Today people increasingly have the opportunity to opt-in to "usage-based" automotive insurance programs for reducing insurance premiums. In these programs, participants install devices in their vehicles that monitor their driving behavior, which raises some privacy concerns. Some devices collect fine-grained speed data to monitor driving habits. Companies that use these devices claim that their approach is privacy-preserving because speedometer measurements do not have physical locations. However, we show that with knowledge of the user's home location, as the insurance companies have, speed data is sufficient to discover driving routes and destinations when trip data is collected over a period of weeks. To demonstrate the real-world applicability of our approach we applied our algorithm, elastic pathing, to data collected over hundreds of driving trips occurring over several months. With this data and our approach, we were able to predict trip destinations to within 250 meters of ground truth in 10 of the traces and within 500 meters in 20 of the traces. This result, combined with the amount of speed data that is being collected by insurance companies, constitutes a substantial breach of privacy because a person's regular driving pattern can be deduced with repeated examples of the same paths with just a few weeks of monitoring.
A Kalman filter has been developed to integrate the three positioning systems (differential odometer dead reckoning, map matching, and Global Positioning System or GPS) used in the Automatic Vehicle Location System (AVL 2000) being designed and developed in the Department of Surveying Engineering at the University of Calgary. The system is being targeted for on road applications and incorporates a digital map. The filter has been designed to take into account uncertainties via covariance matrices. In wide-open spaces GPS positioning will dominate, while in zones where the GPS signal is obstructed, dead reckoning will be used as interpolation between GPS position fixes. Simulation studies and covariance analyses have been performed on a test route located in a sector of the city of Calgary. > This paper describes the features of an extended Kalman filter algorithm designed to support the navigational function of a real-time vehicle performance and emissions monitoring system currently under development. The Kalman filter is used to process global positioning system (GPS) data enhanced with dead reckoning (DR) in an integrated mode, to provide continuous positioning in built-up areas. The dynamic model and filter algorithms are discussed in detail, followed by the findings based on computer simulations and a limited field trial carried out in the Greater London area. The results demonstrate that use of the extended Kalman filter algorithm enables the integrated system employing GPS and low cost DR devices to meet the required navigation performance of the device under development. A major problem in map building is due to the imprecision of sensor measures. In this paper we propose a technique, called elastic correction, for correcting the dead-reckoning errors made during the exploration of an unknown environment by a robot capable of identifying landmarks. Knowledge of the environment being acquired is modelled by a relational graph whose vertices and arcs represent, respectively, landmarks and inter-landmark routes. Elastic correction is based on an analogy between this graph and a mechanical structure: the map is regarded as a truss where each route is an elastic bar and each landmark a node. Errors are corrected as a result of the deformations induced from the forces arising within the structure as inconsistent measures are taken. The uncertainty on odometry is modelled by the elasticity parameters characterizing the structure.