On-line estimation of time-variant thermal load applied to machine tool structures using a s-domain inverse solution

Thermal deformation of machine tools is of prime concern due to its signifi cant effect on machining errors. To compensate for residual thermal errors, the control system has to incorporate an inverse heat conduction problem I HCP solver to estimate the transient heat input to the structure in real-ti me. The limitations of available IHCP solutions to applications involving r eal-time state estimation of complex, multi-dimensional structures are iden tified. A new s-domain IHCP solution has been developed to resolve these pr oblems and to ensure stability of the solution without using future data. A n accelerated inverse numerical Laplace transformation procedure is develop ed to improve the computational efficiency of the solver. Analysis of resul ts showed the proposed method to be inherently stable and that the random f luctuation in the temperature measurements is considerably attenuated by th e numerical nature of the solution. The results also show that the computat ional time has been improved by at least one order of magnitude over availa ble methods, without compromising the accuracy and stability requirements. Due to the generalized nature of the formulation and the solution algorithm , this method can readily be applied to all classes of machine tools withou t any further developments by the end user. (C) 1999 Elsevier Science Ltd. All rights reserved.