A Route Planning Method With Subdivision Theory For Unmanned Aerial Vehicles

As the high-speed development of the technology of computer, automation and information, modern aerial vehicles are growing quickly. More kinds, higher performance, compressed technique and complex structure–all of these make the operation more complicated. As the increase of difficulty, danger and intensity of the missions, and restricted by pilots'physiologic and mentality, it is much more hard to complete the complex task only by manual operation. For the purpose of solving those problems, Unmanned Aerial Vehicles (UAV) are used to replace the classic flying machines.Unmanned Aerial Vehicles are different from classic ones. It doesn't have to be operated directly by the pilot. As a result, in order to enable the UAV to fly automatically, operators should complete the Route Planning before it gets started to execute the task. That work is much more complicated than it seems like.As a solution for those problems, a task mode named "Rout Planning" is used. By scanning the geographical data within the task range of UAV and calculating with certain mathematics method, the Rout Planning system is able to provide a suitable flying route for the UAV. This technology is applicable to many fields such as meteorological sounding, disaster controlling, communication repeating, crop-dusting, geological survey, ground mapping, traffic controlling and frontier protecting etc.At present, there are several Route Planning Methods for UAV including interpolation function method, heuristic search method, random path map method and evolutionary computation method which is more prevalent recently. Based on the heuristic search method, this paper is going to put forward a kind of improved Route Planning method for UAV, which combines the heuristic search method with a new organizing and coding mode for global geography information–Spherical Subdivision code.Generally speaking, the Spherical Subdivision means that the earth's surface is divided to plenty of small sheets similar to geometric plane surface. The Spherical Subdivision Code means to install the remote sensing data to every small sheet and build the sheet index. It provides a unified system for global geography data integration, which makes it convenient and fast to get the remote information from certain sheet. The Spherical Subdivision Code is different from those classic data format. It makes maps numeralization which provides sheets with the same size and particular binary code. The Spherical Subdivision Code has different levels with different resolutions. It is possible to get data from certain level according to the demand for different precision.The structure of Spherical Subdivision Code is similar to the structure of link, and it can be divided with different topology type according to different requirement. This type of data organization is very good for heuristic search method to extending the nodes, and enables the calculation work faster and more effectively.The sheets of Spherical Subdivision Code are organized at different levels, and at different levels, they have different resolution. If a map is to be displayed, as the demand for resolution increasing, the level of those sheets getting deeper, which makes the frame more and more clear. It is not necessary for all the sheets to be shown at the same time. When a more clear screen is need to be shown, the frames at the upper level have already been decoded, and the only thing should be done is just to decode the sheets at the next level.Spherical Subdivision Code is to provide a method to build a set of uniform global geography data organization. If every Route Planning system for UAV is built based on it, the cross-region use of UAV technology will be enhanced greatly.The process of standard A* heuristic search method for Route Planning is to find out a route with the lowest cost which is picked up by the cost function. As a real entity of machine, the UAV is limited at some aspects such as mechanical property, fuels and energy. Those limiting conditions can be put in the cost function to decrease the number of the nodes to be extended, and it makes the calculating time shorter. Also, based on the advantage of Spherical Subdivision Code, the heuristic search method can be combined with the Spherical Subdivision Code, which is chosen to be the source of geography data information. It is propitious to extending the nodes and increasing the efficiency of Route Planning for UAV.At present, the theory of Spherical Subdivision is at the first step, and it has only some theoretical modules. Whether it can have effective application in the engineering project is not clearly known yet, and it is necessary to do more deeply research work to confirm it. The point mentioned in this paper is just tentative quest which could probably provide some train of thought for putting forward more precise and effective Route Planning method for UAV.