A new approach to tolerance analysis based on tracking local coordinate systems

Abstract

Among current approaches to tolerance analysis in three-dimensional space, the Matrix method based on rigid body kinematics is widely used. However, this method ignores the impact a tolerance feature (TF) may get from the variations of TFs before it, therefore showing its demerits when applied to long and complex dimension chains. For this reason, this paper puts forward a new tolerance analysis model where two local coordinate systems are built at each TF: a nominal one based on the datum of current TF and a tracking one based on the variations of the prior TFs. Then the variations of all TFs along the dimension chain are accumulated. Compared with the Matrix method, the new approach generates results with more accuracy and higher efficiency.

Keywords

• matrix method
• tolerance analysis
• tracking local coordinate system
• nominal local coordinate system
• tolerance accumulation