2016 (vol. 26) - Number 4
Practical and asymptotic stability of fractional discrete-time scalar systems described by a new model
D. Krokavec, A. Filasova, P. Liscinsky:
On fault tolerant control structures incorporating fault estimation
Hyperchaos, adaptive control and synchronization of a novel 4-D hyperchaotic system with two quadratic nonlinearities
H. Górecki, M. Zaczyk:
Analytic solutions of transcendental equations with application to automatics
Predictor-based stabilization for chained form systems with input time delay
S. Daniar, R. Aazami, M. Shiroei:
Multivariable predictive control considering time delay for load-frequency control in multi-area power systems
Analysis and comparison of the stability of discrete-time and continuous-time linear systems
M. Rachik, M. Lhous:
An observer-based control of linear systems with uncertain parameters
Identification of stable elementary bilinear time-series model
New observer-based control design for mismatched uncertain systems with time-delay
A control Lyapunov function approach to adaptive control of HIV-1 infection
|J. M. Lemos, M. S. Barao|
(Univeristy of Evora, Portugal)
This paper presents an algorithm for nonlinear adaptive control of the viral load in HIV-1 infection. The infection model considered is a reduced complexity nonlinear state-space model with two state variables, that represent the plasma concentration of uninfected and infected CD4+ T-cells of the human immune system. The viral load is assumed to be proportional to the concentration of infected cells. First, a change of variables that exactly linearizes the system is obtained. For the resulting linear system the manipulated variable is obtained by state feedback. To compensate for the uncertainty in the infection parameter of the model an estimator based on a Control Lyapunov Function is designed.
keywords: nonlinear adaptive control, HIV-1 infection, immunology, exact linearization, control Lyapunov function
Sliding mode approach to torque and pitch control for an wind energy system using FPGA
|B. Subudhi, P.S. Ogeti|
(National Institute of Technology, Rourkela, India)
Wind energy, being a fluctuating resource, requires a tight control management to ensure stability when integrated with the grid system. This has triggered interest towards developing advanced controllers. Hence this paper presents the study of a variable speed wind energy conversion system that uses a Double Fed Induction Generator (DFIG). Above rated wind speed, pitch control has been applied and below the rated speed torque control has been adopted. Generator torque control is able to reduce the effects of the pitch actuator limitations. Sliding mode control is applied for torque and pitch control in WECS and it has been implemented in MATLAB SIMULINK and FPGA to achieve control of active and reactive power exchange between the stator of the DFIG and the grid. Performance parameters like pitch angle, active, reactive power, turbine speed, and DC voltage has been compared by using SMC, Hill Climbing (HC) Algorithm and Perturb and Observe (P&O) Algorithm and performance for these three methods has been simulated and implemented in FPGA. Total Harmonic Distortion for all the performance parameters has been reported. Hardware implementation of developed algorithm was accomplished with the help of Xilinx system generator and Xilinx Tool Kit.
keywords: wind-energy conversion systems (WECSs), sliding mode control (SMC), torque, pitch control, hill climbing (HC), perturb and observe (P&O), FPGA
Positive stable realizations for fractional descriptor continuous-time linear systems
(Bialystok University of Technology, Poland)
A method for computation of positive asymptotically stable realizations of fractional descriptor continuous-time linear systems with regular pencil is proposed. The method is based on the decomposition of the improper transfer matrix into strictly proper matrix and a polynomial matrix. A procedure for decomposition of a positive asymptotically stable realization is given and illustrated by a numerical example.
keywords: positive, stable, realization, procedure, descriptor, continuous-time, linear system
Backstepping sliding mode controller improved with fuzzy logic: Application to the quadrotor helicopter
|S. Zeghlache, D. Saigaa, A. Harrag, A. Bouguerra|
(University of Msila, Algeria)
(University of Blida, Algeria)
In this paper we present a new design method for the fight control of an autonomous quadrotor helicopter based on fuzzy sliding mode control using backstepping approach. Due to the underactuated property of the quadrotor helicopter, the controller can move three positions (x, y, z) of the helicopter and the yaw angle to their desired values and stabilize the pitch and roll angles. A first-order nonlinear sliding surface is obtained using the backstepping technique, on which the developed sliding mode controller is based. Mathematical development for the stability and convergence of the system is presented. The main purpose is to eliminate the chattering phenomenon. Thus we have used a fuzzy logic control to generate the hitting control signal. The performances of the nonlinear control method are evaluated by simulation and the results demonstrate the effectiveness of the proposed control strategy for the quadrotor helicopter in vertical flights.
keywords: fuzzy sliding mode, backstepping, quadrotor helicopter, dynamic modeling, underactuated systems
Hybrid synchronization of n-scroll Chua and Lur'e chaotic systems via backstepping control with novel feedback
|R. Suresh, V. Sundarapandian|
(Vel Tech Dr. RR & Dr. SR Technical University, India)
This paper investigates the backstepping control design with novel feedback input approach for controlling chaotic systems to guarantee the complete synchronization as well as the anti-synchronization of chaotic systems, viz. n-scroll Chua (K. Wallace et.al. 2001) and Lur'e chaotic systems. Our theorems on hybrid synchronization for n-scroll Chua and Lur'e (J.Suyken et.al. 1997) chaotic systems is established using Lyapunov stability theory. Based on the Lyapunov function, the backstepping control is determined to tune the controller gain based on the precalculated feedback control inputs. The backstepping scheme is recursive procedure that links the choice of a Lyapunov function with the design of a controller and guarantees global stability performance of strict-feedback chaotic systems. Since the Lyapunov exponents are not required for these calculations, the backstepping control method is effective and convenient to synchronize the chaotic systems. Mainly this technique gives the flexibility to construct a control law. Numerical simulations are also given to illustrate and validate the hybrid synchronization results derived in this paper.
keywords: chaos, hybrid-synchronization, n-scroll Chua system, Lur'e system, backstepping control
Dead-beat and reaching law based sliding mode control laws for perishable inventories with transportation losses
|A. Bartoszewicz, M. Maciejewski|
(Technical University of Lodz, Poland)
This paper describes discrete sliding mode (SM) supply management strategies for inventory systems with perishable goods and transportation losses. In the considered systems, the stock used to satisfy the unknown, bounded and time-varying demand is replenished with some delay from a distant supply source. The on-hand stock deterioration during lead-time delay, as well as commodity losses in supply process are explicitly taken into account. Two supply management strategies are proposed. The first one ensures fast reaction to the imposed demand variations, but may result in excessive control signal magnitude at the beginning of the inventory management process. Therefore, in order to conform to supplier limitations we also develop an alternative control strategy based on the concept of the reaching law. That strategy helps reduce the initial supply rate and satisfy the supplier limitations. A number of desirable properties of both proposed strategies are formulated and formally proved. These properties include full customer demand satisfaction and elimination of the risk of exceeding the warehouse capacity.
keywords: sliding mode control, perishable inventories, inventory control