Iterative construction of low-altitude UAV air route network in urban areas: Case planning and assessment

doi:10.1007/s11442-020-1798-4

Abstract

Abstract:

With the rapid increase of Unmanned Aircraft Vehicle (UAV) numbers, the contradiction between extensive flight demands and limited low-altitude airspace resources has become increasingly prominent. To ensure the safety and efficiency of low-altitude UAV operations, the low-altitude UAV public air route creatively proposed by the Chinese Academy of Sciences (CAS) and supported by the Civil Aviation Administration of China (CAAC) has been gradually recognized. However, present planning research on UAV low-altitude air route is not enough to explore how to use the ground transportation infrastructure, how to closely combine the surface pattern characteristics, and how to form the mechanism of “network”. Based on the solution proposed in the early stage and related researches, this paper further deepens the exploration of the low-altitude public air route network and the implementation of key technologies and steps with an actual case study in Tianjin, China. Firstly, a path-planning environment consisting of favorable spaces, obstacle spaces, and mobile communication spaces for UAV flights was pre-constructed. Subsequently, air routes were planned by using the conflict detection and path re-planning algorithm. Our study also assessed the network by computing the population exposure risk index (PERI) and found that the index value was greatly reduced after the construction of the network, indicating that the network can effectively reduce the operational risk. In this study, a low-altitude UAV air route network in an actual region was constructed using multidisciplinary approaches such as remote sensing, geographic information, aviation, and transportation; it indirectly verified the rationality of the outcomes. This can provide practical solutions to low-altitude traffic problems in urban areas.

Key words: UAV air route network, urban area, iterative construction, remote sensing, geographic information

XU Chenchen, LIAO Xiaohan, YE Huping, YUE Huanyin. Iterative construction of low-altitude UAV air route network in urban areas: Case planning and assessment[J].Journal of Geographical Sciences, 2020, 30(9): 1534-1552.

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Step	Key technology	Required elements	Optional elements	Required data processing
I	Hierarchi- cal planning	Road network: urban expressway, urban main road, community or campus internal trunk road Mobile base station.	Roads around buildings within a community or campus.	Road network: extract the road area and its center line and measure the road width. The road is stored in the form of shapefile. A road is a record composed of the coordinate values of feature points. Mobile base station: analyze the communication coverage limit and determine the regional route height limit accordingly.
II	Utilizing positive constraints	None. The positive constraint element is only auxiliary but not required.	Urban green belt, isolation belt, grassland, street trees, parks, and other green areas; rivers, large areas of waters, ditches, and other water sources.	Green space: the relative position with the road determines the translation direction and translation distance, and thus the direction and translation distance matrices. Water area: the relative position with the road determines the translation direction and translation distance, and thus the direction and translation distance matrices.
III	Avoiding negative constraints	General obstacles: buildings, mobile base station tower poles, street lamps, power lines (poles), etc.	Other obstacles, such as terrain in constructing the route in mountainous areas.	Mobile base station: the clearance boundary modeling of the tower pole is used to build an “obstacle” environment, and the communication coverage is modeled to analyze the spatial signal distribution. Other ground objects: to construct a mathematical model of clearance boundary.

Types	Function	Constraints	Height (m)	Minimum height (m)	Platform
1	Connecting urban areas with the outside area	Higher than most of ground objects in urban area	70-300	70	Fixed wing/multi- rotor UAV
2	Main traffic routes inside the urban areas	Higher than lamps, trees, and buildings along roads	50-70	50	Multi-rotor UAV
3	Internal air route of community units in urban area	None	15-50	30	Multi-rotor UAV

Code	Type	Sheltering factor
12	Farmland	0
23	Open woodland (canopy density 10%-30%)	2.5
41	Waters	0
51	High-rise buildings	7.5
52	Low-rise buildings	5
53	Other construction land: factories and mines, large industrial zones, oil fields, salt fields, quarries and other patches of land; traffic roads, airports, and special areas	10
61	Others, including of unexploited land (e.g., deserts, salt flats, marshes)	0

Type	Population exposure risk index (PERI)
	Average	Variance	Average	Variance	Average	Variance
	Type 1		Type 2		Type 3
Class I	62.42	62.92	158	0	117.47	62.14
Class II	21.75	9.05	25.98	15.35	23.92	17.88
Class III	21.74	8.89	25.06	14.05	25.37	22.17