Abstract: Abstract： This paper proposed a novel highprecision, robust and fast spatial straightness error evaluation algorithm called 3 points highprecision fast algorithm (3PHFA) to deal with the problem of low precision and low efficiency when evaluating spatial straightness errors. With reference to the related national standard for construction of mathematics models, the algorithm mainly includes 3DLSA fitting, space coordinate translation, coordinate projection, and determining minimum circumscribed circle (MCC), which can determinate the minimum cylindrical surface (MCS). By adding the highly effective search algorithm to the 3DLSA algorithm, it almost improves the evaluation accuracy by 20% in less than 1 second. Compared with other evaluating algorithms, the 3PHFA has the advantages of high efficiency and accuracy, and better robustness. It is applicable to the realtime processing system such as coordinate measuring machine (CMM), and has a good practical value for evaluating machine parts.

Key words: Key words： spatial straightness, 3 points highprecision fast algorithm(3PHFA), minimum circumscribed circle(MCC), error evaluation