Showing papers in "International Journal of Automation and Control in 2019"

A memristor-based system with hidden hyperchaotic attractors, its circuit design, synchronisation via integral sliding mode control and an application to voice encryption

Abstract: A memristor-based system with hyperchaos and hidden attractors is introduced in this research work. The proposed four-dimensional memristor-based system exhibits both line equilibrium and no-equilibrium for different choice of parameters. An experimental emulation of the memristor-based system is carried out by an electronic circuit. An adaptive integral sliding mode controller is designed for globally synchronising a pair of memristor-based hyperchaotic systems with unknown parameters. As another application, the memristive system with hyperchaos is applied for voice encryption, which has potential applications in cryptosystems, computing and secure communication.

Robust observer-based synchronisation of chaotic oscillators with structural perturbations and input nonlinearity

Abstract: This paper presents a generalised robust adaptive chaotic synchronisation method for chaotic systems with structural perturbations One control input is used to synchronise both systems exponentially fast based on Lyapunov theory This approach cannot only make the outputs of both master and slave systems reach synchronisation 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 classes of chaotic systems with input nonlinearity affected by structural perturbations The propose approach offers a systematic design procedure for robust adaptive synchronisation of a large class of chaotic systems in the chaos research literature As an illustration of the effectiveness and robustness of the proposed strategy, synchronisation 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 synchronisation in the presence of exoteric perturbations and structural uncertainties

A new three-dimensional chaotic system: its adaptive control and circuit design

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.

LQG controller design for a quadrotor UAV based on particle swarm optimisation

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 optimisation (PSO) variants. Such a PSO-designed LQG controller is optimised in order to stabilise 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 optimisation problem. Such an optimisation problem is formulated to minimise 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 harmony search algorithm (HSA) and water cycle algorithm (WCA) metaheuristics for the stabilisation 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.

Real-time implementation of nonlinear state and disturbance observer-based controller for twin rotor control system

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.

Chaos control of a four-dimensional fundamental power system using pole placement-based proportional integral sliding mode control

Abstract: In this paper, the problem of chaos control for a four-dimensional fundamental power system (FDFPS) model is investigated. Pole placement-based proportional integral sliding mode control (PISMC) is designed to control the chaos present in the system. Proportional integral sliding mode control law is derived by placing the poles at appropriate location to control the chaotic behaviour in four-dimensional fundamental power systems. The sufficient condition is derived for the asymptotic stability of the sliding manifold using Lyapunov stability theory. The proposed controller reduces the chattering, simplifies the design of power system stabiliser. Further the proposed pole placement-based PISMC is compared with conventional SMC approach. MATLAB is used for simulation. Simulation results show the effectiveness of proposed PISMC scheme.

Complete synchronisation of non-identical fractional order hyperchaotic systems using active control

Abstract: This manuscript investigates the complete synchronisation of non-identical fractional order 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 synchronisation between master and slave system. Simulations results show that our scheme can not make the two systems synchronised, but also let them remain chaotic states.

A mixed-method for order reduction of linear time invariant systems using big bang-big crunch and eigen spectrum algorithm

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) optimisation and eigen spectrum algorithm. The cosmological theory based BB-BC optimisation has the advantage of numerical simplicity with relatively fewer control parameters which makes this algorithm easier to implement. BB-BC optimisation 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 centre of mass or minimal cost approach. Eigen spectrum is based on the preservation of centroid and stiffness of the original system into reduced model which guarantees 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 spectrum approach whereas the minimisation of 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.

Adaptive terminal sliding mode control of high-order nonlinear systems

Abstract: In recent decades, controller design has been attracted a great deal of interest of many researchers in control community which can make the job of many other researchers in different area of research easier. The present study aims to design a finite time adaptive control input for a high-order nonlinear system in presence of a variety of mismatched uncertainties and external disturbances. Adaptive terminal sliding mode control (ATSMC) method is used to design robust controller in a finite time. Also, adaptive concept is employed in ATSMC to estimate the upper bound of mismatched uncertainties and external disturbances and their estimations are used in control input. The finite time stability proof is performed by defining a proper candidate Lyapunov function. Numerical simulation results are carried out in Simulink/MATLAB to reveal the correctness of proposed design in this research. Finally, the performance criterion, integral of the square value (ISV), is defined to provide a numerical comparison between the proposed adaptive controller and non-adaptive controller.

Control of continuous-time chaotic (hyperchaotic) systems: F-M synchronisation

Abstract: In this paper, a new type of chaos synchronisation between different dimensional chaotic systems is proposed. The novel scheme is called F-M synchronisation, since it combines the inverse generalised synchronisation with the matrix projective synchronisation. In particular, the proposed approach enables F-M synchronisation to be achieved between n-dimensional master system and m-dimensional slave system in different dimensions. The technique, which exploits nonlinear controllers, stability property of integer-order linear continuous-time dynamical systems and Lyapunov stability theory, proves to be effective in achieving the F-M synchronisation. Finally, simulation results are reported, with the aim to illustrate the capabilities of the novel scheme proposed herein.

Design and simulation of self-tuning fractional order fuzzy PID controller for robotic manipulator

Abstract: Two-link robotic manipulator system is completely nonlinear and time-varying multi-input-multiple output. In this research, the fractional order fuzzy PID (FOFPID) controller is proposed in order to control the robotic manipulator position. Since real control systems are generally nonlinear systems, therefore, better control of these systems requires the usage of an adaptive or nonlinear controller. So we applied a fuzzy system in order to determine the coefficients of a FOPID controller based on particle swarm optimization (PSO) algorithm. In definition of fitness function for this optimization, we considered integral of absolute error (IAE) and integral of absolute change in controller output (IACCO). Finally, in order to compare this controller with the FPID controller, numerical simulations were performed on the robotic manipulator. The results demonstrate that the overshoot of FOFPID controller is less than the FPID and proposed controller has less oscillations amplitude, totally, its performance is better than the FPID controller.

Hybrid intelligent controller design for an unstable electromagnetic levitation system: a fuzzy interpolative controller approach

Abstract: This article presents the design and implementation of hybrid intelligent controller for the dynamically nonlinear and unstable electromagnetic 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 stabilises 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.

PLC-based implementation of supervisory control for flexible manufacturing systems using theory of regions

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 as one 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 controller (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 work, a control synthesis method using the theory of regions is implemented with a Java application on PLCs of a flexible manufacturing system (FMS) installed in our research laboratory in the University of Lorraine in Metz, France.

Nonlinear multivariable tracking control: application to an ethanol process

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.

A linear algebra controller based on reduced order models applied to trajectory tracking for mobile robots: an experimental validation

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.

An optimised 2-DOF IMC-PID-based control scheme for real-time magnetic levitation system

Abstract: This paper addresses an optimised 2-DOF internal model-based PID controller for unstable magnetic levitation system. Here, the proposed controller is realised using IMC control theory and its parameter are calculated using Maclaurin series expansion. Particle swarm optimisation (PSO) algorithm is used for obtaining an optimised 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.

Super-twisting algorithm-based integral sliding mode control with composite nonlinear feedback control for magnetic levitation system

Abstract: The paper aims to discuss the issues of actuator saturation and external disturbance in the magnetic levitation (maglev) system. The proposed technique is composed of composite nonlinear feedback (CNF) and super-twisting algorithm (STA)-based integral sliding mode (ISM) control to tackle the problem of actuator saturation and external disturbances simultaneously. The composite nonlinear feedback scheme comprises of linear feedback law which provides stability and fast response whereas the nonlinear feedback law takes care of input saturation and reduces the overshoot. The super-twisting algorithm (STA)-based integral sliding mode (ISM) controller is designed for disturbance rejection. A super-twisting algorithm-based approach is applied on ISM scheme to eliminate the chattering effect and make it continuous in nature for its direct implementation to the physical maglev system. The designed scheme is successfully tested on real-time feedback instruments model of the maglev system.

Intelligent proportional-integral sliding mode control of wind turbine systems based particle swarm optimisation

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 optimise the energy captured from the wind, and minimise the mechanical stress in the system. In order to guarantee the wind power capture optimisation without any chattering problems, this study propose to combine the sliding mode control (SMC), proportional integral (PI) control and particle swarm optimisation (PSO) algorithm. The PSO technique with efficient global search is used to optimise 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 (PSO-PISMC) 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.

CDM-based two degree of freedom PI controller tuning rules for stable and unstable FOPTD processes and pure integrating processes with time delay

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 (TD) 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 utilising 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.

A FPGA-based state space controller

Abstract: For 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 high processing speed. In this context, this paper presents the implementation of state space controller (SSC) on FPGA. 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). The performance of FPGA-based SSC is validated by implementing it in an inverted pendulum control system. The design is mapped on xilinx virtex-5 FPGA device with a maximum frequency of 449.438MHz.

Designing dynamic fractional terminal sliding mode controller for a class of nonlinear system with uncertainties

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 has 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.

Hybrid Petri network super twisting sliding mode control of wind turbine for maximum power point tracking

Abstract: This paper deals with a hybrid sliding mode control and super twisting algorithm second order sliding mode control with Petri network (HSMC-STA) applied to reach the maximum power point tracking (MPPT) of a variable speed wind energy conversion system. It is aimed to solve the main and major undesired phenomenon faced by conventional sliding mode control, the high frequency oscillations (chattering), and to reduce the transient response (rise time) of super twisting algorithm second order sliding mode control systems. The design of a hybrid controller based on switching Petri network sliding mode control (PNSMC) is proposed, wherein a Petri network is used to supervise and switch between the classical sliding mode control law and the super twisting control law. The new hybrid controller is tested in a Simulink/MATLAB environment. Simulation results of the proposed control scheme present good dynamic and steady-state performance compared to the classical SMC and high order sliding mode with respect to the reduction of the chattering phenomenon and transient response.

Nominal model selection and guidance computer design for antitank guided missile

Abstract: The great developments in applied mathematics and computational capabilities facilitate the design and implementation of robust 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 necessitate somehow accurate model with different uncertainties for the system. The flight path is evaluated considering the HIL environment.