ISWC2002
The Comfort Assessment of Wearable Computers
James F. Knight, Chris Baber,
Anthony Schwirtz and Huw W. Bristow
ISWC2002
Ergonomics
• Interest in human aspects of wearing technology
• How does the technology affect the human?• Aspects of the technology to assess
• Size• Weight• Positioning
• Need a dependant variable
ISWC2002
Previous work
• Measured responses to musculoskeletal loading
• Body posture and movement
• Problems• Use of specialised
expensive equipment• Need for specialist
knowledge• Time consuming
• Need for quick method of assessment
ISWC2002
Subjective assessment
• Comfort• Discomfort one of the main causes for non-use of
personal protective equipment (Abeysekera & Shahnavaz, 1990; Akbar-Khanzadeh & Biesi,
1995)
• Usually assessed as unidimensional• Wearing something can affect the wearer in
numerous ways• Need a multidimensional tool
ISWC2002
Comfort Descriptors
• Generate terms that describe different elements of comfort based on:
• The concept of wearing something
• Wearing some electrical or mechanical device
• Wearing something that has the ability to measure, record or determine some aspect of the wearer
• 92 terms generated• Need to reduce number of terms
ISWC2002
Comfort Descriptor Matrix
• Eight participants given cards with terms and definitions written on them.
• Participants asked to group the terms based on self selected criteria.
• Term by term association matrix developed.
Accurate data
Aching Adaptation Alignment Amount Annoying Appearance Awkwardness BalanceBlood flow
Blunt hitting
BruisingBumping
intoChafing Change Clamminess
Accurate data - - - - - - - - - - - - - - - -Aching 0 - - - - - - - - - - - - - - -Adaptation 0 0 - - - - - - - - - - - - - -Alignment 2 0 0 - - - - - - - - - - - - -Amount 1 1 1 2 - - - - - - - - - - - -Annoying 0 2 0 0 1 - - - - - - - - - - -Appearance 1 1 0 1 1 3 - - - - - - - - - -Awkwardness 0 0 2 0 0 0 1 - - - - - - - - -Balance 0 0 2 1 0 0 0 5 - - - - - - - -Blood flow 0 4 0 0 0 1 0 0 0 - - - - - - -Blunt hitting 0 3 0 0 0 1 0 0 0 5 - - - - - -Bruising 0 4 0 0 0 1 0 0 0 4 5 - - - - -Bumping into 0 2 1 1 0 2 0 2 2 2 2 2 - - - -Chafing 0 5 0 0 0 1 0 0 0 4 3 6 2 - - -Change 0 1 3 0 0 1 0 4 4 1 1 1 3 1 - -Clamminess 0 6 0 0 0 1 0 1 1 5 3 5 2 4 2 -Clowning 1 1 0 1 1 4 7 1 0 0 0 0 0 0 0 0Cold 0 1 0 1 1 1 0 0 0 3 3 2 1 2 1 1Compensation 1 0 3 1 0 0 1 2 2 0 0 0 1 0 5 0Conscious 1 1 1 1 2 2 3 0 2 0 0 0 0 0 0 0Constricting blood 1 3 0 1 0 0 1 1 1 6 3 2 1 2 1 5Constricting movement 0 1 2 0 1 1 0 1 1 2 2 1 0 1 0 1Cool (fashionable) 0 1 1 0 1 4 6 2 1 0 0 0 0 0 0 0Counteraction 1 0 2 2 0 0 1 1 1 0 0 0 0 0 4 1Cramped 0 0 1 1 1 3 1 2 3 0 0 0 1 0 1 1Damage 4 0 0 2 0 0 1 0 0 0 0 0 0 0 0 0Dangerous 4 0 0 2 0 1 2 0 0 0 0 0 0 0 0 0Difficult 0 0 3 0 0 1 0 6 5 0 0 0 4 0 4 1Digging in 0 3 0 0 0 1 0 0 0 6 6 3 2 3 1 4Dropping 0 0 2 2 1 0 0 1 3 0 1 0 0 0 0 0Embarrassing 1 1 0 1 1 4 7 1 0 0 0 0 0 0 0 0Explosion 4 0 0 2 0 0 1 0 0 0 0 0 0 0 0 0Falling over 2 1 0 1 0 1 2 1 2 1 1 1 3 1 1 1Fit 1 1 0 4 1 1 0 1 2 1 2 1 1 1 2 2Flapping 0 0 1 3 1 0 0 1 2 1 2 0 1 0 0 0Friction 0 1 0 1 0 1 0 0 0 3 3 3 1 3 1 1General fatigue 0 3 0 0 0 2 0 2 1 2 1 2 3 2 2 3Hot 0 1 0 1 1 1 0 0 0 3 3 2 1 2 1 1Impeding activity 0 1 0 0 0 2 0 2 2 1 1 1 3 1 3 2Impeding movement 0 2 0 0 0 2 0 2 2 2 2 1 2 1 4 3Impeding sensation 0 2 1 0 1 1 0 3 3 2 2 1 3 1 4 3Inertia 0 0 1 3 1 0 0 1 2 0 0 0 1 0 0 0Inhibited movement 0 1 0 0 0 1 0 3 2 1 1 1 3 1 3 2Intrusive 1 0 1 0 1 3 1 1 3 0 0 0 0 0 0 0Irritating 0 1 0 0 0 6 2 1 2 1 1 1 1 1 2 2Jerky 0 1 1 0 0 2 0 4 2 1 1 1 4 1 3 1Knocking 0 3 0 1 0 1 0 0 0 5 7 5 2 3 1 3Location 0 1 1 2 1 1 0 1 2 1 1 1 2 1 2 1Loose 1 0 0 3 1 0 1 1 2 0 1 0 1 0 1 1Mental work rate 0 1 2 0 3 2 1 1 2 0 0 0 0 0 0 0Modified movement 0 0 4 0 0 0 0 3 2 0 0 0 1 0 3 0Muscular fatigue 0 5 0 0 1 2 1 2 1 3 3 2 4 2 2 3Obstruction 0 2 1 0 0 1 0 2 2 2 2 1 2 1 3 3Over heating 4 0 0 2 0 0 1 0 0 0 0 0 0 0 0 0
ISWC2002
Multidimensional Scaling• Multidimensional scaling finds
the structure in a set of distance measures between objects or cases.
• Accomplished by assigning observations to specific locations in a conceptual space.
• Distances between points in space match the given dissimilarities.
• By applying the association matrix to MDS 6 groups of comfort terms derived.
ISWC2002
Comfort Groups• Emotion
• Concerns about appearance, embarrassment, conspicuousness
• Attachment• Physical feel of the device on the body
• Harm• Physical affect on the body, damage to the body
• Perceived change• The wearer feels physically different, upset
• Movement• The device affects movement
• Anxiety• Worry about the device, safety and reliability (white coat syndrome)
ISWC2002
Comfort Rating ScalesTitle Endpoints Description
Emotion Low/High I am worried about how I look when I wear this device. I feel tense or on edge because I am wearing the device.
Attachment Low/High I can feel the device on my body. I can feel the device moving.
Harm Low/High The device is causing me some harm. The device is painful to wear.
Perceived change Low/High Wearing the device makes me feel physically different. I feel strange wearing the device.
Movement Low/High The device affects the way I move. The device inhibits or restricts my movement.
Anxiety Low/High I do not feel secure wearing the device.
Emotion
Low High
Attachment
Low High
Harm
Low High
Perceived change
Low High
Movement
Low High
Anxiety
Low High
ISWC2002
SensVest
• Part of the Lab of Tomorrow project.
• Designed to house components that measure and transmit physiological data
• heart rate• temperature• acceleration
• Used as a teaching tool to record aspects of every day activities.
ISWC2002
SensVest Comfort Assessment• Comfort assessment is being
used to evaluate the SensVest
• Comfort measured after carrying out self selected activities
• eg. Walking, sitting, bending, raising and rotating arms
• 10 postgraduate students (age: 252)
ISWC2002
SensVest Comfort Assessment• Comfort measured after
wearing SensVest in accelerometry data collection sessions
• Wrist acceleration during throwing
• Body acceleration during whole body activities
• 14 undergraduates took part in both sessions (age: 19 1)
Wrist acceleration when throwing
-1
0
1
2
3
4
5
0 1 2 3 4 5 6 7 8 9 10
Time (s)
Acc
eler
ati
on
(g
)
Dynamic body acceleration
-2
-1
0
1
2
3
4
0 20 40 60 80 100 120
Time (s)
Acc
eler
ati
on
(g
)
Stand
SitWalk Run
Jump
ISWC2002
SensVest Comfort
• General pattern• Attachment, Perceived
change and Movement scored highest
• Harm and Anxiety scored lowest
• Between conditions• Dynamic condition
scored highest
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101214161820
Emotion Attachment Harm PerceivedChange
Movement Anxiety
Comfort Dimension
CR
S S
core
General Throwing Dynamic
ISWC2002
SensVest Comfort• Emotion
• Aesthetics, size and bulk, feel conspicuous
• Attachment• Size, weight, pulls shirt out of shape, move during dynamic activity
• Harm• Not painful, increased during dynamic activity – components collide with the
body
• Perceived change• Size, bulk, due to attachment issues
• Movement• Size, components around shoulder affect arm movement
• Anxiety• Low in general condition (no data collected) increased in accelerometry studies
(data collected)• Dynamic activity – damage to the device
ISWC2002
Redesigned SensVest
• Vest design• Smaller, lighter• Cooler• Can be worn over or
under own shirt• Adjustable size
ISWC2002
Comfort of new SensVest
• Comfort scored when carrying out self selected activities
• CRS scores lowered for new design
• New design improved comfort
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Emotion Attachment Harm Perceivedchange
Movement Anxiety
Comfort Dimension
CR
S S
core
SensVest Redesigned SensVest
ISWC2002
WECA PC
• Wearable PC that displays different web pages depending on your location.
• Worn in side bag over the shoulder
• Measures 17x4x10cm• Weighs 600g• See Bristow et al.
ISWC2002
WECA PC Comfort
• Comfort assessed under two conditions
• General condition • After carrying out self selected activities
(as used in SensVest study)
• After User trials• Using the WECA PC while walking around the
University of Birmingham campus
• See Bristow et al.
ISWC2002
WECA PC Comfort
• General pattern• Attachment, Perceived
change and movement scored highest
• Harm scored lowest
• Between conditions• Comfort scores
increased in field studies
• Greatest increase in Emotion and Anxiety
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101214161820
Emotion Attachment Harm PerceivedChange
Movement Anxiety
Comfort Dimension
CR
S S
core
Laboratory Field
ISWC2002
WECA PC Comfort• Emotion
• Size and bulk, feel conspicuous, increased in social environment
• Attachment• Size and bulk, loose fitting, moves during movement
• Harm• Not painful
• Perceived change• Size, bulk, due to attachment issues
• Movement• Size, position, inhibits arm swing when walking
• Anxiety• Low in general condition (not interacting with device) • High in field study (interacting with device)
ISWC2002
Implications
• Studies show comfort should be measured over a range of dimensions
• Cognitive factors of comfort should be measured
• Comfort should be measured in the field when carrying out a number of activities
• Knowledge of context and situations of use are important
ISWC2002
Conclusions
• CRS provide a tool to assess comfort over a range of dimensions for wearable technology
• CRS can be used to measure comfort specific for device or dimension
• CRS may assist designers decide what aspect of devise needs alteration to improve comfort and make more wearable
• Used pre and post CRS can be used to determine the effectiveness of any modification made to design
