Linear Position Measurments

Inductive Analog Distance Sensor

is a device that measure the position of an object. The output signal depends on the electrical conductivity of the metal to be detected and the distance between the sensor and the object.

Potentiometer

Potentiometer is the simplest Form of analog position sensing. The function of a linear potentiometer is based on the voltage divider principle.
By moving the wiper will change the value of the resistance.
If no load is connected to the divider, then V2 :



always in the potentiometer an amplifier is attached in order to prevent any errors caused by a high current.

Ultrasonic Sensors

Sound frequency which is above 20kHz is described as ultrasonic.

Ultrasonic transceivers are made up of two parts:

• Transmitter: that produces or generates ultrasound waves.

• Receiver: that receives ultrasonic sound from the transmitter and measure a signal in volts which is proportional to the distance between two devices.

The majority of ultrasonic receivers determine the timing between the sound generated signals and the echo received signals and since the sound speed is known, the distance can be calculated.

Other devices use the same principle of ultrasonic such as:

• RADAR: uses radio waves
  
• SONAR: uses sound waves
  
• LIDAR: uses laser light

Advantages of ultrasonic sensors:

• can reflect easily from structures
• they are cheap, small, and simple

Applications of ultrasonic sensors:

• they are used in cars to measure distance to prevent accidents.

• they are used in robots to detect objects and avoid colliding with them.

• they are used to measure the water level in a tank.

Optical Analog Sensors

there are several There are several methods of optically sensing distance, such as laser interferometers and diffuse sensors with or without fiber optics.







Contact-less Laser Distance Measuring
Device up to 500m with an Accuracy of
±1.5mm

Proximity Sensors

Proximity Sensors

*Definition:

A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. A proximity sensor often emits an electromagnetic or electrostatic field, or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal.

*Types of proximity sensors:

· Inductive

· Capacitive

· Sonar

· Radar

*Applications:

* Car bumpers that sense distance to nearby cars for

parking.

*Ground proximity warning system for aviation safety.

* Automatic Door Sensors manufacturers.

References:

ar.wikipedia.org/wiki/

www.sensors-transducers.machinedesign.com/