Sensor in robotics

P. V. Logics . January 31, 2023


 What is a Sensor?

A sensor is a device that detects any physical quantity such as pressure, light, heat, temperature, humidity, etc. from the outside environment and responds according to the input to produce a desired output in a format that is easy to read for the user.

The output produced by a sensor Is an electric signal that can be either converted to human readable form by a display or transmitted over a network or supplied to a processing device, etc. Some common examples of sensors are temperature sensor, pressure sensor, humidity sensor, proximity sensor, photo sensor, motion sensor, etc.

What is a Sensor? A sensor is a device that detects any physical quantity such as pressure, light, heat, temperature, humidity, etc. from the outside environment and responds according to the input to produce a desired output in a format that is easy to read for the user. The output produced by a sensor Is an electric signal that can be either converted to human readable form by a display or transmitted over a network or supplied to a processing device, etc. Some common examples of sensors are temperature sensor, pressure sensor, humidity sensor, proximity sensor, photo sensor, motion sensor, etc. What is a Transducer? A device that is used for transforming energy from one form to another form is known as transducer. The transducer can also be used for the transformation of a non-electrical physical quantity into an electric signal. The major components of a transducer are input device, processing device and output device. The process of conversion of energy from one form to another in a transducer is known as transduction. Where, the transduction is complete in following two steps – It first senses the Input signal, Strengthen the input signal for further processing to produce output. In case of a transducer, the input device of the transducer measures the physical quantity and then transfers an analog signal proportional to the physical quantity to the processing device. The processing device (or conditioning device) modifies, filters or attenuates the analog signal so that it can be accepted by the output device. Generally, transducers are used for conversion of different types of energies such as mechanical energy, light energy, acoustic energy, thermal energy, electromagnetic energy, etc. Some common examples of transducers are microphone, light bulb, loud speaker, etc. Difference between Sensor and Transducer Sensors and transducers are used in electrical and electronic instruments for the measurement of physical quantities. However, there are many differences between them that are listed in the following table − Basis of Difference Sensor Transducer Definition A sensor is a device which converts the physical parameter of a quantity into corresponding electrical output. A transducer is a device that transforms energy from one form to another, such as speed into electrical signal. Main components A sensor does not have any other component except itself. The components of a transducer are − input device (sensor), processing device (signal conditioning), and output device. Dependency All the sensors are not transducers. A sensor is the part of all the transducers. Complexity A sensor is less complicated in its construction and processing. Transducer is a relatively more complex device because it involves the transformation of energy from one form to another. Function A sensor detects the change in the physical parameter of quantity to produce corresponding electrical signal. Transducer converts the energy into a different form. Feedback Sensor does not provide any feedback to the system. Which means, it only measures the change in the physical quantity and cannot give input to the system on its own. Transducer generally provides a feedback to the system through the output device after processing. Examples Common examples of sensor are: temperature sensor, photo sensor, proximity sensor, etc. Examples of transducers are: strain gauge, microphone, loud speaker, piezoelectric element, etc. Types of Robot Sensors There are different type of sensors are available to choose from and the characteristics of sensors are used for determining the type of sensor to be used for particular application. Types of Robot Sensors 1) Light Sensor Light sensor is a transducer used for detecting light and creates a voltage difference equivalent to the light intensity fall on a light sensor. The two main light sensors used in robots are Photovoltaic cells and Photo resistor. Other kind of light sensors like phototransistors, phototubes are rarely used. The type of light sensors used in robotics are: Photo resistor – It is a type of resistor used for detecting the light. In photo resistor resistance varies with change in light intensity. The light falls on photo resistor is inversely proportional to the resistance of the photo resistor. In general photo resistor is also called as Light Dependent Resistor (LDR). Photovoltaic Cells – Photovoltaic cells are energy conversion device used to convert solar radiation into electrical electric energy. It is used if we are planning to build a solar robot. Individually photovoltaic cells are considered as an energy source, an implementation combined with capacitors and transistors can convert this into a sensor. 2) Proximity Sensor Proximity sensor can detect the presence of nearby object without any physical contact. The working of a proximity sensor is simple. In proximity sensor transmitter transmits an electromagnetic radiation and receiver receives and analyzes the return signal for interruptions. Therefore the amount of light receiver receives by surrounding can be used for detecting the presence of nearby object. Infrared (IR) Transceivers – In IR sensor LED transmit the beam of IR light and if it find an obstacle then the light is reflected back which is captured by an IR receiver. Ultrasonic Sensor – In ultrasonic sensors high frequency sound waves is generated by transmitter, the received echo pulse suggests an object interruption. In general ultrasonic sensors are used for distance measurement in robotic system. 3) Sound Sensor Sound sensors are generally a microphone used to detect sound and return a voltage equivalent to the sound level. Using sound sensor a simple robot can be designed to navigate based on the sound receives. Implementation of sound sensors is not easy as light sensors because it generates a very small voltage difference which will be amplified to generate measurable voltage change. 4) Temperature Sensor Temperature sensors are used for sensing the change in temperature of the surrounding. It is based on the principle of change in voltage difference for a change in temperature this change in voltage will provide the equivalent temperature value of the surrounding. 5) Acceleration Sensor Acceleration sensor is used for measuring acceleration and tilt. An accelerometer is a device used for measuring acceleration. The two kinds of forces which affect an accelerometer is:- Static Force – It is the frictional force between any two objects. By measuring this gravitational force we can determine the how much robot is tilting. This measurement is useful in balancing robot, or for determining whether robot is driving on a flat surface or uphill. Dynamic Force – It is the amount of acceleration required to move an object. Measurement of dynamic force using an accelerometer tells about the velocity/speed at which robot is moving. Accelerometer is comes in different configuration. Always use the one which is most appropriate for your robot. Some factors need to be considered before selecting accelerometer is: Sensitivity Bandwidth Output type: Analog or Digital Number of Axis: 1,2 or 3 Proximity Sensors This a type of IoT sensor where it identifies the existence or non-existence of the surrounding object or finds the object properties. Then it converts the detected signal into the form that is clearly understood by the user or might be a simple electronic device that gets in no contact with them. Proximity Sensor Circuit The application of proximity sensors is mainly in the retail domain where they can find out the movement and association that exists between the product and the consumer. With this users can receive quick notifications of discount updates and exclusive offers of interesting products. And the other domain is in automobiles. For instance, when you reverse a car, you will be getting sounds if any obstacle is found, and here the operation of the proximity sensor is implemented. There are many other types of proximity sensors and those are: Capacitive sensors Inductive sensors Photoelectric sensors What is an electrical sensor? An electrical sensor (also called an electronic sensor) is a device that detects a physical parameter of interest (e.g. heat, light, sound) and converts it into electrical signal that can be measured and used by an electrical or electronic system. Put simply, a sensor converts stimuli such as heat, light, sound and motion into electrical signals. These signals are passed through an interface that converts them into a binary code and passes this on to a computer to be processed. Electrical sensors are used wherever information on the state of an electrical system is needed and are employed in everything from railway systems to fan, pump, and heater monitoring


What is a Transducer?

A device that is used for transforming energy from one form to another form is known as transducer.

The transducer can also be used for the transformation of a non-electrical physical quantity into an electric signal. The major components of a transducer are input device, processing device and output device. The process of conversion of energy from one form to another in a transducer is known as transduction. Where, the transduction is complete in following two steps –

It first senses the Input signal,

Strengthen the input signal for further processing to produce output.

In case of a transducer, the input device of the transducer measures the physical quantity and then transfers an analog signal proportional to the physical quantity to the processing device. The processing device (or conditioning device) modifies, filters or attenuates the analog signal so that it can be accepted by the output device.

Generally, transducers are used for conversion of different types of energies such as mechanical energy, light energy, acoustic energy, thermal energy, electromagnetic energy, etc. Some common examples of transducers are microphone, light bulb, loud speaker, etc.

Difference between Sensor and Transducer

Sensors and transducers are used in electrical and electronic instruments for the measurement of physical quantities. However, there are many differences between them that are listed in the following table −

Basis of Difference Sensor Transducer

Definition

 A sensor is a device which converts the physical parameter of a quantity into corresponding electrical output.

A transducer is a device that transforms energy from one form to another, such as speed into electrical signal.

Main components

A sensor does not have any other component except itself.

The components of a transducer are − input device (sensor), processing device (signal conditioning), and output device.

Dependency

All the sensors are not transducers.

A sensor is the part of all the transducers.

Complexity

 A sensor is less complicated in its construction and processing. Transducer is a relatively more complex device because it involves the transformation of energy from one form to another.

Function A sensor detects the change in the physical parameter of quantity to produce corresponding electrical signal. Transducer converts the energy into a different form.

Feedback Sensor does not provide any feedback to the system. Which means, it only measures the change in the physical quantity and cannot give input to the system on its own. Transducer generally provides a feedback to the system through the output device after processing.

Examples Common examples of sensor are: temperature sensor, photo sensor, proximity sensor, etc. Examples of transducers are: strain gauge, microphone, loud speaker, piezoelectric element, etc.

Types of Robot Sensors

There are different type of sensors are available to choose from and the characteristics of sensors are used for determining the type of sensor to be used for particular application.

Types of Robot Sensors

1) Light Sensor

Light sensor is a transducer used for detecting light and creates a voltage difference equivalent to the light intensity fall on a light sensor.

The two main light sensors used in robots are Photovoltaic cells and Photo resistor. Other kind of light sensors like phototransistors, phototubes are rarely used.

The type of light sensors used in robotics are:

  • Photo resistor – It is a type of resistor used for detecting the light. In photo resistor resistance varies with change in light intensity. The light falls on photo resistor is inversely proportional to the resistance of the photo resistor. In general photo resistor is also called as Light Dependent Resistor (LDR).
  • Photovoltaic Cells – Photovoltaic cells are energy conversion device used to convert solar radiation into electrical electric energy. It is used if we are planning to build a solar robot. Individually photovoltaic cells are considered as an energy source, an implementation combined with capacitors and transistors can convert this into a sensor.

2) Proximity Sensor

Proximity sensor can detect the presence of nearby object without any physical contact. The working of a proximity sensor is simple. In proximity sensor transmitter transmits an electromagnetic radiation and receiver receives and analyzes the return signal for interruptions. Therefore the amount of light receiver receives by surrounding can be used for detecting the presence of nearby object.

Infrared (IR) Transceivers – In IR sensor LED transmit the beam of IR light and if it find an obstacle then the light is reflected back which is captured by an IR receiver.

Ultrasonic Sensor – In ultrasonic sensors high frequency sound waves is generated by transmitter, the received echo pulse suggests an object interruption.

In general ultrasonic sensors are used for distance measurement in robotic system.

3) Sound Sensor

Sound sensors are generally a microphone used to detect sound and return a voltage equivalent to the sound level. Using sound sensor a simple robot can be designed to navigate based on the sound receives.

Implementation of sound sensors is not easy as light sensors because it generates a very small voltage difference which will be amplified to generate measurable voltage change.

4) Temperature Sensor

Temperature sensors are used for sensing the change in temperature of the surrounding. It is based on the principle of change in voltage difference for a change in temperature this change in voltage will provide the equivalent temperature value of the surrounding.

5) Acceleration Sensor

Acceleration sensor is used for measuring acceleration and tilt. An accelerometer is a device used for measuring acceleration.

The two kinds of forces which affect an accelerometer is:-

  1. Static Force – It is the frictional force between any two objects. By measuring this gravitational force we can determine the how much robot is tilting. This measurement is useful in balancing robot, or for determining whether robot is driving on a flat surface or uphill.
  2. Dynamic Force – It is the amount of acceleration required to move an object. Measurement of dynamic force using an accelerometer tells about the velocity/speed at which robot is moving.

Accelerometer is comes in different configuration. Always use the one which is most appropriate for your robot. Some factors need to be considered before selecting accelerometer is:

Sensitivity

Bandwidth

Output type: Analog or Digital

Number of Axis: 1,2 or 3

Proximity Sensors

This a type of IoT sensor where it identifies the existence or non-existence of the surrounding object or finds the object properties. Then it converts the detected signal into the form that is clearly understood by the user or might be a simple electronic device that gets in no contact with them.

  • Proximity Sensor Circuit

The application of proximity sensors is mainly in the retail domain where they can find out the movement and association that exists between the product and the consumer. With this users can receive quick notifications of discount updates and exclusive offers of interesting products. And the other domain is in automobiles.

For instance, when you reverse a car, you will be getting sounds if any obstacle is found, and here the operation of the proximity sensor is implemented.

There are many other types of proximity sensors and those are:

  1. Capacitive sensors
  2. Inductive sensors
  3. Photoelectric sensors

What is an electrical sensor?

An electrical sensor (also called an electronic sensor) is a device that detects a physical parameter of interest (e.g. heat, light, sound) and converts it into electrical signal that can be measured and used by an electrical or electronic system.

Put simply, a sensor converts stimuli such as heat, light, sound and motion into electrical signals. These signals are passed through an interface that converts them into a binary code and passes this on to a computer to be processed.

Electrical sensors are used wherever information on the state of an electrical system is needed and are employed in everything from railway systems to fan, pump, and heater monitoring


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