Alternatives: Which New Technologies Are Filling the Gap When Drones Are Restricted?

When drones are forced to make emergency landings in remote mountainous areas due to insufficient battery life, unable to enter urban core areas for delivery due to airspace restrictions, or have medical supply transportation interrupted by severe weather, people are gradually realizing that drones, as representatives of “air logistics”, are not omnipotent. Plagued by issues such as energy technology bottlenecks, fragmented global regulations, and poor adaptability to complex environments, they have repeatedly stumbled in the process of large-scale commercialization. However, the demand for “efficient, accurate, and full-domain coverage” in logistics transportation has never ceased. Against this backdrop, a batch of emerging technologies are filling the capability gaps of drones from multiple dimensions including ground, low-altitude, and underwater, forming a new transportation system featuring “air-ground integration and water-land coordination”. From autonomous ground robots to tethered low-altitude platforms, from pipeline capsule express to underwater unmanned vehicles, these complementary technologies not only address the inherent shortcomings of drones but also expand the boundaries of logistics transportation.

I. The “Capability Ceiling” of Drones: Restrictions Spur Demand for Complementary Solutions

The application limitations of drones have been fully exposed in practical operations, and these “ceiling-level” restrictions have become the direct driving force for the rise of new technologies. Their core pain points can be categorized into three types, each corresponding to specific demands for complementary technologies.

(1) Performance Limitations: The Irreconcilable Dilemma Between Endurance and Load Capacity

As mentioned earlier, restricted by battery energy density, drones have always faced the dilemma of “short endurance and low load capacity”. Consumer-grade logistics drones typically have a single flight time of no more than 40 minutes and a load capacity of less than 5kg, making it difficult to meet the needs of medium-to-long-distance and heavy-load transportation. In rural logistics scenarios, if agricultural products need to be transported from township warehouses to county-level distribution centers (a distance of 20-30 kilometers), drones require 1-2 mid-way recharges, taking more than 2 hours for a one-way trip—far less efficient than traditional tricycles. Meanwhile, drones are extremely sensitive to the environment and cannot operate normally in heavy rain, strong winds, fog, and other weather conditions, resulting in unstable transportation services. In 2023, due to heavy rainfall during the flood season in southern China, the delay rate of drone delivery orders reached 60%, forcing logistics companies to seek weather-independent alternatives.

(2) Regulatory Limitations: Operational “Forbidden Zones” Under Airspace Control

Strict global airspace management restrictions have made it difficult for drones to operate in densely populated urban core areas, military restricted zones, and areas around airports. In China, for example, low-altitude airspace in urban built-up areas requires advance approval, with the approval process usually taking 1-3 working days, failing to meet the needs of instant delivery. In Europe, cities like Paris and London have directly banned small drones from flying in downtown areas to reduce noise pollution and safety risks. Furthermore, differences in national regulations for cross-border transportation have further compressed the operational space of drones. When drones cannot enter these “forbidden zones”, technical solutions capable of operating on the ground or in specific enclosed spaces are needed to take over transportation demands.

(3) Scenario Limitations: “Capability Blind Spots” in Complex Environments

In complex scenarios such as indoor warehouses, underground garages, and narrow alleys, the positioning accuracy and obstacle avoidance capabilities of drones drop significantly, making collisions highly likely. For instance, in large e-commerce warehouses, drones struggle to maneuver between dense shelves and cannot replace manual labor for the full “picking-sorting” process. In enclosed environments like mines and tunnels, signal blockage causes drones to lose navigation capabilities, unable to complete material transportation tasks. The uniqueness of these scenarios requires complementary technologies to have stronger environmental adaptability and operational flexibility.

It is these multi-dimensional restrictions that have spawned an urgent demand for alternative technologies. Complementary technologies are not intended to completely replace drones, but to form “advantage complementarity” with them—drones handle fast transportation in remote areas and open airspace, while emerging technologies take on transportation tasks in urban core areas, complex environments, and medium-to-long-distance trunk lines, collectively building a full-domain coverage logistics network.

II. Ground Complementation: Comprehensive Upgrade from “Wheeled Mobility” to “Intelligent Delivery”

The ground is the main battlefield of logistics transportation and the most mature field for complementary technologies. Relying on autonomous driving, artificial intelligence, the Internet of Things, and other technologies, ground transportation equipment is transitioning from “manual operation” to “autonomous operation”, accurately filling the capability gaps of drones in urban and enclosed scenarios.

(1) Autonomous Delivery Robots: A New Choice for Urban “Last-Mile” Delivery

Autonomous delivery robots are currently the most mature ground complementary technology, focusing on solving the urban “last-mile” delivery problem. Compared with drones, their advantages lie in being free from airspace restrictions, stable operation in complex road conditions, larger single-load capacity (up to 10-50kg), and lower operational costs. These robots usually adopt a wheeled design, equipped with multi-modal perception devices such as lidar, cameras, and ultrasonic sensors, enabling autonomous navigation, obstacle avoidance, traffic light recognition, and automatic pickup and delivery.

In terms of application scenarios, autonomous delivery robots have covered multiple fields such as food delivery, express delivery, and fresh produce. Meituan’s “autonomous delivery vehicles” have been deployed in universities, industrial parks, and communities in more than 20 cities across China, capable of carrying 20-30 food delivery orders with a cruising range of over 100 kilometers and an attendance rate of over 90% in severe weather. JD’s “Xiaomanlv” delivery robots carry out express delivery in rural areas, adapting to complex terrains such as muddy roads and field paths, solving the difficulty of rural “last-mile” delivery. Additionally, during the pandemic, autonomous delivery robots undertook material delivery tasks in isolation areas, reducing the risk of human contact.

Technically, the maturity of L4-level autonomous driving technology provides core support for delivery robots. By integrating deep learning algorithms and high-precision maps, the positioning accuracy of robots can reach centimeter-level, enabling accurate recognition of pedestrians and vehicles and real-time obstacle avoidance decisions. Meanwhile, the application of “vehicle-road coordination” technology further enhances safety—robots can receive traffic light and road condition warning information via 5G networks to adjust driving routes in advance. Compared with drones, autonomous delivery robots have lower operational costs, with a single unit’s daily operational cost being only 1/3 of that of drones, and are easier to maintain, making them suitable for large-scale deployment.

(2) Intelligent Unmanned Vehicles: A “New Force” in Medium-to-Short-Distance Trunk Transportation

For 10-100km medium-to-short-distance trunk transportation that drones cannot cover, intelligent unmanned vehicles are becoming an important complementary force. These vehicles are usually modified based on traditional trucks or dedicated chassis, equipped with autonomous driving systems, cargo management systems, and remote monitoring platforms, enabling “point-to-point” autonomous transportation, suitable for enclosed or semi-enclosed scenarios such as logistics parks, industrial parks, and ports.

In the field of port logistics, the application of intelligent unmanned vehicles is the most mature. Large ports such as Tianjin Port and Shanghai Port have deployed unmanned container trucks on a large scale to transport containers between terminals and yards. Taking Tianjin Port as an example, its unmanned container trucks are equipped with multi-line lidar and Beidou positioning systems, with a positioning accuracy of ±2cm, enabling autonomous driving in complex port environments and accurate docking with loading and unloading equipment. Operational efficiency is 30% higher than manual driving, with 24-hour uninterrupted operation. In logistics parks, intelligent unmanned vehicles can realize “warehouse-to-warehouse” cargo transfer, reducing manual handling costs and cargo damage rates.

Compared with drones, intelligent unmanned vehicles have stronger load capacity (up to several tons to dozens of tons), longer cruising range (electric unmanned vehicles generally have a range of over 200km, and fuel-powered ones can reach over 1000km), and are not affected by weather, providing more stable transportation services. At the same time, intelligent unmanned vehicles can form “air-ground coordination”—in logistics parks, unmanned vehicles are responsible for cargo distribution; outside the parks, drones handle delivery to remote areas, achieving “seamless connection”.

(3) Pipeline Capsule Express: An “Efficient Channel” in Enclosed Spaces

In enclosed scenarios such as indoor and underground environments, pipeline capsule express technology has become an ideal alternative to drones with its advantages of “non-contact, high security, and zero interference”. This technology involves laying dedicated pipelines inside buildings or underground, encapsulating goods in intelligent capsules, and realizing autonomous transportation through motor drive or pneumatic pushing, suitable for office buildings, hospitals, communities, and other scenarios.

In medical scenarios, the application value of pipeline capsule express is particularly prominent. Large hospitals such as Peking Union Medical College Hospital and Shanghai Ruijin Hospital have laid pipeline logistics systems internally for transporting medical supplies, test samples, medical records, and other materials. Taking Peking Union Medical College Hospital as an example, its pipeline system covers multiple areas including outpatient clinics, inpatient departments, and laboratories. The capsule carrier has a load capacity of up to 5kg and a transportation speed of 0.8-1.2m/s. The sample transportation time from the laboratory to the inpatient department has been shortened from 20 minutes by manual delivery to 3 minutes, while avoiding the risk of sample contamination during transportation. In office buildings, pipeline capsule express can realize fast delivery of documents and office supplies, improving work efficiency.

The core advantage of pipeline capsule express lies in “enclosed operation”—it is not affected by the external environment, with extremely high safety and stability, low noise, and low energy consumption, making it suitable for use in densely populated enclosed spaces. With the development of 3D printing technology, the construction cost of pipelines has been significantly reduced, and it is expected to be promoted in more scenarios in the future.

III. Low-Altitude Complementation: “New Flight Solutions” Breaking Through Drone Limitations

In low-altitude areas, drones are not the only flight tools. A batch of low-altitude transportation technologies based on new power sources and new structures are emerging, overcoming the endurance and load shortcomings of traditional drones and playing an irreplaceable role in specific scenarios.

(1) Tethered Drones: “Low-Altitude Platforms” for Long-Duration Airborne Operations

The endurance bottleneck of traditional drones makes it difficult for them to undertake long-duration tasks such as aerial surveillance, communication relay, and emergency lighting. Tethered drones, which are powered by ground cables, can achieve “unlimited endurance” and become the best complementary solution for such scenarios. Their principle is: the drone is connected to a ground power supply system through a high-strength cable, which not only provides continuous power but also transmits data, allowing the drone to stay airborne at a fixed altitude for a long time (up to several days or even weeks).

In emergency rescue scenarios, the value of tethered drones is particularly significant. After disasters such as earthquakes and floods, ground communication infrastructure is often damaged. Tethered drones can carry communication equipment to take off, build temporary communication base stations, and ensure smooth communication for rescue teams. At the same time, the high-definition cameras and infrared thermal imagers they carry can monitor disaster areas 24 hours a day, helping rescuers find trapped people. During the 2023 Turkey earthquake, tethered drones carried by the Chinese rescue team stayed airborne over the disaster area for 72 consecutive hours, providing key communication and monitoring support for rescue operations.

In industrial applications, tethered drones can also be used in fields such as border patrol, large-scale event security, and environmental monitoring. Compared with traditional drones, they do not require frequent battery replacement, resulting in higher operational efficiency. Compared with helicopters, they have lower costs (only 1/10 of helicopters) and are easier to operate, making them suitable for large-scale deployment. Currently, the load capacity of tethered drones has reached 5-50kg, capable of carrying more types of equipment, with continuously expanding application scenarios.

(2) Electric Vertical Takeoff and Landing (eVTOL) Vehicles: Complementary Potential as “Flying Taxis”

For medium-to-short-distance passenger transportation and heavy-load cargo transportation, electric vertical takeoff and landing (eVTOL) vehicles are becoming important supplements to drones. eVOTL adopts a design combining multi-rotors and fixed wings, enabling vertical takeoff and landing (no runway required) while having high-speed cruising capabilities. With a load capacity of up to several hundred kilograms and a cruising range of over 100 kilometers, they are suitable for urban air mobility (UAM), intercity logistics, and other scenarios.

In the logistics field, the large load capacity of eVTOL enables it to undertake transportation tasks that drones cannot complete. For example, EHang Intelligent’s EH216-S eVTOL has a maximum load capacity of 250kg, capable of transporting large medical equipment, industrial parts, and other goods. The transportation time from Guangzhou Baiyun Airport to Nansha Port has been shortened from 2 hours by ground transportation to 30 minutes. In the passenger transportation field, eVTOL is regarded as the prototype of “flying taxis”, which can alleviate urban ground traffic congestion and is currently undergoing pilot operations in countries such as Singapore and the United States.

Compared with traditional drones, eVTOL has higher safety standards, usually adopting multi-redundancy designs (such as multi-motors and multi-battery packs) to ensure safe landing even if some components fail. At the same time, it can fly at higher altitudes (up to 1000 meters or more), avoiding complex environments in urban low altitudes. With the advancement of battery technology and the improvement of regulations, eVTOL is expected to achieve large-scale commercialization within the next 5-10 years, becoming an important force in low-altitude transportation.

(3) Hydrogen Fuel-Powered Flight Platforms: “Low-Altitude Tools” for Long Endurance

To break through the energy density bottleneck of lithium batteries, hydrogen fuel-powered flight platforms are becoming a new direction in low-altitude transportation. These platforms are powered by hydrogen fuel cells, with an energy density of 600-800Wh/kg, 2-3 times that of lithium batteries, a cruising range of 200-500 kilometers, and a hydrogen refueling time of only 3-5 minutes, greatly improving operational efficiency.

In logistics scenarios, hydrogen fuel-powered flight platforms can be used for medium-to-long-distance trunk transportation. For example, the “Rainbow-4” hydrogen fuel drone developed by China Aerospace Science and Technology Corporation has a maximum load capacity of 500kg and a cruising range of over 300 kilometers, capable of delivering goods from urban logistics hubs to surrounding satellite cities without mid-way refueling. In the agricultural field, hydrogen fuel-powered plant protection drones have an endurance of more than 8 hours and a single operation area of 1000 mu, 3-4 times that of traditional lithium battery plant protection drones.

The core advantages of hydrogen fuel-powered flight platforms lie in “long endurance and fast refueling”, but they currently face problems such as difficult hydrogen storage and transportation, high costs, and insufficient infrastructure. With the maturity of hydrogen fuel cell technology and the improvement of infrastructure such as hydrogen refueling stations, these platforms are expected to become important alternatives to drones in the future, especially in scenarios with high requirements for endurance and load capacity.

IV. Underwater Complementation: Opening Up a New Track for “Blue Logistics”

In water scenarios such as oceans and rivers, drones are completely ineffective, while technologies such as underwater unmanned vehicles (UUVs) and unmanned ships are opening up a new track for “blue logistics”, filling the gap in water transportation.

(1) Underwater Unmanned Vehicles (UUVs): “Invisible Stewards” for Deep-Sea Transportation

Underwater Unmanned Vehicles (UUVs) are divided into Remotely Operated Vehicles (ROVs) and Autonomous Underwater Vehicles (AUVs), which can complete tasks such as cargo transportation, equipment maintenance, and resource exploration in deep-sea environments, suitable for marine engineering, deep-sea rescue, and other scenarios. In deep-sea logistics, UUVs can transport materials to underwater workstations, submarines, or offshore drilling platforms, solving the problem that traditional ships cannot reach deep-sea areas.

For example, in the development of oil and gas fields in the South China Sea, CNOOC uses AUVs to transport tools, spare parts, and other materials to underwater drilling platforms. The AUV has a maximum diving depth of 3000 meters and a cruising range of over 100 kilometers, capable of autonomously avoiding underwater obstacles and accurately docking with the material receiving devices of the platform. The transportation efficiency is more than 10 times higher than that of traditional diver delivery. In deep-sea rescue, UUVs can carry rescue equipment into dangerous areas such as sunken ships and underwater caves to search for trapped people and deliver rescue materials.

The core technologies of UUVs lie in underwater navigation and communication—achieving precise navigation through inertial navigation, acoustic positioning, and other technologies, and transmitting data through acoustic communication systems. With the application of artificial intelligence technology, the autonomous decision-making ability of UUVs is constantly improving, enabling them to adapt to more complex underwater environments.

(2) Unmanned Ships: “New Carriers” for Water Trunk Transportation

Unmanned ships are important complementary technologies for surface transportation, divided into inland river unmanned ships and ocean-going unmanned ships, capable of autonomous loading and unloading, navigation, and berthing, suitable for inland river logistics, ocean transportation, and other scenarios. Compared with traditional ships, unmanned ships do not require crew, reducing operational costs by 30%-50%, and can sail 24 hours a day, greatly improving transportation efficiency.

In inland river logistics scenarios, the application of unmanned ships is relatively mature. Pilot projects of unmanned ships have been carried out in basins such as the Yangtze River and Pearl River in China for transporting bulk commodities such as coal and building materials. For example, the “China Merchants 01” unmanned ship developed by China Merchants Group has a load capacity of 500 tons and a cruising range of over 500 kilometers, capable of autonomous navigation through a