Super-twisting Second-order Sliding Mode Control Research Articles

Passive Super-Twisting Second-Order Sliding Mode Control Strategy for Input Stage of MMC-PET

When the operating state of the power system changes, a modular multilevel converter power electronic transformer (MMC-PET) based on modular multilevel converters cannot perform efficient energy transfer and power conversion under conventional control strategies. To address the above problems, this paper proposes a passive, second-order super-helical sliding mode control strategy for MMC-PET by combining passive control and second-order super-helical sliding mode control with a stronger anti-interference capability. First, a Euler–Lagrange model based on positive and negative sequence separation is established according to the mathematical model of the MMC; second, the model of the system is passively analyzed, and a passive controller is designed according to its passivity, and the passive controller is further optimized by using the super-helical second-order sliding mode control, which improves the overall robustness and interference immunity; finally, the effectiveness and superiority of the super-twisting second-order sliding mode passive control strategy is demonstrated by verifying it through the construction of the MMC-PET simulation model and testing it under various non-ideal working conditions.

Trajectory Following Control of an Unmanned Vehicle for Marine Environment Sensing.

An autonomous surface vehicle is indispensable for sensing of marine environments owing to its challenging and dynamic conditions. To accomplish this task, the vehicle has to navigate through a desired trajectory. However, due to the complexity and dynamic nature of a marine environment affected by factors such as ocean currents, waves, and wind, a robust controller is of paramount importance for maintaining the vehicle along the desired trajectory by minimizing the trajectory error. To this end, in this study, we propose a robust discrete-time super-twisting second-order sliding mode controller (DSTA). Besides, this control method effectively suppresses the chattering effect. To start with, the vehicle's model is discretized using an integral approximation with nonlinear terms including environmental disturbances treated as perturbation terms. Then, the perturbation is estimated using a time delay estimator (TDE), which further enhances the robustness of the proposed method and allows us to choose smaller controller gains. Moreover, we employ a genetic algorithm (GA) to tune the controller gains based on a quadratic cost function that considers the tracking error and control energy. The stability of the proposed sliding mode controller (SMC) is rigorously demonstrated using a Lyapunov approach. The controller is implemented using the Simulink® software. Finally, a conventional discrete-time SMC based on the reaching law (DSMR) and a heuristically tuned DSTA controller are used as benchmarks to compare the tracking accuracy and chattering attenuation capability of the proposed GA based DSTA (GA-DSTA). Simulation results are presented both with or without external disturbances. The simulation results demonstrate that the proposed controller drives the vehicle along the desired trajectory successfully and outperforms the other two controllers.

Auto-landing algorithm for quadrotor UAV using super-twisting second-order sliding mode control in the presence of external disturbances

Auto-landing algorithm for quadrotor UAV using super-twisting second-order sliding mode control in the presence of external disturbances

Super-Twisting Sliding Mode Control for the Trajectory Tracking of Underactuated USVs with Disturbances

For an underactuated unmanned surface vehicle (USV), time-varying external disturbances affect the accuracy of trajectory tracking. To ensure trajectory tracking accuracy, in this paper the reduced-order extended state observer (ESO) and the super-twisting second-order sliding mode controller are adopted. The ESO is designed to address the unknown time-varying sideslip angle in the guidance law. Additionally, the super-twisting technology contributes to a reduced chattering effect of the sliding mode. The Lyapunov method is used to analyze the stability of the tracking system and prove that the proposed controllers can ensure the convergence of the tracking errors in finite time. The simulation experiments of the proposed super-twisting sliding mode control (STSMC) and adaptive sliding mode control (ASMC) methods are compared. The results show that the STSMC method enables the USV to complete the task of the reference trajectory tracking. The chattering of the STSMC is also significantly reduced compared to that of the ASMC.

Passivity-based adaptive robust super-twisting nonlinear control for electro-hydraulic system with uncertainties and disturbances

In this paper, a passive-based adaptive robust super-twisting nonlinear controller (PBARSNC) is proposed for high accuracy torque tracking control of the novel electro-hydraulic loading system with disturbances and uncertainties. The construction of the stability of this electro-hydraulic control system is given using passivity theory that results in a passivity-based controller (PBC). Considering parameter uncertainties and constant or slowly varying disturbances, adaptive law is adopted in the passivity-based controller. Furthermore, super-twisting second-order sliding mode control is used to reject modeling uncertainties and matched disturbances. Passivity theory, adaptive method and super-twisting algorithm are synthesized via the recursive design method. The proposed passive-based adaptive robust super-twisting nonlinear control can guarantee the torque tracking performance in the presence of various uncertainties, which is very important for high-accuracy tracking control of hydraulic servo systems. Extensive simulations are carried out to verify the high-accuracy tracking performance of the proposed control strategy.

Distributed time cooperative control of multi-missile systems via second-order sliding mode

Aiming at intercepting hidden aerial targets, a distributed time cooperative system of decoy-attacker heterogeneous missiles is provided. The decoy missiles of the system constrain a hidden target to maneuver. After the target is fully exposed, the decoy missiles will cooperate with the attacker missiles to achieve cooperative interception via sliding mode time cooperative guidance law. Then, a super-twisting second-order sliding mode control eliminates the chattering problem of sliding mode control, and the attacking time convergence of guidance law is verified by the Lyapunov function. Finally, simulation results show that the cooperative system can completely distribute time cooperation in expected conditions and has a good performance in cooperative attacks with an effective interception.

Tracking and synchronization control strategy of vehicle dual-motor steer-by-wire system via super-twisting SOSMC and MDCS

This paper proposes a novel vehicle dual-motor steer-by-wire (SBW) system to improve the reliability and safety of traditional SBW system. However, the dual-motor SBW system is a strongly coupled, nonlinear and multivariable system, whose biggest challenge is the tracking and synchronization control. In order to improve the tracking and synchronization control performance of dual-motor SBW system, a tracking and synchronization control strategy of vehicle dual-motor SBW system via super-twisting second-order sliding mode control (SOSMC) and mean deviation coupling structure (MDCS) is proposed. Firstly, the steering motor model, rack and pinion model and vehicle dynamics model are established. Then, the angle tracking controller based on super-twisting SOSMC is designed to ensure the robustness and tracking performance of each motor. Next, the MDCS and the angle synchronization controller based on super-twisting SOSMC are proposed to compensate the synchronization error between dual-motor caused by mismatched driving force, external interference and parameter uncertainty. Finally, the simulation analysis is carried out by using Carsim/Simulink and the hardware-in-the-loop experiment is implemented based on the dual-motor experimental platform. The simulation and experimental results verify the effectiveness of the proposed control strategy.

Photovoltaic Energy Conversion Systems with Sliding Mode Control

A new sliding-mode-control-based power conversion scheme is proposed for photovoltaic energy conversion systems. The perturbation and observation (P&O) maximum power-point tracking (MPPT) approach is adopted for optimizing the power generation capabilities from solar panels. Due to the inherent nonlinear dynamics of power converters, we need to adopt a nonlinear control approach to optimize the energy conversion efficiency and tolerate the fluctuations and changes of load and sunlight irradiance. In this manuscript, novel first-and higher-order sliding mode control approaches are proposed, aiming to provide a systematic approach for the robust and optimal control of solar energy conversion, which guarantees Lyapunov stability and consistent performance in the face of external perturbations and disturbances. Moreover, to eliminate the chattering phenomenon inherent in the first-order approach, super-twisting second-order sliding mode control is developed for the buck-boost converter. Furthermore, the output of DC–DC converter supplies a voltage-oriented-control (VOC)-based space-vector pulse-width-modulated inverter to generate three-phase AC power to the grid. To demonstrate the robustness and effectiveness of the proposed scheme, computer simulations and dSPACE hardware-in-the-loop platform have been carried on for examining the proposed sliding-mode-control-based solar energy conversion system.

Research on Control Method of PEMFC Cathode Oxygen Excess Ratio

Proton exchange membrane fuel cell (PEMFC) is considered to be a promising new energy technology due to its high power density and low operating temperature. Oxygen excess ratio (OER) is one of the main factors that affect the performance of fuel cell systems. The key of OER control is to prevent the "oxygen starvation" phenomena by controlling the air flow input of the cathode. The net output power is optimized to improve the performance of the system while maintaining the system working properly. First of all, a sixth-order dynamic model of PEMFC based on the air supply system is established in MATLAB, and the function equation of the oxygen excess ratio to the load current is obtained. Based on PID control, fuzzy control and super-twisting second-order sliding mode control, an improved fuzzy-sliding mode control strategy is proposed to realize OER control. Simulation results show that this method has good robustness and fast adjustment performance.

Path Following Control of Autonomous Four-Wheel-Independent-Drive Electric Vehicles via Second-Order Sliding Mode and Nonlinear Disturbance Observer Techniques

In this article, we aim to investigate the path following control problem for four-wheel-independent-drive electric vehicles with consideration of modeling errors and complex driving scenarios. In order to guarantee operational safety and robustness, a supertwisting second-order sliding mode (SOSM) control strategy is employed to suppress the heavy chattering issue existing in the traditional sliding mode control (SMC). To degrade the lumped disturbance, a nonlinear disturbance observer (NDOB) technique is proposed to estimate the disturbance and compensate the modeling error. Then, a composite control strategy, which combines the SMC algorithm and NDOB technique is proposed based on stability analysis of the corresponding closed-loop system. Finally, hardware-in-the-loop experimental results show that the supertwisting SOSM control algorithm with the NDOB technique can achieve better tracking performance and suppress the chattering phenomenon.

Decoupled inputs sliding mode controllers for a fuel cell-supercapacitor module in hybrid generation applications

The development of Multiple Input/Multiple Output (MIMO) sliding mode control setups for a fuel cell/supercapacitor module is presented in this paper. The main objective of the proposed controllers consists in simultaneously satisfying the demand and regulating the DC bus voltage, even in the presence of model uncertainties and strongly varying operating conditions. Two design approaches are utilized to synthetise different control setups, each one capable to robustly deal with such control challenges: on one hand, variable-gains first-order sliding mode and, on the other, supert-wisting second-order sliding mode control. The stability of the nonlinear controlled system is formally analysed. Extensive simulations are conducted, to comparatively assess the performance of the proposed MIMO sliding mode controllers. Both control setups exhibited highly satisfactory results, demonstrating robustness to external disturbances and parameter variations, proving to be more suitable than classic linear PID controllers.

Second‐order sliding mode control for power optimisation of DFIG‐based variable speed wind turbine

Power optimisation is quite important for the doubly-fed induction generator (DFIG)-based variable speed wind turbine (VSWT) in the modern renewable power generation system. However, the VSWTs are generally non-linear and uncertain systems. This study proposes a super-twisting second-order sliding mode (SOSM) control scheme to maximise the wind energy capture of a DFIG-based VSWT system, and regulate the stator reactive power to follow the grid requirements. By regulating the generator rotor voltage, the designed SOSM controller makes the wind turbine rotor speed track the optimal speed to maximise the power generation, and controls the rotor current to follow the external reference to regulate the stator reactive power. A quadratic form Lyapunov function is adopted to determine the range of controller parameters and guarantee the finite time stability. Simulation results on a 1.5 MW DFIG-based VSWT demonstrate the effectiveness of the proposed control strategy.

Decentralized multi-machine power system excitation control using continuous higher-order sliding mode technique

A new decentralized continuous higher-order sliding mode (HOSM) excitation control scheme is proposed to enhance transient stability and robustness of multi-machine power system. Power angle deviations are chosen as sliding variables. The HOSM control for uncertain nonlinear multi-machine power system is equivalently transformed into finite time stability problem of uncertain integrator chains. The alleged continuous HOSM excitation controller is composed of geometric homogeneous continuous control and super-twisting second-order sliding mode control law to achieve finite time convergence and overcome power system uncertainties. An adaptive gain, constructed for the super-twisting control item, enables reducing the switching control amplitude of excitation voltage to the minimum possible value along with a finite time convergence. The first-order and second-order time derivatives of power angles are estimated by the exact robust differentiators. Finite time stability of closed-loop power system is strictly proved. Simulation results for a three-machine system and 10-machine 39-bus New England power system demonstrate the effectiveness of the proposed decentralized continuous HOSM excitation control approach.

Higher-order sliding mode control for trajectory tracking of air cushion vehicle

Abstract The air cushion vehicle (ACV) is an amphibian complex system with strong nonlinearity, internal unmodeled dynamics, and external disturbances. This article presents a new multivariable higher-order sliding mode (HOSM) control scheme on trajectory tracking of ACV. With two longitudinal thrusters, the ACV is modeled as an uncertain nonlinear system with less degree of freedom to be actuated. The control approach includes nominal continuous control law and super-twisting second-order sliding mode control part. The former is employed to stabilize nominal systems at origin in finite time and improve transient process. The latter is used to alleviate chattering of controlling force in surge and controlling torque in yaw, and overcome system uncertainties. A Lyapunov approach is used to testify finite time stability. The simulations for straight line and circular trajectories are presented to evaluate the applicability, robustness and superiority of the proposed approach.

Novel quasi-continuous super-twisting high-order sliding mode controllers for output feedback tracking control of robot manipulators

In this paper, a robust output feedback tracking control scheme for uncertain robot manipulators with only position measurements is investigated. First, a quasi-continuous second-order sliding mode (QC2S)-based exact differentiator and super-twisting second-order sliding mode (STW2S) controllers are designed to guarantee finite time convergence. Although the QC2S produces continuous control and less chattering than that of a conventional sliding mode controller and other high-order sliding mode controllers, a large amount of chattering exists when the sliding manifold is defined by the equation [Formula: see text]. To decrease the chattering, an uncertainty observer is used to compensate for the uncertainty effects, and this controller may possess a smaller switching gain. Compared to the QC2S controller, the STW2S has less chattering and tracking error when the system remains on the sliding manifold [Formula: see text]. Therefore, to further eliminate the chattering and obtain a faster transient response and higher tracking precision, we develop a quasi-continuous super-twisting second-order sliding mode controller, which integrates both the merits of QC2S and STW2S controllers. The stability and convergence of the proposed scheme are theoretically demonstrated. Finally, computer simulation results for a PUMA560 robot comparing with conventional QC2S and STW2S controllers are shown to verify the effectiveness of the proposed algorithm.

Super-twisting second-order sliding mode control for a synchronous reluctance motor

This article presents the design and implementation of a super-twisting second-order sliding-mode controller (SOSMC) for a synchronous reluctance motor. Second-order sliding-mode control is an effective tool for the control of uncertain nonlinear systems since it overcomes the main drawbacks of the classical sliding-mode control, i.e., the large control effort and the chattering phenomenon. Its real implementation implies simple control laws, and ensures an improvement in the sliding accuracy with respect to conventional sliding-mode control. This article proposes a novel scheme that is based on the technique of super-twisting second-order sliding-mode control. First, SOSMC is derived mathematically, and then the performance of the proposed method is verified by simulations. The proposed SOSMC shows robustness for variations in the motor parameters and an improvement in the chattering phenomenon.

History-dependent modified sliding mode interception strategies with maximal capture zone

In order to construct the guidance strategy in a realistic nonlinear noise-corrupted interception endgame against a maneuverable target, a linearized zero-sum differential game is considered. Assuming perfect information in this game, sufficient conditions are established, which guarantee that a continuous interception strategy with memory (history-dependent) has the maximal capture zone. Two examples of such a strategy are analyzed: a modified super-twisting second-order sliding mode control and a modified integral sliding mode control. Simulation results of the original nonlinear interception endgame demonstrate that these strategies considerably reduce the chattering created by the classical game optimal bang-bang strategy without deteriorating the homing performance.