Automatic correction of past position errors for location and inventory tracking

Abstract

A method is provided for calibrating past position estimates from a positioning system that provides real-time position estimates of a mobile object. The method first stores the real-time position estimates, which as time goes by become past position estimates and naturally form a first past trajectory depicting the past movement of the mobile object. Subsequently, a calibrated past trajectory is determined, which includes calibrated past position estimates that correspond to the same time instances as the past positions in the first past trajectory. When real-time positions have low qualities, this method calibrates them at a later time by using (higher-quality) real-time positions both before and after them. Errors in the past positions are then corrected based on the calibrated past trajectory. When used with event detectors that indicate inventory transactions, this method can correct position errors associated with inventory events so as to improve the performance of inventory tracking.