EM Field Head Tracking System specifications: Difference between revisions

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[[File:SphereHeadTrackingSystem.png|thumb|Schematic of the Sphere Head Tracking System]]
==Introduction==
==Introduction==
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.
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:
 
{| class="wikitable"
! 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==
==Parts==
[[EMF Head Tracking System Schematics.png]] %todo
===Lock-in amplifiers===
[[File:RobotLab_Lockin_Settings.JPEG|300px|thumb|right|Lock-in amplifier settings]]
%todo
===Oscillators===
===Oscillators===
===Amplifiers===
===Amplifiers===

Revision as of 13:48, 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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