Inertial Navigation Electro-Optical Aiding During GPS Dropouts

Inertial navigation with low-cost IMU’s can be an acceptable sole navigation source during short periods of GPS signal dropout due to intentional or unintentional interference. However, as the dropout period continues, the inertial navigation error reach unacceptable levels. In this paper, a technique is presented where relative or absolute position estimates derived from onboard captured image data are used to update the inertial navigation solution during GPS dropouts. This optical aiding technique is described and test results shown from aircraft and ground-based navigation trials. INTRODUCTION Several military and commercial platforms are currently installing navigation sensors concurrently with the introduction of high quality visual capabilities and digital mapping/imagery databases. The Navigation/ElectroOptic Sensor Integration Technology (NEOSIT) software application, developed for CECOM, is designed to optimally integrate navigation data, sensor imagery and image or terrain database to estimate and correct for errors in each data source. The modular design is to allow the NEOSIT application to be used with sensors and navigation already installed on different host platforms and with digital mapping and imagery data sources with varying degrees of precision. The NEOSIT software application is designed to operate in three modes. The first mode uses the precision GPS/inertial imagery metadata to extract target coordinates from the imagery. The second mode is used to correct for offsets in the image or terrain database registration coordinates. The third mode of operation is to provide a back-up navigation capability in the event of GPS drop-outs by applying reference points from the imagery to update the on-board navigation solution. NEOSIT SOFTWARE APPLICATION NEOSIT APPLICATION GPS/INERTIAL