线性化误差对于UWB系统定位精度影响分析

Influence of linearization error on positioning accuracy of UWB system

针对目前常用的超宽带算法,扩展卡尔曼滤波(EKF)在解算过程中产生的线性化误差,对定位结果产生影响,而无损卡尔曼滤波(UKF)算法可以不进行线性化过程进行解算,避免误差的产生。文中首先对UWB定位系统线性化误差进行分析,在此基础上提出UKF和TDOA相结合的定位模型,通过实验比较两种算法的定位精度。实验结果表明UKF算法定位结果相比于EKF算法在U方向上有明显提升,误差稳定在10 cm之内。同时,通过改变初始坐标偏差,来进一步比较两种算法的定位效果,结果表明,初始偏差设置为0.5 m时,UKF算法比EKF算法U方向精度提升15%;初始偏差设置为1 m时,UKF算法U方向精度提升60%以上;初始偏差设置为5 m和10 m时,UKF算法U方向精度提升可以达到90%。EKF算法会产生不可忽略的线性化误差且误差会随着初始偏差增大而增大,UKF算法则可以保持较好的定位精度和稳定性。

In view of the commonly used UWB algorithm,EKF will produce linearization error in the process of solution,which has an impact on the positioning results,while UKF algorithm can avoid the linearization process to solve the error.In this paper,firstly,the linearization error of UWB positioning system is analyzed.On this basis,a positioning model combining UKF and TDOA is proposed,and the positioning accuracy of the two algorithms is compared through experiments.The experimental result shows that compared with EKF algorithm,UKF algorithm has a significant improvement in U direction,and the error is stable within 10 cm.At the same time,by changing the initial coordinate deviation to further compare the positioning effect of the two algorithms,the result shows that when the initial deviation is set to 0.5 m,the UKF algorithm improves the u-direction accuracy by 15%compared with the EKF algorithm;when the initial deviation is set to 1m,the UKF algorithm improves the u-direction accuracy by more than 60%;when the initial deviation is set to 5 m and 10 m,the UKF algorithm improves the u-direction accuracy by 90%.To sum up,EKF algorithm will produce non negligible linearization error and the error will increase with the increase of initial deviation.UKF algorithm can maintain good positioning accuracy and stability.