  Vehicle localization in highway tunnels is a challenging issue for autonomous
vehicle navigation. Since GPS signals from satellites cannot be received inside
a highway tunnel, map-aided localization is essential. However, the environment
around the tunnel is composed mostly of an elliptical wall. Thereby, the unique
feature points for map matching are few unlike the case outdoors. As a result,
it is a very difficult condition to perform vehicle navigation in the tunnel
with existing map-aided localization. In this paper, we propose tunnel
facility-based precise vehicle localization in highway tunnels using 3D LIDAR.
For vehicle localization in a highway tunnel, a point landmark map that stores
the center points of tunnel facilities and a probability distribution map that
stores the probability distributions of the lane markings are used. Point
landmark-based localization is possible regardless of the number of feature
points, if only representative points of an object can be extracted. Therefore,
it is a suitable localization method for highway tunnels where the feature
points are few. The tunnel facility points were extracted using 3D LIDAR.
Position estimation is conducted using an EKF-based navigation filter. The
proposed localization algorithm is verified through experiments using actual
highway driving data. The experimental results verify that the tunnel
facility-based vehicle localization yields precise results in real time.
