Tuning methods

Tuning Methods Based on Known Process Models. 8-14... 

Tuning Methods When Process Model Is Unknown. 8-15... 

The two Ziegler-Niehols PID tuning methods provide a useful rule of thumb empirieal approaeh. The eontrol system design teehniques diseussed in Chapters 5 and 6 however will generally yield better design solutions. 

An optimal model-based PID tuning method for the control of poly-butadiene latex reactor... 

In the present study, we propose a tuning method for PID controllers and apply the method to control the PBL process in LG chemicals Co. located in Yeochun. In the tuning method proposed in the present work, we first find the approximated process model after each batch by a closed-loop Identification method using operating data and then compute optimum tuning parameters of PID controllers based on GA (Genetic Algorithm) method. 

At this point, one may be sufficiently confused with respect to all the different controller tuning methods. Use Table 6.3 as a guide to review and compare different techniques this chapter and also Chapters 7 and 8. 

There are a variety of feedback controller tuning methods. Probably 80 percent of all loops are tuned experimentally by an instrument mechanic, and 75 percent of the time the mechanic can guess approximately what the settings will be by drawing on experience with similar loops. We will discuss a few of the time-domain methods below. In subsequent chapters we will present other techniques for tinding controller constants in the Laplace and frequency domains. 

Simulate several first-order lag and second-order lag plus deadlime processes on a digital computer with a relay feedback. Compare the ultimate gains and frequencies obtained by the auto-tune method with the real values of cu and obtained from the transfer function. 

This tuning method should be viewed as giving preliminary controller settings which can be used as a benchmark for comparative studies. Note that the procedure guarantees that the system is stable with all controllers on automatic and also that each individual loop is stable if aU others are on manual (the F... 

The tuning settings based on the process reaction curves obtained by the open-loop tuning method, in addition to the Ziegler-Nichols method (Table 2.38), can also be selected by other methods. Figure 2.39 compares the load responses and Figure 2.40 compares the set point responses of these methods. 

How quickly the controller responds and with how little oscillation, depends on the application. The following are some of the available tuning methods, of which we will consider the last two in detail (see textbooks1-11 for numerous other methods) ... 

Measurements of the controlled and the manipulated variables are used to estimate the parameters of a simple process model. This process model is then used to calculate the new control parameters based on a pre-selected tuning method. 

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