Design And Implementation Of Airborne Lidar System For3D Terrain Mapping

In recent years, the airborne laser scanning technology has become one of the mostadvanced technologies in the field of terrain mapping, and has been widely applied in lots offields such as terrain surface mapping, natural disaster evaluation,3D building modeling, etc.One of the key elements that have made airborne laser scanning technology wildly spread inthe industry since its emerging is the fact that the data are natively collected in3D and haveobvious advantages in their accuracy, density and rapidity, compared with traditional mappingtechnologies. Nevertheless, in contrast to that of overseas countries such as United States,Germany and Canada, the domestic research on laser scanning technological system startsrelatively late and develops relatively slowly, due to the wide sources of the errors in thissystem and the high requirement for the accuracy of the data. This thesis intends to further theresearch and development of the airborne laser scanning system integrated with the platformof the small unmanned helicopter.This thesis has independently designed and developed an advanced laser scanningsystem featured with low cost, high precision and high autonomy. First of all, based on theessential principles of the laser scanning, this thesis discusses the generation of the laser pointcloud in detail, and emphatically analyzes the main error sources of the positioningsystem(GPS) and attitude system(AHRS). In addition, starting from the component selection,the hardware circuit design and the software design, this paper illustrates the implementationmethods of the related hardware and software in such aspects as the data collection and pointcloud generation and so on. Furthermore, on the basis of the essential principles of kalmanfilter, this paper explores the implementation of the seventeen-order Extended KalmanFiltering algorithm and parameter adjustment. Finally, the correctness and validity of thedesign of this system are verified by the field tests and flight experiments.The main innovations of this paper are as follows:1. The airborne system selects STM32F407chip as main control chip which is based onthe latest Cortex-M4architecture. Using LWIP protocol and USB protocol, design and realizea multi-sensor data acquisition system with the characteristics of high synchronization rate, high reliability and high integration.2. In order to improve the accuracy of the kalman filter output, this study employs theerror model of gyro and accelerometer, and then explores and implements the seventeen-orderkalman filter algorithm based on UAV navigation model.3. Combining with the actual scanning experiments, this paper puts forward a number ofmeasures for improving the accuracy of kalman filter; at the same time, it summarizes theinstructive manuals for the application of this system. What‘s more, many practical laserscanning experiments prove the correctness and feasibility and the significant practicability ofthis airborne laser scanning system.