Calibrating Non-GPS Navigation Sensors for Use in Robot Localization

Michael A. Zmuda and Yu T. Morton

Abstract:	Localization is the process of knowing an agent’s location at any given time. Global Positioning Systems (GPS) can provide a robot’s position directly. Since indoor settings, interference, or urban multi-path environments can prevent GPS from being an option, developing non-GPS localization techniques can be useful for autonomous robots. A wide range of other sensors, such as lidars, stereo vision, and RF sensors, have been used for navigation and localization purposes. One difficulty with implementing such systems is that the error-model for the sensor’s measurement is unknown, or the sensor behaves erratically in different environments. This paper presents an approach to take a new sensor with unknown characteristics and quickly insert it into a system to perform robot localization. The work described here measures the strength of RF signals from transmitters placed at known locations. With the proper models, signal strength can be used to infer the distance between a transmitter and the receiver. Location ambiguities are partially resolved using multiple transmitters. To use a new RF transmitter and receiver with unknown characteristics, our approach requires the user to systematically collect sample measurements using the sensor. Since only a sparse set of measurements is typically collected, we model the sensor’s characteristics in order to predict measurement values in situations not observed in the data collection process. The collected data is analyzed to develop these probabilistic models, which are then installed on a moving robot to help determine its location. Experiments are conducted using the Cross Bow MICA2 transmitter and receiver. Using the known locations of two transmitters, and the inferred model of the signal strength, robot localization with accuracy about 10cm is obtained.
Published in:	Proceedings of the 2007 National Technical Meeting of The Institute of Navigation January 22 - 24, 2007 The Catamaran Resort Hotel San Diego, CA
Pages:	1137 - 1146
Cite this article:	Zmuda, Michael A., Morton, Yu T., "Calibrating Non-GPS Navigation Sensors for Use in Robot Localization," Proceedings of the 2007 National Technical Meeting of The Institute of Navigation, San Diego, CA, January 2007, pp. 1137-1146.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In