Autocollimation System with Extended Distance for Angular Rotation Measurements in SEMS Applications

Problem statement: When working with large-scale objects a group of robots is efficient to use. Robots may be combined into SEMS for synchronous operations like welding, cutting or moving objects. Such operations imply restrictions on the tool’s angular positioning precision. To measure the angular rotation of controlled elements with high accuracy, autocollimation systems can be applied. The systems currently available on the market, do not possess long working distance, therefore, the problem is relevant. Purpose of research: This study focuses on the special type of an autocollimation system reflector: mirror tetrahedron with one of flat surfaces replaced with the cylindrical ones. This type of reflector has a number of advantages over other trihedral elements with a flat angle between two surfaces deviating from 90°; or flat mirrors; or a right-angle prism, which provides an extended measurement range and working distance. Results: Mathematical study shows that the autocollimation system proposed has the measurement range reaching ± 20°, which is more than ten times increase in comparison with its analogues—Taylor Hobson Ultra Autocollimator: ± 30′, Davidson Optronics D-638 Autocollimator: ± 20′, Opto Sigma TM-2070: ± 70′). The working distance can be extended to 30m. Practical significance: The autocollimation system described in the paper can be applied for a group of robots, operating on a large-scale object. For instance, it can be welding or cutting tool positioning. These tools are placed on the moving parts of SEMS, and it is critical for the initial position of the tool to be determined with high accuracy. The autocollimation system can ensure high precision for angular positioning of the SEMS moving elements, which are placed at different distances from the base.