基于低成本惯导和运动约束的农机高精度定位系统研究

High-precision Localization of Autonomous Agricultural Machinery Using Low-cost IMU and Motion Constraints

北斗定位系统(BDS)能够实现厘米级的定位,在农机导航系统中获得了广泛应用。然而,单纯的卫星定位系统存在一些局限性,比如易受外界遮挡、数据频率低等。因此,在导航系统中集成惯性元件并发展组合导航技术成为重要研究方向。考虑到高性能惯导成本很高,不利于推广应用,本文研究了农业场景下,使用低成本惯导和BDS构成组合导航系统。为提高定位精度,解决由BDS中断导致误差发散的问题,设计了零速修正。同时,分析了BDS/INS组合导航系统中航向角误差不可观测的原因和误差来源,设计了航向约束方法。当BDS信息可用时,利用双天线航向角信息来抑制航向角误差的累积;当BDS中断时,使用零角速度修正。通过现场实验验证,当BDS可用时,零速修正可以将位置、速度和水平姿态的精度分别提高20%、40%和15%以上,航向约束可以将航向角精度提高90%以上;BDS中断时,零速修正可以将位置、速度的精度提高90%以上,水平姿态的精度提高80%以上,航向约束可以将航向角精度提高40%以上。

The Beidou positioning system(BDS)can achieve centimeter level positioning,and has been widely used in agricultural machinery navigation systems.However,a simple satellite positioning system has some limitations,such as being vulnerable to external occlusion and low data frequency.Therefore,integrating inertial components and developing integrated navigation technology in navigation systems is an important trend.Considering the high cost of high-performance inertial navigation,which is not conducive to promotion and application,the use of low-cost inertial navigation and BDS was studied to constitute an integrated navigation system in agricultural scenarios.In order to improve positioning accuracy and solve the problem of error divergence caused by BDS interruption,zero speed correction was designed.At the same time,the causes and sources of unobservable heading angle errors in the BDS/INS integrated navigation system were analyzed,and a heading constraint method was designed.When BDS information was available,dual antenna heading angle information was used to suppress the accumulation of heading angle errors.When BDS was interrupted,zero angular velocity correction was used.Field experiments verified that when BDS was available,zero speed correction can improve the accuracy of position,velocity,and horizontal attitude by more than 20%,40%,and 15%,respectively.Heading constraints can improve the accuracy of heading angle by more than 90%.When BDS was interrupted,zero speed correction can improve the accuracy of position and speed by more than 90%,horizontal attitude accuracy by more than 80%,and heading constraint can improve the accuracy of heading angle by more than 40%.