Integrated Control for Crystal Growth Furnace in Space

Crystal growth furnace in space is a complex system which has the characteristics of pure-delay, strong-coupling and nonlinearity. To meet the high precision temperature control of the crystal growth, a new integrated control software for crystal growth furnace in space is presented. The software has the modules of system identification, parameter tuning, computer-aided simulation and real-time system control. The correlation coefficient and the least squares method are used to accomplish the identification of the process model, the parameters of the controller are tuned by Hooke-Jeeves mode searching method, PID and Feed-forward algorithm are used to control the multi-zone furnace together. To simulate the process of controlling, it can adjust the parameters of the controller. After attaining a result of meeting requirement, it uses the parameters of the controller getting in simulation to control the furnace in real time on line. Through the integrated control software, we achieve batter results, when the three zones temperatures rise to 700ºC, the stabilities of the three zones are all less than ± 0.3ºC. The strong-coupling among these three zones are suppressed clearly. The basic principle, powerful functionality, attractive features are discussed in details. The application of this software shows its effectiveness.