Sliding Mode Type Research Articles

Underactuated rotary inverted pendulum control using robust generalized dynamic inversion

The article applies the robust generalized dynamic inversion control methodology to the problem of stabilizing upright equilibrium configuration of the under-actuated rotary inverted pendulum system while tracking rotary motion of the actuated arm. The proposed robust generalized dynamic inversion control law comprised equivalent and switching control parts. The equivalent control part works to enforce a virtual constraint dynamics of the controlled state variables by means of Moore–Penrose generalized inversion. The switching control part is of the sliding mode type, and it improves robustness against unmodeled system dynamics, parametric uncertainties, and external disturbances. The robust generalized dynamic inversion control design on the linearized model of the under-actuated rotary inverted pendulum is shown to guarantee semi-global asymptotically stable tracking performance. Numerous computer simulations and experiments are conducted on the Quanser rotary inverted pendulum system, revealing that the proposed algorithm has better convergence and tracking performance than conventional sliding mode and generalized dynamic inversion control strategies when both are applied separately.

The Secure Transmission of Videos Using the Karhunen-Loéve (K-L) Decomposition and the Synchronization of the Unified Chaotic System with the Hyperchaotic Chen System

A unique secure communication scheme that can be used for the transmission of gray-scale and color videos is presented in this paper. The proposed scheme is developed by using the Karhunen-Loéve (K-L) decomposition and the synchronization of the unified chaotic system with the hyperchaotic Chen system. First, the gray-scale or color video is represented by a set of N frames. In order to reduce the data, the K-L decomposition is used to come up with data coefficients and eigenfunctions that optimally obtain the crux of the N frames. Using only the most energetic eigenfunctions to approximate the original frames results in computational savings. The data coefficients corresponding to the most energetic eigenfunctions are encrypted and transmitted using a master system composed of a combination of the unified chaotic system and the hyperchaotic Chen system. At the receiver end, these coefficients are recovered and a controller of the sliding mode type is utilized forcing the master and slave systems to synchronize. Simulation results illustrate how the proposed control law is able to synchronize the master and the slave systems. In addition, a demonstration of the recovery of the original frames using the decrypted data coefficients along with the eigenfunctions of the frame is provided. The presented simulations indicate that the proposed scheme results in an excellent performance.

A Robust Consensus Algorithm for Current Sharing and Voltage Regulation in DC Microgrids

In this paper, a novel distributed control algorithm for current sharing and voltage regulation in DC microgrids is proposed. The DC microgrid is composed of several distributed generation units, including buck converters and current loads. The considered model permits an arbitrary network topology and is affected by an unknown load demand and modeling uncertainties. The proposed control strategy exploits a communication network to achieve proportional current sharing using a consensus-like algorithm. Voltage regulation is achieved by constraining the system to a suitable manifold. Two robust control strategies of sliding mode type are developed to reach the desired manifold in a finite time. The proposed control scheme is formally analyzed, proving the achievement of proportional current sharing, while guaranteeing that the weighted average voltage of the microgrid is identical to the weighted average of the voltage references.

Joint space tracking control of underwater vehicle-manipulator systems using continuous nonsingular fast terminal sliding mode

To ensure satisfactory control performance for the underwater vehicle-manipulator systems, a novel continuous nonsingular fast terminal sliding mode controller is proposed and investigated using time delay estimation in this article. Complex lumped unknown dynamics including the strong nonlinear couplings and external disturbance are properly compensated with time delay estimation, which are mainly based on the time-delayed signals of underwater vehicle-manipulator systems and can provide with a fascinating model-free feature. Afterwards, the satisfactory tracking control performance and good robustness under heavy lumped uncertainties are ensured using the continuous nonsingular fast terminal sliding mode term with a fast terminal sliding mode–type reaching law. Therefore, the proposed controller is easy to use thanks to time delay estimation, and can ensure good control performance owing to continuous nonsingular fast terminal sliding mode. Stability of the closed-loop control system is analyzed using Lyapunov stability theory, and theoretical tracking errors are calculated and presented. Finally, the effectiveness and advantages of the proposed controller are demonstrated through comparative 7-degree-of-freedom pool experiments.

Decentralized Sliding Mode Control of Islanded AC Microgrids With Arbitrary Topology

This paper deals with modeling of complex microgrids and the design of advanced control strategies of sliding mode type to control them in a decentralized way. More specifically, the model of a microgrid including several distributed generation units (DGUs), connected according to an arbitrary complex and meshed topology, and working in islanded operation mode, is proposed. Moreover, it takes into account all the connection line parameters and it is affected by unknown load dynamics, nonlinearities and unavoidable modeling uncertainties, which make sliding mode control algorithms suitable to solve the considered control problem. Then, a decentralized second-order sliding mode control scheme, based on the suboptimal algorithm is designed for each DGU. The overall control scheme is theoretically analyzed, proving the asymptotic stability of the whole microgrid system. Simulation results confirm the effectiveness of the proposed control approach.

A Novel Sensorless Fuzzy Sliding-Mode Control of Induction Motor

A novel fuzzy sliding-mode structure has been proposed for the model reference adaptive system(MRAS) based sensorless control of an induction motor in this paper. The design includes a hybrid MRAS from measured stator terminal voltages and currents. The estimated speed is used as feedback in an indirect vector control system achieving the speed control without using shaft mounted transducers. Fuzzy sliding-mode structure includes two nonlinear controllers, one of which is sliding mode type and the other is PI-fuzzy logic based controller, the latter define a new control structure. Both controllers are combined by means of an expert system based on Takagi-Sugeno fuzzy reasoning. The sliding mode controller acts in the steady state. The new structure has two advantages: sliding-mode controller increasing system stability and PI-like fuzzy logic based controller reducing the chattering in permanent state. The scheme has been implemented and experimentally validated.

Design of Robust Higher Order Sliding Mode Control for Microgrids

This paper deals with the design of advanced control strategies of sliding mode type for microgrids. Each distributed generation unit (DGu), constituting the considered microgrid, can work in both grid-connected operation mode (GCOM) and islanded operation mode (IOM). The DGu is affected by load variations, nonlinearities and unavoidable modelling uncertainties. This makes sliding mode control particularly suitable as a solution methodology for the considered problem. In particular, a second order sliding mode (SOSM) control algorithm, belonging to the class of Suboptimal SOSM control, is proposed for both GCOM and IOM, while a third-order sliding mode (3-SM) algorithm is designed only for IOM, in order to achieve, also in this case, satisfactory chattering alleviation. The microgrid system controlled via the proposed sliding mode control laws exhibits appreciable stability properties, which are formally analyzed in the paper. Simulation results also confirm that the obtained closed-loop performances comply with the IEEE recommendations for power systems.

A Novel Sensor Less Control of Induction Motor Based on Fuzzy Sliding-Mode Structure

A novel fuzzy sliding-mode structure has been proposed for Extend Kalman Filter (EKF) based on sensorless control of an induction motor in this paper. Fuzzy sliding-mode structure includes two nonlinear controllers, one of which is sliding mode type and the other is PI-fuzzy logic based controller. The new structure has two advantages: sliding-mode controller increasing system stability and PI-like fuzzy logic based controller reducing the chattering in permanent state. The scheme has been implemented and experimentally validated.

A multi-regulator sliding mode control strategy for output-constrained systems

This paper proposes a multi-regulator control scheme for single-input systems, where the setpoint of a regulated output must be changed under the constraint that a set of minimum-phase outputs remain within prescribed bounds. The strategy is based on a max–min selector system frequently used in the aerospace field. The regulators used for the regulated and limited outputs are of the sliding mode type, where the sliding variable is defined as the difference between an output and its allowable limit. The paper establishes overall asymptotic stability, as well as invariance properties leading to limit protection. The design methodology is illustrated with a detailed simulation example on thrust control of a turbofan engine.

An Adaptive “Sliding-mode” Observer for Nonlinear Systems with Unknown Inputs and Noisy measurements

AbstractAn estimator for nonlinear systems with unmatched unknown inputs is presented. The observer is of sliding mode type and guarantees the estimation of the system's estate and unknown unmatched inputs up to an arbitrarily small tolerance. It is also assumed that measurements are contaminated by noise. Adaptation is used to update some of the estimator's gains online, which compensate for the system's uncertainties and noise. The estimator design and the convergence analysis follows the trend of literature on discontinuous sliding-mode observers however, our design results in a continuous dynamic system which steers the trajectories to an arbitrarily small neighbourhood of the sliding mode.

Nonlinear control of the underactuated two-link manipulator using the sliding-mode type partial linearisation method

In this paper, a control method for an underactuated two-link manipulator is proposed. This manipulator is a two-degree-of-freedom system with single actuator at the joint of two links. In the proposed method, using the sliding-mode type partial linearisation method which has a robustness for input disturbance, sub-controllers for two state variables based on angle of each link are designed. The control input is consisted of two sub-inputs by regarding each sub-input as input disturbances for each other. Numerical simulation is performed to show the effectiveness of the proposed method.

Hardware in the Loop Simulation of Vehicle Stability Control using Regenerative Braking and Electro Hydraulic Brake for Hybrid Electric Vehicle

Abstract In this paper, hardware in the loop simulation(HILS) for a hybrid electric vehicle(HEV) braking performance is performed to investigate the vehicle stability control algorithm in the varying road surface condition. The vehicle stability control algorithm consists of the optimal braking torque distribution between the regenerative braking and the electro hydraulic braking. In addition to the optimal braking torque distribution, a sliding mode type wheel slip control algorithm is proposed to maintain the target slip ratio. The HILS system is composed of 4 wheel calipers and the electro hydraulic brake(EHB) module, and dynamic model of the HEV powertrain constructed by MATLAB Simulink is used as a software part. It is found from the HILS results that vehicle stability control algorithm using the regenerative braking, EHB and slip ratio control is able to provide the improved braking performance such as shorter braking distance, smaller error of the sideslip angle and yaw rate.

Anti-Lock Braking Control of a Hybrid Brake-By-Wire System

This paper presents a non-linear sliding mode type controller for slip regulation in a braking event for a hybrid electromagnetic-electrohydraulic brake-by-wire (BBW) system. The anti-lock braking system (ABS) controller modifies the brake torque command generated by a supervisory controller based on a driver request via the brake pedal sensor. The brake torque command is then generated by a closed-loop actuator control algorithm to control the eddy current brake (ECB) and electrohydraulic brake (EHB) systems. The proposed control algorithm shows very good slip regulation in a braking event on low friction coefficient surfaces when compared with non-ABS braking. It has been observed that the eddy current brake provided most of the torque while the electrohydraulic brake compensated for the difference between ABS torque command and estimated ECB torque. The result is a very smooth ABS stop minimizing the noise, vibration, and harshness (NVH) of current hydraulic ABS systems. It is also shown that the closed-loop system is stable in the sense of Lyapunov stability theory.

Robust sliding mode control of non-linear systems with delay: a design via polytopic formulation

This paper outlines the possibility to control non-linear uncertain systems with single, possibly time-varying state-delay. These systems are submitted to additive perturbations (possibly non-vanishing). The control is of sliding mode type and the sliding surface is designed to maximize the calculable set of delays which do not destabilize the relay–delay system. The way to deal with the non-linear parts of the model relies on a polytopic formulation, i.e. a decomposition into a non-linear combination of linear models, whose weighting coefficients satisfy a convex property. The conditions for the existence of the sliding regime are studied by using both a Lyapunov–Krasovskii functional and a Lyapunov–Razumikhin function. The optimization procedure for the choice of the sliding surface is expressed in terms of LMIs. An example illustrates the proposed method.

Combining the Principles of Sliding Mode, Direct Torque Control, and Space-Vector Modulation in a High-Performance Sensorless AC Drive

A sensorless induction motor drive is presented, in which the principles of sliding-mode control, direct torque control (DTC), and space-vector modulation are combined to ensure high-performance operation, both in the steady state and under transient conditions. Merits of the classic DTC transient behavior are preserved, while the steady-state operation is significantly improved. The torque and flux controllers, and motor state observer are of the sliding-mode type. The inverter is directly controlled on the basis of torque and flux errors, using space-vector pulsewidth modulation. Computer simulations and experimental results presented demonstrate the robustness, accuracy, quickness, and low-chattering, wide-speed-range operation of the drive.

Robust adaptive synchronization of Rossler and Chen chaotic systems via slide technique

This Letter considers the robust adaptive synchronization problem of Rossler and Chen chaotic systems with different time-varying unknown parameters. When system's unknown parameters vary in bound intervals and the bounds of intervals are unknown, a robust adaptive controller is designed. In order to increase the robustness of the closed loop systems, the key idea is that a sliding mode type of controller is employed. Besides, instead of the estimate values of systems' unknown parameters being taken as updating object, a new updating object is introduced in constructing controller. The proposed controller can make the states of Rossler and Chen chaotic systems globally asymptotically robustly synchronized. Simulation results are given to show the effectiveness of the proposed method.

Stochastic output noise effects in sliding mode state estimation

This paper is devoted to the analysis of effects of stochastic output noises acting on a stochastic continuous time system which states are estimated using mixed (linear and sliding-mode type) observers. Such observers provide the stable (with probability one) estimates. The 'averaged' norm of estimation error converges to a zone where size is proportional to the acting noise power. The main technique of the proof is based on the 'averaging concept' applied within the frame of stochastic Lyapunov-like analysis. The stochastic calculus (It@ formula) as well as some basic principles for stochastic processes are used to obtain the convergence results. The size of the obtained zone is analysed as a function of the sliding mode gain parameter. It is shown that the sliding mode term helps a high-gain linear observer to make this zone smaller. The illustrative example dealing with the circuit of a full bridge boost type PFP (power factor precompensator) concludes this study.

Speed control of induction motors using a novel fuzzy sliding-mode structure

This paper presents a new approach to indirect vector control of induction motors. Two nonlinear controllers, one of sliding mode type and the other PI-fuzzy logic-based, define a new control structure. Both controllers are combined by means of an expert system based on Takagi-Sugeno fuzzy reasoning. The sliding-mode controller acts mainly in a transient state while the PI-like fuzzy controller acts in the steady state. The new structure embodies the advantages that both nonlinear controllers offer: sliding-mode controllers increasing system stability limits, and PI-like fuzzy logic based controllers reducing the chattering in permanent state. The scheme has been implemented and experimentally validated.

Sliding mode rest-to-rest stabilization and trajectory tracking for a discretized flexible joint manipulator

In this article, a difference flatness approach is used for trajectory tracking tasks of an approximately (Euler) discretized model of a nonlinear, single link, flexible joint manipulator. The system's flat output is commanded to follow a prescribed trajectory achieving a desired angular position maneuver. A new robust discrete time feedback controller design technique, of the sliding mode type, is then proposed for the closed loop regulation of the link position around the prescribed trajectory. The effectiveness of the approach is illustrated by means of digital computer simulations in a rest-to-rest stabilization maneuver and in a sinusoidal reference trajectory tracking task.

Multirate Implementation of a Quasi-Sliding Mode Control

In this paper a discrete time sliding-mode type controller is proposed and it is implemented by using a multirate output sampling scheme. This strategy avoids the use of state observers, the uncertainty in the model parameters and disturbances being counteracted by the robustness of the sliding mode control structure. This controller does not involve switching, and it is applied to control stable and unstable systems. Also by simulations, the controller has shown to be robust against changes in the plant model parameters.