The Comfort Assessment of Wearable Computers

1
The Comfort Assessment of Wearable Computers

• James F. Knight, Chris Baber,
• Anthony Schwirtz and Huw W. Bristow

2
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

3
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

4
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

5
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

6
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.

7
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.

8
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)

9
Comfort Rating Scales
10
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.

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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 25?2)

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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)

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SensVest Comfort

• General pattern
• Attachment, Perceived change and Movement scored
  highest
• Harm and Anxiety scored lowest
• Between conditions
• Dynamic condition scored highest

14
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

15
Redesigned SensVest

• Vest design
• Smaller, lighter
• Cooler
• Can be worn over or under own shirt
• Adjustable size

16
Comfort of new SensVest

• Comfort scored when carrying out self selected
  activities
• CRS scores lowered for new design
• New design improved comfort

17
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.

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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.

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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

20
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)

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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

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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