This paper proposes a fixed-time trajectory tracking control strategy for robotic manipulators facing dynamic uncertainties and input saturation, combining prescribed performance control with adaptive reinforcement learning. A prescribed performance function is designed to strictly constrain tracking errors within predefined transient and steady-state boundaries throughout system operation. An adaptive actorcritic framework with dynamic parameter adjustment is developed, where the actor network generates control policies and the critic network evaluates action-value functions in real time based on system states. An anti-saturation compensation law, derived from transformed error signals, is constructed to mitigate actuator saturation effects. Furthermore, an adaptive nonsingular terminal sliding mode controller is incorporated to ensure fixed-time convergence of tracking errors independent of initial conditions. Lyapunov-based stability analysis rigorously establishes the boundedness and convergence properties of the closed-loop system. Comprehensive simulation results demonstrate the effectiveness and performance advantages of the proposed control scheme.
Yan Li, Xin Liu, Yan Zhang et al.· 2026 IEEE International Conf...· 0 citations
With the deep integration of aerospace technology and information technology, large-scale low Earth orbit (LEO) satellite constellation networking has become the core infrastructure supporting the development of new-generation communications, navigation, remote sensing and other fields by virtue of its advantages such as global coverage, low latency and high bandwidth. Large-scale LEO constellation networking realizes interconnection between satellites, satellites and ground, and satellites and user terminals through inter-satellite links and satellite-ground links, constructing a "space-ground-user" three-in-one information transmission system. Compared with traditional ground networks and small-scale LEO constellations, large-scale LEO satellite networking is characterized by a large number of satellites, strong on-orbit dynamics, high link openness, dynamic changes in networking topology, frequent switching of inter-satellite links, diverse access terminals, and constrained node resources. The traditional boundary defense concept is not applicable, and existing protection measures suffer from insufficient protection efficiency, poor adaptability and lack of coordination, making it difficult to comprehensively cope with various network security threats. This paper systematically sorts out the core characteristics and typical security threats of large-scale LEO satellite networking, deeply analyzes the core concepts and key technologies of zero-trust access authentication, proposes a zero-trust access authentication framework adapted to large-scale LEO satellite networking, clarifies the overall architecture, core modules and implementation process of the framework, and verifies the security and feasibility of the framework through logical analysis.
Dan Liu, Mingyang Xia, Xin Liu· International Conference on...· 0 citations
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