Contour error compensation for NC machine tools based on synchronized measurement of tool-tip motion and error analysis
Kotaro Nagaoka, Atsushi Matsubara, Cefu Hong
Feed drive systems of NC machine tools have several error
factors that are caused by the control and mechanical system.
Those errors prevent improvement of the motion accuracy.
Geometric errors such as straightness error and squareness error
can be compensated for by subtracting the amount of the tool
tip error from the reference position. However, by considering
position reference changes time-by-time during the tracking
control, the compensated result of the actual position becomes
different from the compensating command because of delayed
servo response. In this research, we propose a compensating
method using the expanded two-degrees-of-freedom control
structure. The proposed controller possesses two reference
models; one is for the original position reference and the other
is for the compensating command for the position. The
effectiveness of the proposed method is verified by a numerical
simulation and an experiment.