Browse Definitions :
Definition

proximity sensing

Proximity sensing is the ability of a robot to tell when it is near an object, or when something is near it. This sense keeps a robot from running into things. It can also be used to measure the distance from a robot to some object.

The simplest proximity sensors do not measure distance. A bumper can be passive, simply making the robot bounce away from things it hits. More often, a bumper has a switch that closes when it makes contact, sending a signal to the controller causing the robot to back away. When whiskers hit something, they vibrate. This can be detected, and a signal sent to the robot controller.

A photoelectric proximity sensor uses a light-beam generator, a photodetector, a special amplifier, and a microprocessor. The light beam reflects from an object and is picked up by the photodetector. The light beam is modulated at a specific frequency, and the detector has a frequency-sensitive amplifier that responds only to light modulated at that frequency. This prevents false imaging that might otherwise be caused by lamps or sunlight. If the robot is approaching a light-reflecting object, its microprocessor senses that the reflected beam is getting stronger. The robot can then steer clear of the object. This method of proximity sensing won't work for black objects, or for things like windows or mirrors approached at a sharp angle.

An acoustic proximity sensor works on the same principle as sonar. A pulsed signal, having a frequency somewhat above the range of human hearing, is generated by an oscillator . This signal is fed to a transducer that emits ultrasound pulses at various frequencies in a coded sequence. These pulses reflect from nearby objects and are returned to another transducer, which converts the ultrasound back into high-frequency pulses. The return pulses are amplified and sent to the robot controller. The delay between the transmitted and received pulses is timed, and this will give an indication of the distance to the obstruction. The pulse coding prevents errors that might otherwise occur because of confusion between adjacent pulses.

A capacitive proximity sensor uses a radio-frequency ( RF ) oscillator, a frequency detector, and a metal plate connected into the oscillator circuit. The oscillator is designed so that a change in the capacitance of the plate, with respect to the environment, causes the frequency to change. This change is sensed by the frequency detector, which sends a signal to the apparatus that controls the robot. In this way, a robot can avoid bumping into things. Objects that conduct electricity to some extent, such as house wiring, animals, cars, or refrigerators, are sensed more easily by capacitive transducers than are things that do not conduct, like wood-frame beds and dry masonry walls.

Also see robotics , Pressure sensing , and texture sensing .

This was last updated in August 2011
SearchCompliance
  • ISO 31000 Risk Management

    The ISO 31000 Risk Management framework is an international standard that provides businesses with guidelines and principles for ...

  • pure risk

    Pure risk refers to risks that are beyond human control and result in a loss or no loss with no possibility of financial gain.

  • risk reporting

    Risk reporting is a method of identifying risks tied to or potentially impacting an organization's business processes.

SearchSecurity
  • Pretty Good Privacy (PGP)

    Pretty Good Privacy or PGP was a popular program used to encrypt and decrypt email over the internet, as well as authenticate ...

  • email security

    Email security is the process of ensuring the availability, integrity and authenticity of email communications by protecting ...

  • Blowfish

    Blowfish is a variable-length, symmetric, 64-bit block cipher.

SearchHealthIT
SearchDisasterRecovery
  • What is risk mitigation?

    Risk mitigation is a strategy to prepare for and lessen the effects of threats faced by a business.

  • fault-tolerant

    Fault-tolerant technology is a capability of a computer system, electronic system or network to deliver uninterrupted service, ...

  • synchronous replication

    Synchronous replication is the process of copying data over a storage area network, local area network or wide area network so ...

SearchStorage
  • direct access

    In computer storage, direct access is the process of reading and writing data on a storage device by going directly to where the ...

  • kibi, mebi, gibi, tebi, pebi and exbi

    Kibi, mebi, gibi, tebi, pebi and exbi are binary prefix multipliers that, in 1998, were approved as a standard by the ...

  • holographic storage (holostorage)

    Holographic storage is computer storage that uses laser beams to store computer-generated data in three dimensions.

Close