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Robotic Sensors


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A2

 a

Robotic Input Devices

 b

Sight

The most complex sensor is the video camera or a web-cam. Processing these images is not easy. The cameras use Charge Coupled Devices or CCD devices to convert the image into thousands or even millions of pixels. These are available for infrared, visible and ultraviolet light. The sensor output can be processed using an Artificial Neural Network or with a conventional computer.

Robotics CCD.JPG

Much simpler sensors can "see".

 c

Sound

Electret-mic.jpg

 d

Ultrasound

 e

Touch

 f

Smell

 g

Taste

 h

Location

Straight line absolute position sensing using a Gray code scale.

GrayCode.gif

Absolute rotation sensing with a circular Gray code scale.

GrayCode-wheel.gif

Relative position sensing using a slotted wheel that interrupts an infrared beam.

Slotted-disk-2.gif

A potentiometer can be used to measure angular position. As the robot part rotates, the potentiometer shaft also turns. The output voltage from the potentiometer is proportional to the robots angular position.

 i

Resolution

 j

Obstacle Sensing

 k

Categorising Input Sensors

There is a long list. Here are a few examples.

   l

Active Sensors

 m

Passive Sensors

 n

Analogue Sensors

  • Electret Microphone - contains an FET pre-amp
  • Accelerometer - Detect the orientation of a phone
  • Light Dependent resistor
  • Thermistor
  • Potentiometer
  • Moving Coil Microphone
  • Conducting Polymer - Changes resistance when deformed.
  • Hall effect sensor - Measures magnetic fields.
  • Capacitor - Capacitance changes with the input
    • plate overlap might change
    • plate spacing might change
    • material between the plates might change
 o

Digital Sensors

  • Optical Switch - IR-LED with photodiode and a transistor switch
  • Shaft Encoders
  • Switch - Resistance = zero or infinity.
  • Microswitch
  • Reed Switch
  • Any kind of switch
 p

TASK: Categorise Output Sensors (as above)

 

 

 

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