Module 4 Proximity Sensors Eng Asma Abu Baker

Module 4: Proximity Sensors Eng. Asma Abu Baker

Outlines • • Analog Sensors Digital Sensors Proximity sensors Inductive sensor Capacitive sensor Optical sensor Ultrasonic sensor

Recap • Definition: senses the input physical variable and converts it into a measurable signal Sensor / transducer Name Physical variable Measurable signal

Proximity sensors 1. Ultrasonic Sensor 2. Optical sensor 3. Inductive sensor 4. Capacitive sensor

Ultrasonic proximity sensor • can detect solid, liquid, granular and powdery substances

Ultrasonic sensor application • Detect the object within a specified range. • Detection range almost 100 cm measure the distances of the nearby car Detecting the presence of a person Detect the presence of the car

Ultrasonic sensor application Sensing Liquid Levels Control of lifting vehicles

Optical proximity sensors • Optical proximity sensors are used for counting boxes, breakage and jam detection Almost 10 cm detection range

Inductive proximity sensors • Inductive proximity sensors are used to detect the presence of metals • Detection range is very small.

Capacitive proximity sensors • Capacitive proximity sensors are used to detect metallic and non-metallic objects such as wood, paper, liquid and so on. • Detection range is very small.

Counting Application

Types of sensors • Binary / Digital sensor (switches) – Output has two values only • Analog sensors – Output has many values : Range

Temperature Thermocouple o. C output 25 o. C 0. 1 mv 30 o. C 0. 3 mv 35 o. C 0. 6 mv 40 o. C 0. 9 mv 45 o. C 1 mv 50 o. C 1. 3 mv 55 o. C 1. 5 mv Does thermocouple have only two values or many values ? Many values, then its analog sensor

Temperature o. C RTD output 30 o. C 0. 114 kΩ 35 o. C 0. 116 kΩ 40 o. C 0. 118 kΩ 45 o. C 0. 12 kΩ 50 o. C 0. 122 kΩ 55 o. C 0. 124 kΩ 60 o. C 0. 125 kΩ Does the RTD have only two values or many values ? Many values, then its analog sensor

Temperature Thermister o. C output kΩ 25 1. 4 30 1. 1 35 0. 99 40 0. 82 45 0. 7 50 0. 6 55 0. 51 Does thermistor have only two values or many values ? Many values, then its analog sensor

Binary sensors , optical sensor How many values I am reading ? Two values, then its binary sensor

Binary sensors, Optical sensor Physical variable Measureable signal Object exist 0 volts Object don’t exist 24 volts

Analog sensors, Ultrasonic sensor How many values I am reading ?

• Sensors can operate – by contact – Without contact (Proximity sensors ) • They are selected based on the application. Is this sensor operates by contact, or without contact ?

Advantages of contactless proximity sensor • Precise and automatic sensing of position. • Contactless sensing protects objects from damage. • Fast response, and do not include moving parts which can wear out.

Lab Activity 1 Don’t switch on the power supply till I check the circuit for you

Select Pulse The clock is S 2

Lab Activity 1 1. Connect Optical sensor 2. Connect inductive sensor

Conclusion • Proximity sensors application • Analog and digital sensors