Improved Sliding Mode Research Articles

Improved Sliding Mode Control of a Wind Turbine System Based on a Developed Permanent Magnet Synchronous Generator

Improved Sliding Mode Control of a Wind Turbine System Based on a Developed Permanent Magnet Synchronous Generator

Improved Sliding Mode Control for Tracking Global Maximum Power of Triple Series Parallel Ladder Photovoltaic Array under Uneven Shadowing

Abstract This paper presents an innovative way for enhancing the performance of photovoltaic arrays under uneven shadowing conditions. The study focuses on a triple series parallel ladder configuration to exploit the benefits of increased power generation while addressing the challenges associated with uneven shadowing. The proposed methodology focuses on the implementation of improved sliding mode Control technique for the global maximum power point tracking efficiently. Sliding mode control is known for its robustness in the presence of uncertainties and disturbances, making it suitable for dynamic and complex systems such as photovoltaic arrays. This work employs a comprehensive simulation framework to comment the performance of the suggested improved sliding mode control strategy at uneven shadowing scenarios. Comparative analysis has been done to show the effectiveness of the suggested method than the traditional control strategies. The results demonstrate a remarkable enhancement in the tracking accuracy of the global maximum power point, leading to enhanced energy harvesting capabilities under challenging environmental conditions. Furthermore, the proposed approach exhibits robustness and adaptability in mitigating the effect of shading on the photovoltaic array, thereby increasing overall system efficiency. This research contributes valuable insights into the development of advanced control strategies for photovoltaic arrays, particularly in the context of triple series parallel ladder configurations operating under uneven shadowing conditions. Under short narrow shading condition, the improved sliding mode control method tracking the maximum power more compared to perturb & observe is 20.68%, incremental conductance is 68.78%, fuzzy incremental conductance is 19.8%, and constant velocity sliding mode control is 1.25%. The improved sliding mode control method has 60% less chattering than constant velocity sliding mode control under shading conditions.

Application of Improved Sliding Mode and Artificial Neural Networks in Robot Control

Mobile robots are autonomous devices capable of self-motion, and are utilized in applications ranging from surveillance and logistics to healthcare services and planetary exploration. Precise trajectory tracking is a crucial component in robotic applications. This study introduces the use of improved sliding surfaces and artificial neural networks in controlling mobile robots. An enhanced sliding surface, combined with exponential and hyperbolic tangent approach laws, is employed to mitigate chattering phenomena in sliding mode control. Nonlinear components of the sliding control law are estimated using artificial neural networks. The weights of the neural networks are updated online using a gradient descent algorithm. The stability of the system is demonstrated using Lyapunov theory. Simulation results in MATLAB/Simulink R2024a validate the effectiveness of the proposed method, with rise times of 0.071 s, an overshoot of 0.004%, and steady-state errors approaching zero meters. Settling times were 0.0978 s for the x-axis and 0.0902 s for the y-axis, and chattering exhibited low amplitude and frequency.

Trajectory Tracking Control of Mobile Manipulator Based on Improved Sliding Mode Control Algorithm

Research on trajectory tracking control for climbing welding robots holds significant importance in the field of automated welding. However, existing trajectory tracking methods suffer from issues such as jitter and slow speed. In this paper, an improved sliding mode control strategy is proposed based on the self-designed wall-climbing welding mobile manipulator. Firstly, a new adaptive sliding mode control strategy is proposed for the mobile platform based on the kinematic model. By introducing a new approach law, the controller is designed when the distance between the center of mass is unknown. Secondly, regarding the manipulator, we analyze simplified dynamic equations, extract uncertain components, and utilize a CNN for compensation. This compensation strategy is integrated into the sliding mode control law, achieving precise control over the manipulator and effectively resolving issues like slow tracking speeds, large errors, and chattering. The stability of the robot control system is proved by the Lyapunov function. Through simulation analysis and experimental validation, the proposed control method is confirmed to be feasible and superior.

Improved Sliding Mode Variable Structure Control of Robot Manipulators with Flexible Joints based on Singular Perturbation

This paper discusses the kinematics analysis method of six link mechanism based on virtual prototype technology and Adams. Firstly, the kinematics mathematical model of the six-bar linkage is deduced. Then, based on the design and development process of virtual prototype technology, the virtual prototype model of the six-bar press is established in ADAMS software. Finally, the kinematics simulation analysis is carried out for the model. The proposed method provides a reference for the parametric and optimal design analysis of the multi bar linkage of the mechanical press.

Improved sliding mode tracking control for spacecraft electromagnetic separation supporting on-orbit assembly

This paper addresses the electromagnetic separation problem for mass-unknown spacecraft in elliptical orbits that play a significant role in on-orbit assembly and other future space missions. First, the relative motion dynamics model between the platform (target spacecraft) and module (chaser spacecraft) is presented with the lumped disturbance resulting from external disturbances, elliptical eccentricity and unknown mass, and a compliant reference trajectory is designed by applying the idea of trigonometric-function. Then, an improved sliding mode controller is developed to ensure that the tracking errors of relative motion can converge to near the equilibrium point. In order to avoid adverse impacts, the elliptical eccentricity and unknown mass are fully considered by using the developed control approach, and the global asymptotic stability of the closed-loop system is analyzed by strict theoretical proof. Combined with spacecraft electromagnetic docking technology, the electromagnetic separation scheme can make on-orbit assembly easy to achieve with certain advantages, e.g., it doesn’t consume propellant and thus doesn’t cause plume contamination, and has reversible, continuous and non-contact characteristics. Finally, numerical simulations are performed to illustrate the effectiveness and feasibility of the developed control approach.

Position Sensorless Control of SRMs Based on Improved Sliding Mode Speed Controller and Position Observer

Position Sensorless Control of SRMs Based on Improved Sliding Mode Speed Controller and Position Observer

Sensorless FCS-MPCC PMSM Drives with Improved Sliding Mode Observer and Low-Complexity Discrete Vector Selection – An Assessment

Sensorless FCS-MPCC PMSM Drives with Improved Sliding Mode Observer and Low-Complexity Discrete Vector Selection – An Assessment

Improved Sliding Mode Control for a Robotic Manipulator With Input Deadzone and Deferred Constraint

Improved Sliding Mode Control for a Robotic Manipulator With Input Deadzone and Deferred Constraint

Time-Varying Disturbance Observer Based Improved Sliding Mode Single-Loop Control of PMSM Drives With a Hybrid Reaching Law

Time-Varying Disturbance Observer Based Improved Sliding Mode Single-Loop Control of PMSM Drives With a Hybrid Reaching Law

Research on a Permanent Magnet Synchronous Motor Sensorless Anti-Disturbance Control Strategy Based on an Improved Sliding Mode Observer

This paper designs an improved sliding mode observer (ISMO) compound control scheme combined with a disturbance observer to solve the chattering and anti-disturbance problems of the traditional sliding mode observer (SMO) for permanent magnet synchronous motor (PMSM) in a sensorless control system. First, the sign function is replaced by an exponential type input function, and the fuzzy control rules are developed to automatically regulate the boundary layer control coefficient of the exponential input function, thereby changing the convergence characteristics of the exponential input function and improving the system observation accuracy. Then, the integral sliding mode surface and the quadratic radical term function of the square of the state variable are introduced to reduce system chattering. The proposed ISMO is proved using Lyapunov’s law to guarantee the whole system is stable. Based on the exponential input function and the integral sliding surface, an improved sliding mode disturbance observer (ISMDO) is constructed as a feed-forward compensator, which can optimize the dynamic performance of the improved observation system and ensure the strong robustness of the system by compensating the q-axis current. Finally, MATLAB/Simulink simulation and experimental platform verification have been carried out, which confirms the feasibility of the proposed composite control scheme.

Sensorless Control Method for SPMSMs Based on Improved Sliding Mode Reaching Rate

Due to the advantages of simple structure, small size, and high power density, permanent magnet synchronous motors (PMSM) have attracted the research interest of many scholars both domestically and abroad. However, traditional PMSM equipped with sensors, encoders, and other devices tend to have high equipment costs and rely heavily on the accuracy of the sensors for control effectiveness. Therefore, sensorless control has become a hot trend in the PMSM control field. In response to the chattering problem in sliding mode algorithms, this study first optimized the sliding mode reaching rate of a sensorless control system and applied it to construct a sliding mode observer and speed controller. Next, the improved sliding mode reaching rate-based sensorless control system was modeled and simulated in Matlab/Simulink, and its control performance was compared and analyzed with that of the traditional sliding mode reaching rate and replicated sliding mode reaching rate. Finally, comparative experiments were conducted on a test bench, and the results showed that, under the action of the improved sliding mode reaching rate, the chattering range of the output speed of the motor was +2%~+5%, which optimized the output speed of the PMSM and achieved the purpose of weakening the chattering.

Control Strategy Based on Improved Sliding Mode Control for T-type 3L PV Grid-connected Inverter

This paper analyzes the mathematical model and working principle of a T-type 3 L PV inverter and introduces the control structure of a grid-connected PV inverter. In view of the influence of the sliding mode controller (SMC) rooted on the traditional reaching law (RL) on the control performance for grid-connected PV inverters as the current inner loop, such as large THD, this paper proposes a novel RL in the inner loop SMC to improve the tracking effect and robustness of the controller. The design method of each link of the SMC based on the proposed novel RL is described in the paper. Then, the stability analysis of the improved SMC is carried out. The experiment has been carried out on the experimental operating platform of the T-type 3 L PV grid-connected inverter system. The experimental results allow expressing that the designed control strategy can modify the dynamic performance of the system, reduce the harmonic distortion rate of the incoming current, and maintain the system with strong anti-interference capability under the premise of making the PV power generation system operate stably.

Trajectory Tracking Control of Autonomous Vehicles Based on an Improved Sliding Mode Control Scheme

This paper addresses the issue of external unknown environmental interference affecting the trajectory tracking performance and driving stability of autonomous vehicles. This seriously impacts the performance and stability of the vehicle while driving. In order to provide precise, reliable, and safe trajectory tracking performance for autonomous vehicles, this paper proposes a recursive integral terminal sliding mode control (RITSMC) method. The proposed RITSMC combines the advantages of recursive integral sliding mode (RISM), terminal sliding mode (TSM), and adaptive algorithms, and can effectively achieve precise trajectory tracking and driving stability of autonomous vehicles. Furthermore, compared with traditional methods, an adaptive algorithm is introduced on the recursive sliding surface to enable real-time adaptation of the control parameters of the recursive controller, further improving the trajectory tracking accuracy and driving stability of autonomous vehicles. The stability of this control system is demonstrated by using a Lyapunov function. Finally, multiple simulation tests were conducted on different lane speeds on both wet and dry asphalt road sections. By comparing the simulation results, it was found that the proposed RITSMC exhibits excellent performance in terms of the precision of tracking trajectories and the stability of driving, in contrast to traditional sliding mode controllers (SMC) and integral terminal sliding mode controllers (ITSMC).

A Fast Sliding Mode Speed Controller for PMSM Based on New Compound Reaching Law With Improved Sliding Mode Observer

To reduce the convergence time and improve the anti-disturbance capability of the permanent magnet synchronous motor (PMSM) drivers, a fast sliding mode speed controller based on a new compound reaching law (NCRL) and disturbance observer compensation technique is proposed. Firstly, to solve the conflict between fast convergence rate and chattering reduction in the existing solutions, the NCRL is proposed by introducing the exponential function and the power term piecewise function. The convergence of NCRL is proved and the reaching time is certified to be independent of the system’s initial state. The proposed NCRL can effectively reduce the reaching time, and smooth the output signal while maintaining the high tracking performance of the controller under different conditions. However, external load disturbances may degrade the performance of the proposed NCRL-based speed controller. The proposed controller is then combined with an improved sliding mode observer (ISMO), named the NCRL+ISMO method, to improve the estimation accuracy of the lumped disturbance and the robustness of the system. The stability of the proposed method is analyzed by the Lyapunov function. Experimental results show that the proposed method can reduce speed fluctuation and convergence time, and enhance anti-disturbance capability.

Vector Control of PMSM Based on Improved Sliding Mode Observer and Controller

This paper presents a sensorless speed control method of permanent magnet synchronous motor (PMSM) applying sliding-mode control theory, to enhance the observation precision and improve robustness of control system. Firstly, an improved full-order sliding mode observer (FSMO) with sigmoid function is gifted to weaken the high-frequency (HF) chattering caused by conventional sliding mode observer (SMO). The quadrature phase-locked loop (PLL) is used to calculate high-precision rotor location and speed, avoiding the use of filter. Then the nonsingular fast terminal sliding mode controller (NFTSMC) in speed controller is introduced to replace traditional proportional integral (PI) controller to improve the dynamic performance of control system. The outcomes verify that the presented control method enhances the overall observation precision, suppresses HF chattering, and increases dynamic and stable state response of PMSM.

An Improved Sliding Mode Controller for MPP Tracking of Photovoltaics

Maximum power point tracking (MPPT) through an effective control strategy increases the efficiency of solar panels under rapidly changing atmospheric conditions. Due to the nonlinearity of the I–V characteristics of the PV module, the Sliding Mode Controller (SMC) is considered one of the commonly used control approaches for MPPT in the literature. This paper proposed a Backstepping SMC (BSMC) method that ensures system stability using Lyapunov criteria. A fuzzy inference system replaces the saturation function, and a modified SMC is used for MPPT to ensure smooth behavior. The proposed Fuzzy BSMC (FBSMC) parameters are optimized using a Particle Swarm Optimization (PSO) approach. The proposed controller is tested through various case studies on account of MPP’s dependence on temperature and solar radiation. The controller performance is assessed in partial shading conditions as well. The simulation results show that less settling time, a small error, and enhanced power extraction capability are achieved by applying the PSO-based FBSMC approach compared to the conventional BSMC- and ABC-based PI control presented in previous research in different scenarios. Moreover, the proposed approach provides faster adaptation to temperature and solar radiation variation, ensuring faster convergence to the MPP. Finally, the robustness of the proposed controller is validated by providing variation within the system components. The result of the proposed controller clearly indicates the lowest value of RMSE measured between PV voltage and the reference voltage, as well as the RMSE between PV power and maximum power. The results also show that the proposed MPPT controller exhibits the highest dynamic efficiency and mean power.

Anti-disturbance Position Sensorless Control of PMSM Based on Improved Sliding Mode Observer with Suppressed Chattering and No Phase Delay

Anti-disturbance Position Sensorless Control of PMSM Based on Improved Sliding Mode Observer with Suppressed Chattering and No Phase Delay

Improved Sliding Mode Traction Control Combined Sliding Mode Disturbance Observer Strategy for High-Speed Maglev Train

To improve the robustness and dynamic tracking performance of the stator current control for the long stator linear synchronous motor (LSLSM) used in high-speed maglev train traction system, a composite current control strategy combining a sliding mode current controller (SMCC) and a sliding mode disturbance observer (SMDO) is proposed in this article. First, the LSLSM mathematical model in double feed mode is optimized. Then, an SMCC is designed based on the model. An improved stability criterion is proposed and the SMCC switching gain is obtained quantitatively to meet the current following speed required for the stator changeover process. As disturbance factors, parameter perturbation of the LSLSM and the stator changeover will bring about transient current fluctuations and chattering. Therefore, an SMDO is designed to estimate the disturbances and perform feed-forward compensation for the SMCC, thereby improving the robustness and suppressing the current chattering. Finally, the hardware-in-the-loop experiments verify the effectiveness of this strategy and compare it with the traditional current control strategy.

An Improved Sliding Mode Control Method to Increase the Speed Stability of Permanent Magnet Synchronous Motors

A permanent magnet synchronous motor (PMSM) plays an important role in the operation performance of an electric vehicle. In order to increase the speed stability of PMSMs, an improved sliding mode control (SMC) method is proposed in this paper. Firstly, the control process of a PMSM is divided into parts, which are the torque closed-loop control and speed closed-loop control. Secondly, an integrated control method with proportional integral (PI) and inverter switching frequency is adopted in order to increase the torque performance of the PMSM. Lastly, compared with the traditional SMC method, an improved SMC method with saturation function is proposed in order to decrease the speed fluctuation of the PMSM from 7.7% to 5.9%, thereby increasing the speed stability of the PMSM. The results of the experimental test indicate that both the speed stability and starting performance of the PMSM are increased by the improved SMC method.