adaptive chaotic synchronization method for chaotic systems with structural perturbations. One control input is used to synchronize both systems exponentially fast based on Lyapunov theory. This approach can not only make the outputs of both master and slave systems reach synchronization with the passage of time between both systems but it can also reduce the effect of external perturbations and input nonlinearities. By assuming bounded solutions of the nominal uncoupled systems, sufficient conditions have been derived for boundedness of the solutions of two different class of chaotic systems with input nonlinearity affected by structural perturbations. The propose approach offers a systematic design procedure for robust adaptive synchronization of a large class of chaotic systems in the chaos research literature. As an illustration of the effectiveness and robustness of the proposed strategy, synchronization problem of a master system consists of a perturbed modified Colpitts oscillator and an observer consisting of a Chua oscillator. It was found that the controller maintains robust stable synchronization in the presence of exoteric perturbations and structural uncertainties.
Keywords: Chaos synchronization; Adaptive observer; Lyapunov theory; synchronization; input nonlinearity.
An optimized 2-DOF IMC-PID based Control Scheme for Real-time Magnetic Levitation System
by Avadh Pati, Richa Negi
Abstract: This paper addresses an optimized 2-DOF internal model based PID controller for unstable magnetic levitation system. Here, the proposed controller is realized using IMC control theory and its parameter are calculated using Maclaurin series expansion. Particle Swarm Optimization (PSO) algorithm is used for obtaining an optimized 2-DOF IMC-PID controller. The proposed method is simpler to use due to its explicit tuning method as compared to other frequency response methods. The real-time experimental results are given, illustrating the effectiveness of proposed controller. The suggested controller not only improves the transient and tracking response but also maintains the robustness of maglev system under various disturbance environments. The performance of the proposed controller is compared with conventional PID controller.
Keywords: Maglev System; Internal Model Control; PID controller; Particle Swarm Optimization; 2-DOF IMC PID Controller; Stability Analysis; Robustness; Disturbance Rejection.
Adaptive Wavelet Network Controller design for Nonlinear Time Delay Systems in the presence of Actuator Failure
by Mahshid Rahimifard, Marzieh Kamali, Maryam Zekri
Abstract: This paper presents an adaptive wavelet network controller for a class of strict-feedback uncertain nonlinear systems with unknown time delays and in the presence of external disturbances and actuator failure. The type of considered actuator failure is loss of effectiveness, in which the system input may lose unknown fraction of its effectiveness during the system operation. Wavelet networks are utilized to approximate unknown nonlinear functions and the proposed adaptive-neural controller is constructed based on dynamic surface control (DSC) design method. By applying the appropriate LyapunovKrasovskii functionals, the boundedness of all the closed-loop signals is guaranteed and the tracking error is proved to converge to a small neighborhood of the origin. The performance of the proposed adaptive-neural control approach is illustrated by applying a theoretical system and a chemical reactor system. The simulation results indicate the effective capabilities of the proposed control algorithm.
Keywords: Adaptive neural control; Wavelet networks; Nonlinear time delay systems; DSC.
NONLINEAR MULTIVARIABLE TRACKING CONTROL: APPLICATION TO AN ETHANOL PROCESS
by María Cecilia Fernández, María Nadia Pantano, Ricardo F. A. Machado, Oscar Alberto Ortiz, Gustavo Scaglia
Abstract: In this paper, a controller based on linear algebra for a fed-batch ethanol production process is proposed. It involves finding feed rate profiles (control actions obtained as a linear equations system solution) in order to make the system follow predefined concentration profiles. A Monte Carlo experiment is used for controller tuning. Moreover, several tests (adding parametric uncertainty, perturbations in the control action and in the initial conditions) are carried out so as to evaluate the controller performance. A comparison with other controller is made and the demonstration of the error convergence is included.
Keywords: fed-batch bioprocess; ethanol production; nonlinear model control; profile tracking control; numeric methods/linear algebra.
Real-Time Implementation of Nonlinear State and Disturbance Observer Based Controller for Twin Rotor Control System
by Bhanu Pratap, Shubhi Purwar
Abstract: A nonlinear state observer based controller for the twin rotor control system (TRCS) with actuator saturation is developed in this paper. The TRCS exemplifies a higher order multiple-input-multiple-output (MIMO) system having nonlinear dynamics with significant cross couplings. A nonlinear local state observer for TRCS is implemented by coordinate transformation that transforms the plant model in an approximate normal form. On the basis of proposed observer, a feedback controller for TRCS is implemented in real-time. To tackle the external disturbances and friction on the rotor shaft, a nonlinear disturbance and friction observer (NDFO) has been employed. To take into account control input within practical range, a compensator using Chebyshev neural network (CNN) is augmented to the proposed control scheme. The simulation and experimental results are highlight that the controlled response has fast convergence, high degree of tracking with small errors, bounded control effort under the effect of friction and disturbance.
Keywords: Chebyshev neural network; nonlinear coupled system; nonlinear friction; observer based control; twin rotor control system.
Nonlinear control scheme based on a second order sliding mode: application to DFIG supplied by five-level PWM inverter
by Ahmed Benzouaoui, Zoubir Ahmed-foitih, Mohamed Faycal Khelfi
Abstract: Adaptive control is a set of approaches used for the automatic adjustment of the controller parameters in order to achieve or maintain a certain level of performance when the parameters of the control process vary over time or unknown. The parameters of the controller are adapted to ensure also that there is no overestimation of the gain with real a priori unknown value of uncertainties. The proposed control approach consists in using second-order sliding mode with a dynamically adapted control gain that guarantees the stability and robustness of the control law even with the presence of uncertainties and perturbation of the system. The control is applied by simulation (Matlab-Simulink) on a doubly fed induction generator (DFIG) integrated into a variable speed wind turbine and controlled by super twisting sliding mode control. The simulations indicate the efficiency of the proposed approach especially in the case of change of the reference speed and/or the parameters variation.
Keywords: Adaptive second order sliding mode control; chattering; doubly fed induction generator; five-level inverter; wind energy.
H Control of Asynchronous Networked Control Systems with Markov Time Delays
by Xiaoqiang Sun, Weijie Mao
Abstract: In this paper, the solutions to the H∞ synthesis problems of stochastic asynchronous discrete-time (DT) networked control systems (NCSs) with random communication time delays are proposed according to the following steps. Firstly, a new Lyapunov-Krasovskii functional is explicitly constructed to analyze the stochastic stability of the systems. Both sensor-to-controller (S-C) and controller-to-actuator (C-A) random networked-induced delays, which are two Markov chains, are considered in the analysis. Moreover, the stochastic sampling of S-C and holding of C-A are also considered in the analysis. Secondly, based on a specified definition of the state with delay and a more rigorous inequality, sufficient delay-dependent stability conditions can be transformed into the form of linear matrix inequalities (LMIs) by slack matrix method and the lemma of Schur complement. The LMIs are less conservative and have fewer tuning parameters and lower dimensions. Therefore, the LMIs can be conveniently solved by LMI tools. Finally, the proposed theory is validated by a simulation example.
Keywords: H∞ synthesis; DT asynchronous system; random delay; Markov chain; stochastic sampling and holding; delay-dependent LMIs.
LQG Controller Design for a Quadrotor UAV Based on Particle Swarm Optimization
by Rabii Fessi, Soufiene Bouallègue
Abstract: This paper deals with the modelling and the Linear Quadratic Gaussian
(LQG) control design of a quadrotor Unmanned Aerial Vehicle (UAV)
using different Particle Swarm Optimization (PSO) variants. Such a
PSO-designed LQG controller is optimized in order to stabilize the
position and the heading of the studied Vertical Take-Off and Landing
(VTOL) quadrotor. Both canonical and recent variants of PSO algorithm, with linearly decreasing of inertia weight~(PSO-In) and perturbed updating strategy~(PSO-gbest), are considered for the systematically design and tuning of the LQG weighting matrices. These effective control parameters of the LQG approach
represent the decision variables of the PSO-based LQG optimization
problem. Such an optimization problem is formulated to minimize
various performance time-domain criteria, like the Integral of
Absolute Error (IAE) and the Maximum Overshoot (MO) index, under
nonlinear constraints related to the step responses of the
closed-loop quadrotor dynamics. All proposed PSO algorithms are
compared with each other and with the well known Harmonic Search Algorithm~(HSA) and Water Cycle Algorithm~(WCA) metaheuristics for the stabilization problem of the position and heading dynamics of the VTOL drone. Demonstrative simulation results are carried out in order to show the effectiveness of the proposed
PSO variants-tuned LQG control approach.
Keywords: Quadrotor UAV; modelling; position and heading stabilization,
LQG weighting matrices tuning; Particle Swarm Optimization.
PLC-Based implementation of Supervisory Control for Flexible Manufacturing Systems using Theory of Regions
by Sadok Rezig, Chekib Ghorbel, Zied Achour, Nidhal Rezg
Abstract: The supervisory control is a common theory for the synthesis of Petri net (PN) supervisors for discrete event systems given a PN model and a control specification for the maximum permissive behaviour. The theory of regions asrnone of control synthesis method generates a PN controller to satisfy the control specification. Though the theory of regions has for over a decade received a considerable attention in academy, still very few applications exist. The real cause of this seems to be a contradiction between the abstract controller and its physical implementation. This is evident in particular when the implementation is supposed to be based on a Programmable Logic Controllers (PLC), as is the case for flexible manufacturing systems. Indeed, since the synchronous PLC is based on signals, the PN supervisor remains asynchronous; this explains its implementation difficulty. In this paper, we propose a synthesis method of PN monitor using a Java application implemented on PLCs of a Flexible Manufacturing System (FMS) installed in our research laboratory in the University of Lorraine in Metz, FRANCE.
Keywords: Petri nets; Theory of regions; Program Logic controller; Supervisory control; Flexible Manufacturing System.
Design and simulation of self-tuning Fractional Order Fuzzy PID controller for robotic manipulator
by Reza Rouhi Ardeshiri, Hoda Nikkhah Kashani, Atikeh Reza-Ahrabi
Abstract: Two-link robotic manipulator system is completely non-linear and time-varying multiinput- multiple output. Therefore designing a controller that has high accuracy and good performance is the researchers' attention. In this paper, the Fractional Order Fuzzy PID (FOFPID) controller is proposed in order to control the robotic manipulator position. This controller has been designed by a fuzzy system and a fractional order PID controller. Fractional order PID (FOPID) controller, can be more flexible than classic PID controller function. Since real control systems are generally non-linear systems, therefore, better control of these systems requires the usage of an adaptive or non-linear controller. Therefore, in this work we applied a fuzzy system in order to determine the coefficients of a fractional order PID controller based on particle swarm optimization (PSO) evolutionary algorithm to determine the fractional order operators. In definition of fitness function for the optimization problem, we considered Integral of Absolute Error (IAE) and Integral of Absolute Change in Controller Output (IACCO). Finally, in order to compare the proposed controller with the conventional controller (FPID), numerical simulations were performed on the robotic manipulator. The results clearly demonstrate that the overshoot of FOFPID controller is less than FPID. In addition the proposed controller has less oscillations amplitude and has a high robustness against noise which improves the performance of trajectory tracking system.
Keywords: Robotic manipulator; Fractional calculus; FOFPID controller; Fuzzy logic controller; PSO algorithm.
Synthesize of MPC Controller for Uncertain Systems subject to Input and Output Constraints: Application to Anthropomorphic Robot Arm
by Imen Dakhli, Elyes Maherzi, Mongi Besbes
Abstract: This paper proposes a synthesis of a dynamic controller under constraints. It is based on Model Predictive Control (MPC) approach and resolution of a convex optimization problem with Linear Matrix Inequalities (LMI). The controller guarantees the closed-loop stability for polytopic time-varying uncertain systems. Conditions are provided for the controller design based on the parameter dependent Lyapunov functions (PDLF). A new demonstration is developed based on the relaxation technique, to include a slack variables Gi. The new LMI's formulation offers an additional degree of freedom for the controller design. Input and output constraints are also taken into account during the design of the controller. This approach allows varying and adjusting the dynamic of system by taking into account input/output constraints.
Keywords: Model Predictive Control (MPC); Dynamic controller; Linear matrix inequality (LMI); Parameter dependent Lyapunov functions (PDLF); Input / Output Constraint.
Hybrid intelligent controller design for an unstable Electromagnetic Levitation System: A fuzzy interpolative controller approach
by Ravi Gandhi, Dipak Adhyaru
Abstract: This article presents the design and implementation of hybrid
intelligent controller for the dynamically nonlinear and unstable Electro-
Magnetic Levitation System (EMLS). The hybrid design is having the
intelligence of the Fuzzy Interpolative Controller (FIC) with estimation ability
and noise immunity achieved by means of the Kalman filter. The Fuzzy
Inference System (FIS) is replaced by fuzzy linear interpolation networks based
on look-up table to form the fuzzy rule base in ordered to reduce the
computational complexity and to boost up the execution speed of the control
approach as compared to conventional Mamdani or Sugeno type FIS toolkits.
The proposed design stabilizes the EMLS under wide initial and assorted
operating conditions. Further, the proposed controller maintains the
performance robustness under 0-25% of vertical payload disturbance by
holding the steel ball within the safe limits. Simulation results are presented to
validate the novelty and effectiveness of the proposed approach for EMLS.
Keywords: Fuzzy Interpolative Controller (FIC); Kalman filter; hybrid
intelligent control; Electromagnetic Levitation System; set-point filter;
Optimal Preview Control Design of Pneumatic Servo System: A Comparative Analysis
by Randeep Kaur, Jyoti Ohri
Abstract: This paper describes the development of a preview controller based on optimal control theory for positioning control of a pneumatic servo system. The preview theory of tracking control using the future information has been studied extensively but did not get enough applications in the field of servo control systems, used in modern industrial processing, that will increase the accuracy and efficiency of the industrial product. In the pneumatic servo system, the position of pneumatic cylinder is the command input and its future information can be known a priori. The proposed control system is composed of feedback from the state of the plant and feed-forward from the reference signal by using future information. The validity of the proposed control system is confirmed by simulation and comparative analysis is done with optimal control. Simulation results imply that good performance and good phase characteristics can be obtained using optimal preview controller.
Keywords: Pneumatic Servosystem; Preview Control; Optimal Control; Algebraic Riccati Equation; Performance Index; Tracking.
Stabilisation of a rotary inverted pendulum system with double-PID and LQR control: Experimental verification
by Teng Fong Tang, Shin Horng Chong, Kee Kiat Pang
Abstract: Rotary inverted pendulum (RIP) system is an under-actuated system. The RIP system consists of a pendulum, which is rotating freely in the vertical plane. A swing-up action using a pivot arm in the horizontal plane would then result in the pendulum to achieve upright equilibrium point. This paper describes the design of a double Proportional-Integral-Derivative (PID) controls with a Linear Quadratic Regulator (LQR) controller for the stabilisation control of a RIP system. The dynamic model of the RIP system is described too. The LQR controller was tuned using Taguchi method. The double-PID controller was designed using Ziegler-Nichols method, which the LQR controller is embedded in the RIP system to improve the stabilisation performance. The effectiveness of the double-PID and LQR controller is clarified with a RIP experimentally. The proposed controller has demonstrated succeed stable the pendulum within 0.5 degrees in 3 seconds and the rotary arm within 22.5 degrees.
Keywords: rotary inverted pendulum; mathematical modelling; linear quadratic regulator; proportional-integral-derivative; Taguchi method; Ziegler-Nichols method.
Special Issue on: Observer-based Fuzzy, Neural and Adaptive Control Advances and Applications
Design of a proportional integral observer based on sliding mode principle for uncertain Takagi-Sugeno fuzzy systems: applications to a turbo-reactor
by Ilyes Elleuch, Atef Khedher, Kamel Ben Othman
Abstract: This work deals with the problem of state and fault estimation for systems described by Takagi-Sugeno fuzzy systems. The state and fault estimation is made using a proportional integral observer based on the sliding mode principle. Only sensor faults are considered in this work. In order to estimate this kind of fault, a particulate mathematical transformation is used. The application of this mathematical transformation to the initial system output allows to conceive an augmented system where the initial sensor fault appears as an unknown input. An adaptive mathematical form is used for the sign function to facilitate the determination of the proportional gains of the conceived observer. The observer convergence conditions are formulated in the form of linear matrix inequalities (LMI) allowing computing the observer gains and the Lyapunov theory is used to guarantee the system stability with faults. The proposed proportional integral sliding mode observer is applied to turbo-reactor showing the efficiency of the fault and state estimation.
Keywords: state estimation; Takagi-Sugeno; unknown input; sensor faults; multiple model.
Sliding surface-based obstacle avoidance for second order multi-agent systems
by Asma Essghaier, Lotfi Beji, Azgal Abichou
Abstract: This paper studies formation keeping along with obstacle avoidance for second-order multi-agent systems. First, the flexible virtual structure (FVS) approach, used to model the communication topology between the agents of the formation, is recalled and relationship with graph theory-based communication exchange to achieve consensus is established. Second, using the regulation function (RF) which permits to change the behaviour of the system's solution without affecting convergence, obstacle avoidance is investigated for one agent (leader/co-leader) of the formation. Particularly, RF was used to ensure obstacle avoidance for first order agents and is extended in this work for second order agents. Relationship between the dynamic agent and a sliding surface with first order kinematics is established and condition on the sliding surface parameter is developed to ensure obstacle avoidance. Also, new shapes of the obstacle are considered namely square and rhombus. Finally, in order to perform a coordinated obstacle avoidance of a multi-agent system when only a subset of agents namely co-leaders, selected from the boarder, has obstacle information, one defines control laws which permit to control motions of the remaining formation agents.
Keywords: obstacle avoidance; second order multi-agent systems; flexible virtual structure; FVS; regulation function; consensus; graph theory.
Synchronisation control for ships in underway replenishment based on dynamic surface control
by Yongchao Liu, Jialu Du, Xin Hu
Abstract: In order to ensure safe underway replenishment operation between two ships, it is necessary to keep the distance and avoid collision between the supply and the supplied ships. A virtual trajectory locating on one side of the supplied ship with a relatively fixed distance from the trajectory of the main ship is introduced. A nonlinear synchronisation control law is developed for the supply ship in the underway replenishment under environmental disturbances incorporating a robust term based on signum function into the dynamic surface control (DSC) technique. It is proved that the designed synchronisation control law can force the supply ship to track the virtual trajectory with arbitrarily small errors, while guaranteeing that all signals in the synchronisation closed-loop control system are uniformly ultimately bounded so that synchronisation motion control is realised between two ships. Simulation results on a supply ship illustrate the effectiveness of the proposed synchronisation control law.
Keywords: underway replenishment; synchronisation control; dynamic surface control; virtual trajectory.
Fuzzy sliding mode control for three-tank system based on linear matrix inequality
by El Mehdi Mellouli, Mohammed Alfidi, Ismail Boumhidi
Abstract: A novel method-based fuzzy sliding mode (FSM) and linear matrix inequality (LMI) approach is presented in this paper to design a new robust adaptive fuzzy controller for a perturbed multi-input multi-output (MIMO) three-tank system with unknown dynamics and without chattering problem that is produced by the traditional sliding mode control. The proposed method uses the adaptive fuzzy system Takagi-Sugeno (TS) to approximate the unknown dynamics model of the three-tank system which is considered a very complicated system due to the high nonlinearity and cross coupling. Moreover, to overcome the external disturbance and the fuzzy approximation errors due to the modelling system, an auxiliary control term-based sliding mode is incorporated in the control law. Linear matrix inequality is used to determine the parameters of the dynamic compensator which is added to improve more performance of the closed-loop system in the sliding mode. The stability and robustness of the proposed method are proved, and the simulation is given to demonstrate the tracking performance of the proposed approach.
Keywords: indirect adaptive fuzzy technique; sliding mode control; linear matrix inequality; LMI; Lyapunov stability.
Adaptive iterative learning control of nonlinearly parameterised strict feedback systems with input saturation
by Hocine Benslimane, Abdesselem Boulkroune, Hachemi Chekireb
Abstract: In this paper, a new adaptive iterative learning control scheme is proposed to deal with nonlinearly parameterised strict feedback systems under alignment condition in the presence of input saturation constraint. The learning controller is designed by using the command filtered adaptive backstepping design procedure. The nonlinearly connected parameters are separated from the local Lipschitz continuous nonlinear functions and then learning laws are designed in iteration domain. To overcome the problem of input saturation, an auxiliary system is constructed with the same order as that of the systems under consideration. It is proved that the proposed control scheme can guarantee that all signals of the resulting closed-loop system remain bounded, and the tracking error converges to zero as the iteration number goes to infinity. A simulation example is included to illustrate the effectiveness of the proposed scheme.
Keywords: adaptive iterative learning control; AILC; Lyapunov functional; nonlinearly parameterised functions; input saturation constraint; backstepping method; strict feedback systems.
Robust fuzzy fault tolerant control for induction motor subject to sensor fault
by Habib Ben Zina, Moez Allouche, Maha Bouattour, Mansour Souissi, Mohamed Chaabane, Larbi Chrifi-Alaoui
Abstract: This study presents a strategy of fault tolerant control (FTC) to keep the vector controlled induction motor (IM). The aim is to minimise the effect of the sensor fault and the parametric uncertainties. Firstly, a fuzzy proportional multiple integral observer (PMIO) is used to estimate simultaneously the system state and the sensor fault. Secondly, a feedback robust state tracking control is synthesised to guarantee the control performances. The proposed controller is based on a T-S reference model to specify the desired trajectory. The performances of the trajectory tracking are analysed using the Lyapunov theory and the L2 optimisation. The gains of the observer and controller are obtained by solving a set of LMIs constraint. Finally, simulation results are given to show the effectiveness of the proposed control scheme.
Keywords: induction motor; fault tolerant control; FTC; H∞ theory; Lyapunov theory; L2 performance; linear matrix inequality; LMI; sensor faults.
Design and analysis of BFOA optimised PID controller with derivative filter for frequency regulation in distributed generation system
by Tulasichandra Sekhar Gorripotu, Darapureddi Vijaya Kumar, Manmadha Kumar Boddepalli, Ramana Pilla
Abstract: In this article, a bacterial foraging optimisation algorithm (BFOA)-based proportional integral derivative controller with derivative filter (PIDF) is proposed for frequency regulation of multi source hybrid power system. Initially, a two area, unequal area power system with PIDF controllers, are considered. The area 1 comprises of reheat thermal power system incorporated with distributed generation (DG) system comprising of wind turbine generators (WTGs), diesel engine generators (DEGs), fuel cells (FCs), aqua-electrolyser (AE), ultra capacitor (UC) and battery energy storage system (BESS). The area 2 comprises of hydrothermal power system. The gains of the PID controller with derivative filter are optimised by using integral time multiply absolute error (ITAE) criterion. The superiority of PIDF controller is demonstrated by comparing the dynamic responses with integral derivative (ID) and proportional integral (PI) controllers. The simulation results show that the performance of dynamic responses with PIDF controller is superior to others. Further, robustness analysis is performed by varying the system parameters and wind power variations. It is observed from the simulation results that the optimum gains of the proposed controller need not be reset even if the system is subjected to wide variation in loading condition and system parameters.
Keywords: bacterial foraging optimisation algorithm; BFOA; distributed generation; frequency regulation; proportional integral derivative controller with derivative filter; PIDF; robustness analysis.