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Human-body measurements
Devices
Evaluation of
Interactive Systems
Human-body Measurement devices
(adapted from Halla Olafsdottir’s class)
Skeletal Muscles
EMG = ELECTROMYOGRAPHY
Heart
EKG/ECG = ELECTROCARDIOGRAM
Heart Rate
Blood Pressure
Brain
EEG = ELECTROENCEPHALOGRAM (electrical activity)
fNIR = Functional near-infrared spectroscopy (blood composition)
Skin
Skin Conductance
Caroline Appert - 2016/2017
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Skeletal muscles
EMG
ElectroMyoGraphy (EMG)
Device example:
Electrical activity of skeletal
muscles recorded
Electrode placement very
important for a good recording
MyoBand
www.getmyo.com
Surface
Intramuscular (needle)
Measures can indicate stress,
physical and mental.
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Heart
Brain
ElectroCardioGram (EKG/ECG)
ElectroEncephaloGram (EEG)
Heart’s electrical activity
Measures brain’s spontaneous electrical activity
Heart Rate
Can indicate
Beats/min
Abnormal brain activity
Blood Pressure
Pressure in the arteries
Alertness (sleepy vs. alert)
When heart is pumping & filling (120/90)
Stages of sleep….
Measures that can indicate stress, physical and mental.
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EEG
Brain
Device Example:
functional Near InfraRed
Spectroscopy (fNIR)
MindSet
Measures oxygen levels
changes in the prefrontal
cortex
neurosky.com
Used to estimate amount of
brain activity for example
during cognitive tasks
biopac.com
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Skin
Kinematics Measurement Devices
Measure electrical conductance of the skin
which varies with moisture level (galvanic
skin response - GSR)
Kinematics is the science that describes
movements with respect to time and space
Sweat is controlled by the sympathetic
nervous system (reflex in case of harmful
event)
Used for stress estimation
Variables: Position, displacement, velocity,
acceleration…
We measure: Joint angle, position in space,
acceleration….
! External factors such as temperature
and humidity affect GSR measurements
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Kinematics - references
Acceleration
Body Planes
An accelerometer measures the acceleration it
experiences relative to free fall (translational
movements)
Axes of Motion
Translations: along the axes
Rotation: around the axes
Can measure angle relative to earth and direction of
movement
Can be uniaxial, 2 axial, 3 axial
Every movement can be
described by those 6 degrees
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Orientation
Joint angles
A gyroscope measures relative changes in
orientation (rotational movements)
A goniometer measures an angle
or allows an object to be rotated
to a precise angular position
Can be
Manual, Electric
Uniaxial, 2-axial
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2D Positioning
3D Positioning
Photogrammetric & Cinematography
(Muybridge 1880’s)
Optical systems
utilize data captured from image sensors to
triangulate the 3D position of a marker (3DOF)
rotational information must be inferred from the
relative orientation of three or more markers
Markers
Active (Diode’s/LED’s)
Passive (retroreflective)
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3D Positioning
3D Positioning
Electromagnetic-based systems
Inertial systems
calculate position and orientation by the relative
magnetic flux of three orthogonal coils on both
the transmitter and each receiver (6DOF)
Combo of Accelerometers (linear acceleration),
Gyroscopes (rotation) and Magnetometers
(direction of the earths magnetic field)
potential interferences with magnetic and electrical objects in the
environment
Mobile systems
xsens.com
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3D Positioning
EYE TRACKERS
Mechanical Systems
Eye movements
“Exoskeleton” equipped with Goniometers
Saccade (fast eye movement to move focus to
object)
Smooth pursuit (following moving objects)
Fixation (movement stops and eye acquires
content)
We perceive world during fixations
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metamotion.co
m
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EYE TRACKERS
Kinetic Measurement Devices
Infrared light illuminates eyes & sensor/
camera captures the reflection of the eyes.
Kinetics is the science that examines the
forces that produce the movement and
result from the movement
Record: Movement & fixations
Types: Head mounted & External
Variables: Forces & moments
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KINETICS
KINETICS
Force transducers
Force Plates
Force measuring device that gives an electrical
signal proportional to the force applied to it.
4 corner type: 4 tri-axial transducers mounted at
each corner
1 axis & 3 axis
Central support type force plate
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Measurement devices
Human-body measurements
Can be used for both evaluation & input
Can be used for both evaluation & input
EMG as input…
EEG as input…
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Human-body measurements
Sensors’ RAW signal is usually very noisy
Valuable Information in a practically useless format
e.g., EMG
Is negative or positive
Can not be used to quantify force
Can not be used for comparison
Needs to be processed
Rectified
Filtered
Normalized…
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