Adaptive Sliding Mode Control Method Research Articles

A novel predefined performance barrier function based adaptive sliding mode control method for RLV under mismatched disturbance

PurposeThis paper aims to present a novel adaptive sliding mode control (ASMC) method based on the predefined performance barrier function for reusable launch vehicle under attitude constraints and mismatched disturbances.Design/methodology/approachA novel ASMC based on barrier function is adopted to deal with matched and mismatched disturbances. The upper bounds of the disturbances are not required to be known in advance. Meanwhile, a predefined performance function (PPF) with prescribed convergence time is used to adjust the boundary of the barrier function. The transient performance, including the overshoot, convergence rate and settling time, as well as the steady-state performance of the attitude tracking error are retained in the predetermined region under the barrier function and PPF. The stability of the proposed control method is analyzed via Lyapunov method.FindingsIn contrast to conventional adaptive back-stepping methods, the proposed method is comparatively simple and effective which does not need to disassemble the control system into multiple first-order systems. The proposed barrier function based on PPF can adjust not only the switching gain in an adaptive way but also the convergence time and steady-state error. And the efficiency of the proposed method is illustrated by conducting numerical simulations.Originality/valueA novel barrier function based ASMC method is proposed to fit in the amplitude of the mismatched and matched disturbances. The transient and steady-state performance of attitude tracking error can be selected as prior control parameters.

Fractional order adaptive sliding mode control method of manipulator

A new controller (NAFOFTSMC) is designed and successfully applied to the manipulator system. Compared with traditional integer-order sliding mode control methods (IOSMC), the fractional order sliding mode control method (FOSMC) adopted additional degrees of freedom and, to some extent, weakens the drawback of sliding mode control chattering problem. Fractional-order adaptive rate compensation is utilized to compensate for the total disturbance set of the system. The new sliding surface reduces the derivative signals that are difficult to obtain due to external interference and other factors in the robotic arm system. It also reduces the unknown parameters for adjustment, increases the proportion term, and thus enables the system to have higher control accuracy and shorter adjustment time. While designing the controller, the stability is proved at the end of the fourth section. At the same time, this control method was compared and analyzed with IOSMC, simple FOSMC, and a Pre-improved controller (AFOFTSMC).

Adaptive sliding mode and RBF neural network based fault tolerant attitude control for spacecraft with unknown uncertainties and disturbances

Taking the external disturbance, model uncertainty, actuator failure, and actuator saturation into consideration, this paper investigates the nonlinear fault-tolerant attitude control problem for the spacecraft. First, to deal with the disturbance and uncertainty with unknown boundaries, an adaptive sliding mode control method is proposed to stabilize the state variables of the spacecraft attitude control system. Then the actuator failure and saturation are further considered, and the second spacecraft fault-tolerant attitude controller is derived based on adaptive sliding mode control and radial basis function (RBF) neural networks. The adaptive control gains reduction technique is applied in the design process, which can weaken the chattering phenomenon of the controller to some extent, and the stability of the attitude control system is analyzed through Lyapunov theory. In the proposed controller, model information and external disturbance are not required and only the system states are needed. Furthermore, the boundaries of the model uncertainty, external disturbance, actuator fault and saturation are assumed to be existing but unknown by the proposed controllers. These features make the proposed attitude controllers need few modeling information of the spacecraft, or maintain strong robustness even if the model or external environment occurs significant changes. Finally, numerical simulations demonstrate the great performance of the proposed fault-tolerant attitude control method.

Event‐triggered based finite‐frequency control for vehicle electrohydraulic suspension with force tracking

AbstractThis study investigates the problem of event‐triggered based finite‐frequency control for vehicle electrohydraulic suspensions with force tracking. A novel hierarchical control methodology is proposed by designing event‐triggered finite frequency and active force tracking controllers to improve the suspension performance. In practical application, active suspension system can be constructed as the network control system under consideration of the electrohydraulic actuator's nonlinear dynamics and parametric uncertainties, and in‐vehicle network delay in a unified framework. Then, due to the more sensitiveness of the human body to vertical vibrations in 4–8 Hz and limited in‐vehicle network communication resource, an event‐triggered finite frequency controller is developed based on the generalized KYP lemma and Lyapunov stability theory. The triggered condition is designed for the network control system with in‐vehicle network delay. Other physical constraints including suspension working space, tire dynamic load and actuator saturation are also introduced in this controller design. It can generate the target force to satisfy suspension performance requirements under each triggered instant period. Furthermore, since the nonlinearity and uncertainty always exist in the electrohydraulic actuator, a filter‐based adaptive sliding mode control method is employed to design the active force tracking controller. It can precisely drive electrohydraulic actuator to track the target constant force generated by event‐triggered finite frequency controller. Finally, the results validate the effectiveness and saving communication resource capability of the proposed control methodology.

Nonlinear Robust Adaptive Sliding Mode Control Strategies Involve a Fractional Ordered Approach to Reducing Dengue Vectors

This study presents an innovative approach by integrating adaptive sliding mode control strategies with fractional order modeling to address the challenge of reducing Aedes aegypti mosquito populations, the primary vector of Dengue - a widespread and debilitating disease. By employing the Atangana-Baleanu-Caputo fractional operator to model the dynamics of the mosquito population, we achieve a more precise representation of complex and non-linear behaviors. The motivation behind adopting the Adaptive Sliding Mode Control (ASMC) approach lies in the critical need to efficiently control Aedes aegypti mosquito populations, a key step in combating the prevalence of dengue. The ASMC method dynamically adjusts control parameters based on evolving conditions, enhancing its adaptability to the changing dynamics of mosquito populations.The Lyapunov stability theorem ensures the reliability of tracking convergence and control structure. Additionally, we implement the Toufik Atangana method to solve both state and adjoint fractional differential equations using the ABC derivative operator. This incorporation adds a novel dimension to the study, providing a comprehensive framework for addressing the intricate dynamics inherent in the Aedes aegypti mosquito population. To assess the effectiveness of the proposed strategy, a numerical performance index is introduced at the end of the abstract. This index justifies the controller’s efficacy by comparing it to other conventional controllers. The inclusion of this quantitative measure reinforces the significance of the proposed strategy in the context of dengue prevention and control efforts.

Dynamics analysis, synchronization and FPGA implementation of multiscroll Hopfield neural networks with non-polynomial memristor

The number of attractors in a memristor-based multiscroll Hopfield Neural Network (HNN) is typically coupled with the number of polynomials, which leads to a coupling between the computational complexity and resource utilization in circuit implementation. To decouple this relationship, we propose a non-polynomial memristor that satisfies the Lipschitz condition. Regardless of whether it is used to simulate synaptic behavior, simulate the impact of electromagnetic radiation, or a combination of both scenarios, it can conveniently control the generation of single-direction or multiple-direction multiscroll attractors without adding or reducing any terms. By constructing Lyapunov functions, the sufficient condition for these multiscroll memristor HNNs to be bounded is obtained. After improving the feasibility of linear matrix inequalities, a strongly adaptive observer is proposed. After uniting an adaptive sliding mode control method, we propose a new adaptive synchronization scheme to simulate neural network synchronization. Finally, the digital circuit implementation and functional verification of these memristor-based multiscroll HNNs are completed using a field-programmable gate array (FPGA). Based on this, an image encryption circuit is designed so that the FPGA can directly encrypt images and transmit them to the IO device.

Research on solar sail attitude maneuvering method based on adaptive sliding mode control

A solar sail is a spacecraft propulsion system that uses the pressure of light to push a spacecraft. It consists of a lightweight support structure that deploys a large area of flexible film. During attitude maneuvering in space, the solar sail will excite vibrations in the flexible support structure and film, which can affect the accuracy of the attitude control system. To address this issue, this article first establishes a rigid-flexible coupled dynamic model of the solar sail that includes attitude motion and flexible structure elastic vibrations. Then, based on an adaptive sliding mode control method, a solar sail attitude maneuvering method is proposed. Finally, a numerical simulation is conducted using a hexagonal-shaped solar sail as the object. The numerical simulation results show that the attitude maneuvering method has the performance of attitude tracking and attitude stabilization, can meet the requirements of large-angle attitude maneuvering for solar sail spacecraft, and has strong robustness to model parameter uncertainty.

The controlling the hydraulic electro drive system on the basis of the adaptive sliding mode control method

In this paper, presents the construction of an automatic control system for mobile lifting machines applied in industry and traffic. The control algorithm is built on the basis of calculations from the actual system taking into account the estimation of the nonlinear factors of frictional moment uncertainty, on the basis of the adaptive sliding mode control method. Using programming and simulation tools on the basis of MATLAB/Simulink to demonstrate the research results. The results of the simulation study are the basis for the design and calculation of the hydraulic electro drive system, which shows the practical effectiveness of the study of electromechanical traction electric transmission systems such as mobile lifting machines. The motion uses hydraulic valve systems to transmit power control (lifting and lowering as required).

Cascade Control of Grid-Connected NPC Converters via Sliding Mode Technique

This paper proposes a two-stage control strategy including an adaptive sliding mode control (ASMC) and a nonlinear high-gain observer (HGO) for the three-level neutral-point-clamped (NPC) converter in dc microgrids. In the outer loop, an ASMC is utilized to regulate the dc-link voltage. By introducing an adapted gain, the tradeoff between the chattering and dynamic performance of the classic sliding mode control is overcome, thus the transient response of the NPC converter can be further enhanced without increasing the chattering. In addition, a nonlinear HGO is cooperated with the ASMC method to reject exogenous disturbance for the NPC converter, which not only assures a high disturbance rejection capacity but also accommodates the inevitable measurement noise in the actual applications. For the inner loop, in consideration of the parameter uncertainty, a high-gain observer-based second-order sliding mode (SOSM) control is adopted to assure the steady state performance and the robustness of the NPC converter. Finally, a set of comparative experimental results confirm the effectiveness and superiority of the proposed control scheme implemented in the NPC converter. Additionally, the robustness under parameter variation of the proposed method is also validated.

Sliding Mode Control of Ball Screw Meta-Action Unit Based on Disturbance Compensation and Inertia Identification

To solve the problems of dynamic model parameter perturbation and external disturbances during the operation of the ball screw meta-action unit, an adaptive sliding mode control method based on disturbance compensation and inertia identification is proposed in this paper. First, a model of the ball screw meta-action unit is established and the dynamic equation is derived. Taking into account the uncertainty of the dynamic parameters, a least squares method with a forgetting factor is introduced to identify the moment of inertia in real time, and the identification results are utilized to adaptively adjust the sliding mode control law. Second, a nonlinear disturbance observer is designed to effectively observe the load disturbance, and the observed value is substituted into the sliding mode control as feedforward compensation to improve the anti-interference ability of the controller. Committed to the chattering of traditional sliding mode control, an improved adaptive exponential sliding mode reaching law is exploited to construct a novel sliding mode controller, thereby suppressing the slid mode chattering more thoroughly. Finally, the superiority of the proposed method is verified by MATLAB/Simulink simulation and compared with the other two control methods; the control method proposed in this paper can effectively improve the tracking performance of the system and has good robustness.

Vibration control of a thin rectangular plate subjected to moving masses using an adaptive sliding mode control method

AbstractThis study investigates the vibration control of a plate subjected to moving masses. The plate model reflects the dynamic behavior more accurately than the beam model which is usually used in the existing literature. However, the vibration control of plates subjected to moving masses is also more challenging as more degrees of freedom need to be taken into account. In addition, the measurement of system status and uncertainty problems in practical application is another nodus. In this paper, combining an adaptive sliding‐mode control (ASMC) strategy and a modal coordinate reconstruction (MCR) method, the MCR‐ASMC method is proposed. The MCR method is employed to capture the plate dynamic behavior for feedback to the ASMC. The ASMC strategy realizes vibration control through the adaptive updating of parameters. Numerical results demonstrate the effectiveness of the proposed method and excellent control performance in vibration suppression of moving mass problems.

Sliding Mode Control of Servo Feed System Based on Fuzzy Reaching Law

An adaptive sliding mode control method based on the fuzzy exponential convergence law is proposed to solve the jitter problem caused by the sliding mode control of the servo-feed system and to improve the tracking performance of the system. The design of fuzzy rules for adaptive adjustment of convergence law parameters in sliding mode control improves the convergence speed of the sliding mode function, eliminates unknown disturbances in the system, and weakens the chattering of the system. The proposed method is simulated and experimentally verified by a parallel mobile platform. The results show that the sliding mode control method based on the fuzzy convergence law has strong disturbance suppression capability, high position tracking accuracy, and effective chattering suppression, and the maximum tracking error is reduced by 43.1% and 31.5%, respectively, compared with PID control and exponential sliding mode control.

A composite neural network-based adaptive sliding mode control method for reluctance actuator maglev system

A composite neural network-based adaptive sliding mode control method for reluctance actuator maglev system

Synchronization of uncertain general fractional unified chaotic systems via finite-time adaptive sliding mode control.

This paper employs two adaptive sliding mode control (ASMC) strategies to accomplish finite-time synchronization of uncertain general fractional unified chaotic systems (UGFUCSs) when uncertainty and external disturbance exist. First, general fractional unified chaotic system (GFUCS) is developed. GFUCS may be transitioned from general Lorenz system to general Chen system, and the general kernel function could compress and extend the time domain. Furthermore, two ASMC methods are applied to finite-time synchronization of UGFUCSs, where system states arrive at sliding surfaces in finite-time. The first ASMC approach utilizes three sliding mode controllers to achieve synchronization between chaotic systems, while the second ASMC method needs just one sliding mode controller to produce synchronization between chaotic systems. Finally, the effectiveness of the proposed ASMC approaches is verified using numerical simulations.

Orientation control of the Wave Glider with uncertain environment disturbances and unknown variable hydrodynamics coefficients: Theory and simulation

This research proposes an Adaptive Sliding Mode Control method to solve the yaw angle control problem of the Wave Glider with complex uncertain environment disturbances generated by wave, wind and current. Furthermore, hydrodynamics coefficients variation caused by marine organisms attaching is considered and handled. Moreover, the results of this research can provide a unified solution for the existing control modes, which can help the design of the course planing of a Wave Glider.

Adaptive sliding mode control for unknown uncertain non-linear systems with variable coefficients and disturbances

Sliding Mode Control is one type of robust control, but the classical method often requires prior knowledge of the uncertainties. This study presents a new adaptive sliding mode control method, which can handle the control problem for unknown uncertain non-linear systems without prior knowledge. Furthermore, it can make the state error of different systems converge at the same boundary. Two illustrative examples are presented to highlight the main features of the approach after five systems with complex disturbances are taken as cases to show the applicability of the proposed method.

Taylor‐based adaptive sliding mode control method for robot manipulators

AbstractThis paper develops a novel Taylor‐based adaptive sliding mode control method (ASMC) for robot manipulators. In the first new scheme, sliding mode control (SMC) is effectively enhanced using the Taylor expansion for achieving a less conservative sign‐function gain that enables chattering attenuation. After that, a new Taylor‐based adaptive SMC scheme is proposed without prior knowledge of the upper bound of uncertainty and the Taylor expansion coefficients. Then, a new Taylor‐based boundary layer ASMC scheme is proposed for chattering attenuation. As a fact, no chattering is expected to be observed as long as the sliding surface remains an invariant set. However, the sliding surface will not be an invariant set unless the sign‐function is precisely determined on the sliding surface. It is verified that the sign‐function cannot be precisely determined on the sliding surface due to the presence of uncertainty, hence, the chattering phenomenon. In the new Taylor‐based boundary layer ASMC scheme, the conventional ASMC is modified by removing the sign‐function in the vicinity of the sliding surface and using the Taylor expansion to estimate and compensate for the uncertainty. Compared to a time‐delay ASMC applied to a robot manipulator, the Taylor‐based ASMC scheme exhibits a less conservative sign‐function gain resulting in chattering attenuation.

Optimal adaptive barrier-function super-twisting nonlinear global sliding mode scheme for trajectory tracking of parallel robots

Compared to serial robots, parallel robots have potential superiorities in rigidity, accuracy, and ability to carry heavy loads. On the other hand, the existence of complex dynamics and uncertainties makes the accurate control of parallel robots challenging. This work proposes an optimal adaptive barrier-function-based super-twisting sliding mode control scheme based on genetic algorithms and global nonlinear sliding surface for the trajectory tracking control of parallel robots with highly-complex dynamics in the presence of uncertainties and external disturbances. The globality of the proposed controller guarantees the elimination of the reaching phase and the existence of the sliding mode around the surface right from the initial instance. Moreover, the barrier-function based adaptation law removes the requirement to know the upper bounds of the external disturbances, thus making it more suitable for practical implementations. The performance and efficiency of the controller is assessed using simulation study of a Stewart manipulator and an experimental evaluation on a 5-bar parallel robot. The obtained results were further compared to that of a six-channel PID controller and an adaptive sliding mode control method. The obtained results confirmed the superior tracking performance and robustness of the proposed approach.

A uniform reaching phase strategy in adaptive sliding mode control

In adaptive sliding mode control methods, an updating gain strategy associated with finite-time convergence to the sliding set is essential to deal with matched bounded perturbations with unknown upper-bound. However, the estimation of the finite time of any adaptive design is a complicated task since it depends not only on the upper-bound of unknown perturbation but also on the size of initial conditions. This brief proposes a uniform adaptive reaching phase strategy (ARPS) within a predefined reaching-time. Moreover, as a case of study, the barrier function approach is extended for perturbed MIMO systems with uncertain control matrix. The usage of proposed ARPS in the MIMO case solves simultaneously two issues: giving a uniform reaching phase with a predefined reaching-time and adapting to the perturbation norm while in a predefined vicinity of the sliding set.

Target Tracking of Snake Robot with Double-Sine Serpentine Gait Based on Adaptive Sliding Mode Control

This paper studies the target tracking control strategy of a snake robot and proposes an adaptive sliding mode control method. The strategy ensures the robot follows the target path by controlling the joint angle through feedback, pushing the robot to reach the target position through gait function. In order to achieve target tracking, a kinematic model of a snake robot was first established in this paper. Then, we used double-sine serpentine gait to solve the problem of low steering efficiency caused by regular serpentine gait, and we explored the relationship between control parameters and robot steering. On the basis of gait, in order to further improve the efficiency of target tracking for the snake robot, an adaptive sliding mode control method, based on a new sliding mode reaching law, was proposed. Finally, the effectiveness and practicability of the proposed strategy was demonstrated by comparative analysis and simulation experiments.