  This paper suggests an integrated navigation system for an unmanned ground
vehicle operating in an unknown cluttered environment. The navigator supports
time-critical mobility making it possible for a mobile robot to reach a target
from the first attempt without the need for a dedicated exploration and mapping
stage. The robot only uses necessary and sufficient egocentric local sensory
data collected on its way to the target. The construction of the navigation
structure revolves around key properties of the harmonic potential field
approach to motion planning. The robots trajectory is well-behaved and
direct-to-the-goal. It contains only the minimum number of detours necessary to
accommodate the sensory data and maintain the robot in a safe, goal-oriented
state. The navigation structure is developed and its theoretical basis is
explained. Extensive experimental validation of its properties and performance
is carried-out using the X80 robotic platform
