Optimal sensor location design in automated coordinate checking fixtures

This article proposes a method for the optimal design of sensor locations in an automated coordinate checking fixture (CCF) used for at-machine assessments of the dimensional accuracy of manufactured automotive space frame components, From coordinate measurements obtained by the sensors, shape parameters of a formed space-frame extrusion are estimated. There are two main issues to be addressed, namely, the optimal number of sensors to be used and the best locations of these sensors. These issues are resolved with the use of two matrices: the Fisher information matrix to account for sensor error and the prediction matrix to consider influence of each sensor, The optimal design method also addresses a unique feature of optimal selection of fixture locators for part localization. An example is given to illustrate the successful use of this method for a simple bent tube component.