Azimuth estimation of landmarks by mobile autonomous robots using one scanning antenna

摘要

In this article method of estimating the landmark azimuth for the tasks of mobile autonomous robot's navigation in the miss of GPS has been described. There are the several methods for measuring azimuth of targets in traditional radars. All of them assume, that the echo signals from the target differ by some parameters from other signals, for example, by the Doppler shift frequency. The case of a fixed landmark on the background of stationary objects of environment has been analyzed in the article. Wherein, difference determination between the echo signals from the landmarks and the signals reflected from the environment without a landmark will find difficulty. The differences appear when space is scanning by the robot's antenna. As a result, the random process of signal amplitude is appeared at the input of the receiver, in which possible jumps of the amplitude can arise due to the presence of a landmark in the angular range of the antenna directivity pattern. The system of stochastic differential equations has been developed. It allows to determine the probability of the amplitude jump detection, the speed of system operation, the estimates of amplitude and its variance. The landmark azimuth has been determined as the average time of estimating the maximum probability of detecting the amplitude jump multiplied by the scanning speed of the antenna. If the amplitude of the echo signal from the landmark is commensurate with the mean amplitude of the signals reflected from the surrounding area, the errors of measuring azimuth at the selected threshold may be acceptable for practice.