PARAMETER-ESTIMATION AND MODEL VERIFICATION OF FIRST-ORDER QUASI-STATIC ERROR MODEL FOR 3-AXIS MACHINING CENTERS

This paper is the second in a series of three papers addressing the pr oblem of modeling and compensation of quasistatic machine-tool errors. In the first paper of this set, a general nth order model for the geo metric errors of a machine was developed. The use of such a model as t he basis of an on-line compensation scheme for a machine-tool requires that its parameters be known and changes in their magnitudes (due to mechanical and thermal changes) tracked during its operation. This pap er presents a parameter estimation approach which requires observation of components of the volumetric error of the machine at certain point s in the machine's work space. What is the minimal number of observati ons required and What are the best locations for these observation poi nts in a machine's work space? are questions answered in this paper. T he estimation procedure is discussed for a first order model; however, it generalizes to any order error model. Experimental evidence of the effectiveness of the first order model error model in adequately repr esenting the quasistatic errors of a machine-tool is presented. The ef fectiveness of the parameter estimation approach is also demonstrated. Finally, the use of the model and parameter estimation procedure as t he basis of a compensation scheme that is practicable in a production environment is discussed.