Hybrid Controller for Tracking Systems

Abstract

This chapter presents a hybrid controller which can be used with tracking systems especially with laser tracker systems. The controller consists of an analog PI controller and a microcontroller. Special features like e.g. an absolute distance measurement technique or a search algorithm in case of beam loss is implemented. With the help of the distance measurement the controller gain is adjusted automatically by digital potentiometers. Due to the usage of standard elements it is cost effective and easy to use. The controller is designed for working with an interferometer in a laser tracker system but can also act as an autonomous system because of the integrated absolute distance measurement technique. A distance of about eight meters between the tracker unit and the reflector is easily achieved in experiment without static tracking errors. Furthermore, the lateral offset of the laser beam does not exceed a quarter of the beam diameter and thus guarantees stable interferometer functionality.