Model predictive control of incremental sheet forming for geometric accuracy improvement

Incremental sheet forming (ISF) is a highly flexible sheet forming process, but it suffers from poor geometric accuracy. This paper presents a feedback control strategy using model predictive control (MPC) to obtain improved geometric accuracy in ISF. Based on the incremental deformation mechanism of ISF, a novel model for shape state prediction has been proposed. The step depth of the toolpath was optimised based on shape state feedback during the forming process. Two different cases were studied for experimental validation of the developed control strategy. Comparisons between formed parts in both controlled and uncontrolled ISF processes were implemented in terms of cross-sectional profiles, formed depth at the bottom area and global deviation distribution. Results show that the geometric accuracy in ISF with feedback control has been greatly improved at the bottom area of the formed parts compared with a standard ISF approach without control. Improved geometric accuracy has been achieved on the wall of the parts as well.