Visibility analysis and synthesis for assembly fixture certification usingtheodolite systems

In automotive sheet metal assembly part positioning and clamping is accompl ished by fixtures consisting of fixture elements, such as pins and blocks. The locations of these elements are determined during process design and ne ed to be certified during the construction and installation of an assembly line. Usually, theodolite systems are used to certify the locations of thes e elements by measuring the trihedron points on the fixture elements. Howev er, no systematic method exists for the selection and placement of measurin g systems. As a result, the current certification procedure is very time-co nsuming and is prone to error, This paper presents an algorithm for the opt imal setup and placement of theodolite systems based on visibility analysis and synthesis. For a given tooling fixture, the visibility map is introduc ed to represent the set of potential measurement locations when a number of fixture elements are lo be measured. From the set of potential measurement locations, an optimal setup will be selected based on minimizing the numbe r of theodolite heads by optimally locating these theodolites. This approac h will minimize measurement setups and improve measurement accuracy.