Traditional Sliding Mode Control Research Articles

Proxy-Based Sliding-Mode Tracking Control of Piezoelectric-Actuated Nanopositioning Stages

In this paper, a proxy-based sliding-mode control (PBSMC) approach is proposed for robust tracking control of a piezoelectric-actuated nanopositioning stage composed of piezoelectric stack actuators and compliant flexure mechanisms. The essential feature of the PBSMC approach is the introduction of a virtual coupling proxy, which is controlled by the sliding-mode controller (SMC) to track the desired position. Simultaneously, due to the virtual coupling, a proportional-integral-derivative (PID) controller on the other side of the proxy ensures the position of the end-effector of the stage to follow the position of the proxy. Therefore, the PBSMC guarantees the end-effector to track the desired trajectory. The advantages of the developed PBSMC lie in the facts that 1) the discontinuous signum function in the traditional SMC is omitted without any approximation. Hence, the output of the PBSMC is continuous, which does not suffer from the chattering phenomenon; and 2) the PBSMC laws are developed without having the necessity to include the nominal system model, hysteresis model or the state observer. Hence, the PBSMC provides a novel effective yet simple control method, which permits to avoid the lack of performances from PID and the chattering from SMC, and permits to combine the advantages from them. The stability of the closed-loop control system is proved through Lyapunov analysis. Finally, comparative studies are performed on a custom-built piezo-actuated stage. Experimental results show that the tracking errors of the PBCM are reduced by 74.22%, as compared to the traditional PID controller, with the desired sinusoidal trajectory under the 50-Hz input frequency, which clearly demonstrates the superior tracking performance of the PBSMC.

Self-repairing control of a helicopter with input time delay via adaptive global sliding mode control and quantum logic

This study proposes a solution to the problem of designing adaptive global sliding mode controllers for a class of linear helicopter systems with actuator faults and time delay. An adaptive global sliding mode control approach is proposed based on dynamic nonlinear sliding mode function and adaptive law. The advantages of the controller include elimination of the reaching movement of traditional sliding mode control, realization of online identification of the fault value, and overcoming of the effect of the actuator faults and time delay. In addition, quantum information technique is used to increase the control accuracy of helicopter. Simulation results demonstrate the efficiency and superiority of the proposed method.

Permanent Magnet Synchronous Motor Vector Control Based on Weighted Integral Gain of Sliding Mode Variable Structure

Aiming at the slow dynamic response and the chattering problem from conventional exponential reaching law sliding mode applied in permanent magnet synchronous motor vector control in current loop, firstly this paper used weighted integral type sliding mode control algorithm to design the current loop controller. For the second step, the stabil- ity of the system was proved with lyapunov stability theory. Simulation results show that current controller of vector con- trol system based on weighted integral gain sliding mode has strong robustness to parameter perturbation and external dis- turbance compared with traditional sliding mode control, and improves system's dynamic response and control precision.

Chattering-free adaptive fast convergent terminal sliding mode controllers for position tracking of robotic manipulators

The paper documents a new continuous adaptive fast terminal sliding mode control approach for position tracking of robotic manipulators. Combining linear sliding mode and terminal sliding mode, a fast nonsingular terminal sliding mode manifold is presented. Considering the discontinuous property of the sign function, which is often used in traditional sliding mode controller and will result in high-freqsency chattering in the control channel, the proposed controller adopts the continuous saturation function for chattering elimination. Besides the continuous property, convergence to the origin asymptotically and in finite time can be guaranteed in theory with the proposed controller, which is quite different from traditional boundary layer technique, where only bounded motion around the sliding manifold can be ensured. For asymptotic stability, it is only required that the lumped uncertainty is bounded, but the upper bound may be unknown by virtue of the designed adaptive methodology. The obtained results are applied to the problem of position tracking for robotic manipulators. Detailed simulations with some comparisons under various conditions demonstrate the effectiveness of the proposed method.

An adaptive sliding mode control technology for weld seam tracking

A novel adaptive sliding mode control algorithm is derived to deal with seam tracking control problem of welding robotic manipulator, during the process of large-scale structure component welding. The proposed algorithm does not require the precise dynamic model, and is more practical. Its robustness is verified by the Lyapunov stability theory. The analytical results show that the proposed algorithm enables better high-precision tracking performance with chattering-free than traditional sliding mode control algorithm under various disturbances.

Fuzzy Fractional Order Sliding Mode Control for Automatic Clutch of Vehicle AMT

The automatic clutch driving system of vehicle automated manual transmission (AMT) is a typical nonlinear system. A fast and accurate position control is difficult to achieve because of the nonlinearity of the load changes caused by the clutch diaphragm spring, the cushion spring, and other nonlinear components and because of the uncertainty of the load changes caused by the cushion spring deformation in the clutch engagement process at varying temperatures on the friction surface. In this paper, based on the theory of fractional calculus and traditional sliding mode control, the method of fuzzy fractional order sliding mode control (FFOSMC) is proposed for clutch control. By selecting the fractional order sliding surface, the laws of control are designed; and self-tuning of the switch gain is realized with the fuzzy controller. Theoretical analysis and numerical simulation revealed that compared with the traditional fuzzy integer order sliding mode controller, FFOSMC achieves better dynamic performance in position control and better robustness against load disturbance and other uncertain factors.

Minimum sliding mode error feedback control and observer for satellite attitude control and determination

This paper proposes a new controller and observer (minimum sliding model error feedback control/observer, MSMEFC/O) for the attitude control and determination systems (ACDS) of satellite. It is known that the ACDS plays a significant role in the overall performance of a satellite system, especially under the influence of uncertain disturbances from the space. It is clear that any controller and observer with the capacity to deal with uncertain disturbances will improve the performance of ACDS. It is shown that the proposed MSMEFC, based on the new concept of “equivalent control error”, can compensate for various kinds of uncertain disturbances. In addition, the relationship between the equivalent control error and the uncertain disturbances is described. The robustness and steady-state error corresponding to MSMEFC are investigated to show its theoretical advantages over the traditional sliding mode control. Furthermore, the minimum sliding mode error feedback observer is also proposed based on the theory of MSMEFC. Finally, the new MSMEFC/O concept is applied to satellite ACDS, which guarantees global asymptotic convergence of attitude control and determination with high accuracy. Numerical simulations are performed to show the efficacy of the proposed MSMEFC/O in the presence of severe uncertain disturbances.

Adaptive hybrid High-Order terminal sliding mode control of MIMO uncertain nonlinear systems and its application to robot manipulators

This paper proposes an adaptive hybrid high-order terminal sliding mode (HHOTSM) control approach for a class of high-order multiple-input and multiple-output (MIMO) uncertain nonlinear systems and its application to robotic manipulators. The techniques of the terminal sliding mode (TSM) control and a type of traditional sliding mode control (SMC) are combined to establish the HHOTSM controller, in which the first-order sliding mode term is designed based on the TSM, while the high-order sliding mode term is defined based on the idea of the high-order sliding mode approach. Thus, the proposed method offers a valuable elimination of the singularity problem encountered in traditional TSM control, as well as the reaching phase problem. It is guaranteed that the tracking errors will converge to zero in some finite time that can be set arbitrarily, and the actual control input signal is smooth and free of chattering effects. Furthermore, an adaptive tuning law is incorporated to reject the effects of unknown system uncertainties. The convergence and stability of the proposed method are verified by the Lyapunov stability theory. Simulation results of a robot manipulator are presented to demonstrate the effectiveness and applicability of the proposed method.

Continuous sliding mode controller with disturbance observer for hypersonic vehicles

In this paper, a continuous sliding mode controller with disturbance observer is proposed for the tracking control of hypersonic vehicles to suppress the chattering. The finite time disturbance observer is involved to make that the continuous sliding mode controller has the property of disturbance rejection. Due to continuous terms replacing the discontinuous term of traditional sliding mode control, switching modes of velocity and altitude firstly arrive at small regions with respect to disturbance observation errors. Switching modes keep zero and velocity and altitude asymptotically converge to their reference commands after disturbance observation errors disappear. Simulation results have proved the proposed method can guarantee the tracking of velocity and altitude with continuous sliding mode control laws, and also has the fast convergence rate and robustness.

Robust adaptive sliding mode control of a photovoltaic water pumping system using fuzzy wavelet network and PSO algorithm

This paper presents a novel method that combines fuzzy wavelet network with sliding mode control (FWNSM) to track the maximum power point (MPPT) for a photovoltaic pumping system. For the best use, the photovoltaic (PV) generator must operate at its maximum power point (MPP). Traditional sliding mode control (SMC) can be used to achieve the robust tracking. However, in the presence of large uncertainties the SMC produces the chattering phenomenon due to the higher needed switching gain. In order to reduce this gain, fuzzy wavelet network (FWN) is used for the estimation of model unknown parts and hence enable a lower switching gain to be used. This FWN is trained online using the back-propagation (BP) algorithm. A second robust control term is added to compensate the FWN errors. Particle swarm optimisation (PSO) algorithm is used in this study to optimise the learning rate of BP algorithm in order to improve the network performance in term of the speed of convergence. The stability and effectiveness of the proposed method are proved by Lyapunov method and the simulations are given to demonstrate the performance of the proposed approach by the comparison with traditional SMC.

Design Method of Active Disturbance Rejection Variable Structure Control System

Based on lines cluster approaching theory and inspired by the traditional exponent reaching law method, a new control method, lines cluster approaching mode control (LCAMC) method, is designed to improve the parameter simplicity and structure optimization of the control system. The design guidelines and mathematical proofs are also given. To further improve the tracking performance and the inhibition of the white noise, connect the active disturbance rejection control (ADRC) method with the LCAMC method and create the extended state observer based lines cluster approaching mode control (ESO-LCAMC) method. Taking traditional servo control system as example, two control schemes are constructed and two kinds of comparison are carried out. Computer simulation results show that LCAMC method, having better tracking performance than the traditional sliding mode control (SMC) system, makes the servo system track command signal quickly and accurately in spite of the persistent equivalent disturbances and ESO-LCAMC method further reduces the tracking error and filters the white noise added on the system states. Simulation results verify the robust property and comprehensive performance of control schemes.

Switched Reluctance Generator Output Voltage Ripple Reduction Based on Fuzzy Sliding Mode

Aiming at the problem of Switched Reluctance Generator output voltage ripple, this paper designs a fuzzy sliding mode controller based on the analysis of various factors affecting the output voltage ripple. The traditional sliding mode controller has quick convergence, but it has chattering problem. This paper introduces the fuzzy control to select the appropriate sliding mode gain. It can combine with traditional angle control to adjust the output voltage by adjusting the conduction angle. It is more effective in shortening the adjustment time and reducing the overshoot and steady-state of error compared with the classical PID control. Meanwhile, it also solves the chattering problem of traditional sliding mode control. Finally, it makes use of nonlinear model structure to validate that it is effective in restraining voltage ripple and improving the dynamic performance of the system and the voltage quality.

A novel artificial intelligent control system to suppress the vibration of a FGM Plate

In this paper, an adaptive neuro-fuzzy sliding-mode-based genetic algorithm (ANFSGA) control system is proposed to control functionally graded material (FGM) plates. The model of the FGM plate is considered by the finite element method based on the classical laminated plate theory. Moreover, to show the performance of the proposed ANFSGA intelligent control system, a traditional sliding-mode control (SMC) system and an adaptive neuro-fuzzy (ANF) SMC system are designed to suppress the vibrations of the FGM plate as a comparison. The proposed genetic algorithm control system uses the ANF SMC system in the crossover and mutation operation. In this way, the online learning ability can be used by adjusting the control parameters to deal with external disturbance. The control objective is to drive the system state to the original equilibrium point and thus, the asymptotically stability of the proposed control system can be achieved.

Study of Nonsingular Fast Terminal Sliding-Mode Fault-Tolerant Control

This paper studies fault-tolerant control (FTC) designs based on nonsingular terminal sliding-mode control and nonsingular fast terminal sliding-mode control (NFTSMC). The proposed active FTC laws are shown to be able to achieve fault-tolerant objectives and maintain stabilization performance even when some of the actuators fail to operate. In comparison to existing sliding-mode control (SMC) fault-tolerant designs, the proposed schemes not only can retain the advantages of traditional SMC, including fast response, easy implementation, and robustness to disturbances/uncertainties, but also make the system states reach the control objective point in a finite amount of time. Moreover, they also resolve the potential singularity phenomena in traditional terminal and faster terminal SMC designs; meanwhile, the proposed NFTSMC fault-tolerant scheme also possesses the benefit of faster state convergence speed of NFTSMC. Finally, the proposed analytical results are also applied to the attitude control of a spacecraft. Simulation results demonstrate the benefits of the proposed schemes.

An Intelligent Second-Order Sliding-Mode Control for an Electric Power Steering System Using a Wavelet Fuzzy Neural Network

An intelligent second-order sliding-mode control (I2OSMC) using a wavelet fuzzy neural network with an asymmetric membership function (WFNN-AMF) estimator is proposed in this study to control a six-phase permanent magnet synchronous motor (PMSM) for an electric power steering (EPS) system. First, the dynamics of the steer-by-wire (SBW) EPS system and six-phase PMSM drive system with a lumped uncertainty are described in detail. Then, to alleviate the chattering phenomena in a traditional sliding-mode control (SMC), a second-order sliding-mode control (2OSMC) is designed. Moreover, the I2OSMC is developed to improve the required control performance of the EPS system. In the I2OSMC, the WFNN-AMF estimator with accurate approximation capability is employed to estimate the lumped uncertainty. Furthermore, the adaptive learning algorithms for the online training of the WFNN-AMF are derived using the Lyapunov theorem to guarantee the asymptotical stability of the closed-loop system. In addition, a 32-bit floating-point digital signal processor (DSP), i.e., TMS320F28335, is adopted for the implementation of the proposed control approach. Finally, some experimental results are illustrated to demonstrate the validity of the proposed I2OSMC using the WFNN-AMF estimator for the EPS system.

Robust Stabilization of a Class of Uncertain Fractional-order Chaotic Systems via a Novel Sliding Mode Control Scheme

This paper proposes a novel sliding mode control (SMC) scheme to stabilize a class of fractional-order chaotic systems. Through constructing two sliding mode variables, the control problem of n-dimensional system can be transformed to the equivalent stabilizing problem of a reduced-order system. Subsequently, on the basis of second-order sliding mode (SOSM) technique, a robust control law is designed, which strongly attenuates the chattering phenomenon inherent in traditional sliding mode controller, and guarantees the existence of sliding motion in a finite time. The stability of two sliding mode variables to the origin is proved by conventional and fractional Lyapunov theories, respectively. Finally, two numerical examples are provided to illustrate the effectiveness of the proposed approach.

Design of sliding-mode control based on fuzzy disturbance observer for minimization of switching gain and chattering

In this paper, we propose the sliding mode control (SMC) based on the fuzzy disturbance observer for systems with disturbances to minimize the switching gain and reduce chattering phenomenon. The proposed method exhibits the following two attractive features. First, using the universal approximation and the adjustable parameter of the fuzzy system, the switching gain in proposed control law is only required to be designed greater than the sum of magnitude of the disturbance approximation error and the fuzzy reconstruction. It implies that the proposed controller is less dependent on the range of switching gain to stabilize the system than SMC; thus, the minimization of switching gain can reduce the chattering. Second, the proposed method exhibits much better control performance than the traditional SMC and Nonlinear Disturbance Observer (NDOB)-based SMC, such as reduced chattering and good performance. The stability of the proposed control system is proved using Lyapunov method. To verify the effectiveness of the minimization of switching gain and chattering, we show the performance of the proposed method through some simulations of the inverted pendulum.

Suppressing vibration in a functionally graded material plate using genetic algorithm particle swarm optimization and sliding mode control system

In this paper, a particle swarm optimization sliding mode control system is proposed to suppress the vibration of a functionally graded material (FGM) plate. The dynamic response repression of the FGM plate containing distributed piezoelectric sensors and actuators under the effect of a nonlinear control system is presented. The formulation of the problem is based on the classical laminated plate theory and the principle of virtual displacements. The particle swarm optimization is used for the vibration control of the (FGM) plate. In this study, a function of the sliding surface is considered as an objective function and then the control effort is produced by the particle swarm method and sliding mode control strategy. To verify the accuracy and stability of the proposed control system, a traditional sliding mode control system is designed and fabricated to suppressing the vibration in the FGM plate.

ABS Sliding Mode Variable Structure Control Based on Index Reaching Law

ABS(antilock brake system) is one of the most important active safety technology for modern vehicles which could enhance vehicle active safety. In this paper, an improved sliding mode control method based on reaching law has been proposed to solve the vibration problem in traditional sliding mode control. The ABS control strategy has been designed based on the sliding mode variable structure control. On this basis, the ABS single wheel depending on control strategy has been designed to ensure the braking stability. By hardware-in-loop simulation, the results demonstrate that ABS sliding mode variable structure control could enhance braking stability performance and improve the control effect on high friction and low friction road.

Sliding-Mode Control for Piezoelectric Actuators Based on Hysteresis Observer

A sliding-mode control (SMC) scheme based on hysteresis observer is designed in this paper for precision trajectory tracking of piezoelectric actuators. A mathematical model considering the dynamics of a mass-spring-damper trio and the hysteresis friction force describing the parameters of bristle stiffness, damping and viscous is proposed. A lumped uncertain function composed of the mechanical parameters, displacement and its deriviation, hysteresis friction force and external load force is estimated by a hysteresis observer. An asymptotically stable sliding surface is defined. Lyapunov stability theory is applied to guarantee the asymptotical stability for the trajectory tracking error. Experiments are conducted to validate the effectiveness of the proposed method. Results show that a satisfied tracking response to a sinusoidal trajectory is achieved, and the positioning errors under a triangle scanning contour are dramatically reduced compared with the traditional SMC.