A precision automatic vehicle location system for use in construction automation

A prototype automatic position and control system is being developed for use in position-sensitive construction processes. The system, operating in the 400-450 MHz UHF band, provides three-dimensional location information within the construction site. The three-dimensional data from the system are available in near real time as input to a CAD database of the construction project. The vehicle to be located is equipped with a spread spectrum beacon transmitter and its position is found using a hyperbolic phase ranging system. Several methods of improving the accuracy of the system in the presence of multipath interference have been investigated. A computer simulator has been developed using Monte Carlo analysis to predict system error performance and thus evaluate the effectiveness of various multipath defeating techniques. Antenna diversity and receiver diversity have been found to improve dramatically the overall accuracy. Weighting techniques are used to reject data contaminated with large multipath errors.<>