Discrete-time Integral Sliding Mode Control Research Articles

PSO-enhanced discrete-time integrated sliding mode-based control of three-level NPC converter for grid-connected PV-FC distributed generation system

This study proposes the control of a three-level NPC converter applied in a PV-FC hybrid generation system based on discrete-time integral sliding mode control (DISMC) combined with the particle swarm optimization (PSO) technique. First, the comprehensive depiction and modeling of the system's main components are initially presented. Then, the controller's detailed design procedure is given. The sliding manifold is designed to have a fast dynamic response, and its stability analysis is verified using the Lyapunov direct method. Next, the optimization procedure is introduced to calculate the optimal values of the DISMC gains. Furthermore, a power management strategy is examined within the proposed control system to maximize the utility of the power produced by the hybrid system; the control is done through the designed PSO-DISMC to allow decoupled control of the active and reactive powers in two distinct modes of operation (the feeder-flow control (FFC) and the unit-power control (UPC) modes). The simulation of the approach is conducted in MATLAB/Simulink, and the findings demonstrate the effectiveness and robustness of the proposed control strategy.

A Discrete-Time Integral Sliding Mode Control Law for Systems With Matched and Unmatched Disturbances

A Discrete-Time Integral Sliding Mode Control Law for Systems With Matched and Unmatched Disturbances

A generalized reaching‐law‐based discrete‐time integral sliding‐mode controller with matched/mismatched disturbance attenuation

AbstractA generalized reaching‐law‐based (RL‐based) discrete‐time integral sliding‐mode controller, which is versatile for either matched or mismatched disturbances, is designed in this paper to obtain high output tracking accuracy and avoid tremendous control efforts. Specifically, a disturbance decomposition‐based discrete‐time integral sliding surface is designed, and a generalized discrete‐time reaching law is established. Different from the existing integral sliding surfaces, the proposed sliding surface synthesizes a disturbance‐related integral term that is defined based on disturbance decomposition; this is crucial to the disturbance attenuation. Moreover, different from the available discrete‐time reaching laws, the proposed reaching law introduces an adaptive exponential term into the control gains, and hence, the conventional RL‐based discrete‐time integral sliding‐mode control (DISMC) and the equivalent‐control‐based (EC‐based) DISMC can be integrated. Rigorous analysis shows that the closed‐loop system is stable, the control effort can be satisfactory, and the steady‐state output tracking accuracy is of order for both matched and mismatched disturbances. The proposed method is proven effective through numerical simulations.

Consensus of Discrete-Time Nonlinear Multiagent Systems Using Sliding Mode Control Based on Optimal Control

This article investigates the optimal sliding mode control approach for consensus of nonlinear discrete-time high-order multi-agent systems (MASs). First, the nonlinearity and communication delay in the MAS is solved by designing a distributed discrete-time integral sliding mode control law, together with a proof of reachability of the sliding mode surface, as well as a proof that the chattering of the system is attenuated. In addition, the optimal controller is designed based on the model obtained after the distributed sliding mode control law is applied to the system. The merits of the proposed distributed sliding mode controller with the fusion of optimal control are that it can reduce the chattering of the MASs and their existence of quasi-sliding modes, as well as tolerate the negative impact caused by communication delay among agents. The MASs can achieve consensus quickly with the combined action of the sliding mode controller and the optimal controller. Finally, two examples are given to verify the effectiveness of the control method proposed in this paper.

Spatially Distributed Networked Sliding Mode Control

A robust control algorithm for spatially distributed multi-input networked control systems with time-varying transmission delays is proposed. In order to increase the dependability of the spatially distributed scheme, a pivotal requirement to the algorithm is the exclusive usage of locally available information in each controller node. This ensures that no communication between the controller nodes is necessary. The algorithm consists of a buffering mechanism and discrete-time integral sliding mode control laws which are capable of rejecting matched perturbations with bounded change rate. The effectiveness of the proposed approach is demonstrated by means of a numerical simulation.

Flight Control for UAV Loitering Over a Ground Target With Unknown Maneuver

This paper proposes a flight controller for an unmanned aerial vehicle (UAV) to loiter over a ground moving target (GMT). We are concerned with the scenario that the stochastically time-varying maneuver of the GMT is unknown to the UAV, which renders it challenging to estimate the GMT's motion state. Assuming that the state of the GMT is available, we first design a discrete-time Lyapunov vector field for the loitering guidance and then design a discrete-time integral sliding mode control (ISMC) to track the guidance commands. By modeling the maneuver process as a finite-state Markov chain, we propose a Rao-Blackwellised particle filter (RBPF), which only requires a few number of particles, to simultaneously estimate the motion state and the maneuver of the GMT with a camera or radar sensor. Then, we apply the principle of certainty equivalence to the ISMC and obtain the flight controller for completing the loitering task. Finally, the effectiveness and advantages of our controller are validated via simulations.

Optimal Discrete-time Integral Sliding Mode Control for Piecewise Affine Systems

This paper presents an optimal discrete-time integral sliding mode control for constrained piecewise affine systems. The proposed scheme is developed on the basis of linear quadratic regulator approach and differential evolution algorithm in order to ensure the stability of the closed-loop system in discrete-time sliding mode and the optimization of response characteristics in presence of control input constraints. Moreover, the controller is designed such that chattering phenomenon is avoided and finite-time convergence to the sliding surface is guaranteed. The follow-up of a reference model is also ensured. The efficiency of the proposed method is illustrated with an inverted pendulum system.

Discrete-time Integral Sliding Mode Control with Anti-windup

Discrete-time Integral Sliding Mode Control with Anti-windup

Maximum power point tracking for the permanent magnet synchronous generator‐based WECS by using the discrete‐time integral sliding mode controller with a chattering‐free reaching law

In this study, a single sensor-based maximum power point tracking (MPPT) algorithm is presented for permanent magnet synchronous generator-based wind energy conversion system (WECS). The MPPT method used in this study uses only the wind speed sensor to generate the reference point required for the maximum power. A discrete-time controller is proposed to bring the system to the reference point determined by the MPPT algorithm. The designed MPPT controller consisting of a new discrete-time reaching-law approach and a discrete-time integral sliding mode control (SMC). The designed discrete-time SMC-based controller is implemented by using an Acorn RISC Machine (ARM)-based LM4F120 microcontroller, and its performance is examined on a WECS emulator prepared in the laboratory. The results got from the real-time studies prove that the proposed controller has the satisfactory performance to bring the system to the MPP. The performance of the proposed controller is also compared with the conventional sliding mode controller and perturb and observe method. The obtained results proved that the proposed controller has a better performance than the other controllers in terms of the settling time and output voltage's ripple.

An O(T^2) Boundary Layer in Sliding Mode for Time-Delay Systems

A new discrete-time integral sliding mode control scheme is proposed for a class of linear multi-input systems with state delays. Based on the Lyapunov stability theory and one-step delayed disturbance approximation, a sliding mode controller not only drives the sliding mode into the O(T^2) boundary, but also achieves the O(T^2) boundary for state regulation. A novel integral sliding surface is introduced so that reaching phase is eliminated. Chattering phenomenon is eliminated and the knowledge of upper bound of external disturbances is not required. The validity of the proposed control methodology is demonstrated by simulation results.

Discrete–Time Integral Sliding Mode Control with Disturbances Compensation and Reduced Chattering for Pv Grid–Connected Inverter

Abstract In the paper a new discrete-time integral sliding mode control (DISMC) with disturbances compensation and reduced chattering for grid-connected inverter is proposed for active and reactive power regulation. Differently by many SMC proposed in literature that have a time-continuous formulation in spite have been implemented with digital processor, the proposed DISMC is fully formulated in discrete-time, taking into account the effects introduced by a microprocessor-based implementation. As will be demonstrated such approach consents to reduce the chattering about the sliding manifold within a boundary layer of O(T2) thickness instead of O(T) (being T the sampling period of the control algorithm). Moreover it introduces a correction of the control vector which eliminates the influence of modeling error and external disturbances improving stability and robustness of the controlled system. Constant converter switching frequency is achieved by using space vector modulation, which eases the design of the ac harmonic filter. In the paper, after a detailed formalization of the proposed control algorithm, several numerical and experimental results on a three-phase grid-connected inverter prototype are shown, proving the effectiveness of the control strategy.

Robust tracking and model following of uncertain dynamic systems via discrete-time integral sliding mode control

A discrete-time integral sliding mode control scheme is proposed to realize the problem of robust tracking and modeling following for a class of uncertain linear systems. It will be shown that the proposed scheme guarantees the stability of closed-loop system and achieves zero-tracking error in the presence of parameter uncertainties and external disturbances. The selection of switching surface and the existence of sliding mode are two important issues, which have been addressed. This scheme assures robustness against system uncertainties and disturbances. Chattering phenomenon and reaching phase are eliminated. Moreover, the knowledge of upper bound of uncertainties is not required. Both the theoretical analysis and illustrative example demonstrate the validity of the proposed scheme.

On the Integral Sliding-Mode Control for Sample-data Systems with State Time-Delay

Abstract A discrete-time integral sliding mode control (DISMC) scheme is proposed for sample-data systems with state time-delay and disturbance. A steady-state error about the magnitude of O(T 2 ) is achieved for some delay systems. A variable replacement is applied to transform the original system to a new delay-free system; then a DISMC scheme is designed for the new system. Comparing with the existing methods dealing with time-delay systems, the new scheme is different and simple for some systems. The illustrative example demonstrates the validity of the proposed scheme.

On the Discrete-Time Integral Sliding-Mode Control

A new discrete-time integral sliding-mode control (DISMC) scheme is proposed for sampled-data systems. The new control scheme is characterized by a discrete-time integral sliding manifold which inherits the desired properties of the continuous-time integral sliding manifold, such as full order sliding manifold with pole assignment, and elimination of the reaching phase. In particular, comparing with existing discrete-time sliding-mode control, the new scheme is able to achieve more precise tracking performance. It will be shown in this work that, the new control scheme achieves O(T2) steady-state error for state regulation with the widely adopted delay-based disturbance estimation. Another desirable feature is, the proposed DISMC prevents the generation of overlarge control actions due to deadbeat response, which is usually inevitable due to the existence of poles at the origin for a reduced order sliding manifold designed for sampled-data systems. Both the theoretical analysis and illustrative example demonstrate the validity of the proposed scheme