Pedestrian Dead Reckoning

A localization technique that estimates a pedestrian's position by tracking their movement from a known starting point using inertial sensors (accelerometers and gyroscopes) found in smartphones. The accelerometer detects individual steps through peak detection, while the gyroscope tracks changes in walking direction. In accessibility, PDR is used alongside BLE beacons in indoor navigation systems for blind pedestrians, providing continuous position estimates between beacon readings. PDR helps maintain localization accuracy with fewer beacons, reducing the cost of instrumenting buildings for accessible navigation. A key limitation is that errors accumulate over time (drift), so PDR works best when periodically corrected by other localization sources like beacon signals.