基于无串扰超声测距系统的室内环境建模-检测技术与自动化装置专业论文.docx

ABSTRACT With the expansion of mobile robot’s work area, it proposes new challenge to the robot’s intelligence and autonomation, which is the ability of working in an unknown environment. Firstly, the robot is needed to be able to model the unknown environment and create the environment map. This thesis introduces the design and implementation of indoor environment modeling based on non-crosstalk sonar system. In the non-crosstalk sonar system, the Gold sequence combined with BFSK is applied as the excitation sequence. The cross-zero polarity correlation method is adopted to process the echo signal and to capture the time-of-flight (TOF) of ultrasound. The hardware platform is designed based on FPGA, including transceiver integrated circuit, signal processing circuit, RS-232 communication module, etc. A special ultrasonic transducer array is designed and driven by an stepping motor, so it can achieve 360° environmental scanning. During the process of scanning, FPGA controller sends sonar data to the computer via serial communication. Then the data is saved in a file and processed as follow: transformation of coordinates, data preprocessing, which means the object-shape is recognized by using BP network, and Region of Constant Depth extracting. To build a geometric feature map, a modified TBF algorithm and Least Square method are applied to improve the accuracy of the map. The grid map is built by using Bayes Estimation and refined by the point estimations from modified TBF algorithm. After the comparison of two maps, the combination of the two maps can be used in navigation. KEY WORDS：Ultrasonic Ranging, FPGA, Coding, Environment Modeling, Bayes Estimation 目 录 第一章 绪论1 1.1 选题背景及意义 1 1.2 研究现状及存在问题 2 1.2.1 几何特征图 3 1.2.2 栅格地图 4 1.2.3 拓扑地图 5 1.2.4 混合表达地图 5 1.3 研究思路 6 1.4 主要贡献 6 1.5 内容安排 7 1.6 本章小结 8 第二章 无串扰超声测距系统的设计与实现9 2.1 理论基础 10 2.1.1 超声测距原理 10 2.1.2 超声的编码与调制 11 2.1.3 渡越时间捕获 13 2.2 超声收发电路和信号调理电路 16 2.3 FPGA 的数字处理设计 18 2.4 测距实验结果 22 2.5 本章小结 24