基于PWA融合模型的注塑过程保压段建模及控制策略

doi:10.11949/0438-1157.20191539

化工学报 ›› 2020, Vol. 71 ›› Issue (3): 1103-1110.DOI: 10.11949/0438-1157.20191539

基于PWA融合模型的注塑过程保压段建模及控制策略

黄耀波(),刘佳新,徐祖华(),赵均,邵之江

浙江大学控制科学与工程学院，工业控制技术国家重点实验室，浙江杭州 310027

收稿日期:2019-12-18 修回日期:2019-12-26 出版日期:2020-03-05 发布日期:2020-03-05
通讯作者: 徐祖华
作者简介:黄耀波（1994—），男，硕士研究生, 21432009@zju.edu.cn
基金资助:
国家重点研发计划项目(2017YFB0603703);NSFC-浙江两化融合联合基金项目(U1509209)

Modeling and control strategy for packing-stage of injection molding process based on PWA fusion model

Yaobo HUANG(),Jiaxin LIU,Zuhua XU(),Jun ZHAO,Zhijiang SHAO

National Laboratory of Industrial Control Technology, College of Control Science and Engineering, Zhejiang University, Hangzhou 310027, Zhejiang, China

Received:2019-12-18 Revised:2019-12-26 Online:2020-03-05 Published:2020-03-05
Contact: Zuhua XU

摘要/Abstract

摘要：

注塑过程是典型的批次过程，由注射、保压、冷却等阶段构成。保压段是决定制品质量的一个重要阶段，且具有较大的非线性和时变性。分段仿射(piece-wise affine, PWA)模型能够有效描述保压段的特性，但是PWA模型硬切换方式会导致输出跳变问题，因此提出一种基于时间划分的PWA融合模型，在子模型切换过程中引入切换区间，通过线性加权方法进行模型融合，并采用基于分离最小二乘的辨识方法进行参数估计。在此基础上，设计了基于内模整定的多模型PID控制方法。注塑机实验结果表明了算法的有效性。

关键词: 注塑过程, PWA融合模型, 分离最小二乘, 多模型PID控制

Abstract:

The injection molding is a typical batch process and consists of three stages: filling, packing-holding and cooling. Packing-holding is an important stage to determine product quality and has obvious nonlinear and time-varying characteristics. Piece-wise affine (PWA) model can effectively describe the dynamics of packing-holding stage, but the hard switching of PWA model will lead to the output jump problem. Therefore, we propose a novel time-partitioned PWA fusion model, in which the switching regionis introduced between adjacent sub-models and model fusion is realized by linear weighting method. Then, an identification algorithm based on separable nonlinear least-squares is developed to estimate model parameters. Based on this, a multi-model PID control method based on internal model tuning is designed.Experimental results of injection molding machine show the effectiveness of the algorithm.

Key words: injection molding process, PWA fusion model, separable least-squares, multi-model PID control

中图分类号:

TP 13

黄耀波, 刘佳新, 徐祖华, 赵均, 邵之江. 基于PWA融合模型的注塑过程保压段建模及控制策略[J]. 化工学报, 2020, 71(3): 1103-1110.

Yaobo HUANG, Jiaxin LIU, Zuhua XU, Jun ZHAO, Zhijiang SHAO. Modeling and control strategy for packing-stage of injection molding process based on PWA fusion model[J]. CIESC Journal, 2020, 71(3): 1103-1110.

图/表 11

图1 线性加权权重函数

Fig.1 Weighting function of linear weighting

图2 辨识算法整体流程

Fig.2 Process of identification algorithm

图3 MDS算法的旋转、扩展、收缩

Fig.3 Rotation, expansion and shrinkage of MDS

图4 多模型PID控制器示意图

Fig.4 Diagram of multi-model PID controller

图5 注塑机外观图

Fig.5 Appearance of injection molding machine

图6 标称轨迹附近GBN测试r(t)—设定值；y(t)—保压压力；u(t)—阀门开度；t—采样时刻

Fig.6 GBN test near nominal trajectory

表1 阶次为1的PWA融合模型切换区间及损失函数值

Table 1 Switching intervals and loss function for order=1

区间个数	次序					J
区间个数	1	2	3	4	5	J
1	328/329					0.9067
2	136/154	329/329				0.9002
3	136/154	329/329	573/580			0.8975
4	143/191	216/218	404/433	500/503		0.8819
5	136/154	278/278	318/320	404/434	500/503	0.8862

图7 PWA融合模型不同结构的CIC值

Fig.7 CIC criterion for different structure of PWA fusion model

图8 PWA融合模型的切换区间

Fig.8 Switching intervals of PWA fusion model

表2 多模型PID控制器参数

Table 2 Parameters of multi-model PID controller

PID参数	PWA子模型
PID参数	1	2	3	4	5
$K c$	0.7250	0.7607	0.6497	0.6390	0.5930
$τ i$	0.0904	0.1168	0.0892	0.0959	0.0855
$τ d$	0.0457	0.0829	0.0489	0.0800	0.0480

表2 多模型PID控制器参数

Table 2 Parameters of multi-model PID controller

PID参数	PWA子模型
PID参数	1	2	3	4	5
$K c$	0.7250	0.7607	0.6497	0.6390	0.5930
$τ i$	0.0904	0.1168	0.0892	0.0959	0.0855
$τ d$	0.0457	0.0829	0.0489	0.0800	0.0480

图9 保压段多模型PID控制实验

Fig.9 Multi-model PID control experiment for packing stage

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基于PWA融合模型的注塑过程保压段建模及控制策略

Modeling and control strategy for packing-stage of injection molding process based on PWA fusion model

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