Raj Madhavan Gamini Dissanayake Hugh F. Durrant-Whyte Autonomous Underground Navigation of an LHD Using a Combined ICP and EKF Approach. 3703-3708 1998 conf/icra/1998 ICRA db/conf/icra/icra1998-4.html#MadhavanDD98 http://dx.doi.org/10.1109/ROBOT.1998.681413