Over the past decade, wireless sensor networks have
advanced in terms of hardware design, communication protocols,
resource efficiency, and other aspects. Recently, there has been
much focus on mobile wireless sensor networks, and several
small-profile sensing devices that are able to control their own
movement have already been developed. Unfortunately, resource
constraints inhibit the use of traditional navigation methods,
because these typically require bulky, expensive, and sophisticated
sensors, substantial memory and processor allocation,
and a generous power supply. Therefore, alternative navigation
techniques are required. In this paper we present TripNav, a
localization and navigation system that is implemented entirely
on resource-constrained wireless sensor nodes. Localization is
realized using radio interferometric angle of arrival estimation,
in which bearings to a mobile node from a small number of
infrastructure nodes are estimated based on the observed phase
differences of an RF interference signal. The position of the
mobile node is then determined using triangulation. A digital
compass is also employed to keep the mobile node from deviating
from the desired trajectory. We demonstrate using a real-world
implementation that a resource-constrained mobile sensor node
can accurately perform waypoint navigation with an average
position error of 0.95 m.