simulink经纬度计算

我想请教下，目前我使用simulink搭建了一个飞行器的6DOF模型。通过6DOF导出的Xe（Flat earth frame），Ve由Xe积分而得到；然后经过Flat to LLA模块转换为经纬度信息。但是我将Ve的信息导出到workspace后，通过一阶积分得到ENU的位置增量，通过loca2latlong函数得到经纬度，与simulink模型直接计算出来的经纬度对比，其中经度误差较大，在某些时间段有1e-3 deg的误差，维度和高度误差较小。请问您知道这是什么原因导致的呢，采用的都是WGS84模型。如果我想要提高精度的话，将位置转换到地心笛卡尔坐标系后，再计算经纬，计算精度会有提升吗

I would like to ask for advice, currently I have built a 6DOF model of a flying vehicle using simulink. The Xe (Flat earth frame) is exported from 6DOF, and the Ve is obtained by integrating the Xe; then it is converted to latitude and longitude information by Flat to LLA module. However, after I export the Ve information to workspace, I get the position increment of ENU by first order integration, and get the latitude and longitude by loca2latlong function, and compare it with the latitude and longitude directly calculated by simulink model, in which the error of longitude is larger, with 1e-3 deg error in some time periods, and the error of dimension and altitude is smaller. Do you have any idea what is causing this, using both WGS84 models. If I want to improve the accuracy, will the calculation accuracy be improved by converting the position to geocentric Cartesian coordinate system and then calculate the latitude and longitude?