Higher Order Sliding Mode Research Articles

High-Order Sliding Control for a Wind Energy Conversion System Based on a Permanent Magnet Synchronous Generator

This paper presents the output power control of a wind energy conversion system (WECS) based on a permanent magnet synchronous generator (PMSG). It is assumed that the considered wind module integrates a stand-alone hybrid generation system, jointly with a battery bank, a variable ac load, and other generation subsystems. The operation strategy of the hybrid system determines two possible operation modes for the WECS, depending on the power requirements of the load and the wind availability. The paper deals with the design of a combined high-order sliding mode (HOSM) controller for the power control of the WECS on both operational modes. The main features of the obtained controller are its chattering-free behavior, its finite-time reaching phase, its simplicity, and its robustness with respect to external disturbances and unmodeled dynamics. The performance of the closed-loop system is assessed through representative computer simulations.

High-Order Sliding Modes for a Robot Driven by Pneumatic Artificial Rubber Muscles

It is known that classical sliding mode control generates chatter which is undesirable. One way to reduce this chatter is the use of high-order sliding mode (HOSM) control. The HOSM control techniques are applied to the first 2 d.o.f. of a robot actuated by pneumatic artificial rubber muscles (PARMs). The PARMs are arranged in opposite pairs (antagonistic configuration). The objective is to show that without the use of the equivalent control, it is still possible to control the robot by the use of HOSM and at the same time reduce the chatter. Experimental results are presented and comparison between two second-order sliding controls established.

Higher Order SM Block Control of Nonlinear Systems with Unmodeled Actuators

In this paper, a control strategy is proposed for robust stabilization of nonlinear perturbed plants in the presence of actuator unmodeled dynamics. The block control technique is applied to design a nonlinear SM manifold for achieving the error tracking, and High Order Sliding Mode (HOSM) algorithm is implemented to ensure finite time convergence of the state vector to the designed SM manifold. A robust exact differentiator is designed to obtain the estimates of the sliding variable and its derivatives. The proposed method is applied to design robust controllers for a power electric system in the presence of the exciter system unmodeled dynamics.

High order sliding mode control of a sensorless induction motor

Abstract A new High Order Sliding Mode (HOSM) controller and an adaptive observer for sensorless induction motors (IM) drive are designed. The adaptive interconnected observer estimates the fluxes, the angular velocity, the load torque, and the stator resistance. The speed-flux control law is an original HOSM one: a sliding manifold is designed in order to ensure finite-time convergence of sliding variable and its high order time derivatives. The Lyapunov theory is used to prove the stability of the observer then the stability of the “observer-controller”. To test the feasbility of the proposed solutions, a significant low frequency benchmark is used by considering the sensorless control problem of IM. Robustness with respect to parameters variations is proved and experimentally verified.

HOSM observer for a class of non-minimum phase causal nonlinear MIMO systems

Abstract A higher order sliding mode observer is proposed for asymptotic identification of the full state vector and the vector of unknown inputs for MIMO nonlinear causal systems with unstable internal dynamics. The problem is addressed via consistent application of exact higher order sliding mode (HOSM) differentiators in conjunction with the method of stable system center (SSC). A numerical example illustrates the performance of the proposed algorithm.

Homogeneous High-Order Sliding Modes

Homogeneity features of dynamic systems are known to provide for a number of general practically important features. In particular, the finite-time convergence is easily proved, and the asymptotic accuracy is readily calculated in the presence of input noises, delays and discrete sampling. General uncertain single-input-single-output regulation problems are only solvable by means of discontinuous control via the so-called high-order sliding modes (HOSM). The homogeneity approach facilitates the design and investigation of new HOSM controllers, featuring such attractive properties as practical continuity of the control in the presence of noises. Robust output-feedback controllers are produced, using robust exact homogeneous differentiators. The asymptotic accuracy of the obtained controllers is the best possible under given circumstances. The dangerous chattering effect is removed by means of a standard procedure. The resulting systems are robust with respect to the presence of unaccounted-for fast stable dynamics of actuators and sensors. Simulation results and applications are presented in the fields of control, signal and image processing.

Actuator Fault Diagnosis Using High-Order Sliding Mode Differentiator (HOSMD) and Its Application to a Laboratory 3D Crane

Abstract Actuator fault diagnosis problem is studied for a class of nonlinear systems with relative degrees from the inputs to the outputs higher than one. This type of nonlinear systems include many mechanical systems, and their actuator fault diagnosis problem can be very challenging because of nonlinearities and high relative degrees. In this paper, in order to solve the actuator fault diagnosis problem for the considered nonlinear systems, 2nd-order and 3rd-order sliding mode differentiators are used and actuator fault diagnosis schemes are proposed to achieve fault detection and isolation. Computer simulations are carried out to compare the efficacy of the proposed fault diagnosis schemes on a laboratory 3D Crane model with noisy measurements. The fault diagnosis schemes are further tested through experiments on a laboratory 3D Crane in terms of actuator fault detection and isolation.

Observation of linear systems with unknown inputs via high-order sliding-modes

A high-order sliding-mode observer is designed for linear time invariant systems with single output and unknown bounded single input. It provides for the global observation of the state and the output under sufficient and necessary conditions of strong observability or strong detectability. The observation is finite-time-convergent and exact in the strong observability case. The accuracy of the proposed observation and identification schemes is estimated via the sampling step or magnitude of deterministic noises. The results are extended to the multi-input multi-output case.

High-order, sliding-mode-based precise control of direct-drive systems under heavy uncertainties

The high-performance control of direct-drive (DD) systems requires the full system dynamic effects to be taken into account owing to the eliminated gear mechanism. The actuator dynamics and structural flexibilities become of increased importance, particularly when high-speed, high-accuracy operation of lightweight structures is aimed for; however, in most related literature, these effects are neglected to avoid increased computational complexity at the expense of compromising the tracking accuracy of the system in the transient and steady state. As a solution to the problem, in this study, high-order, sliding-mode (HOSM) controllers (HOSMCs) are developed, which exploit the robustness properties of sliding-mode controllers (SMCs) while also increasing accuracy by reducing chattering effects. Different from standard HOSMCs, which are derived by artificially increasing the system order, the third-order HOSM (3-HOSM) control laws in this study are derived by including the actuator dynamics and structural flexibilities in the control design process. Two HOSMCs are developed for this purpose: one with a discontinuous input and one with a continuous input aimed at reducing chattering. The performance of the novel HOSMCs is tested by simulations for the precise position and tracking control of a one-degree-of-freedom (1DOF) DD weapon-positioning system as an example of a direct-drive system under heavy uncertainties and external disturbances. The improved accuracy obtained, particularly with the novel continuous-input 3-HOSMC, motivates the implementation of the schemes for demanding control applications under heavy uncertainties.

Integral High-Order Sliding Modes

Integral sliding mode approach is extended to high-order sliding modes (HOSMs), and allows choosing transient dynamics, or assigning a transient-time function of initial conditions. The resulting controller is robust and capable of controlling outputs of uncertain smooth SISO systems of a known permanent relative degree. The control smoothness can be deliberately increased.

Nonminimum‐phase output tracking in causal systems using higher‐order sliding modes

AbstractAsymptotic output tracking in a class of causal nonminimum‐phase uncertain nonlinear systems is addressed via higher‐order sliding modes (HOSMs). Local asymptotic stability of the output‐tracking error dynamics is provided. An output reference profile and an external disturbance forcing the internal dynamics are defined by an unknown linear exosystem. Its characteristic polynomial (which is used in the output‐tracking control algorithm) is identified online by using a HOSM parameter observer. A numerical example illustrates efficiency of the developed HOSM control algorithm. Copyright © 2007 John Wiley & Sons, Ltd.

Control of chaotic oscillators via a class of model free active controller: Suppresion and synchronization

The goal of this work is related with the control of chaotic oscillators for chaos suppression and synchronization purposes. The proposed methodology is related with a class of robust active control (RAC) law, where the stabilizing part of the control structure is related with an integral high order sliding-mode and proportional form of the so-called control error. The proposed controller is applied to chaos suppression, synchronization and anti-synchronization tasks for nonlinear oscillators with different order and structure. Numerical experiments illustrate the satisfactory performance of the proposed methodology, when it is applied to Duffing and Chen oscillators.

Continuous Traditional and High-Order Sliding Modes for Satellite Formation Control

Continuous Traditional and High-Order Sliding Modes for Satellite Formation Control

Sensorless second-order sliding-mode speed control of a voltage-fed induction-motor drive using nonlinear state feedback

A high-performance and robust sensorless speed-control scheme of a voltage-fed induction motor has been developed in which the control of speed and flux is decoupled. A robust control strategy, specifically a sliding-mode technique, is considered here. Standard sliding-mode control is a type of nonlinear controller and is robust to system uncertainties and parameter variation. However, it suffers from the chattering problem. Higher-order sliding mode (HOSM) is one of the solutions which does not compromise robustness. In particular, a super-twisting higher-order sliding-mode algorithm coupled with equivalent control is considered in the paper for both speed and flux control of the motor. A design procedure is developed to determine the controller gains. Although the use of HOSM control provides robustness, accurate knowledge of rotor flux and machine parameters is still the key factor in obtaining a high-performance and high-efficiency induction-motor drive. Sensorless flux-estimation schemes discussed in the literature suffer from problems associated with pure integration, instability and sensitivity to stator-resistance mismatch at low-speed operation. In the paper, a stable sensorless adaptive rotor-flux estimator using the full induction-machine model is proposed. Stable-model-reference-adaptive-system (MRAS) speed- and stator-resistance estimators based on current estimation are proposed and design details are presented. A stable load-torque MRAS estimator has also been developed. Experimental results are presented to verify the stability of the induction-motor drive in various operating modes.

Higher-order sliding mode control of a diesel generator set

Diesel engines are used as prime movers and independent power sources in many applications because of their advantages in terms of fuel efficiency, robustness and reliability. This paper presents the results of isochronous speed controller design and experimental analysis of robustness and efficiency of a turbocharged diesel generator set (genset). The steady state performance and transient response of the genset speed utilizing second-order sliding mode techniques with a super twisting sliding mode control algorithm are assessed. The algorithm does not require the time derivative of the sliding variable. It only uses the measured genset speed and does not require the use of an observer. A modification made to the algorithm shows improvement of the genset performance over a wide operating envelope. The influence of this methodology and modification of the algorithm on overall generator performance, in particular in the presence of large load changes and in terms of fuel efficiency, exhaust emissions, starting speed transient response and steady speed variation, are assessed. An algorithm for tuning the higher-order sliding mode (HOSM) controller for the genset is established and presented. The robustness of the controller is investigated and the performance is compared with that obtained by a commercial genset controller and a classical proportional-integral controller.

Teleoperation Over IP Network: Network Delay Regulation and Adaptive Control

This paper proposes a solution to control a remote manipulator robot (PUMA560) using IP network. A method is described to control this remote manipulator based on High-Order Sliding Mode so as to obtain a constant product time delay × bandwidth. Since previous method supposes a constant transmission delay, we put it over a low level mechanism (Network Delay Regulator) satisfying this criterion. This method eliminates the delay jitter in order to make remote estimation, prediction and control with a constant mean time delay. Under this condition, the stability condition of this algorithm is then studied. Some simulation results illustrate the performance of the High-Order Sliding Mode to dynamically force the remote system according to the Network Round Trip Time (NRTT).

High Order Sliding-mode Control of Uncertain Linear Systems

High order sliding control of linear systems with unmatched perturbations is considered. A closed-loop system matrix assignment design procedure is proposed. The method is a modification of back-stepping design to take the advantage of scaling. A new high order sliding mode controller is presented, in which a nonlinear scaling function is used to achieve sliding mode.

Graphs and Matrices

Graphs and Matrices