Energy in Unmanned Systems

State-of-the-art

• Hybrid Energy Systems: Most hydrogen-powered unmanned systems (e.g., drones) utilize a hybrid configuration where hydrogen fuel cells serve as the primary power source, complemented by Lithium-ion batteries for handling peak power demands during take-off, climbing, or maneuvering.
• Energy Management Strategies (EMS): Research focuses on developing rule-based and optimization-based EMS algorithms. These algorithms dynamically manage power split between the fuel cell and battery to maximize system efficiency, extend operational endurance, and protect components from degradation.
• System Integration & Lightweighting: Significant effort is dedicated to the integration of lightweight composite hydrogen storage tanks (Type III and IV) and compact fuel cell stacks to minimize the overall system weight and volume, which is critical for aerial platforms.
• Cluster-Level Challenges: Initial research explores simple cluster energy management, such as dynamic role assignment (e.g., shifting leader/follower roles based on remaining energy) and mission path re-planning to ensure the entire cluster can complete its objective without individual failures.
• Refueling Logistics: Current systems rely on centralized hydrogen refueling, which presents a logistical challenge for sustained operations of large clusters, especially in remote areas.

Future Development Directions:

• AI-Driven Intelligent EMS: Future systems will leverage machine learning and digital twin technologies to create predictive, self-optimizing EMS. These systems will forecast mission energy demands in real-time and preemptively manage resources for the entire cluster.
• Multi-Energy Integration: Development will move towards tri-hybrid systems integrating solar, hydrogen, and batteries. Solar panels could provide in-situ recharging for batteries or even assist in electrolytic hydrogen production for ultra-long-endurance missions.
• Standardized & Modular Hydrogen Storage: A key trend is the move to standardized, swappable hydrogen cartridge systems (e.g., drawer-type modules). This allows for rapid re-energizing of entire clusters in the field, dramatically improving operational tempo.
• Resilient and Decentralized Infrastructure: Research will focus on mobile hydrogen refueling stations and even on-demand hydrogen production units (using solar or wind) deployed near the operation area, breaking dependence on fixed infrastructure.
• Advanced Cluster Energy Management: Future directions include cooperative energy sharing between unmanned vehicles within a cluster (e.g., mid-air battery swapping or power transfer concepts) and sophisticated algorithms for energy-aware swarm coordination, where the mission plan continuously adapts to the collective energy state of the entire swarm.