Active Markov Localization for Mobile Robots Dieter Fox To navigate reliably in indoor environments, a mobile robot must know where it is. Over the last few years, there has been a tremendous scientific interest in algorithms for estimating a robot's location from sensor data. Most existing localization approaches are passive, i.e., they do not exploit the opportunity to control the robot's effectors during localization. In this talk we will introduce an active localization approach based on a geometric variant of Markov localization. The approach provides rational criteria for (1) setting the robot's motion direction (exploration), and (2) determining the pointing direction of the sensors so as to most efficiently localize the robot. Furthermore, we will propose another extension of Markov localization which significantly improves the robustness of position estimation even in densely populated environments. The experiments given in this talk demonstrate that our implementation of Markov localization in combination with these extensions is able to (1) robustly estimate the position of a mobile robot even in densely populated environments, (2) detect localization failures, and (3) autonomously (re-)localize a mobile robot from scratch.