Abstract-This paper introduces a positioning system for walking rior mapping of buildings and improved situation awareness persons, called "Personal Dead-reckoning" (PDR) system. The PDR for soldiers. system does not require GPS, beacons, or landmarks. The system is therefore useful in GPS-denied environments, such as inside buildAs mentioned, our proposed PDR system does not require ings, tunnels, or dense forests. Potential users of the system are mili-GPS. This is an important distinction, since GPS is not availtary and security personnel as well as emergency responders. able indoors. Furthermore, GPS is unreliable under dense foliThe PDR system uses a 6-DOF inertial measurement unit (IMU) age, in so-called "urban canyons," and generally in any enviattached to the user's boot. The IMU provides rate-of-rotation and ronment, in which a clear view of a good part of the sky is not acceleration measurements that are used in real-time to estimate the available. location of the user relative to a known starting point. In order to reduce the most significant errors of this IMU-based system caused There are some other approaches to personal position estiby the bias drift of the accelerometers we implemented a technique mation without GPS. Typically, these other systems require known as "Zero Velocity Update" (ZUPT). With the ZUPT techexternal references, also called "fiducials,"' which in most nique and related signal processing algorithms, typical errors of our cases must be installed in the work space at precisely sursystem are about 2% of distance traveled for short walks. This typiveyed locations before the system can be used. This installacal PDR system error is largely independent of the gait or speed of tion is time consuming and expensive, and in the cases of the user. When walking continuously for several minutes, the error emergency response or urban combat completely unfeasible. Earlier versions of our system used an impractically large IMU. In fields [3] , which may be undesirable in security-related applithe most recent version we implemented a much smaller IMU. This cations. Generally, fiducial-based systems perform well and paper discussed specific problems of this small IMU, our measures are able to provide absolute position and orientation in realfor eliminating these problems, and our first experimental results time. If the application permits the installation of fiducials with the small IMU under different conditions. ahead of time, then these systems have the significant advan-
The main idea of PDR techniques is to integrate inertial measurements with Zero Velocity Update (ZUPT) constraints to reduce errors REF .
Personal Dead-reckoning System for GPS-denied Environments
2007 IEEE International Workshop on Safety, Security and Rescue Robotics
2007 IEEE International Workshop on Safety, Security and Rescue Robotics
Computer Science