Over the past decade, wireless sensor networks have advanced in terms of hardware design, communication protocols, and resource efficiency. Recently, there has been growing interest in mobility, and several small-profile sensing devices that control their own movement have been developed. Unfortunately, resource constraints inhibit the use of traditional navigation methods because these typically require bulky, expensive sensors, substantial memory, and a generous power supply. Therefore, alternative navigation techniques are required. In this paper, we present a navigation system implemented entirely on resource-constrained sensors. Localization is realized using triangulation in conjunction with radio interferometric angle-of-arrival estimation. A digital compass is employed to keep the mobile node on the desired trajectory. We also present a variation of the approach that uses a Kalman filter to estimate heading without using the compass. We demonstrate that a resource-constrained mobile sensor can accurately perform waypoint navigation with an average position error of 0.95 m.