Order Sliding Mode Control Technique Research Articles

Analysis of single phase ZSI fed PV system in weak grids using fractional order sliding mode control technique

Nowadays, Photovoltaic (PV) system’s contribution to the power grid is increasing immensely. The PV system is linked with power grid through one or more inverters and a power conditioning unit to ensure smooth power delivery while also maintaining system voltage and frequency stability. However, due to grid load expansion, weak power grids have emerged as the dominant one today. As a result, the voltage and frequency of the grid got distorted. It may cause serious damage to the entire system in some cases. A single phase ZSI with the proposed Fractional order SMC technique is used to address these issues. The single phase ZSI consists of only two power switches and perpetuates the voltage transfer ratio like full bridge inverter. It also corroborates the sharing of power, regulatesactivepower,voltage, frequency, reactive powerand alleviates the harmonics in current. The input voltage of inverter is boostedby using theshoot through state and it also improvesthe reliability of inverter. The execution of the single phaseZSI withproposed FOSMCtechnique is assessed in MATLAB/Simulink to bear out the magnificent features of the proposed FOSMC in weak grid.

Design of improved direct torque control based on a five level torque controller and a new Sugeno-Takagi fuzzy super-twisting controller applied to an induction machine

This paper deals with the design and Hardware In Loop (HIL) verification of a novel intelligent Super-twisting Sliding Mode Speed Controller (STSMSC) based on a Sugeno-Takagi Fuzzy Logic System (STFLS) for an induction motor controlled by an improved Modified Direct Torque Control (MDTC) approach. Indeed, Conventional Super-twisting Sliding Mode Speed Controller (CSTSMSC) is chosen as an alternative solution for attenuating the chattering phenomenon brought on by the discontinuous control law of the First Order Sliding Mode Speed Control (FOSMSC) and maintaining its advantages like simplicity, robustness and accuracy. Moreover, the STSMSC is a type of a second order sliding mode control technique that needs only the information about the sliding surface, not its time derivative. However, the choice parameters of the CSTSMSC existing in the control law effects the tracking accuracy, the overshoot and the amplitude of the chattering. Therefore, an STSMSC based on an STFLS (STFLS-STSMSC) is proposed for online tuning of these parameters in transient and steady state operations. In fact, the STFLS is considered as an intelligent supervisor to adjust these parameter values according to the system state, which consequently provides excellent performance consisting in a higher robustness rate under disturbances and uncertainties, tracking with excellent accuracy and reduced chattering in steady state and transient operations. Numerous simulation and HIL co-simulation results are presented to demonstrate the effectiveness of the suggested STFLS-STSMSC based MDTC implemented on a Xilinx FPGA Zynq 7000 SoC ZC702.

Adaptive second order sliding mode guidance law for missile-target interception with fuzzy logic system

This paper presents the design of a 3D missile guidance law based on a second order sliding mode control technique employing an adaptive tuning law and a fuzzy gain scheduling. At the outset, the super-twisting sliding mode guidance law is obtained to overcome the chattering phenomenon. Then, without the knowledge about the bounds of disturbances, an adaptive law is used to determine the control gains. The results are enhanced using a fuzzy module that provides the controller parameters according to a set of linguistic rules. Finally, a comparative set of simulation results are given. To verify the performance and effectiveness of the proposed guidance law, we compare the performances of the traditional sliding mode (SM) guidance law, the traditional super-twisting sliding mode (STWSM) guidance law, the adaptive super-twisting sliding mode (ASTWSM) guidance law and the adaptive fuzzy super-twisting, sliding mode (AFSTWSM) guidance law. The simulation scenarios consider fundamental target movements. The results demonstrate that the proposed adaptive guidance laws display better performance in terms of miss distance, intercept time, and final closing velocity compared the alternatives considered in this study.

Fractional order sliding mode control based on delayed output observer for unmanned aircraft system

PurposeThis paper aims to design the fractional order sliding mode controller for highly maneuverable remote piloted unmanned aircraft with time-varying delays.Design/methodology/approachWith the assumption that the time-varying delays are bounded and identical for different outputs, an observer-based control technique is implied which reformulates the state variables based on the system model and delayed outputs. The estimated state variables are fed as feedback into the controller. Based on the delayed output observer, a fractional order sliding mode controller is designed. Further, the stability of the closed-loop system is analyzed and asymptotical convergence is realized using Lyapunov–Razumikhin theorem.FindingsThe simulation is done in Matlab and Simulink. The parametric variations and trajectory tracking results are illustrated which looks propitious.Practical implicationsIn practical operation, measurement signal is often delayed, which significantly degrade the control performance or even disturb the stability. It is emphasized to choose attitude as the evaluation indicator for unmanned aerial vehicle time delay.Originality/valueA novel fractional order sliding mode control technique is designed to enhance the trajectory tracking, thus autonomous flight performance, of the aircraft system. Also, the main idea behind this novel procedure is formulated for minimizing the parametric variations in presence of time delays.

A HOSM control algorithm to stabilize the quadrotor vehicle with experimental validation

A High Order Sliding Mode control technique to stabilize the quadrotor vehicle is presented in this paper. The simplified nonlinear equations are evoked to develop the control algorithms. The closed-loop system using this sliding mode methodology is robust even in presence of unknown disturbances and uncertainties parameters in the model. The control scheme is validated in simulations and some experiments are developed to prove the experimental feasibility of the control strategy. Simulation and experimental results demonstrate the well performance of the proposed algorithms.

Blood Glucose Regulation via Double Loop Higher Order Sliding Mode Control and Multiple Sampling Rate

Diabetes is a serious disease during which the body's production and use of insulin is impaired, causing glucose concentration level to increase in the bloodstream. The blood glucose dynamics is described using the Bergman minimal model. Higher order sliding mode control techniques, including the prescribed convergence law, the smooth second order, the quasi-continuous, and the super-twisting control algorithm, are studied for the double loop robust stabilization of the glucose concentration level of a diabetic patient in presence of the parameter variations and meal disturbance. In the inner loop super-twisting control stabilizes the glucose pump-actuator that yields a dynamical collapse of the loop. In the outer loop the higher order sliding mode controller generates a command to the pump-actuator in terms of insulin injection rate. The higher order sliding mode differentiator is employed to facilitate the controllers. The efficiency of the proposed controllers and observers/differentiators, i.e. robustness and high accuracy, in presence of physical disturbances like food intake and parametric uncertainties is confirmed via simulations. Two sampling rates are successfully employed in the simulations: a smaller one for the system and the controller and the larger one for the glucose sensor.