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To solve the problem of asynchronous speed between the coaxial in-wheel motors of distributed drive electric vehicle caused by changes in the road surface, load, and other factors during the regenerative braking of the vehicle, which may result in a yaw motion of the vehicle and a reduction in vehicle stability, a synchronization control strategy of regenerative braking for distributed drive electric vehicles is proposed. Firstly, a ring-coupled synchronous control strategy with the current compensation module is designed. Then, the speed controller of a permanent magnet synchronous in-wheel motor and a compensation controller of synchronous control are designed based on the non-singular fast terminal sliding mode control. Combining this with the regenerative braking control strategy, a regenerative braking synchronization control strategy is designed. The simulation results show that compared with the existing synchronization control strategy, the designed new ring-coupled synchronization control strategy can improve the speed synchronization performance between the motors after the disturbance. Moreover, compared with the conventional regenerative braking control strategy, the regenerative braking synchronization control strategy can reduce the speed synchronization error between the motors during the regenerative braking process, so as to improve the synchronization and output stability of the motors during the braking process.

This study studies the problem of synchronisation control for spacecraft formation via extended state observer approach over directed communication topology. The attitude kinematics and dynamics of spacecraft are described by Lagrangian formulations, and the decentralised controller is designed with time-varying external disturbances and unmeasurable velocity information. In particular, the estimation of disturbances obtained via extended state observer is used for the decentralised controller design. A novel Lyapunov function is proposed to show that both static regulation and dynamic synchronisation are realised. Finally, simulation results are given to demonstrate the effectiveness of the controllers proposed in this study.

This study presents a fault-tolerant output synchronisation control approach for a class of non-linear multi-vehicle systems. Firstly, adaptive fault diagnosis observers are designed for vehicle systems by utilising local measurements. Adaptive thresholds for distributed fault-detection of each vehicle system are derived. Then an adaptive fault estimation algorithm is proposed. Using the online obtained fault information, an adaptive fault-tolerant control protocol is designed to ensure the output synchronisation of the networked vehicle systems. It is proved that the proposed active fault-tolerant control protocol is capable of maintaining the output synchronisation performance of the multi-vehicle systems, at an acceptable level, in the presence of faults. Finally, simulation results are presented to show the effectiveness of the proposed algorithms.

This study presents a solution to the problem of cooperative path following of multiple underactuated marine surface vehicles subject to dynamical uncertainties and ocean disturbances. The dedicated control designs are categorised into two envelopes. One is to steer individual underactuated marine surface vehicle to track a given spatial path; and the other is to synchronise the along-path speeds and path variables under the constraints of an underlying communication network in order to hold a desired formation pattern. Within these two formulations, a robust adaptive path-following controller is first designed for individual vehicle based on neural networks and a dynamic surface control (DSC) technique. Then, the along-path speeds and path variables are synchronised to each vehicle owing to the proposed decentralised synchronisation control law building on graph theory and Lyapunov theory. The key features of the developed controllers are that, first, the DSC technique simplifies the controller design by introducing first-order filters and avoids the calculation of derivatives of virtual control signals. Second, the developed controllers with filtering adaptive laws allow for fast learning without generating high-frequency oscillations in control signals. Rigorous theoretical analysis demonstrates that all signals in the closed-loop system are uniformly ultimately bounded. Simulation results are provided to show the efficacy of the proposed method.

With the widespread integration of renewable energy into distribution networks, energy storage systems are playing an increasingly critical role in maintaining grid stability and sustainability. Hydrogen, as a key zero-carbon energy carrier, offers unique advantages in the transition to low-carbon energy systems. To facilitate the coordination between hydrogen and renewables, this paper proposes a flexible on-grid and off-grid control method for an electric–hydrogen hybrid AC-DC microgrid which integrates photovoltaic panels, battery energy storage, electrolysers, a hydrogen storage tank, and fuel cells. The flexible control method proposed here employs a hierarchical structure. The upper level adopts a power management strategy (PMS) that allocates power to each component based on the states of energy storage. The lower level utilises the master–slave control where master and slave converters are regulated by virtual synchronous generator (VSG) and active and reactive power (PQ) control, respectively. In addition, a pre-synchronisation control strategy which does not rely on traditional phase-locked loops is introduced to enable a smooth transition from the off-grid to on-grid mode. The electric–hydrogen microgrid along with the proposed control method is modelled and tested under various operating modes and scenarios. The simulation results demonstrate that the proposed control method achieves an effective power dispatch within microgrid and maintains microgrid stability in on- and off-grid modes as well as in the transition between the two modes.

This study presents a fully distributed control paradigm for secondary control of islanded AC microgrid (MG). The proposed method addresses both voltage and frequency restoration for inverter‐based distributed generators (DGs). The MG system has droop controlled DG units with predominantly inductive transmission lines and different communication topologies. The restoration scheme is fully distributed in nature, and the DGs need to communicate with their neighbours using a sparse communication network. The proposed control scheme is efficient to provide quick restoration of the voltage and frequency whilst accurate power‐sharing is achieved despite disturbances. Further, convergence and stability analysis of the proposed control scheme is presented. The proposed algorithm avoids the need for a central controller and complex communication structure thereby reducing the computational burden and the risk of single‐point‐failure. The performance of the proposed control scheme has been verified considering variations in load and communication topologies and link delay by pursuing an extensive simulation study in MATLAB/SimPowerSystem toolbox. The proposed control scheme supports plug‐and‐play demand and scalability of MG network. The proposed control scheme is also compared with the neighbourhood tracking error based distributed control scheme and observed that the former exhibit faster convergence and accurate performance despite disturbances in MG network.

This study is concerned with the non-fragile mixed ℋ∞/l2 − l∞ synchronisation control problem for discrete-time complex networks with Markov jumping-switching topology under unreliable communication links. The network topology under consideration is assumed to be governed by a Markov chain with time-varying transition probabilities (TPs). The variation of TPs is subject to a kind of slow switching signals; that is, the average dwell time (ADT) switching. The focus is on the design of non-fragile mixed mode-dependent/-independent controllers such that the underlying network reaches stochastic mean-square synchronisation with a mixed ℋ∞/l2 − l∞ performance level for an admissible switching signal with ADT. By using a new mixed ℋ∞/l2 − l∞ performance index, combined with the switched control method, the solutions to the considered problem are formulated. Finally, simulation results demonstrate the effectiveness of our proposed approach.

To address the issues of easy overturning and poor safety of crawler work machines operating on steep slopes in hilly and mountainous areas, this study develops a structural design scheme based on a “three-layer frame” structure. An omnidirectional leveling system with hydraulic interconnection is designed to maintain platform stability by ensuring a stationary central point during leveling. Furthermore, a sliding mode synchronization control method based on a disturbance observer is proposed to reduce the synchronization error of the hydraulic cylinders and enhance leveling precision. The system’s performance is validated through an AMESim-MATLAB/Simulink co-simulation platform, demonstrating significant improvements over traditional PID control. Specifically, both lateral and longitudinal leveling times are reduced, rise time decreases by 21.8% on average, and overall leveling time is reduced by 35.5%, with synchronization errors maintained within ±6 × 10−4 m. Finally, physical prototype testing further confirms the system’s effectiveness, achieving an average body inclination error of 2.55% and a hydraulic cylinder synchronization error of 8.2%. These findings validate the feasibility and superiority of the proposed omnidirectional leveling system for the crawler work machine in hilly and mountainous regions.

This paper studies the fractional-order disturbance observer (FODO)-based adaptive sliding mode synchronization control for a class of fractional-order chaotic systems with unknown bounded disturbances. To handle unknown disturbances, the nonlinear FODO is explored for the fractional-order chaotic system. By choosing the appropriate control gain parameter, the disturbance observer can approximate the disturbance well. On the basis of the sliding mode control technique, a simple sliding mode surface is defined. A synchronization control scheme incorporating the introduced sliding mode surface and the designed disturbance observer is then developed. Under the control of the synchronization scheme, a good synchronization performance is realized between two identical fractional-order chaotic systems with different initial conditions. Finally, the numerical simulation results illustrate the effectiveness of the developed synchronization control scheme for fractional-order chaotic systems in the presence of external disturbances.

This paper investigates the finite-time optimal synchronisation problem for leader-follower multi-agent systems and its application to the harmonic oscillator models. Neural networks are introduced to fit the nonlinear terms of multi-agent systems due to the existence of unknown dynamics. In our designed framework, by modelling each agent as a resonator, their interactions and environment can be shaped as a networked system. In pursuit of synchronized actions among adjacent agents, the actor-critic reinforcement learning algorithm is implemented. To simplify the algorithm and eliminate persistent incentive conditions simultaneously, gradient descent method is applied to a novel positive function. Furthermore, a finite-time control strategy, based on reinforcement learning algorithms, has been devised to ensure that the system not only achieves control objectives within finite time but also minimizes the energy consumption in the process. Finally, the validity of the theoretical method is proven by the Lyapunov stability theory and numerical simulation.