Ultrasound-Aided Pedestrian Dead Reckoning for Indoor Navigation
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Joined: Sep 2010
12-01-2011, 03:41 PM
Faculty of Computer Science
University of Twente
Enschede, The Netherlands.
Ad hoc solutions for tracking and providing navigation sup- port to emergency response teams is an important and safety- critical challenge. We propose a navigation system based on a combination of foot-mounted inertial sensors and ul- trasound beacons. We evaluate experimentally the perfor- mance of our dead reckoning system in different environ- ments and for different trail topologies. The inherent drift observed in dead reckoning is addressed by deploying ultra- sound beacons as landmarks. We study through simulations the use of the proposed approach in guiding a person along a defined path.
Simulation results show that satisfactory guidance perfor- mance is achieved despite noisy ultrasound measurements, magnetic interference and uncertainty in ultrasound node locations. The models used for the simulations are based on experimental data and the authors’ experience with actual sensors. The simulation results will be used to inform future development of a full real time system. Categories and Subject Descriptors: C.3 [Special-Purpose and Appl
Search and rescue is a challenging and dangerous activ- ity. The environment is often unfamiliar and changing, and visibility can be limited. The rescue operations are time- critical and hence quick decision making support and close coordination within teams are required. Ad hoc tracking and navigation support for emergency response is an impor- tant and safety-critical challenge. A report on theWorcester warehouse fire, in which six firefighters died, highlights the difficulty to keep track of firefighters within the building as one of the major causes for loss of lives , and a report on fatalities in structure fires linked 29 casualties between 1990– 2000 to firefighters becoming lost inside the structure . The application pull for new technologies to address safety of emergency responders is evident in major initiatives in- cluding fire services, fire protection agencies and relevant industries [9, 15, 18] but new research is required to tackle the problem of ad hoc tracking and navigation.
We envisage a system that will aid the search and rescue operation by tracking the responders’ position and inform- ing the incident commander about their location inside the building, and by guiding the responders within the building under poor visibility conditions, thereby helping them reach victims faster and leave the building quickly and safely when necessary.
Inertial navigation or pedestrian dead reckoning (PDR) has been applied to tracking and navigation of first respon- ders with promising results. However the position error in a purely inertial system increases with time and requires correction from external sources. A common practice is to periodically use GPS to correct position estimates . But for most indoor scenarios GPS is unavailable. Embedding sensors or tags into the building fabric to act as landmarks is another solution but this only works in modified buildings and cannot be rapidly deployed in arbitrary locations. We plan to address the problem of positional drift by having the responders themselves deploy landmarks as they progress into an unknown environment. We will specifically use ultrasound nodes. The “breadcrumb” trail thus created can be used to assist the PDR in guiding the responders back to their starting point, or guiding other responders to- wards a victim or an alternative exit. The benefit of the deployed landmarks is particularly interesting when locat- ing multiple responders relative to each other and enables better coordination within teams.
In this work we look at what could be achieved using such a sytem for guiding the user to the required destination. Through simulations we show that PDR alone is not suf- ficient but that by deploying ultrasound sensors along the path the user can be successfully guided to their destination. We also show that this applies even in the presence of noisy ultrasound measurements, magnetic interference and when the locations of the ultrasound nodes are only known with some uncertainty.
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