Precise Calibration of Pseudolite Positions In Indoor Navigation System

摘要

Pseudolite is a kind of electronic device, which transmitsrnalmost the same signal as GPS satellites except that it isrnfixed on the ground. The advantage of using pseudolite inrnoutdoor navigation system is an improvement ofrnpositioning accuracy and integrity, which is from thernaugmentation to GPS satellite geometry.rnNowadays, one of potential pseudolite application fieldrnis the indoor navigation system. As like outdoorrnnavigation system, which uses GPS satellite signals,rnthere are also similar error sources in indoor navigationrnsystem, which uses pseudolite. The main error sourcesrnare multipath and pseudolite position errors which isrnsimilar to the ephemeris error in outdoor navigationrnsystem. The pseudolite position error can be eliminatedrnif and only if the positions of pseudolites are exactlyrncalibrated. Otherwise, there will be bias type positioningrnerrors. Therefore, the calibration of pseudolite positionsrnis one of the most critical factors which influence thernindoor navigation accuracy.rnWith the above motivation, efforts were made torndevelop a efficient procedure to calibrate the pseudoliternpositions precisely for the indoor navigation system. Therndevloped procedure uses only 5-6 user’s position set,rnwhich is optimized for the guessed pseudoliternconstellation in the calibration loop. So the key point ofrnthis procedure is to determine that how many user’srnposition should be used and where they should bernplaced.rnIn simulation, we used 6-pseudolite indoor navigationrnsystem. And the results show that all the pseudoliternpositions can be calibrated within 1-2cm if we use thernoptimized user’s position set.