Improvement of Controller and Variable Cycle Design for a Cycle-to-Cycle Plastic Reheat System

S. Yang and B. Boulet (Canada)


Cycle-to-cycle control, industrial automation, repetitive control, thermoforming.


In this paper, we improve the cycle-to-cycle control scheme for plastic sheet reheat in a thermoforming oven originally proposed in the paper “Cycle-to-Cycle Control of the Thermoforming Reheat Process” [1]. Two types of improvements are implemented. A new linear converter and a variable gain Kp are introduced to improve performance with the same system structure. Furthermore, the idea of variable cycle length is considered in the design to meet the requirements of industrial production. According to the simulation results, the proposed improvements prevent unnecessary adjustment cycles in which the sheet is wasted by providing more consistent end-of-cycle sheet and heater temperatures. The functionality of variable cycle length greatly shortens the reaction time of the system.

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