Difference between revisions of "EM Field Head Tracking System specifications"

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[[File:SphereHeadTrackingSystem.png|thumb|Schematic of the Sphere Head Tracking System]]
 
==Introduction==
 
==Introduction==
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The EMF head tracking system consists of field coils in the walls of a booth that create X,Y and Z (or Horizontal, Frontal and Vertical) oscillating EM fields with different frequencies. The fields are sensed by a small pick-up coil mounted on a glasses frame worn by a subject. The signal is analysed and converted into a position of the subjects head relative to his/her default forward looking resting position.
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The EM Field Head Tracking System is used for recording head movements of the subject during a trial. The system consists of the following parts:
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*Three oscillators at roughly 45, 55 and 65 kHz or 50, 60, 70 kHz for X, Y and Z direction.
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*Three signal amplifiers that amplify the oscillator signals.
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*six field coils that make a cube of roughly 3x3x3 meters.
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*A small pick-up coil mounted on a glasses frame that is worn by the subject during the experiment.
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*Three lock-in amplifiers that split the signal from the pick-up coil in the 3 frequency components and measures their envelope. They output analog signals between -10V and +10V.
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*An acquisition device converts the analog output signals from the lock-in amplifiers to digital.
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*A RZ6 multi I/O processor that records the acquired data.
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*Software that converts the recorded data to head orientations using calibration data.
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The following table contains the channel convention with respect of the three directions:
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{| class="wikitable"
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! Channel
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! Frequency
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! Orientation
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! Color
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! Polarity
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|-
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| Channel 1
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| 45 kHz
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| Frontal
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| Red
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| Front = positive; Back = negative
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|-
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| Channel 2
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| 55 kHz
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| Vertical
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| Blue
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| Right = positive; Left = negative
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|-
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| Channel 3
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| 65 kHz
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| Horizontal
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| Yellow
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| Up = positive; Down = negative
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|}
  
 
==Parts==
 
==Parts==
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[[EMF Head Tracking System Schematics.png]] %todo
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===Lock-in amplifiers===
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[[File:RobotLab_Lockin_Settings.JPEG|300px|thumb|right|Lock-in amplifier settings]]
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%todo
 
===Oscillators===
 
===Oscillators===
 
===Amplifiers===
 
===Amplifiers===

Revision as of 14:48, 23 November 2023

Schematic of the Sphere Head Tracking System

Introduction

The EM Field Head Tracking System is used for recording head movements of the subject during a trial. The system consists of the following parts:

  • Three oscillators at roughly 45, 55 and 65 kHz or 50, 60, 70 kHz for X, Y and Z direction.
  • Three signal amplifiers that amplify the oscillator signals.
  • six field coils that make a cube of roughly 3x3x3 meters.
  • A small pick-up coil mounted on a glasses frame that is worn by the subject during the experiment.
  • Three lock-in amplifiers that split the signal from the pick-up coil in the 3 frequency components and measures their envelope. They output analog signals between -10V and +10V.
  • An acquisition device converts the analog output signals from the lock-in amplifiers to digital.
  • A RZ6 multi I/O processor that records the acquired data.
  • Software that converts the recorded data to head orientations using calibration data.

The following table contains the channel convention with respect of the three directions:

Channel Frequency Orientation Color Polarity
Channel 1 45 kHz Frontal Red Front = positive; Back = negative
Channel 2 55 kHz Vertical Blue Right = positive; Left = negative
Channel 3 65 kHz Horizontal Yellow Up = positive; Down = negative

Parts

Lock-in amplifiers

Lock-in amplifier settings

%todo

Oscillators

Amplifiers

Resonance circuits

Wall coils

Pick-up coil

Lock-in amplifiers

ADC's

recording device

(RZ6 or RA16)

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