Computer Modeling for Injection Molding: Simulation, Optimization, and Control

Chapter 12: Feedback Control

Yi Yang

Department of Control Science and Engineering, Zhejiang University, Hangzhou, Zhejiang, China

Furong Gao

Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong, China

The control strategies for injection molding process are evolving with the development of batch process control theory and control technology. In general, the control algorithms for injection molding can be categorized into two types: control strategies based on feedback and learning control strategies. The learning control strategies will be introduced in Chapter 13. In this chapter, the control strategies based on feedback, including traditional feedback control and advanced feedback control (such as adaptive control, model predictive control, optimal control, and intelligent control strategies), are introduced in detail with the examples of some key molding variables control applications.

12.1 Traditional Feedback Control

The traditional feedback control refers to the control that the controller parameters are determined using classical design methods, and the controller only depends on the real time process measurements, as shown in Figure 12.1.

Figure 12.1 Block diagram of traditional feedback control scheme.

The purpose of such kind of control is to keep the process variable close to the set point in spite of ...