Enhancing Ultrasonic Robot Positioning Accuracy with Parallel Codes Acquisition of Composite Pseudo-noise Sequences

摘要

Ultrasonic robot positioning with composite codes acquisition is investigated in this paper. The indoor robot positioning system was previously examined with single Pseudo-noise (PN) signal sequence. In views of correlation acquisition, the longer the code acquisition time, the longer the path estimation distance, and the worse the robot positioning accuracy. Under comparable period lengths, acquisition time for composite PN codes can be shorter than that of pure PN codes, thus can largely enhance the robot positioning accuracy. In the devised system configuration, three transmitters continuously send out their ultrasonic coding signals to the robot receiver. The robot evaluates its current position by measuring time difference of arrival (TDOA) among the three paths. Optimization algorithms can then be undertaken over the measured TDOAs to obtain more accurate robot location. Based on correlation characteristics of the proposed composite PN codes, we finally make a general analysis on codes acquisition time to the robot positioning accuracy.