Estimating the 3D-position from time delay data of US-waves:: experimental analysis and a new processing algorithm

This paper analyzes the main sources of error in an ultrasonic 3D position measurement system: these include shadowing of some of the receivers, wave interference, air turbulence and the effect of the wind. Some of these phenomena appear as outlier noise in the measurements, against which conventional statistical methods do not give good results. A new algorithm is suggested which improves precision and robustness, by taking advantage of the redundancy in the number of measurements and the use of a modified trimmed median (MTM) filter. The performance of the new technique is demonstrated experimentally in a robotic 3D positioning system, achieving an error inferior to 1 mm in a 3 m x 3 m x 3 m work area. (C) 2002 Published by Elsevier Science B.V.