Validation through HIL of an MPC regulator for thermoforming applications

Thermoforming is a process in which a sheet of thermoplastic material is heated, formed with a mould, and successively cooled to harden a product with a desired shape. During the heating phase, the sheet is heated up to the thermoplastic softening temperature by one or two benches of infrared radiative lamps called heaters. If the material sheet is heated and softened not properly, it can not be formed adequately, resulting in a scrap product. In this paper a sheet heating model is validated with a finite element analysis for quartz tube IR heaters. Quartz tubes are faster and more reactive than ceramic heaters, enabling the use of more flexible power regulation strategies. Hence, the validated model is uploaded over a HIL real-time testbench for rapid control prototyping, enabling the development of a model predictive controller for the optimal online regulation of the heating stage in the thermoforming process.