Evaluation of flatness error based on two upper points and two lower points

Abstract Exchange algorithms is proposed to solve flatness error evaluation based on the reference planes established by initial two upper points and two lower points. Basic geometries of four points have been analyzed to determine the axis of rotation and rotation point under the condition that the reference planes enclose all points. The simple mathematical expression of the rotation angles is given to establish the new reference planes. The method has been validated to evaluate flatness error effectively using the data from literatures and simulation data.