Study Of An Onboard Video System For Micro Unmanned Helicopter

The unmanned helicopter system which has the capability of mission executing independently is of great value for both military and civil, but the R&D of this system was faced with many challenges in the theory and technologies. When the unmanned helicopter in the mission, real-time access to on-site to grasp the image data and process timely is of great important. Some special features such as the flexibility and the ability of slow cruise makes unmanned helicopter have better application in some area compared with fixed-wing aircraft. The unmanned helicopter can spy on the spot in both the cruise mode and near range hover mode, captures the high resolution images with onboard video equipment and transmit the images to the ground site via wireless link. Because of the data transmit rate will trend down as the increasing of distance or external disturbances, the wireless link transmit bandwidth will becomes unstable or even lose data package. To ensure the onboard video system can works effectively and real-time, it's needs the system to adjust the data acquire, store and transmit self-adaptively.This dissertation developed an onboard video system, which can transmit the captured real-time images to the ground site during aviation. A self-adaptive scheme for unman-helicopter image capture, process and transfer was proposed. We also conducted a prototype system design which is includes embedded hardware system design and OS migration and application development base on embedded micro processor and wireless communication device.The major hardware chip was composed of an AT91SAM9G45 and two USB cameras, and a USB wireless card. As the main module chip, AT91SAM9G45 has play a major role in the core of the whole system, USB camera and wireless card were used to collect and transfer image data. According to the hardware structure, software architecture includes control software, image capture software, image compression software, and wireless data transmission software. Each module running under the coordination of the main control software, to execute the adaptive image capture, compresses and transmits function. The Linux porting and software system design has been accomplished based on the embedded hardware.The USB camera driver migrating and the control flow of image capture have been finished, Author also study the porting of the image compression software XVID, the design of WLAN USB driver, the design of the air-ground interactively control. Based on the feature of wireless transmission, the Author also studies how to implement the adaptive methods in the entire image acquisition and transceiver system.