Analyzing error sources and error propagation in an optical scanning 3D triangulation sensor system

Designing fast and high-resolution 3D measurement systems, which are key enabler for the production of the future, is a challenging task, since optical, electrical and mechatronic components with respective specifications need to be integrated. Particularly the resulting measurement uncertainty is of highest interest but can currently only be roughly determined in advance. This paper proposes an uncertainty framework for an optical scanning 3D triangulation sensor system to calculate the influence of the alignment and component specifications on the achievable system performance. This enables to calculate the required uncertainty of each component for given overall uncertainties in the lateral and axial direction. The default and best achievable specification for the manufacturing tolerances of each component, sensor noise and resolution of the detector, and angular resolution of the fast steering mirror used to manipulate the illumination path, are specified in advance. To keep the overall system cost low, the simulation of the optical path is initially performed with the default specifications. By comparing this simulation result with the ideal case, the overall uncertainties and contribution of each component can be determined. If the calculated uncertainties do not meet the requirements, the specification for the component, which contributes most to the uncertainty, can be gradually improved within the maximum specification. The procedure is repeated until the required levels of uncertainty are obtained or until it cannot be further improved since the maximum specifications have been exceeded. This ensures that only the specifications required to achieve the specified uncertainty are tuned.