Temperature Control Strategy For Polymer Hot Embossing System

Polymer has an excellent thermoplastic, light-admitting quality, large variety of types, excellent processability and electric insulation. With these characteristics, polymer is widely used in micro-fluidic devices and micro-optical-electro devices with an increasing demand in market. Hot-embossing is one of the important ways of fabricating polymer micro/nano structures as its simple equipment and capability to achieve high aspect ratio.Temperature is one of the most important control conditions in hot embossing process. It has a significant influence on duplication accuracy, efficiency and draft quality. It is essential to design and implement a high performance temperature controller in order to investigate the hot-embossing technology.According to the mechanism and hardware, the model of the temperature control system is set up. Based on the uncertainty and time-variation of the model parameters, a self-adaptive control strategy is used to get a high control performance. Least-square method combined with graphical method is used to identify the system in order to design a self-adaptive controller, and this method is proved to be an efficient and precious one.Aiming at the demand of the control system, a controller based on self-tuning PID controller is designed. It also makes use of the self-tuning and gain compensation algorithm. The result of system identification is used in tuning the control parameters of the PID controller, the tuning process is independent of control process so that it won't have much influence on other controlled variables in former system; target temperature is assigned to different temperature area to get a corresponding compensation gain; self-tuning algorithm is then used in specifying the transfer point of Bang-Bang control algorithm in order to decrease the error saturation due to the early transmission and the big overshoot due to the late transmission.The control result shows that the system can heat fast and get good accuracy. The overshoot is 0.5℃and the steady-state indication error is±0.2℃. The controller achieves good adaptability and can meet the requirement of the polymer hot-embossing technology.