摘要
为减小GNSS农田平整过程中农田地势信息的采集误差,提高农田三维地形的测量精度,该文提出了一种基于GNSS双天线和姿态航向参考系统(attitude and heading reference system, AHRS)组合的地形测量方法。以GNSS平地系统为试验平台,利用AHRS获取平地铲的姿态角和三轴加速度信息,建立GNSS双天线的位置解算方程组;对采集过程中的误差源进行分析,使用最小二乘法和五点三次平滑法对振动误差进行趋势项消除和平滑处理,获得高精度的农田三维地形测量数据。水泥路面的试验结果表明:位置解算方程可以有效地对双天线的位置信息进行解算,通过误差处理后定位天线测量数据的波动范围减小了9.57%,定向天线测量数据的波动范围减小了8.42%。3块不同面积(35 m×50 m、35 m×100 m和35 m×200 m)的农田平地作业试验结果表明:与单天线地形测量方式相比,双天线测量得到农田平整度的准确性分别提高了14.286%、14.063%和10.084%,最大高程差的准确性分别提高了8.642%、8.333%和8.897%,高差分布列的准确性分别提高了1.536%、3.357%和2.991%。本文提出的地形测量方法可以有效降低采集数据的误差,可为农田平整作业提供高精度的地势信息。
The topographic survey becomes a necessary part of the farmland leveling works in modern precision agriculture. The collected topography data can be used to design a path for the farmland leveling, and further to provide technical support for the calculation of excavation and filling earthwork. However, there are some inevitable measurement errors that caused by the mechanical structure of the devices and/or the profile of the terrain fluctuation during the field operation. This present paper therefore proposed a novel topographic measurement method that combined the GNSS(globe navigation satellite system) dual antennas and AHRS(attitude and heading reference system) to reduce the collecting errors of the farmland topography data in the process of GNSS farmland leveling, and consequently to improve the measurement accuracy of three-dimensional farmland topography. The test platform was based on the GNSS land leveling system, where the GNSS antennas were used to provide the location information, whereas the AHRS was used to obtain the attitude angle and triaxial acceleration information of the land leveler. The calculating equations were established to parse the position of the GNSS double antenna on the land leveler. The error source was also important factor in the process of data acquisition, one of which was the pin-type semi-rigid connection between the tractor and land leveler for the difficult installation of damping device. A four-step error-handling method was proposed to reduce the impact of displacement error. First, to measure the vibration acceleration by AHRS and then to calculate the vibration acceleration of the land leveler in the X, Y and Z axes using the coordinate transformation. Second, to process the acceleration trend term by LSM(least squares method). Third, to calculate the vibration displacement by FFT(fast fourier transform) in the frequency domain, and then to be subtracted by the position information from the GNSS double antenna. Fourth, to dispose the displacements on the X, Y and Z axes by the FPT(five point three times) smoothing method, then to import the final data in the terrain mapping software and to obtain the three-dimensional topographic map of the farmland. This combined GNSS dual antennas/AHRS topographic measuring method has been applied to the GNSS land leveling system, where the functional execution software was programmed by MATLAB and C++. The tests of the cement road and farmland were also carried out under the tractor speed of 1.12 m/s. The results showed that the position information of the double antennas can be obtained in the dynamic environment. After the error processing, the fluctuation data of the positioning antenna can be reduced by 9.57%, and that of directional antenna can be reduced by 8.42%, which was suitable for the GNSS land leveling work. The farmland leveling test showed that the root mean square error(RMSE) of the vertical acceleration was 0.256 m/s^2, and that of the course angle, pitch angle and roll angle were 0.903°, 0.849° and 0.531°, respectively. This values proved that the AHRS can be extended to apply for the topographic survey of farmland. The accuracy of the farmland flatness measured by double antenna increased than that by single antenna topographic survey, ranking in the order of three different areas(35 m×50 m, 35 m×100 m and 35 m×200 m) by 14.286%, 14.063% and 10.084%, respectively, the accuracy of the maximum differential elevation error increased by 8.642%, 8.333% and 8.897%, respectively, and the accuracy of the elevation difference distribution increased by 1.536%, 3.357% and 2.991%, respectively. This finding demonstrated that the double antenna topographic survey system can provide much higher accuracy and more stable topographic information than that of the conventional single antenna field topographic survey method for the GNSS farmland leveling in the precision agriculture.
作者
景云鹏
刘刚
金志坤
Jing Yunpeng;Liu Gang;Jin Zhikun(Key Laboratory of Modern Precision Agriculture System Integration Research,Ministry of Education,China Agriculture University,Beijing 100083,China;Key Laboratory of Agricultural Information Acquisition Technology,Ministry of Agriculture and Rural Affairs,China Agricultural University,Beijing 100083,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2019年第21期166-174,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家重点研发计划项目(2017YFD0701100-2017YFD0701105)
关键词
土地利用
测量
地形
GNSS双天线
姿态航向参考系统
位置解算
误差处理
land use
measurements
topography
GNSS dual antenna technology
attitude and heading reference system
position calculating
error processing
