Deep-Sea Biomimetic Manta Ray Robots: A Comprehensive Review Based on Operational Depth Spectrum, Structures, Energy Optimization, and Control Systems

As deep-sea exploration transitions from large-scale search to precision pinpoint operations, the inherent limitations of traditional "rigid-body and propeller" vehicles-specifically in low-speed maneuverability, environmental compliance, and acoustic stealth-are becoming increasingly apparent. Leveraging its unique integrated "gliding-flapping" locomotion and exceptional maneuverability, the manta ray serves as an ideal biological prototype for next-generation deep-sea operational platforms. From a systems engineering perspective, this paper provides a comprehensive review of the current research status and technical evolution of biomimetic manta ray submersibles. First, a technical pedigree centered on "operational depth" is established, illustrating how design paradigms transition from "mechanism replication" in shallow waters to "pressure adaptation" at full-ocean depths. Second, the mechanical challenges in structural design are explored, demonstrating that a "rigid-flexible" gradient distribution strategy is critical to resolving the conflict between pressure resistance and propulsive compliance. Regarding energy and propulsion, the synergistic effects of hybrid gliding-flapping drives and integrated structural batteries in enhancing long-range endurance and energy efficiency are analyzed. Finally, the evolution of motion control architectures-transitioning from spinal-cord-inspired Central Pattern Generator (CPG) rhythmic control to Deep Reinforcement Learning (DRL) featuring embodied intelligence-is outlined.