Integral Sliding Surface Research Articles

Fault-Tolerant Consensus Control for Discrete-Time Multi-Agent Systems: A Distributed Adaptive Sliding-Mode Scheme

In this brief paper, a fully distributed sliding mode controller with fault compensation is designed to deal with the consensus problem of discrete-time first-order multi-agent systems with actuator faults. A novel fully distributed integral sliding surface (ISS) without global information is proposed to guarantee consensus when agents move on the sliding surface. Based on such a sliding manifold combined with identified faults, a fully distributed sliding mode fault-tolerant controller is constructed, while a sufficient condition is derived to guarantee the finite-time reachability of the distributed ISS. Finally, simulation results verify the effectiveness of the proposed control algorithm.

An Enhanced Adaptive Time Delay Control-Based Integral Sliding Mode for Trajectory Tracking of Robot Manipulators

This article proposes an enhanced adaptive time delay controller (ATDC) for robot manipulators subjected to external disturbances. This approach is model-free and uses time delay estimation (TDE) to estimate complex and unknown robot dynamics. First, to remove the reaching phase and improve the robustness of the control, an integral sliding surface (ISS) is used. Second, to speed up the convergence and compensate for the TDE errors and external disturbances, the gains of time delay control and the sliding mode have been made adaptive. In this article, we clearly point out using the Lyapunov method that the position and velocity tracking errors are guaranteed to be uniformly ultimately bounded (UUB). The effectiveness and the robustness of the designed controller over existing methods are experimentally verified on a parallel Delta robot. The novel model-free proposed control is robust and highly accurate, which is appropriate and recommended for industrial robotic applications.

Adaptive delay dependent sliding mode fault-tolerant controller design for nonlinear systems with unknown time-varying input and state delays

This paper presents a novel adaptive delay-dependent fault-tolerant sliding mode control (SMC) strategy for the class of nonlinear Lipschitz systems with time-varying unknown delays in system states and inputs. A modified integral sliding surface (ISS) based on which the SMC approach is developed using a linear matrix inequality. Lyapunov-Krasovskii stability theory is employed to guarantee asymptotic stability of the closed-loop system such that system states starting from any arbitrary initial conditions with time-varying delays reach the predefined sliding surface in a finite time. It is also proved that states stay on the surface for all subsequent time, and the effects of the actuator’s faults are simultaneously attenuated. Adaptive tuning laws are used to adjust controller parameters and estimate actuators’ faults. The controllers’ structures are more straightforward than the most existing recent fault-tolerant control methods. Simulation results of practical nonlinear inverted pendulum system verified the outstanding merits and capabilities of the proposed scheme in the presence of actuators’ faults and multiple delays in the system states and inputs.

Integral Sliding Mode Anti-Disturbance Control for Markovian Jump Systems with Mismatched Disturbances

This paper addresses an integral sliding mode-based anti-disturbance control algorithm for a type of Markovian jump systems (MJSs), which are influenced by different types of mismatched disturbances. On one hand, as for those disturbances that can be modeled, the disturbance observer (DO) method is introduced to realize the dynamical estimation of disturbances. Based on this, both the integral sliding surface (ISS) and the composite anti-disturbance controller are proposed in succession for rejecting unknown disturbances and guaranteeing the stability of the controlled MJS. Meanwhile, the states of the controlled system are ensured to reach ISS within a finite time. In addition, the L1 performance index is given to attenuate the effects of bounded disturbances. The controller and observer gains can be computed by using convex optimization techniques. The satisfactory stochastic stability and dynamical tracking performance are both also proved. Finally, the simulation results effectively verify all of the required performances.

Event-Triggered Integral Sliding Mode Anti-Disturbance Control for Nonlinear Systems Via T-S Disturbance Modeling

Under the framework of event triggering, this paper discusses a novel integral sliding mode (ISM) anti-disturbance algorithm for a class of nonlinear systems with mismatched disturbances. For the sake of describing more irregular disturbances, T-S fuzzy disturbance models are imported by choosing different basis functions and the corresponding disturbance observer (DO) is then put forward to realize the estimation of unknown disturbances. By utilizing the trigger threshold condition with the estimation information, both the integral sliding surface (ISS) and the event-triggered ISM controller are designed for compensating mismatched disturbances. It is guaranteed that the state trajectories can reach the ISS within a pre-designed finite time. Moreover, not only the system stability, but also the favorable tracking performance and the boundedness of the minimum trigger interval are simultaneously be achieved. Finally, the simulation results of an A4D aircraft model further embody the effective of designed control algorithm.

A Nonlinear Integral Sliding Surface to Improve the Transient Response of a Force-Controlled Pneumatic Actuator With Long Transmission Lines

AbstractA force-controlled pneumatic actuator with long connecting tubes is a well-accepted solution to develop magnetic resonance imaging (MRI)-compatible force control applications. Such an actuator represents an uncertain, second-order, nonlinear system with input delay. The integral sliding mode control, because of guaranteed robustness against matched uncertainties throughout the system response, provides a favorable option to design a robust controller for the actuator. However, if the controller is based on a linear integral sliding surface (LISS), the response of the actuator overshoots, especially when there are large initial errors. Minimizing overshoot results in a smaller controller bandwidth and a slower system response. This paper presents a novel nonlinear integral sliding surface (NLISS) for a sliding mode controller to improve the transient response of the actuator. The proposed surface is a LISS augmented by a nonlinear function of tracking error and does not have a reaching phase when there are initial errors and even multiple steps in the desired trajectory. The surface enables the integral sliding mode controller to offer variable damping, which changes from low to high as the transient error approaches small values and vice versa. Simulation studies and experimental results show that the controller based on the proposed sliding surface successfully eliminates the overshoot without compromising the controller bandwidth, rise, and settling times. For performance evaluation, the controller parameters are tuned using the globalized and bounded Nelder–Mead (GBNM) algorithm with deterministic restarts. The study also establishes the asymptotic stability of the controller based on the proposed sliding surface using Lyapunov's stability criterion.

Control of Fractional-Order Unified Chaotic Systems Subject to External Disturbances Using Twisting Algorithm with Fractional Integral Sliding Surface

This paper focuses on output feedback control of fractional-order unified chaotic systems subject to external disturbances. The output feedback controller is a combination of a high-order sliding mode controller and an observer. The controller based on a twisting algorithm makes use of a fractional integral sliding surface. The observer is a nonlinear state observer. Stability conditions for the output feedback control system are formulated as a linear matrix inequality problem. Numerical studies are given, showing the effectiveness of the method.

Design of Sliding Mode Controller With Proportional Integral Sliding Surface for Robust Regulation and Tracking of Process Control Systems

This paper deals with the design of sliding mode controller (SMC) with proportional plus integral sliding surface for regulation and tracking of uncertain process control systems. However, design method requires linear state model of the system. Tuning parameter of SMC has been determined using linear quadratic regulator (LQR) approach. This results in optimum sliding surface for selected performance index. Matched uncertainty is considered to obtain the stability condition in terms of its upper bound. A conventional state observer has been used to estimate the states. The estimated states are then fed to controller for determining control signal. The simulation study and experimentation on real-life level system have been carried out to validate performance and applicability of the proposed controller.

Adaptive Sliding Mode Control Method Based on Nonlinear Integral Sliding Surface for Agricultural Vehicle Steering Control

Automatic steering control is the key factor and essential condition in the realization of the automatic navigation control of agricultural vehicles. In order to get satisfactory steering control performance, an adaptive sliding mode control method based on a nonlinear integral sliding surface is proposed in this paper for agricultural vehicle steering control. First, the vehicle steering system is modeled as a second-order mathematic model; the system uncertainties and unmodeled dynamics as well as the external disturbances are regarded as the equivalent disturbances satisfying a certain boundary. Second, a transient process of the desired system response is constructed in each navigation control period. Based on the transient process, a nonlinear integral sliding surface is designed. Then the corresponding sliding mode control law is proposed to guarantee the fast response characteristics with no overshoot in the closed-loop steering control system. Meanwhile, the switching gain of sliding mode control is adaptively adjusted to alleviate the control input chattering by using the fuzzy control method. Finally, the effectiveness and the superiority of the proposed method are verified by a series of simulation and actual steering control experiments.

The Development of Anti-Windup Scheme for Time Delay Control With Switching Action Using Integral Sliding Surface

The Time Delay Control with Switching Action (TDCSA) method, which consists of Time Delay Control (TDC) and a switching action of sliding mode control (SMC), has been proposed as a promising technique in the robust control area where the plant has an unknown dynamics with parameter variations and substantial disturbances are preset. When TDCSA is applied to the plant with saturation nonlinearity, however, the so-called windup phenomenon is observed to arise, causing excessive overshoot and instability. The integral element of TDCSA and the saturation element of a plant cause the windup phenomenon. There are two integral effects in TDCSA. One is the integral effect caused by time delay estimation of TDC. The other is the integral term of an integral sliding surface. To solve this problem, we have proposed an anti-windup scheme method for TDCSA. The stability of the overall system has been proved for a class of nonlinear system. Experimental results show that the proposed method overcomes the windup problem of the TDCSA.