Tightly Coupled NavIC and Low-Cost Sensors for Ground Vehicle Navigation

Abstract

The demand for navigation devices for ground vehicles has been increasing significantly. The presently available GNSS receivers in the ground navigation systems cannot meet the required navigation performance in urban and forest areas due to signal obstructions. Further, with few currently available NavIC satellites, computation of navigation solution only with NavIC (Navigation with Indian Constellation) may not be possible several times. Many researchers propose integrating GNSS and MEMS IMU for reliable and robust navigation, at low cost for ground vehicles. Therefore, this study implements the Tightly Coupled Integration (TCI) of NavIC with a low-cost MEMS IMU for ground vehicles. Further, quality NavIC measurements based on C/N0 and elevation angle are chosen to improve the accuracy and robustness. Later, barometer Aided TCI (ATCI) is developed to improve vertical accuracy and applying non-holonomic constraints to improve the standalone MEMS INS performance during outages. Experiments are conducted on real data collected using NavIC/GPS and MEMS IMU devices for urban environments. The results of TCI and ATCI algorithms are analyzed and compared for six modes: i) TCI NavIC/INS, ii) TCI GPS/INS, iii) TCI NavIC/GPS/INS, iv) ATCI NavIC/INS, v) ATCI GPS/INS and vi) ATCI NAVIC/GPS/INS with and without outages. The results show that the ATCI NavIC/INS with three NavIC satellites outperforms TCI NavIC/INS, decreasing the horizontal RMS error from 4.52m to 4.38m and the vertical RMS error from 2.6m to 1.39m. The algorithms and analysis presented in this paper will be useful in developing low-cost navigation solutions for ground vehicles. IEEE