Calibration of Theodolites.

In a previous paper, a system conceived for obtaining high accuracy measurements of robot positions was described. This system employs two (or more) theodolites that are used to determine by triangulation the location of the target attached to the robot. Typical robot working volumes are on the order of cubic meters, thus measurements to a relative error of 1 : 10 sup 5 require knowledge of all system components to micron accuracies. Essentially, complete kinematic models of the theodolites must be used and the simplifying assumptions of ideal planar geometry used in conventional surveying must be abandoned. The original paper described the system concept and described algorithms for triangulation and determination of the baseline, the six degree of freedom transform, between two theodolites. This paper will describe the method for determining the geometric parameters in the theodolite model completing the description of the system. Simulations and a calibration experiment performed on a theodolite are used to illustrate algorithm performance.