Download Slides 1-in-1

Evaluation of
Interactive Systems
Human-body Measurement devices
(adapted from Halla Olafsdottir’s class)
Caroline Appert - 2016/2017
Human-body measurements
Devices
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
2
Skeletal muscles
ElectroMyoGraphy (EMG)
Electrical activity of skeletal
muscles recorded
Electrode placement very
important for a good recording
Surface
Intramuscular (needle)
Measures can indicate stress,
physical and mental.
3
EMG
Device example:
MyoBand
www.getmyo.com
4
Heart
ElectroCardioGram (EKG/ECG)
Heart’s electrical activity
Heart Rate
Beats/min
Blood Pressure
Pressure in the arteries
When heart is pumping & filling (120/90)
Measures that can indicate stress, physical and mental.
5
Brain
ElectroEncephaloGram (EEG)
Measures brain’s spontaneous electrical activity
Can indicate
Abnormal brain activity
Alertness (sleepy vs. alert)
Stages of sleep….
6
EEG
Device Example:
MindSet
neurosky.com
7
Brain
functional Near InfraRed
Spectroscopy (fNIR)
Measures oxygen levels
changes in the prefrontal
cortex
Used to estimate amount of
brain activity for example
during cognitive tasks
biopac.com
8
Skin
Measure electrical conductance of the skin
which varies with moisture level (galvanic
skin response - GSR)
Sweat is controlled by the sympathetic
nervous system (reflex in case of harmful
event)
Used for stress estimation
! External factors such as temperature
and humidity affect GSR measurements
9
Kinematics Measurement Devices
Kinematics is the science that describes
movements with respect to time and space
Variables: Position, displacement, velocity,
acceleration…
We measure: Joint angle, position in space,
acceleration….
10
Kinematics - references
Body Planes
Axes of Motion
Translations: along the axes
Rotation: around the axes
Every movement can be
described by those 6 degrees
11
Acceleration
An accelerometer measures the acceleration it
experiences relative to free fall (translational
movements)
Can measure angle relative to earth and direction of
movement
Can be uniaxial, 2 axial, 3 axial
12
Orientation
A gyroscope measures relative changes in
orientation (rotational movements)
13
Joint angles
A goniometer measures an angle
or allows an object to be rotated
to a precise angular position
Can be
Manual, Electric
Uniaxial, 2-axial
14
2D Positioning
Photogrammetric & Cinematography
(Muybridge 1880’s)
15
3D Positioning
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)
16
3D Positioning
Electromagnetic-based systems
calculate position and orientation by the relative
magnetic flux of three orthogonal coils on both
the transmitter and each receiver (6DOF)
potential interferences with magnetic and electrical objects in the
environment
17
3D Positioning
Inertial systems
Combo of Accelerometers (linear acceleration),
Gyroscopes (rotation) and Magnetometers
(direction of the earths magnetic field)
Mobile systems
xsens.com
18
3D Positioning
Mechanical Systems
“Exoskeleton” equipped with Goniometers
19
metamotion.co
m
EYE TRACKERS
Eye movements
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
20
EYE TRACKERS
Infrared light illuminates eyes & sensor/
camera captures the reflection of the eyes.
Record: Movement & fixations
Types: Head mounted & External
21
Kinetic Measurement Devices
Kinetics is the science that examines the
forces that produce the movement and
result from the movement
Variables: Forces & moments
22
KINETICS
Force transducers
Force measuring device that gives an electrical
signal proportional to the force applied to it.
1 axis & 3 axis
23
KINETICS
Force Plates
4 corner type: 4 tri-axial transducers mounted at
each corner
Central support type force plate
24
Measurement devices
Can be used for both evaluation & input
EMG as input…
EEG as input…
25
Human-body measurements
Can be used for both evaluation & input
26
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…
27