Vehicle Position Determination - Using Markers and Speed Reports

摘要

The use of cell phones as data-collection devices for obtaining automotive traffic-flow information provides the potential for instrumenting large numbers of vehicles at a minimal cost. Effectively incorporating cell phones as sensors in traffic-flow collection systems requires a clear understanding of the accuracy of the data produced by each cell phone. Previous experiments and field trials have typically measured the accuracy of cell-phone data at large - comparing all of the collected cell-phone reports across a given segment of the road against data obtained with traditional techniques such as loop detectors. The approach that we take in this research differs by comparing each individual cell-phone report with the known position of the vehicle at the time of the report. This paper describes the technique we used for accurately determining the actual speed and position of a vehicle at any given point in time during a test trip by using published map data, speed reports from the vehicle itself, position reports from a hand-held GPS unit with an external antenna, and operator inputs.