## 1 Introduction
### UAV and Precision Agriculture  
In recent years, the use of unmanned aerial vehicles (UAV) in agriculture has increased due to the development of UAV technology (see Figure 1). As a mobile robot, UAV is a low-cost alternative detection technology and data analysis technique [16; 17]. There are many types of UAVs, and low-cost UAVs can collect high-resolution data from different points in space. Although UAVs have not yet been applied in most precision agriculture applications, they are increasingly playing an active role in this field in terms of sustainable agricultural practices and profitability [18]. Moreover, the UAV, which is included in agriculture, significantly reduces human resources and provides measurement precision. If the data obtained with the UAV are evaluated and interpreted correctly, they can contribute to the production of the crop and increase productivity. UAVs can be particularly valuable for precision agriculture applications and have strong potential to increase the efficiency of water [19], crop [20] and precision pest management [21]. They can also perform a wide variety of agricultural operations, including soil health monitoring, fertilizer application and weather analysis. A UAV with flexible movements and a camera provides basic support to manpower in situation assessment and surveillance applications. In addition, multiple sensors can be used simultaneously with the UAV, and analyses can be strengthened with sensor fusion. UAVs can be used to extract vegetation indices that allow farmers to continuously monitor crop variability and stress conditions. Therefore, the agricultural UAV market has gradually expanded, and some UAV companies, such as DJI ([[https://www.dji.com/](https://www.dji.com/)]([https://www.dji.com/](https://www.dji.com/)), (Accessed date: 6 December 2021)) and Parrot ([[https://www.parrot.com/](https://www.parrot.com/)]([https://www.parrot.com/](https://www.parrot.com/)) (Accessed date: 6 December 2021)), have developed UAVs for agricultural purposes [22]. To date, UAVs have mainly been used for pest detection/control and monitoring a large number of crops, such as corn, rice and beans. The most common applications performed with UAVs for precision agriculture are monitoring and spraying [24]. In monitoring applications, certain information about the crop and vegetation indices are obtained with image analysis and remote sensing, and thus, various diseases or pests, plant health or plant growth can be monitored. In spraying applications, the required amounts of pesticides and fertilizers are sprayed to increase the yield of the crop and prevent plant diseases. Recently, in addition to these applications, applications such as mapping, weed detection, irrigation and remote sensing have also been applied with UAVs. Moreover, UAVs are expected to be used for purposes such as planting, transportation and soil and field surveys in the future [25]. These missions can also be performed using satellite imagery or aircraft, but UAV applications are more useful when the image resolution, cost and difficulty are considered. In addition, UAVs can carry different types of cameras, such as thermal, multispectral and hyperspectral instruments, and thus, they can capture aerial images with different characteristics [26]. According to the Association for Unmanned Vehicle Systems International (AUVSI), 80% of UAVs will be used in different agricultural applications in the near future. Therefore, it is obvious that the agricultural sector will need UAVs to a much greater extent in the future [4; 24]. Although UAVs are suitable for agricultural applications, they have important technical limitations. Therefore, some questions should be answered to develop advanced and smart agricultural systems. Some of these questions are:  
* A UAV that works in a large agricultural area for crop monitoring, spraying, etc., should fully monitor the field, but is the UAV battery sufficient for this duty period? * Are the size of the land and the flight time of the UAV compatible?