Global Sliding Mode Control Scheme Research Articles

Robust networked power system load frequency control against hybrid cyber attack

AbstractModern network and communication technologies are essential for the implementation and operation of load frequency control (LFC) systems. The measurements of crucial LFC system parameters will be compromised by attackers, rendering data received by the defence inaccurate and causing frequency fluctuations or even system collapse. To detect the potential attack on measured data and keep the LFC performance, an adaptive event‐triggered scheme with fractional order global sliding mode control scheme is proposed in this paper. Furthermore, Markov theory is employed for the modelling process with energy storage to present a multi‐area LFC power system considering renewable energy and hybrid cyber attacks. Stability and stabilisation criteria are built by employing improved Lyapunov stability theory and second‐order Bessel‐Legendre inequality. Finally, a two‐area LFC system under hybrid cyber attacks and a modified IEEE 39‐bus New England test power system with 3 wind farms are simulated to explore the efficacy of the proposed method.

Feedforward-control-based nonlinear control for overhead cranes with matched and unmatched disturbances

In this paper, a composite control method consisting of a feedforward control method and a sliding mode control method is proposed for control of the overhead crane. For existing methods, only matched disturbances are taken into consideration, unmatched disturbances are usually neglected. To address this drawback, a disturbance compensation method is constructed to attenuate the effects of disturbances and a continuous global sliding mode control method is devised to guarantee the stability. More precisely, we first make some transformations on the original model. Then, a disturbance compensation method is proposed and a continuous global sliding mode control scheme is introduced straightforwardly. The stability of the closed-loop system and the convergence of the states are proven through complete theoretical analysis. Finally, simulation and experimental tests are carried out to illustrate the regulation control property of the designed approach as well as its excellent disturbance rejection characteristic.

Fractional-order global sliding mode controller for an uncertain quadrotor UAVs subjected to external disturbances

In the present paper, the problem of designing a global sliding mode control scheme based on fractional operators for tracking a quadrotor trajectory is investigated. The model of the quadrotor system is given with disturbances and uncertainties. To converge in short finite time of the sliding manifold, a classical quadratic Lyapunov function was used and also a global stabilization of the quadrotor system is ensured. The proposed controller can be ensured the robustness against external disturbances and model uncertainties. Some scenarios are illustrated in this paper. Finally, a comparative study to three other controllers is provided to show the validity and feasibility of the proposed method.

Robust load frequency control for networked power system with renewable energy via fractional‐order global sliding mode control

Owing to random load changes and transmission time delays in interconnected power systems with renewable energy, the load frequency control scheme has become one of the main methods to keep stability and security of power systems. To relieve communication burden and increase network utilisation, an adaptive event-triggered scheme is explored. Then, a new fractional-order global sliding mode control scheme comprising the fractional-order term in the sliding surface is adopted to improve robustness of load frequency control. The fractional-order term generates a new degree of freedom and more adjustable parameters to improve control performance. Furthermore, the Markov theory is applied in the modelling process to better describe the uncertainty of parameters and external disturbances. The stability and stabilisation criteria for multi-area power systems load frequency control are put forward by employing the improved Lyapunov function and integral inequalities with auxiliary functions. Finally, two simulation examples containing a two-area power system and modified IEEE 39-bus New England test power system with three wind farms are presented to investigate the effectiveness of the proposed method.

Global Sliding Mode Control for Nonlinear Vehicle Antilock Braking System

In order to further improve the braking performance of the nonlinear antilock braking system (ABS), an improved global sliding mode control scheme is presented. First, a nonlinear global sliding mode surface is designed. The method can eliminate the reaching phase compared with conventional linear sliding mode surface, and guarantee the system robustness during the whole control process. Then, a novel control law is proposed to satisfy the sliding mode reaching condition, and the theoretical proof is given. Simulation results demonstrate that the proposed global sliding mode control scheme enables the wheel slip-ratio to converge to optimal value quickly with the small oscillation, and has relatively short braking distance and braking time, which is very suitable to prevent the wheel from being locked during braking. The proposed global sliding mode control scheme is verified by joint simulation using MATLAB and CarSim, and shows good braking performance when the car is driving under extreme road conditions, which indicates the effectiveness of the proposed sliding mode control scheme.

A New Control Method for Second-Order Multiple Models Control System Based on Global Sliding Mode

This paper proposed a finite time convergence global sliding mode control scheme for the second-order multiple models control system. Firstly, the global sliding surface without reaching law for a single model control system is designed and the tracking error finite time convergence and global stability are proved. Secondly, we generalize the above scheme to the second-order multimodel control system and obtain the global sliding mode control law. Then, the convergent and stable performances of the closed-loop control system with multimodel controllers are proved. Finally, a simulation example shows that the proposed control scheme is more effective and useful compared with the traditional sliding mode control scheme.

Observer-based finite-time sliding mode control for reentry vehicle

Purpose – The purpose of this paper is to design a disturbance observer-based finite-time global sliding mode control scheme for the attitude tracking control problem of the reentry vehicle with parameter uncertainties and disturbances. Design/methodology/approach – Feedback linearization is first introduced to transform vehicle model into three independent second order uncertain subsystems. Then a finite-time controller (FTC) is proposed for the nominal system on the basis of the homogeneity theory. Thereafter the integral sliding mode method is introduced for the vehicle with disturbances. The finite time convergence is achieved and global robustness is also assured by the combination of finite time control method and integral sliding mode strategy. Furthermore, to improve the attitude angle tracking accuracy a novel finite time disturbance observer (DO) is constructed. Findings – Simulation is made for the reentry vehicle with disturbances involved. And the results show the finite-time convergence, tracking accuracy and robustness of the proposed strategy. Originality/value – The proposed control strategy has three advantages. First of all it can achieve finite time convergence and avoid singularity. Moreover, it can also realize global robustness. Finally, a new kind of DO is introduced to improve the tracking accuracy.

An adaptive fast terminal sliding mode control combined with global sliding mode scheme for tracking control of uncertain nonlinear third-order systems

In this paper, an adaptive fast terminal sliding mode control technique combined with a global sliding mode control scheme is investigated for the tracking problem of uncertain nonlinear third-order systems. The proposed robust tracking controller is formulated based on the Lyapunov stability theory and guarantees the existence of the sliding mode around the sliding surface in a finite time. Under the uncertainty and nonlinearity effects, the reaching phase is removed and the chattering phenomenon is eliminated. This scheme guarantees robustness against nonlinear functions, parameter uncertainties and external disturbances. The derivative of the state variable is replaced by a delay term in the form of an Euler approximation of the derivative function. Furthermore, the knowledge of upper bounds of the system uncertainties is not required, which is more flexible in the real implementations. Simulation results are presented to show the effectiveness of the suggested method.

Research of a fuzzy global sliding mode control scheme: A stability control scheme for anti-aircraft missile with swing nozzle thrust vector control

In order to suppress the high-frequency chattering at control input in the premise of keeping robust against system uncertainties, a novel fuzzy global sliding mode controller (FGSMC) is proposed. A nonlinear switching function is designed in order that system trajectory can be set on sliding mode surface at initial time. A fuzzy decision maker, which can adaptively obtain the gain of signum term according to novel fuzzy logic, is proposed and introduced to guarantee the comprehensive properties with respect to the reachability of sliding mode and the smoothness of control input. Moreover, it possesses simple fuzzy inference rules and is easy to be realized in application. The FGSMC is employed to construct the stability control scheme for anti-aircraft missile with swing nozzle thrust vector control. Simulation results on researched anti-aircraft missile present that, in the existence of sustained disturbances, the proposed FGSMC scheme not only possesses better convergent performance, but also suppresses high-frequency chattering to a large extent, compared with conventional sliding mode control scheme.

Global Robust Sliding Mode Tracking Control for Helicopter with Input Time Delay

In this paper, a global sliding mode control scheme is proposed for a helicopter with input time delay and disturbance. We proposed a new method for integral sliding surface. By the design of dynamic nonlinear sliding mode function, the controller has the advantage of eliminating the reaching movement of traditional sliding mode control, overcoming the effect of the disturbance and time delay. The system state variables reached the sliding surface at the very beginning by means of designing a dynamic nonlinear sliding mode function, and moved to the expected state under the control of control law. The efficiency of the proposed method is demonstrated by simulation results.