基于RTK的农机精准定位系统的研究

发布时间：2017-12-28 09:04

本文关键词：基于RTK的农机精准定位系统的研究　出处：《浙江大学》2017年硕士论文　论文类型：学位论文

【摘要】：RTK载波相位差分技术,是实时处理两个接收站载波相位观测量的差分方法,可实时获取厘米级定位解,具有操作性强、应用范围广等优点。高精度的RTK产品几十万的高昂价格,使得RTK定位技术在农业领域的应用尚不广泛。随着国家对农业的大力支持,农业自动化和智能化技术将会快速发展,而获取高精度的定位解是实现农田车辆自动导航的基础。本研究以农田导航的实际应用为首要目的,以美国Swift公司的Piksi定位模块为基础,构建RTK系统进行研究,前期设计实验进行精度分析,后期根据项目要求对电台和天线等部分硬件进行改进,使用滤波算法对改进后的数据进行处理,最终成功将Piksi RTK系统应用在农田拖拉机上。主要研究结果如下:(1)Piksi模块是一款超高性价比的定位模块,RTK静态水平定位精度可达1cm。使用Piksi模块时,要充分考虑周围的环境,附近切不可要有高大建筑物等遮挡;配套的console控制软件可保存3种格式下的6种类型数据,完全满足用户使用需求;串口直接读取的Piksi数据经过了 Swift公司SBP二进制协议的处理,不使用console软件无法直接获取经纬度数据;搭建RTK系统时,基准站需要使用console软件设置经纬度和海拔高度数据后发送给流动站。(2)空间大地坐标与导航切平面坐标的转换满足精度分析的要求;采用标准差(σ)、圆概率误差(CEP)、距离均方根误差(RMS)、2倍均方误差(2DRMS)的指标对Piksi RTK系统静态精度进行分析,Piksi单个模块静态单点的定位精度约为8m,RTK的静态精度(2drms,95%)约为1.5cm;设计的动态双轨实验验证了直线拟合评估动态直线精度的可行性,当流动站在0.4m/s-2.3m/s的平均速度范围内进行直线运动时通过拟合得到的定位精度约为1.5cm;采用测量点到拟合圆心距离与拟合半径的差值评估圆周运动的定位精度,发现在0.4 m/s-1.6 m/s的平均线速度范围内运动时流动站的精度约为1.5cm;考虑到实际应用过程中点对点的问题,拟合分析得到的测量误差整体偏小,初步判定PiksiRTK的真实动态精度约为3 cm-5 cm。(3)PiksiRTK系统的3DR数传电台功率较小,传输距离受限,实际传输距离在开阔环境下约为300 m-400 m;将系统的天线和电台更换为加拿大P900电台和GSM增益天线,经测试在校园内有建筑物遮挡的情况下的传输距离约为1 km,开阔环境下更是可以达到3.5km;随着传输距离的增加,改进后的Piksi RTK系统的定位精度不断下降,利用最小二乘法插值拟合发现传输距离在超过3.2km以后将会下降到亚米级别。(4)采用卡尔曼滤波建立的数据处理模型,传输距离内获取的定位数据经过滤波后的静态和动态精度均可提升一倍左右,滤波后距离基准站1 km内的静态定位精度约为1 cm,满足课题对传输距离和精度的两方面要求;动态卡尔曼滤波模型对直线运动下的数据有很好的纠偏效果,滤波处理后动态误差约为1 cm-3 cm。(5)将改进后的Piksi RTK系统应用到农用拖拉机上,RTK数据产生的轨迹直线度优于拖拉机的GPS轨迹,通过采用地图固定点作为基准站的方法,解决了实际应用的准确度问题,农田实验分析得出Piksi RTK系统的动态精度可达到标称的2 cm-6 cm,与动态模拟实验分析得出的精度一致,滤波后的动态精度约为1cm-3 cm,说明Piksi RTK系统可以达到农田车辆自动导航的要求,在农机精准定位领域有广阔的应用前景。
[Abstract]:The RTK carrier phase difference technology is a real-time difference processing method for two receiver stations to observe the carrier phase. It can get centimeter level positioning solution in real time, and has the advantages of strong operability and wide application. The high - precision RTK products are hundreds of thousands of high prices, making the application of RTK positioning technology in the agricultural field is still not widely used. With the support of the state for agriculture, agricultural automation and intelligent technology will develop rapidly, and obtaining high-precision location solutions is the foundation for automatic navigation of farm vehicles. Based on the practical application of farmland navigation as the primary purpose, the Piksi positioning module of Swift company in the United States as the basis to construct the RTK system research, preliminary design experiment of precision analysis, according to the requirements of the late radio and antenna hardware is improved, so that the improved data filtering algorithm, the ultimate success the application of Piksi RTK system in agricultural tractors. The main results are as follows: (1) the Piksi module is a high performance and cost-effective positioning module, and the static level positioning accuracy of RTK can reach 1cm. Using the Piksi module, to fully consider the surrounding environment, must not be near tall buildings block; console control software can save 3 kinds of 6 types of data format, fully meet the needs of users; Piksi serial data read directly after the Swift SBP binary protocol, do not use console software is unable to get the latitude and longitude data directly; build RTK system, the base station needs to use the console software to set the latitude and longitude and altitude data sent to the mobile station. (2) space geodetic coordinate conversion and navigation cutting plane coordinates satisfy the precision analysis; the standard deviation (sigma), circular error probability (CEP) distance, root mean square error (RMS), 2 times the mean square error (2DRMS) index to analyze the static accuracy of Piksi RTK system, Piksi static single module single point positioning accuracy is about 8m, the accuracy of static RTK (2drms, 95%) is about 1.5cm; the dynamic track of experimental design to verify the feasibility of dynamic evaluation of linear fitting straight line accuracy, positioning accuracy when the mobile station in the average speed range of 0.4m/s-2.3m/s linear motion through the fitting of the location is about 1.5cm; the accuracy of motion difference evaluation circumference measurement points to fitting center distance and fitting radius, found in the range of motion average line speed of 0.4 m/s-1.6 m/s in the mobile station accuracy is about 1.5cm; taking into account the actual application process of neutral point Point problem, the measurement error obtained by fitting analysis is small, and the real dynamic accuracy of PiksiRTK is estimated to be about 3 CM-5 cm. (3) 3DR PiksiRTK system radio power is low, limited transmission distance, transmission distance in open environment is about 300 M-400 m; the system of the antenna and the radio station replaced Canada P900 radio and GSM gain antenna, tested in campus buildings covered by the transmission distance is about 1 km the open environment, but also can achieve 3.5km; with the increase of the transmission distance, the positioning accuracy of Piksi improved RTK system decreased, found that transmission distance in more than 3.2km will be down to sub meter level using the least squares fitting don't. (4) processing model using the Calman filter to establish data transmission distance to obtain the positioning data through static and dynamic accuracy can be filtered doubled around, filtered distance base station within 1 km static positioning accuracy is about 1 cm, meet the two aspects of the transmission distance and the accuracy of the dynamic data; Calman filter model of linear motion of the correction effect is very good, after filtering the dynamic error is about 1 cm-3 cm. (5) will be improved after the application of Piksi RTK system to agricultural tractors, GPS track straightness is better than the tractor to generate the RTK data, by using the fixed point map method as a reference station, solves the accuracy problem of practical application, the dynamic accuracy of the Piksi field testing and analysis of RTK system can reach the nominal 2 cm-6 cm, the accuracy of consistent experimental analysis and dynamic simulation, the dynamic precision filter is about 1cm-3 cm, Piksi RTK system can meet the requirements of the vehicle automatic navigation of farmland, and has broad application prospects in the field of agricultural precise positioning.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P228.4;S22

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