Research on Optical-odometer Application in Vehicle Navigation System

摘要

To get an accurate scale factor of optical odometer, a method aided by DGPS is proposed, and the error compensation for the longitudinal position of optical odometer in vehicle navigation system is further studied. First, the tested data are preprocessed. Although the resolution of optical odometer is less than 2mm, the output noise affected by vehicle shaking attains to 2cm. Because of this, data is reconstructed based on kinematics analysis. The tested data are replaced with reconstructed data if the difference is larger than a threshold. The results show that by this method, the precision of ranging and speed can be improved efficiently, which is less than 0.002m and 0.04m/s respectively. If the output pulse number of odometer and the travel mileage are known, the scale factor can be calculated. The error is obtained through comparing the position data recorded by DGPS with the product of pulse number and the scale factor. It is shown that the linear correlation is remarkable between the data of error and velocity. Therefore the first order model and second order model are established. The compensated results indicate that the longitudinal positioning error can be controlled under 0.2m.