反重力铸造液面加压系统的自调整比例因子模糊控制

Fuzzy Controller with Self-Tuning Scaling Factors for Counter Gravity Casting Filling System

液面加压系统担负着控制合金液上升、充型、结壳、保压等重要任务,其控制精度对反重力铸造铸件的质量具有重要影响。常规模糊控制仅用一组恒定不变的输入、输出比例因子,难以保证被控全过程处于最佳控制状态,在反重力铸造液面加压控制系统中的应用受到限制。将模糊控制中输入与输出比例因子在不同压力偏差范围内进行分段调整:压力偏差较大时,增大输出比例因子,加快动态响应;压力偏差较小时,增大输入比例因子,减少稳态误差。试验结果表明,该液面加压控制系统具有较好的静态性能和鲁棒性,实际压力曲线的跟踪性能良好,升液、充型阶段压力平稳,满足了反重力铸造的控制要求。

Filling system plays an important role in the process control at the stages of molten metal lifting, filling, freezing and pressure maintenance in counter gravity casting （CGC）. Casting quality is affected by control precision of the system to a great extent. Input and output scale factors of conventional fuzzy controller are static and it＇s hard to ensure good state of the system, so application of the fuzzy technology is restricted on the filling system of CGC .The input and output scale factors of fuzzy controller are tuned by range in different errors in this paper, when the error of pressure is large, the output scale factor is increased to speed up dynamic response; in another condition, the input scaling factor is increased in order to reduce steady state error. Experimental results show that, good steady-state precision and well robust has been got by this method. Lifting and filling stage is steady and tracking property is very. good, which indicate that the fuzzy controller with self-tuning scaling factors could be used in CGC.