Working towards scenario-based evaluations of first responder positioning systems

• It is indeed a challenge to create a highly-accurate positioning system for GPS-denied environments, such as indoors and in dense urban environments, or during harsh electromagnetic interference conditions. A priori information concerning for instance building layouts, magnetic field or image information obtained through extensive pre-surveying, or pre-installed infrastructure (e.g. RFID-units or WiFi base-stations), will not be available in many scenarios. However, a reliable positioning system with seamless outdoor and indoor coverage would increase the safety of first responders significantly. Such a system should be lightweight, small, power efficient and relatively inexpensive, yet still provide a high accuracy during extended indoor operations. A camera-based reference system which provides reliable ground truth data in relatively large indoor environments, using a minimum of pre-installed infrastructure, has been designed and evaluated. The reference system will be used to evaluate how errors in for instance foot-mounted inertial navigation systems (INS) or pedestrian dead-reckoning systems grow over time. Loop-closure error analysis is not sufficient for the evaluations of INS since the shape of the trajectory influences the position error. A low-cost, lightweight reference system is often needed when attempting to evaluate the performance of high-accuracy positioning systems during scenario-based exercises. In this work ARToolKitPlus have been used to estimate the camera position relative to a set of pre-installed visual markers. Experiments performed in a very accurate VICON lab show that the toolkit provides sufficient localization accuracy for the intended accuracy. The error is normally less than 0.1 meters at a distance of 1.75 meters from the marker. When the camera-based reference system is used to evaluate a foot-mounted INS, a number of checkpoints with markers will be passed several times. This way the error growth rate in the IMU-based system can be evaluated. Preliminary results from measurements performed with foot-mounted INS are provided and compared with the reference system. Practical considerations concerning sensor fusion of foot-mounted INS with additional sensors, such as magnetometers, barometric altimeters and GPS, will also be provided and particular needs for continued research are pointed out.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Elektroteknik och elektronik -- Signalbehandling (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Electrical Engineering, Electronic Engineering, Information Engineering -- Signal Processing (hsv//eng)

Publikations- och innehållstyp

ref (ämneskategori)

kon (ämneskategori)