Safe trajectory tracking for nonlinear stochastic systems operating in obstacle-cluttered environments remains a significant challenge, as random disturbances and obstacle-induced constraints can simultaneously degrade tracking accuracy and threaten system safety. To overcome this issue, this article develops a safety-aware optimal tracking control framework that integrates stochastic control barrier functions (CBFs) with adaptive dynamic programming (ADP) for obstacle avoidance. To ensure safety, a logarithmic-type stochastic CBF is constructed to enforce obstacle-avoidance constraints, and theoretical guarantees are provided for the stochastic forward invariance (SFI) of the safe set. Furthermore, based on the integral reinforcement learning (RL) framework, an ADP algorithm is developed to relax the need for system dynamics. A critic-only neural network (NN) scheme is employed to approximate the solution of the Hamilton-Jacobi-Bellman (HJB) equation, with a fixed-time weight update rule established to guarantee convergence independent of initial conditions. Meanwhile, an experience replay mechanism is incorporated to relax the persistent excitation condition. It is further shown that the estimation error of the NN weights is fixed-time stable (FxTS). Finally, simulation results demonstrate that the designed method achieves optimal trajectory tracking while ensuring safety under stochastic dynamics, even in scenarios involving multiple obstacles.
Lu-Lu Zhang, Huaguang Zhang, Xiao-Hui Yue et al.· IEEE Transactions on Cyberne...· 0 citations
This paper investigates the secure fault estimation (FE) and fault-tolerant control (FTC) problems for Markov jump systems (MJSs) under limited communication resource. First, a dynamic event-triggered mechanism (ETM) is introduced into the sensor-observer channel to alleviate communication burden. Simultaneously, to ensure network security, a class of deception attacks described by Bernoulli random variables is considered during the transmission of sampled outputs. Based on these, a novel dynamic event-triggered intermediate observer (IO) is constructed, which utilizes the sampled outputs corrupted by attack signals to estimate states, faults and disturbances of MJSs. This observer not only reduces data transmission but is also capable of resisting deception attacks. Furthermore, a fault-tolerant controller is designed to maintain system stability. Second, with the aid of augmentation methods, linear matrix inequality techniques and stochastic stability theory, a joint design method for the observer, fault-tolerant controller and dynamic ETM is developed by constructing a model-dependent Lyapunov function that incorporates a dynamic variable. Third, it is proven that the introduced dynamic ETM is free from Zeno behavior. Finally, the effectiveness of the proposed method is validated on an F-404 aircraft engine model. Note to Practitioners—MJSs, as a class of stochastic switching systems, are capable of accurately describing abrupt variations in system structures or parameters that commonly occur in practical engineering scenarios. This capability has enabled their widespread application in critical fields such as aerospace, power and communications. In these fields, frequent equipment faults pose a significant threat to system safety. On the other hand, with the increasing prevalence of networked systems, continuous data transmission imposes heavy communication burdens and increases energy consumption. Meanwhile, data transmitted over networks is vulnerable to cyber attacks. To address these issues, this paper proposes a FTC method based on a dynamic event-triggered observer. Specifically, a dynamic ETM is incorporated into the observer design, which determines whether data should be transmitted according to real-time system states, thereby avoiding unnecessary communication. Moreover, the designed observer is capable of accurately estimating system states, disturbances and faults using measurements corrupted by deception attacks. Finally, the estimated information is integrated into the fault-tolerant controller for online compensation. In summary, this paper provides a practical FTC solution for MJSs subject to communication resource constraints and deception attacks.
Zhijie Han, Hua-guang Zhang, Zhihong Liang et al.· IEEE Transactions on Automat...· 0 citations
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