Quasi-sliding Mode Control Research Articles

Discrete Time Quasi Sliding Mode Control For Piezo-Actuated Positioning Systems: A Prescribed Performance Control Approach

The piezoelectric actuators (PEAs) with many advantages such as sub-nanometers resolution, low power consumption, quick response, high stiffness, etc., have been widely used in micro/nano positioning systems which play a very important role in many key technologies recently. To achieve high precision in tracking applications based on PEAs, advanced control techniques are needed to cope with the nonlinearity exhibiting between the input voltage and output displacement of the PEAs. This paper proposes a new approach to get high tracking performance by combining discrete-time quasi-sliding mode control (DQSMC) and prescribed performance control (PPC) techniques. The effectiveness of the proposed method is verified by experiments on a piezo-actuated positioning system.

An Approach to Microcontroller-Based Realization of Boost Converter with Quasi-Sliding Mode Control

The paper considers a realization of quasi-sliding mode control for DC–DC boost-type converter on ATmega8 microcontroller. The proposed control law represents a combination of discrete-time sliding mode and generalized minimum variance control techniques. The control design is based on input–output converter model and only the sensed output voltage is used for generating control signal. This approach simplifies the practical realization of boost converter since there is no need for current sensors. By introducing an additional discrete-time integrator in control, the converter accuracy in steady-state under load and input voltage variations is enhanced. The experimental prototype is developed and several experiments are conducted to validate the functionalities of the proposed solution. The maximum load and line regulation errors of the proposed converter are 1.55% and 2.9%, respectively.

Dynamic boundary layer based neural network quasi-sliding mode control for soft touching down on asteroid

Pinpoint landing is a critical step in some asteroid exploring missions. This paper is concerned with the descent trajectory control for soft touching down on a small irregularly-shaped asteroid. A dynamic boundary layer based neural network quasi-sliding mode control law is proposed to track a desired descending path. The asteroid’s gravitational acceleration acting on the spacecraft is described by the polyhedron method. Considering the presence of input constraint and unmodeled acceleration, the dynamic equation of relative motion is presented first. The desired descending path is planned using cubic polynomial method, and a collision detection algorithm is designed. To perform trajectory tracking, a neural network sliding mode control law is given first, where the sliding mode control is used to ensure the convergence of system states. Two radial basis function neural networks (RBFNNs) are respectively used as an approximator for the unmodeled term and a compensator for the difference between the actual control input with magnitude constraint and nominal control. To improve the chattering induced by the traditional sliding mode control and guarantee the reachability of the system, a specific saturation function with dynamic boundary layer is proposed to replace the sign function in the preceding control law. Through the Lyapunov approach, the reachability condition of the control system is given. The improved control law can guarantee the system state move within a gradually shrinking quasi-sliding mode band. Numerical simulation results demonstrate the effectiveness of the proposed control strategy.

Research of Active Power Filter Modeling with Grid Impedance in Feedback Linearization and Quasi-Sliding Mode Control

Active power filter (APF) is the most popular device in regulating power quality issues. Currently, most literatures ignored the impact of grid impedance and assumed the load voltage is ideal, which had not described the system accurately. In addition, the controllers applied PI control; thus it is hard to improve the compensation quality. This paper establishes a precise model which consists of APF, load, and grid impedance. The Bode diagram of traditional simplified model is obviously different with complete model, which means the descriptions of the system based on the traditional simplified model are inaccurate and incomplete. And then design exact feedback linearization and quasi-sliding mode control (FBL-QSMC) is based on precise model in inner current loop. The system performances in different parameters are analyzed and dynamic performance of proposed algorithm is compared with traditional PI control algorithm. At last, simulations are taken in three cases to verify the performance of proposed control algorithm. The results proved that the proposed feedback linearization and quasi-sliding mode control algorithm has fast response and robustness; the compensation performance is superior to PI control obviously, which also means the complete modeling and proposed control algorithm are correct.

Improved Quasi Sliding Mode Control with Adaptive Compensation for Matrix Rectifier

Improved Quasi Sliding Mode Control with Adaptive Compensation for Matrix Rectifier

Quasi-Sliding Mode Control With Orthogonal Endocrine Neural Network-Based Estimator Applied in Anti-Lock Braking System

This paper presents a new control method for nonlinear discrete-time systems, described by an input–output model which is based on a combination of quasi-sliding mode and neural networks. First, an input–output discrete-time quasi-sliding mode control with inserted digital integrator, which additionally reduces chattering, is described. Due to the presence of various nonlinearities and uncertainties, the model of the controlled object cannot be described adequately enough. These imperfections in modeling cause a modeling error, resulting in rather poor system performances. In order to increase the steady-state accuracy, an estimated value of the modeling error in the next sampling period is implemented into the control law. For this purpose, we propose two improved structures of the neural networks by implementing the generalized quasi-orthogonal functions of Legendre type. These functions have already been proven as an effective tool for the signal approximation, as well as for modeling, identification, analysis, synthesis, and simulation of dynamical systems. Finally, the proposed method is verified through digital simulations and real-time experiments on an anti-lock braking system as a representative of the considered class of mechatronic systems, in a laboratory environment. A detailed analysis of the obtained results confirms the effectiveness of the proposed approach in terms of better steady-state performances.

Discrete‐time sliding mode control with state bounding for linear systems with time‐varying delay and unmatched disturbances

This study is concerned with the problem of quasi-sliding mode control design for a class of discrete-time systems with time-varying delay and unmatched disturbances. On the basis of the Lyapunov–Krasovskii method, combined with the reciprocally convex approach, sufficient conditions for the existence of a stable sliding surface are first derived in terms of matrix inequalities. These conditions also guarantee that the state trajectories of the reduced-order system are exponentially convergent within a ball whose radius can be minimised to deal with the effects of time-varying delay and disturbances. A robust quasi-sliding mode control scheme is then developed to drive the system state trajectories towards that ball in a finite time and maintain them therein after subsequent time. A numerical example is given to illustrate the effectiveness of the proposed approach.

PWM based Quasi Sliding Mode Control of Buck Converter

This paper presents the sliding mode control technique with PD type of feedback controller and the design and analysis of a fixed-frequency pulse width modulation based quasi sliding mode voltage controller with PID type of feedback controller for buck converter. A practical design approach that aims at systematizing the procedure for the selection of the control parameters is presented. The robustness of the controller is discussed with line variation and load variation analysis. In addition, a simple method of implementing the proposed adaptive control strategy is discussed to reduce the line variations. Simulation results show satisfactory performance of the proposed switching converter. Keywords: Hysteresis Modulation (HM), Pulse Width Modulation (PWM), Quasi Sliding Mode (QSM), Sliding Mode Control (SMC)

A nonlinear sliding mode observer for the estimation of temperature distribution in a planar solid oxide fuel cell

Compliance to certain temperature constraints is essential for the long life and stable operation of solid oxide fuel cells (SOFCs). However, it is difficult and costly to measure the temperature inside a high temperature, well-sealed cell directly. A nonlinear sliding mode observer has been designed in this paper for estimating the temperature distribution in a hydrogen fed SOFC stack. The observer design is based on a finite-volume parameter SOFC model, which is simplified by quasi-static mass balance assumption. In the observer design, a decoupling pole placement method that applies to multi-timescale systems is proposed to obtain a suitable observer gain. And a quasi-sliding mode control method is adopted to eliminate the chatter caused by the discontinuous control actions of sliding mode control. Theoretical analysis and simulation results are presented to prove the convergence and good performance of the designed observer for estimating the temperature distribution in a SOFC stack during steady-state and transient operation.

Sliding Mode Control of Three-Phase Four-Leg Inverters via State Feedback

To optimize controller design and improve static and dynamic performances of three-phase four-leg inverter systems, a compound control method that combines state feedback and quasi-sliding mode variable structure control is proposed. The linear coordinate change matrix and the state variable feedback equations are derived based on the mathematical model of three-phase four-leg inverters. Based on system relative degrees, sliding surfaces and quasi-sliding mode controllers are designed for converted linear systems. This control method exhibits the advantages of both state feedback and sliding mode control. The proposed controllers provide flexible dynamic control response and excellent stable control performance with chattering suppression. The feasibility of the proposed strategy is verified by conducting simulations and experiments.

Decentralized discrete-time quasi-sliding mode control of uncertain linear interconnected systems

In this paper, a new global decentralized discrete-time quasi-sliding mode control of linear interconnected systems is presented. The proposed controller is free of chattering problem and can be applied to a broader class of large-scale systems. Additionally, it is capable to deal with both known and unknown interconnections among the subsystems. Stability of the reduced-order interconnected systems is analyzed using Lyapunov approach. The proposed decentralized controller guarantees the reachability of the connective sliding manifold. The resultant dynamics are proved to be globally asymptotically stable. Furthermore, the controller is made robust to external disturbances by employing a disturbance estimation scheme. The simulations are performed on model of a two-area power generation system and the results show the efficacy of the proposed scheme.

Discrete-time output feedback quasi-sliding mode control for robust tracking and model following of uncertain systems

A discrete-time output feedback quasi-sliding mode control scheme is proposed to realize the problem of robust tracking and model following for a class of uncertain linear systems in which states are unavailable and estimated states are not required. The proposed scheme guarantees the stability of the closed-loop system and achieves a very small ultimate boundedness of the tracking error in the presence of matched uncertain parameters and external slow disturbances. This scheme ensures the robustness to matched parametric uncertainties and disturbances. Since the proposed controller is designed without any switching element, the chattering phenomenon is eliminated. Furthermore, the knowledge of upper bound of uncertainties is not required. Simulation results demonstrate the effectiveness of the proposed scheme.

Robust Stability for Nonlinear Systems with Time-Varying Delay and Uncertainties via theH∞Quasi-Sliding Mode Control

This paper considers the problem of the robust stability for the nonlinear system with time-varying delay and parameters uncertainties. Based on theH∞theorem, Lyapunov-Krasovskii theory, and linear matrix inequality (LMI) optimization technique, theH∞quasi-sliding mode controller and switching function are developed such that the nonlinear system is asymptotically stable in the quasi-sliding mode and satisfies the disturbance attenuation (H∞-norm performance). The effectiveness and accuracy of the proposed methods are shown in numerical simulations.

Non-switching reaching law based discrete time quasi-sliding mode control with application to warehouse management problem

In this paper a new non-switching type reaching law for sliding mode control of discrete time systems is introduced and applied to the problem of periodic review inventory management. The considered inventory is refilled by multiple suppliers through delivery channels subject to non-negligible commodity losses. The reaching law proposed in this paper is inspired by the earlier work of Gao, Wang and Homaifa, however, in this paper the original formulation is essentially modified in order to avoid undesirable switching, and to ensure good dynamic performance with limited commodity orders. These improvements are obtained by the application of a modified definition of the quasi-sliding mode, and also by the introduction of an adjustable, state dependent sliding variable decrease rate factor. The sliding mode inventory management strategy proposed in this paper ensures full customer demand satisfaction and enables the designer to specify upper limit of the on-hand stock level.

On Fuzzy Sliding Control for a Robot Manipulator

A fuzzy sliding control for the motion of the robot manipulator is proposed. The quasi-sliding mode control (QSMC) was added to the fuzzy control. Therefore the system inputs and fuzzy rules can be reduced in fuzzy sliding control. Then the system will be a Single Input Single Output (SISO) system and it has only five fuzzy rules. This makes design process much more simple. The simulation results show that by employing proposed controller to the position control of a three-axis robot manipulator, the overshoot was drastically reduced. Also fast rising time and a small extent of steady-state error can be obtained.

Quasi-Sliding Mode Control of a High-Precision Hybrid Magnetic Suspension Actuator

A novel 1-DOF hybrid magnetic suspension actuator for precise motion control is presented. The actuator is designed to achieve sub-micron positioning accuracy over a range of motion in excess of 1000 µm while avoiding large nominal levitation currents and iron core saturation. The proposed passive push-active pull configuration offers precise motion control with moderate actuator effort when a payload is to be accurately suspended over a large range of travel. The proposed actuator can be used modularly to control multiple axes of motion in a multi-DOF positioning application that requires millimeter-range travel with submicron accuracy. A Quasi-Sliding Mode controller (QSM) is presented in which the sliding mode dynamics are directly designed, as opposed to the typical Lyapunov function approach that is solely based on stability. Since full knowledge of the state vector is required, a nonlinear high-gain observer was also designed and implemented. Performance of the QSM algorithm in controlling the proposed actuator is compared to that of a PID controller with standard feedback linearization. Several experiments are conducted to demonstrate both the positioning and tracking capabilities of the proposed actuator. The proposed QSM method shows better transient performance than the standard PID feedback linearization approach. QSM also shows better tracking performance, which is highly desirable in systems in which fast and accurate motion control along a desired path is critical.

Quasi-Sliding Mode Control for Impulsive Delayed Vehicle Longitudinal Following System with Bounded and Varying Parameters

In the real automated highway system, various factors to vehicles which are moving make the velocity of vehicles change suddenly. In this paper, assuming that the mass of vehicles, the drag coefficient and the resistance of the ground were uncertain, the controller for a class of time-varying delayed look-ahead vehicle longitudinal following system with impulsive effect was designed by using the idea of quasi-sliding mode control. An example is given at last to test the controller proposed in this paper.

A Novel MPPT Method Based on the Synthesis of Quasi-Sliding Mode Control and Dynamic Equivalent Impedance Matching Method

A systematic procedure to synthesize dynamic equivalent impedance matching method (EIM) based on the quasi-sliding mode control (QSMC) is presented. Aiming at the existing maximum power point tracking (MPPT) methods’ limitation on the dynamic response, control accuracy and robustness, in this paper, with a boost converter used, QSMC is introduced on the basis of EIM and the synthesis (EIM&QSMC) which not only improves the tracking speed and accuracy, but also further enhances the robustness. The simulation results show that compared with EIM, on the condition of load impedance and illumination change, the synthesis improves the MPPT system on the ability to adapt the circuit parameter variation, which has better control effect and practical significance. The design and the models are validated by Matlab / Simulink simulations.

Adaptive Neural Network Sliding Mode Control based on Particle Swarm Optimization for Rotary Steering Drilling Stabilized Platform

This study focuses on the robust control of stabilized platform of rotary steering drilling system. Firstly, the uncertain and nonlinear mathematical model of stabilized platform is given by considering the outside interference, drilling technology and geometrical parameter perturbation of the borehole on stabilized platform under work condition. Then, an adaptive neural network sliding mode control strategy is introduced,, which uses sliding mode control to guarantee system robustness, makes the uncertain upper bound adjust adaptively with RBF neural network to nonlinear approximate the upper bound of overall uncertainty, reduces chattering by quasi-sliding mode control method. Finally, particle swarm optimization algorithm is applied to search the optimal controller parameters, including adaptive parameter of neural network weight, boundary layer thickness and switching function coefficient. Simulation results demonstrate that the control strategy proposed can make stabilized platform get optimal control performance and robustness.

The design of quasi-sliding mode control for a permanent magnet synchronous motor with unmatched uncertainties

In this study, the concept of a quasi-sliding mode control (QSMC) is introduced for the robust control of a permanent magnet synchronous motor (PMSM) system subjected to unmatched uncertainties, and even with input nonlinearity. On the basis of the new concept of QSMC, continuous control is obtained, to avoid the chattering phenomenon. As expected, the system state can be stabilized and driven into a predictable neighborhood of zero. Also, this approach only uses a single controller to achieve chaos control, which reduces the cost and complexity of implementation. The results of numerical simulations demonstrate the validity of the proposed QSMC design method.