Automatic Control System

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Dustin Gordon
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1 Sensor types

2 Automatic Control System Automatic Control System Construction Material or Power Object Output Signal Sensor Disturbances Converter Measuring Device Controller Industry Controller Executive Device

3 Graphic Symbols- Sensors and Detectors PROXIMITY SENSOR PROXIMITY DEVICE (FUNCTIONAL SYMBOL)

4 CAPACITIVE CRYSTAL SET TACTILE SENSOR - TACTILE SENSOR WITH NORMAL CLOSED CONTACT

5 PROXIMITY SENSOR WITH NORMAL OPEN CONTACT CONTACTRON IRON SENSOR

6 SENSORS SELECTION (CLASSIFICATION)

7 1. Contact versus Non-contact Contact sensor : There is physical contact betwen the sensor an the parametr it measures Non-contact sensor : Also called proximitysensors. Proximity indicates that the object is near, but contact is not required.

8 Contact Sensor

9 Non- Contact Sensor

10 2. Digital (binary) versus Analog Digital sensors Have two states: on or off Detect presence/absence of object Counting such as used in a rotary encoder Analog sensors They sense continuous variables (temp, pressure) and provide a continuous (usually linear) voltage or current according to an input/output transfer function. More complex than digital and can provide more information.

11 3. Principles and Designs Sensor principles Inductive Capacitive Resistive Sensor designs Extrinsic Intrinsic

12 4. Digital Sensors Switches Optical (photoelectric) sensors Encoders Ultrasonic sensors Inductive sensors Capacitive sensors

13 5. Industrial sensors Proximity Mechanical Optical Inductive/Capacitive Position/Velocity Potentiometr LVDT Encoders Tachogenerator Force/Pressure Vibration/Acceleration

14 Inductive sensors

15 Types of inductive sensors proximity movement

16 Proximity sensors I. Schematic diagram metal generator liminal construction with hysteresis output amplifier output signal

17 Proximity sensors II. Principle of working metal generator liminal construction with hysteresis output amplifier output signal

18 III.. Parameters Proximity sensors Nominal zone of working Trip - out Switches on Metal plate Hysteresis Zone of working Inductive sensor

19 Frequency of jumpering Sensor Measuring plate St37 Traffic trend Real zone of working Working zone of action

20 Hysteresis of jumpering Corrective coeficiences Repeatability Temperature of working Admission Residual voltage Residual current

21 Movement sensors I. Schematic diagram

22 Movement sensors II. Principle of working

23 III.. Parameters Movement sensors Zone of working Trip - out Switches on Metal plate Hysteresis Zone of working Inductive sensor Corrective coeficiences

24 Hysteresis of frequency Out lowering speed Increase speed Liminal frequencies Maximum frequency of jumpering Time of deceleration

25 IV. Symbol of inductive sensors

26 V. Examples of inductive sensor

27 VI. Inductive sensor in use Quantity control Detection unevenness on packaging

28 VI. Inductive sensor in use Control of screw tight the screws

29 Capacitive sensors

30 Capacitive sensors I. Schematic diagram object periphery of oscillator comparator amplifier active surface screen

31 Capacitive sensors II. Principle of working O b j e c t periphery of oscillator comparator amplifier

32 III. Symbol of capacitive sensors

33 IV. Capacitive sensor in use Silicon Wafer deposition & etching Silicon Wafer proximity Wafer cutting/processing Robot arm control Computer hard disc drive Printing Press/Photocopiers Tooling parallelism/alignment alignment

34 IV. Capacitive sensor in use Detection of movement Detection of position

35 IV. Capacitive sensor in use Counting of rotational speed Steering mechanical process

36 Optical sensors

37 Optical (Photoelectric) Sensors All optical sensors use light to sense objects. Operation method: - Lasers, Incandescend bulbs, or Light emitting diodes (LEDs) are used as light source - The light source is turned off and on (modulation) at a high frequency (could be as hight as several khz) - A photodetector senses the pulsed light - The light emitter and receiver are turned to the modulation frequency.

38 Example of Sensor using LED as a light source

39 Types of Optical Sensors Reflective (Diffuse) Sensors Retroreflective Sensors Thru-beam Sensors Polarizing Photo Sensors Convergent Photo Sensors Fiber Optic Sensors Laser Sensors

40 Reflective (Diffuse) Sensors

41 T - Transmitter R - Receiver Transmitter and receiver are combined into one casing

42 OBJECT T R Work relies on the reflective surface on the target to reflect the light from the transmitter to the receiver

43 Advantages Singular casing (Transmitter + Receiver) Objects detection with high reflect parameter (0,6-0,9)

44 Disadvantages Low detecting distance Sensitive to colour and quality Sensitive to background Dead zone

45 Retroreflective Sensors

46 Transmitter and receiver are combined into one casing Make use of a reflector to reflect the light from the transmitter to the receiver

47 OBJECT T REFLECTOR R

48 Easy instalation Advantages Singular casing ( Transmitter + Receiver) Good working zone

49 Disadvantages Sensitive to lights objects Use reflector Dead zone

50 Thru-beam Sensors

51 System has a separate transmitter and receiver

52 OBJECT T R It s capable of sensing very small object by narrowing the light beam

53 Advantages Detection for long distance Lack of dead zone Detection light objects Detection in several environment

54 Disadvantages Large separate casings Problems with instalation ( set- up Transmitter and Receiver)

55 Typical Application Detecting the presence or absence of an object Positioning and counting Detection the end of travel of an object Packaging machinery Sorting and labelling machinery Textile machinery Pharmaceutical Small part detection High speed detection Door controls

56 Parameters - Operating Temperature (10 C C) - Vibration - Supply Voltage (10 30 VDC or 230 VAC) - Detecting Distance - Output Current - Max. Switching Frequency - Degree of Protection - Hysteresis

57 Encoders An encoder is a device that senses a modification of speed and position and converts it to a digital value

58 There are two main types of rotary encoders: - Incremental - Absolute

59 Principle of working The light from Light Source shines through the lines on disk and Grid Assembly and is then sensed by photo detector

60 Construction of encoder s disk:

61 Incremental encoders: An incremental encoder generates a series of square waves Encoders transform rotary movement into a sequence of electrical pulses

62 There are two main types of incremental encoders: -Tachometer - Quadrature

63 Absolute encoder An absolute encoder provides a word of output with a qunique pattern that represents each position. The output is proportional to the angle of the shaft

64 Principle of working

9/28/2010. Chapter , The McGraw-Hill Companies, Inc.

9/28/2010. Chapter , The McGraw-Hill Companies, Inc. Chapter 4 Sensors are are used to detect, and often to measure, the magnitude of something. They basically operate by converting mechanical, magnetic, thermal, optical, and chemical variations into electric