Robust Fuzzy Sliding Mode Control Research Articles

Optimized robust fuzzy sliding mode control for efficient wastewater treatment: a comprehensive study

Wastewater treatment plants (WWTPs) are plagued by nonlinearities, uncertainties, and disturbances that degrade control performance and may even lead to severe instability. The WWTP control issue has received a lot of research and development during the last several decades. One well-known way of designing a resilient control system is called sliding mode control (SMC). The SMC's greatest strength lies in its innate resistance to disturbances and uncertainty. Incorporating fuzzy SMC would eliminate the chattering effect, the primary drawback of traditional sliding-mode controller, without sacrificing robustness against parametric uncertainties, modeling errors, and variable dynamic loads. This article discusses the hybridization of fuzzy logic with sliding mode control to provide highly excellent stability and accuracy in a control system. As a means of optimizing the fuzzy SMC, the gradient-free optimization technique known as the Jaya algorithm is investigated. By repeatedly altering a population of individual solutions, this population-based method can deal with both limited and unbounded optimization issues.

A novel impedance-based robust fuzzy sliding mode compliance control for the dexterous robot finger with uncertainties

To promote the precision and flexibility of the dexterous robot finger, a novel impedance-based robust fuzzy sliding mode control approach is developed. In the proposed scheme, an impedance control part constructed aims to regulate the contact force; while the robust fuzzy sliding mode controller proposed accounts for enhancing the anti-interference of this uncertain robotic system. Specifically, by analyzing the forward and inverse kinematics of the finger, its dynamical model with unknown and uncertain force disturbances can be established, and based on this model, a novel robust sliding mode impedance force controller has been designed, also, several critical impedance control parameters can be quickly optimized by invoking the fuzzy logic system. Ultimately, the Lyapunov stability of the proposed control is strictly demonstrated in mathematics. The simulations present the efficacy of the proposed scheme in both constrained and unconstrained spaces.

Robust fuzzy sliding mode controller for a skid-steered vehicle subjected to friction variations.

Skid-steered vehicles (SSV) are gaining huge importance in the market due to their applications like construction, agricultural work, material handling etc. The accuracy of performing such tasks require a robust control algorithm. The design of such controller is very challenging task due to external disturbances caused by wheel-ground interaction and aerodynamic effects. This paper proposes robust fractional and integral order fuzzy sliding mode controllers (FSMC, FFSMC) for a skid-steered vehicles with varying coefficient of friction and a displaced center of gravity (CG). FFSMC controller reduces the outcome of forces generated as a result of ground tire interaction during skidding and friction variations. The proposed controllers are implemented for a four-wheel SSV under high-speed turning motion. A simulation environment is constructed by implementing the SSV dynamics with wheel-road model and the performance of the proposed algorithms is tested. The simulation test is conducted for a Pioneer-3AT (P-3AT) robot SSV vehicle with displaced CG and variable coefficient of tires friction. Simulation results demonstrate the efficiency of the proposed FFSMC algorithm in term of reduced state errors and minimum chattering. The proposed controller compensates the effect of different responses of the wheels generated as a result of variable CG. The chattering phenomenon generated by conventional SMCs is also minimized by fuzzy tuning approach.

Robust fuzzy sliding mode control and vibration suppression of free-floating flexible-link and flexible-joints space manipulator with external interference and uncertain parameter

AbstractThe flexibility of the free-floating flexible space manipulator system’s link and joint may affect the control accuracy and cause vibrations. We studied the dynamics modeling, joint trajectory tracking control, and vibration suppressing problem of free-floating flexible-link and flexible-joints space manipulator system with external interference and uncertain parameter. The system’s dynamic equations are established using linear momentum conservation, angular momentum conservation, assumed mode method, and Lagrange equation. Then, the system’s singular perturbation model is established, and a hybrid control is presented. For the slow subsystem, a robust fuzzy sliding mode control is proposed to realize the joint desired trajectory tracking. For the fast subsystem, a speed difference feedback control and a linear-quadratic optimal control are designed to suppress the vibration caused by the flexible joints and the flexible link separately. The simulation comparison experiments under different conditions are taken. The simulate results demonstrate the proposed hybrid control’s validity.

The effect of liquid medium on vibration and control of the AFM piezoelectric microcantilever.

This article investigates the vibration motion and control of the piezoelectric microcantilever (MC) of the atomic force microscope in the amplitude mode in a liquid environment for both free and forced vibrations. The modeled MC includes two electrode layers, a piezoelectric layer, and the geometric discontinuities as a result of these layers and the change in the MC cross section at the probe-MC contact point is modeled. The equations of motion are derived using Hamilton's principle and then discretized with the aid of the finite element method. The system frequency and time response in the free vibration mode when placed in a liquid medium are compared with experimental results. Also, the sample surface topography in the noncontact mode, when passing through the surface roughness, has been modeled as rectangular and wedge-shaped. Furthermore, the control of piezoelectric MC in two cases of near and far from the sample surface is examined. In the case of far from the surface, the system is controlled using the piezoelectric layer installed on the beam, whereas in the case of near the surface, the piezo is turned off due to the existence of nonlinear forces such as Van der Waals and Derjaguin, Muller, and Toporov contact forces and the control is achieved through the base excitation. For system control modeling, the robust fuzzy sliding mode control (FSMC) approach is utilized and the results are compared with those of the simple sliding mode control (SMC) as well as proportional, integral, and derivative control. The presented FSMC approach can remarkably reduce the chattering phenomenon at the SMC input in the liquid medium and accordingly improve the results compared to the other two methods.

Improvement of THD performance of a robust controller for grid-side energy conversion system based on LCL filter without RC sensor

This paper aims to improve the Total Harmonic Distortion (THD) performance, using a robust nonlinear controller, for a Grid-Side Energy Conversion System Based on LCL with damping resistance and without current sensor of the RC branch. The Sliding Mode Control (SMC) increases the THD because of the chattering phenomenon. But, the reduction of THD is considered as an advantage of the LCL filter. These harmonics are also decreased using the robust Fuzzy Sliding Mode Control (FSMC) and the elimination of RC sensor reduces the system cost. The DC bus voltage is controlled using the FSMC, taking into account the power loss. The evaluation of the reliability and performance of the proposed control system is achieved through a comparative study. The simulation and experimental results are carried out to validate the effectiveness of the proposed filter and control method of the grid-side converter. The proposed control system is capable of providing enhanced transient performance similar to that of the SMC, and keeps the steady-state harmonic spectra at the same level as those of the Vector Control (VC).

Hierarchical robust fuzzy sliding mode control for a class of simo under-actuated systems with mismatched uncertainties

The development of the algorithms for single input multi output (SIMO) under-actuated systems with mismatched uncertainties is important. Hierarchical sliding-mode controller (HSMC) has been successfully employed to control SIMO under-actuated systems with mismatched uncertainties in a hierarchical manner with the use of sliding mode control. However, in such a control scheme, the chattering phenomenon is its main disadvantage. To overcome the above disadvantage, in this paper, a new compound control scheme is proposed for SIMO under-actuated based on HSMC and fuzzy logic control (FLC). By using the HSMC approach, a sliding control law is derived so as to guarantee the stability and robustness under various environments. The FLC as the second controller completely removes the chattering signal caused by the sign function in the sliding control law. The results are verified through theoretical proof and simulation software of MATLAB through two systems Pendubot and series double inverted pendulum.

Robust fuzzy sliding mode control based on low pass filter for the welding robot with dynamic uncertainty

PurposeConsidering the external disturbances and dynamic uncertainties during the process of the trajectory tracking, this paper aims to address the problem of the welding robot trajectory tracking with guaranteed accuracy.Design/methodology/approachThe controller consists sliding mode control, fuzzy control and low pass filter. The controller adopts low-pass filter to reduce the high frequency chattering control signal in sliding mode control. The fuzzy control model is used to simulate the external disturbance signal and the dynamic uncertainty signal, so that the controller can effectively restrain the chattering caused by the sliding mode control algorithm, realizing the track of the welding robot effectively and improving the robustness of the robot.FindingsAn innovative experiment device was adopted to realize the performance of the proposed controller. Considering the kinematic and dynamic uncertainty during the process of robot tracking, the tracking accuracy was realized within 0.3 mm.Originality/valueThis paper uses Lyapunov stability theory and Barbalat theorem to analyze the stability of the proposed controller.

Notice of Violation of IEEE Publication Principles: A Novel Robust Fuzzy Integral Sliding Mode Control for Nonlinear Semi-Markovian Jump T–S Fuzzy Systems

This paper addresses the issue of robust fuzzy sliding mode control for continuous-time nonlinear Takagi–Sugeno fuzzy systems with semi-Markovian switching. The focus is on designing a novel fuzzy integral sliding surface without assuming that the input matrices are the same with full column rank and then developing a fuzzy sliding-mode controller for stochastic stability purpose. Based on Lyapunov theory, a set of newly developed linear matrix inequality conditions are established for stochastic stability of the sliding-mode dynamics with generally uncertain transition rates, and then extended to where the input matrix is plant-rule-independent, as discussed in most existing literatures. Furthermore, finite-time reachability of the sliding surface is also guaranteed by the proposed fuzzy sliding-mode control laws. A practical example is provided to demonstrate the effectiveness of the established method numerically.

Robust fuzzy sliding mode control for air supply on PEM fuel cell system

In this paper, an adaptive fuzzy sliding mode controller is employed for air supply on proton exchange membrane fuel cell (PEMFC) systems. The control objective is to adjust the oxygen excess ratio at a given set point in order to prevent oxygen starvation and damage to the fuel-cell stack. The proposed control scheme consists of two parts: a sliding mode controller (SMC) and fuzzy logic controller (FLC) with an adjustable gain factor. The SMC is used to calculate the equivalent control law and the FLC is used to approximate the control hitting law. The performance of the proposed control strategy is analysed through simulations for different load variations. The results indicated that the adaptive fuzzy sliding mode controller (AFSMC) is excellent in terms of stability and several key performance indices such as the integral squared error (ISE), the integral absolute error (IAE) and the integral time-weighted absolute error (ITAE), as well as the settling and rise times for the closed-loop control system.

Robust fuzzy sliding mode control for air supply on PEM fuel cell system

Robust fuzzy sliding mode control for air supply on PEM fuel cell system

Adaptive Fuzzy Sliding Mode Control for MIMO Nonaffine Dutch-Roll System

A robust fuzzy sliding mode controller is presented for a multiple-input–multiple-output (MIMO) Dutch-Roll system with nonaffine inputs and external disturbances. An integrating factor with a nonlinear saturation function is introduced to construct a nonlinear integral sliding mode (NISM) surface to provide better transient response than traditional sliding mode control. Fuzzy logic systems are employed to approximate the unknown nonaffine part of the system directly. Based on Lyapunov method, the tracking errors are guaranteed to be asymptotically stable with the additional adaptive compensation terms. To verify the feasibility and effectiveness of the proposed controller, the Dutch-Roll system is presented for simulation.

Fuzzy sliding mode control algorithm for a four-wheel skid steer vehicle

This research design and implement a robust dynamic feedback controller for a four-wheel skid steering vehicle (SSV) under high- speed cornering motion. First, SSV dynamics are modeled and analyzed to construct the simulation environment and to validate the per- formance of the proposed algorithm. A robust fuzzy-sliding mode controller is then designed to offset the effect of forces induced by wheel—soil interaction during skidding and ground-level fluctuations. It also eliminates the chattering phenomena encountered with conventional sliding mode control. Given P-3AT mobile robot parameters for trajectory tracking and velocity setting, extensive simula- tion results demonstrate the effectiveness of the proposed controller.

Robust Adaptive Fuzzy Sliding Mode Control Based on Fuzzy Compensation for Ammunition Auto-loading Robot

Aimed at the problems of low control accuracy and weak robustness influenced by external disturbance, friction, load changes, modeling errors and other issues in ammunition auto-loading robot control system, a new robust adaptive fuzzy sliding mode controller based on fuzzy compensation is proposed. The control architecture employs fuzzy systems to compensate adaptively for plant uncertainties to distinguish different disturbance compensation terms and approximate each of them respectively. The stability of the robust adaptive fuzzy sliding mode control (SMC) and the convergence of the tracking errors are ensured by using the Lyapunov theory. By analyzing and comparing the simulation results, it is obviously shown that the control system can lighten the effect on the control system caused by different disturbance factors and eliminate the system chattering instead of traditional SMC. As a result, the control system has great dynamic features and robust stability and meets the requirement that the actual motion of ammunition auto-loading robot quickly tracks the scheduled trajectory. DOI : http://dx.doi.org/10.11591/telkomnika.v12i4.4342

Design of a novel adaptive fuzzy sliding mode controller and application for vibration control of magnetorheological mount

This paper presents vibration control of a mixed-mode magnetorheological fluid-based mount system using a new robust fuzzy sliding mode controller. A novel model of controller is built based on adaptive hybrid control of interval type 2 fuzzy controller incorporating with a new modified sliding mode control. The interval type 2 fuzzy is optimized for computational cost by using enhanced iterative algorithm with stop condition, and a new modified switching surface of sliding mode control is designed for preventing the chattering of the system. The controller is then experimentally implemented under uncertain conditions in order to evaluate robust vibration control performance. In addition, in order to demonstrate the effectiveness of the proposed controller, two fuzzy sliding mode control algorithms proposed by Huang and Chan are adopted and modified. The principal control parameters of three controllers are updated online by adaptation laws to meet requirements of magnetorheological mount system which has two operation modes: flow mode and shear mode. It is shown from experimental realization of three controllers that the proposed control strategy performs the best under uncertain conditions compared with two other modified controllers. This merit is verified by presenting vibration control performances in both time and frequency domains.

Robust fuzzy sliding mode controller design for voltage source converter high-voltage DC based interconnected power system

This paper investigates the application of a robust non-linear fuzzy sliding mode controller for a high-voltage direct current (HVDC) system based on voltage source converter (VSC). The dynamic analysis of the VSC-HVDC system is formulated using synchronous reference frame, ie. d-q axis model. Fuzzy logic is used to cancel non-linearity and the sliding mode control (SMC) offers invariant stability to modelling uncertainties pertaining due to converter parameter changes, changes in short circuit ratio and fault on converter and inverter buses. Performance of the propose hybrid approach fuzzy logic SMC (FLSMC) is demonstrated through digital simulation studies on a VSC-HVDC two machine power system using MATLAB software package under wide range of operating conditions. The FLSMC provides excellent transient and steady-state performance as well as complete decoupled control of active and reactive power.

Robust fuzzy sliding mode control for tracking the robot manipulator in joint space and in presence of uncertainties

SUMMARYThis paper proposes a simple fuzzy sliding mode control to achieve the best trajectory tracking for the robot manipulator. In the core of the proposed method, by applying the feedback linearization technique, the known dynamics of the robot's manipulator is removed; then, in order to overcome the remaining uncertainties, a classic sliding mode control is designed. Afterward, by applying the TS fuzzy model, the classic sliding mode controller is converted to fuzzy sliding mode controller with very simple rule base. The mathematical analysis shows that the robot manipulator with the new proposed control in tracking the robot manipulator in presence of uncertainties has the globally asymptotic stability. Finally, to show the performance of the proposed method, the controller is simulated on a robot manipulator with two degrees of freedom as case study of the research. Simulation results demonstrate the superiority of the proposed control scheme in presence of the structured and unstructured uncertainties.

Fuzzy Sliding Mode Control of Robotic Manipulators With Kinematic and Dynamic Uncertainties

Sliding mode control is a very attractive control scheme with strong robustness to structured and unstructured uncertainties as well as to external disturbances. In this paper, a robust fuzzy sliding mode controller, which is combined with an adaptive fuzzy logic system, is proposed to improve the control performance of the robotic manipulator with kinematic and dynamic uncertainties. In this controller, the sliding mode control is employed to improve the control accuracy and the robustness of the robotic manipulator, and the fuzzy logic control is adopted to approximate various uncertainties and to eliminate the chattering without the help of any prior knowledge of system uncertainties. The effectiveness of the proposed controller is then verified by the simulations on a 2-DOF (degrees of freedom) robotic manipulator and the experiments on an SCARA robot with four degrees of freedom. Simulated and experimental results indicate that the proposed controller is effective in the robust tracking of the robotic manipulator with kinematic and dynamic uncertainties.

A Robust Fuzzy Sliding Mode Control Design for Current Source Inverter based STATCOM Application

This paper presents a robust fuzzy sliding mode control of a CSI based STATCOM. The dq-frame state space model is considered for nonlinear mathematical model for the system and controller design. A nonlinear fuzzy logic enhanced sliding mode controller has been proposed to provide active and reactive power control under various faulted operating conditions. Based upon the time domain simulations in MATLAB/SIMULINK environment the proposed controller is tested and it's better performance is shown compare with the conventional PI controllers with respect to voltage stability, damping of power oscillations and improving of transient stability.

Robust Control Of Dc Motor Using Fuzzy Sliding Mode Control With Fractional Pid Compensator

This paper presents a robust fuzzy sliding mode control scheme and the additional compensator. The additional compensator relaying on the sliding-mode theory is used to improve the dynamical characteristics of the drive system. Sliding mode control method is studied for controlling DC motor because of its robustness against model uncertainties and external disturbances. In this method, using high control gain to overcome uncertainties lead to occur chattering phenomena in control law which can excite unmodeled dynamics and maybe harm the plant. In order to enhancement the sliding mode controller performance, we have used fuzzy logic. For this purpose, we have used a Fractional PID outer loop in the control law then the gains of the sliding term and Fractional PID term are tuned on-line by a fuzzy system, so the chattering is avoided and response of the system is improved against external load torque here. Presented implementation results on a DC motor confirm the above claims and demonstrate the performance improvement in this case.