Determination of Aiming Error with Automatic Theodolites

Abstract

Automatic theodolites use the systems for automatic aiming, eliminating the operators’ error. This error is dominant, meaning that it remains in the error budget. For that reason, the automation of this process reduces the total error of angle measurements. However, due to their construction and performance, those systems introduce the error acting like the aiming error. In our study case, we tested two classes of instruments with the automatic aiming systems, with 0.5′′ and 3′′ accuracy, respectively. The experiment comprises measurements of a number of horizontal and vertical directions, variating types of the prisms and distances to them, in order to randomize other error sources. Comparison of the measurements taken in real conditions with the values given by the manufacturers, after the statistical analysis, show that the error of automatic aiming depends on the environmental conditions and the prism type. In the case of high accuracy demands, further attention should be paid on the preparation of a measuring campaign, in order to reduce this effect.