# Automatics

## 31. Influence of Non-linearity on Control

Automatics Chapter 31 Influence of Non-linearity on Control Chapter 31.1 Introduction The most influential non-linearity on the control process is saturation in the power amplifier (another name – actuator) in front of the controller. Therefore, the title of the chapter could be more explicit – “Impact of actuator saturation on the quality of control”. You’ll …

## 30. Control Systems Structures

Automatics Chapter 30 Control Systems Structures Chapter 30.1 Introduction The structures do not depend on the type of controller. It can be PID, two-position and any other, e.g. discontinuous PID variants. Here a small digression to “discontinuous PID variants”. You read the specification of the two-position controller, and there is, for example, the Kp=3 setting …

## 28. PID Controllers Tuning

Automatics Chapter 28 PID controllers tuning Chapter 28.1 Introduction In chapters 23..27 we discussed the principle of operation of the P, PD, I, PI and PID controllers. I think that by manually selecting Kp, Ti and Td settings by trial and error method, you understood their roles well. By the way, you learned the first …

## 29. Disturbances Analysis

Automatics Chapter 29 Disturbances analysis Chapter 29.1 Introduction Automatics has 2 main tasks: 1. Getting the output signal y(t) to the setpoint x(t) by a man – operator of the technological process. The ideal is a steady state where x(t)=y(t). This should also be a “nice” response to the unit step x(t). What “pretty” or …

## 27. PID Control

Automatics Chapter 27 PID control Chapter 27.1 Inroduction We already know that: – The P control, and even more so the PD control, reacts quickly to the step setpoint x(t), but the steady error e(t) is always non-zero. – The PI control provides zero control error, but the course is slower than for P control, …

## 26. PI Control

Automatics Chapter 26. PI Control Chapter 26.1 Introduction From chapter 25.8 of the previous chapter, we learned that: – P Control, and even more so PD, reacts quickly to the setpoint x(t), but does not provide steady error e(t)=0. – With type I Control it is the other way around. The system slowly approaches the …

## 25. I Control

Automatics Chapter 25 I Control Chapter 25.1 Introduction You have already met the simplest type P controller consisting only of a comparator element and an amplifier Kp. It roughly ensured approaching the setpoint x(t) and suppressing disturbances z(t). Then came the PD controller which did the same thing, only much faster and with smaller oscillations. …

## 24. PD Control

Automatics Chapter 24 PD adjustment Chapter 24.1 Introduction The PD controller belongs to the group of PID controllers. Only the integration action has been disabled in it. Unfortunately, it has a basic defect of the P controller. It does not completely eliminate the steady-state error. The closed-loop gain Kz and the steady-state error gain Ke, Ke …

## 23. P Control

Automatics Chapter 23 P Control Chapter 23.1 Introduction The length of this and the following chapters on PID is a bit scary. But courage! Most experiments are repeatable with different parameters. The P type Controller is the simplest continuous Controller. In the following chapters, you will learn about more sophisticated PI and PD controllers and …

## 22. Continuous Control

Automatics Chapter 22 Continuous Control Chapter 22.1 Introduction Fig. 22-1 Fig. 22-1a The most general control diagram showing: – setpoint x(t) – output signal y(t) –other name process variable – disturbance z(t) – control error e(t) Fig. 22-1b A more accurate version in which the entire G(s) object has been divided into an ON/OFF controller …

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