Accuracy Enhancement of a Hexapod Machine Tool

The object of this research is to analyze the error sources of thehexapod machine and develop strategies to enhance its accuracy. Themost significant error sources are identified as the geometric errors,thermal errors and errors due to finite stiffness. Subsequently,considering major inaccuracy factors related to the manufacture,geometry, and kinematics of such machines, a mathematical error ispresented based on volumetric error analysis. In order to understandthe character and propagation of errors on the Hexapod machine tool,sensivity analysis is used to investigate the contribution of the errorsources on accuracy and an error analysis system that graphicallypresents the total error distribution is developed. The developed errorcompensation system is based on the measurement and modeling of thebehavior of the machine tool. It is composed of an interpolationalgorithm based on shape functions for error prediction and a recursivesoftware compensation procedure. In addition, an automatic NC codeconverting software was developed so that the developed system could beapplied to practical machine with Hexapod machines.