Movement Sensing

One of the key applications of physical computers is to allow for natural interaction in a way that conventional computers cannot. People and thereafter users have tendency of moving around, of expressing themselves with bodily movements and appreciate interfaces that effectively rely on such actions as part of the interface.

Key Issues

In order to sense movement, you need to decide what issues are at stake. In effect, what is it that you want to achieve with sensing movement:

  • Position - Do you need to locate something within an area
  • Orientation - Tthe orientation of something within an area
  • Motion - Direction and trajectory of displacement
  • Velocity - How fast something is moving within an area
  • Absolute Position - Where is something within an area
  • Relative Position - Where is something in relation to something else
  • Identity - Do you need to identify what is within an area, when there is only one thing or when there is a multitude of things

in the points above the area to consider is the sensor's field of sensitivity. i.e. the zone where the sensor is effective. It is typically either asurface on the sensing area of the sensor, or a cone shape volume in front of the sensitive part of the sensor.

Examples of sensors

There is an almost limitless number of sensors that you can use, as a rule of thumb choose the simplest one that can do the required job...

  • Detecting presence - Foot switches (e.g. pressure pads), photo-electric switches, motion sensors (all ready as a kit), magnetic switches, video tracking
  • Determining position - IR sensors (Infra Red), Ultrasonic Sensors
  • Determining rotation - Potentiometers, accelerometers, tilt switches, compass, rotary encoders, Gyroscopes