Week 8 | Interaction and Sensors

A user interface is like a joke. If you need to explain it, it’s not that good. Martin Leblank

Input sensors

What to use and why

  • Accelerometer
  • Gyroscope
  • Ultrasonic
  • Infrared
  • Pressure sensitive materials
  • Biometrics


  • MEMS (MicroElectroMechanical System)
  • Usually 3 Degrees of Freedom (3DOF)
  • Measures acceleration, usually in ”g”
  • 1g = 1 standard, sea-level gravitational pull towards earth.
  • Weight = Mass X Acceleration (from gravity) (w=ma) (you have the same mass on earth and the moon but weight more on earth) Gravity is ~ 9.8m/s2


  • Cheap (Roughly 3.50)
  • Reasonably accurate (Roughly 3mm)
  • Good range (5m) • May suffer from noise issues
  • Especially when using multiple
  • Work as fast as trigger to receive time
  • Distance = travel time / 2 * Speed of Sound (343m/s)

Colour Sensor

  • Subject to ambient light issues
  • Cheap units have low “resolution” of colour spectrum.
  • Good single sensor choice for multiple object detection in controlled environment.

Infrared Beam

  • Fast • Variable range / function
  • Beam break
  • Distance
  • May be Subject to interference
  • External sources
  • Other devices
  • Ambient conditions

Reflectance (Sensing distance)

  • Light or Infra Red
  • Can be used to sense distance
  • Subject to interference
  • Can be very accurate
  • Lasers can be used
  • Time of flight measurements

Velostats and Stretching things

  • Velostats are conductive materials made of polymeric foil and carbon black.
  • Originally used as anti-static packaging
  • Great for prototyping
  • Cheap
  • Workable (cut to size)
  • Easy to read (use in a resistor bridge)
  • Great for clothing and flexibility
  • Surprisingly strong
  • Check Adafruit, core-electronics, etc.

ModBox Work

This week the team regrouped and looked at the feedback that the client had supplied us with and looked at the concepts that were chosen. One of Asas’ designs, a moving focus pad machine was chosen and one of mine, a interactive workout mat was chosen.

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