This article focuses on the problem of secure state estimation for cyber-physical systems (CPSs), whose physical plants are modeled as nonlinear strict-feedback systems. The measured output is sent to the designed observer over a wireless communication network subject to denial-of-service (DoS) attacks. Due to the energy constraints of the attackers, the attack duration is upper bounded. Under DoS attacks, the transmission is prevented, which worsens the estimation accuracy of the existing nonlinear observers significantly. To maintain the estimation performance, a novel multiobserver scheme and a switched algorithm are proposed by introducing the hold-input mechanism and the cascade observer technique. In comparison to the existing results, where the estimation error systems may be unstable during the attack time interval, the estimation error of the designed observer converges exponentially, such that the estimation performance is improved effectively. Finally, the theoretical findings are illustrated by simulation results.

中文翻译：

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针对 DoS 攻击的非线性网络物理系统的安全状态估计：一种多观察者方法

本文重点关注网络物理系统 (CPS) 的安全状态估计问题，其物理设备被建模为非线性严格反馈系统。测量的输出通过无线通信网络发送给设计的观察者，受到拒绝服务 (DoS) 攻击。由于攻击者的能量限制，攻击持续时间是有上限的。在 DoS 攻击下，传输被阻止，这大大恶化了现有非线性观测器的估计精度。为了保持估计性能，通过引入保持输入机制和级联观测器技术，提出了一种新的多观测器方案和切换算法。与现有结果相比，估计误差系统在攻击时间间隔内可能不稳定，所设计观测器的估计误差呈指数收敛，有效提高了估计性能。最后，通过仿真结果说明了理论发现。