Optimal pole adaptation and control in thermal rapid prototypingapplications

摘要

This article addresses thermal feedback control ofdistributed-parameter, dynamic nonlinear heat transfer phenomenainvolved in rapid prototyping processes. These mechanisms are capturedin a numerical simulation of the thermal field generated during suchoperations. For the design of a multivariable controller, a linearizedstate-space model of lumped temperatures and heat inputs on a grid isestablished, and its parameters are identified in-process. Thecontroller gains are adapted in real time through optimization of theclosed-loop pole placement by a simplex method, minimizing the distanceof the actual from the desired system eigenvalues. This control strategyis validated both by simulation and in the laboratory, where temperaturefeedback from an infrared camera is used to modulate the power andmotion of a plasma-arc torch in laminated object manufacturing