SignificanceIn recent years, the development of technologies such as artificial intelligence, automatic control, and new materials has given drones the advantages of low cost, high maneuverability, and strong environmental adaptability. UAVs have extensive application value in Vicinagearth Security and many technical fields, such as payload delivery, traffic monitoring, natural disaster rescue, equipment inspection, and other scenarios. What should I do if my drone runs out of battery? How long can a drone fly? How to make a drone fly longer? These questions have puzzled researchers for a long time.
In response to these questions, Professor Li Xuelong from the Institute of Optoelectronics and Intelligence of Northwestern Polytechnical University used more than 27,000 words to discuss drones in ”
UAV Endurance ” (“Science China: Information Science”, 2023, 53(7): 1233-1261) A comprehensive analysis of the aircraft energy supply system was made, and some thoughts and practices were made for the future development of ultra-long-endurance UAVs.
This article works based on the development history of UAVs, this article first reviews the characteristics of the oil-powered UAV system; secondly, analyzes the future development direction based on the classification, principles, characteristics, and bottlenecks of electric UAVs; and finally discusses the unmanned aerial vehicle system. Characteristics, development, and application prospects of optical drones, an important branch of mobility systems. By comparing the current application scenarios and work requirements of UAVs, it was found that the optical system is the optimal solution to achieve the long-endurance flight goal of UAVs.
Figure 1 UAV functional system classification
1. Oil-powered droneTraditional UAVs use oil-powered mode and have the advantages of strong load capacity, endurance, and wind resistance. Therefore, they are widely used in fields such as plant protection, surveying and mapping, meteorological observation, and logistics distribution. However, it also has many inherent flaws, such as complex engine structure, high maintenance costs, and high noise, which limit its application scenarios.
2. Electric dronesElectrically driven drones also show huge application scenarios. Compared with traditional fuel propulsion systems, electric power systems have important advantages such as quietness and environmental protection. Electric drones with high power density, energy density, and cycle life will surely become a future development trend. Currently, drone power systems are mainly divided into fuel cell systems, lithium secondary battery systems, and hybrid systems. At present, electric drones face severe challenges in two aspects: one is to improve the overall performance of the battery to extend the flight time of the drone, and the other is to overcome the battery safety and stability problems caused by increased energy density.To make drones fly longer, people often optimize the structure of the drone, intelligently optimize the working state, optimize the intrinsic properties of the battery, and analyze and screen high-level data to adjust or improve the performance of the battery power system. Although energy storage technology is relatively mature, the weight of the battery pack still restricts its application in drone power systems. Therefore, developing new autonomously charging drones has become a hot topic in current research.
3. Optical droneAn optics-driven drone (ODD) refers to an intelligent unmanned aerial vehicle that can use lasers to replenish energy and thereby achieve unlimited laser energy delivery. During the flight of the optical drone, the photoelectric tracking turntable located on the ground uses intelligent image processing technology to track the drone, achieving large-scale target capture and high-precision target tracking by the drone; then, the laser converts the electrical energy into The high-power laser beam is launched into free space; finally, the photoelectric conversion module of the drone converts the light energy of the laser beam into electrical energy to achieve remote energy replenishment. The main advantage of optical drones is that they can achieve long-distance (kilometer level) energy replenishment, so the energy replenishment process has higher concealment and stronger environmental adaptability. Secondly, the spatial energy concentration of the laser beam is very high, so the size and weight of the equipment at the UAV receiving end are very small and will not have a serious impact on its load capacity. Finally, the energy delivery power of optical drones can reach kilowatts. In addition to small rotary-wing drones, this technology can also be applied to large fixed-wing drones.
Figure 2 Schematic diagram of the optical drone systemKey technologies that need breakthroughs for optical drones includes drone target tracking in complex backgrounds, adaptive compensation of atmospheric turbulence effects, and real-time prediction of obstacle occlusion on the beam transmission path. To cope with the above challenges, Professor Li Xuelong’s research group proposed an intelligent visual tracking algorithm for complex changing targets. It has good illumination, scale, and rotation adaptability, making visual tracking more adaptable to the environment and achieving precise positioning of drones. role. Secondly, to eliminate the impact of atmospheric turbulence on the laser beam, the research team proposed adaptive beam shaping technology, which can realize autonomous dynamic adjustment of the beam intensity distribution on the surface of the photovoltaic cell and improve the effectiveness and reliability of long-distance laser energy transmission links. sex. Finally, to ensure safety during beam transmission, the research team proposed a method of obstacle determination and laser power autonomous adjustment, which can detect obstacles in time based on the target’s reflection characteristics and other determination methods, and autonomously adjust the laser power to a safe range. .Optical drones have long-term endurance, so they can play a role in various complex and time-consuming tasks, and have important application value in on-site security. Representative applications include low-altitude pseudolites, relay communication network establishment, express transportation, power inspections, loyal wingmen, extraterrestrial exploration, etc.
Figure 3 Application scenarios of optical drones
(A) Low-altitude “pseudolite”; (B) Establishment of relay communication network; (C) Express transportation; (D) Power inspectionConclusion and OutlookThe problem of insufficient endurance of traditional powered UAVs severely limit their application in complex and time-consuming tasks. The photodynamic drone proposed in this article is the product of the cross-fusion of artificial intelligence and optical engineering. In the future, photodynamic drones are expected to realize all-day (day/night), long-distance (kilometer level), and autonomous wireless energy replenishment. Therefore, they will be deeply involved in social governance, such as traffic control, security patrols, and disasters. Rescue, contactless logistics and distribution, etc. In addition, due to the thin atmosphere and sparse obstructions during extraterrestrial exploration, using a laser as the power source is the most suitable and stable power source for this type of scientific research drone. Therefore, breaking through the key technologies of optical drones and developing stable extraterrestrial optical drones is one of the effective ways for my country to achieve overtaking in corners in the field of extraterrestrial exploration. Article information