# Applied Research of the UAV Illumination Measurement System in Sports Stadiums
## 2 Materials and Methods  
### Illumination Acquisition System Architecture  
The visualization function is defined as spectral luminous efficiency to represent the visual sensitivity of the human eye at different wavelengths, according to the human eye vision properties. Since stadium illuminance is mainly suitable for athletes and spectators, the process of measuring sports stadium illuminance needs to make the response of the detection equipment consistent with that of the human eye. And the illuminance sensor, which is the main information input for the dynamic measurement system, needs to have the characteristics of fast measurement speed and high measurement accuracy. The photodiode illumination sensor is chosen as the system's illumination acquisition component, which is made with ROHM Semiconductor's BH1750 FVI chip. It is commonly used in electronic devices and projects that require light detection and measurement. Key features of the BH1750 FVI include its compact size, low power consumption, and digital output. It uses a built-in 16-bit analog-to-digital converter (ADC) to provide accurate light intensity readings. The sensor is capable of measuring a wide range of light levels, from very low to high intensities. As a real-time acquisition system mounted on a UAV, the system should have low power consumption and be small in size, and it also needs to have high real-timeperformance. The STM32 chip made in STMicroelectronics is used as the central processing unit of the operating system proposed in this paper. The STM32 model chosen for this paper is the STM32F103 RCT6 in order to facilitate the mounting, which is characterized by small size, low power consumption, and fast processing speed. Furthermore, it can be powered by the FreeRTOS operating system, which has higher real-time performance as a result of the multithreaded operation through time-slice rotation. The system also has the function of transmitting illumination data to the cloud platform wirelessly, which is based on the WiFi communication module, named ESP826 made in Espressif Systems [18]. The total data-transfer rate of the ESP8266 model is designed for 2 Mbps, and the model number is ESP8266-01S. WiFi wireless transmission technology is easy to network, and no wiring is required for data transmission [14]. Meanwhile, the data-transmission distance can reach about 100 m. To cope with illuminance measurements at different height levels, the laser distance sensor is selected. In this paper, the distance sensor of the type is ToF Sense-UART, which can be easily communicated with different modules. OneNET IoT platform is selected as a data-receiving platform in wireless transmission that supports adaptation to various network environments and protocol types. The IoT platform has rich functions, including fast access to various sensors and smart hardware, rich APIs, application templates to support the development of various industry applications, and so on. As for the UAV-carrying platform, the HUBSON ZINO2+ UAV was chosen as the platform of illumination acquisition. It is a professional-grade UAV that can hover accurately and stably indoors or outdoors, and it can load with a weight of 500 g. The UAV supports a variety of flight modes, such as variable speed and constant speed flight. In addition, the mobile app provides real-time feedback, recording the single flight time and hovering position. The HUBSAN ZINO2+ UAV used in this experiment has an optical flow positioning function, which is mainly used to determine the position information of the indoor environment. When the UAV is indoors, the optical-flow navigation system, which is a positioning method that has been used in UAV positioning and control systems in recent years, can determine the current position information based on the information acquired by a specific camera that is on the tail of the UAV.