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.

11. 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)

12. 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)

13. 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.

18. 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.

19. 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)

21. 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

22. 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