The Ergonomic Implications of Gesturing

Examining Single and Mixed Use with Appropriate Placement

Lindsey Muse B.A., S. Camille Peres Ph.D., Adrian GarciaUniversity of Houston-Clear Lake

The Problem: Research not keeping up with Technology•Number of products with touch screen

capabilities is increasing•Limited research available concerning the

ergonomic impacts of gesturing

▫Existing research is almost completely based on subjective measurements

•Designers and developers need objective measures accompanied with subjective measures to understand the impact of gesturing on the body to help avoid injury

Areas of Interest for Ergonomics(Independent Variables)

•Types of touch screen devices▫Handheld▫Pad▫Laptop▫Desktop

•Input Styles:▫Single Use: Touch only▫Mixed Use: Touch and keyboard or mouse where

it applies• Possible placement for each product

▫Desk, Lap, Hand while sitting, Hand while standing

Conditions

Participants•100 participants from within and outside of the University of Houston-Clear Lake▫Outside the university

$1oo each for participation▫Within the university

One hour of participation credit for every hour in the study

•Participants will be selected so they have some experience with at least one of the gesture input devices

Objective Measures

•Surface EMG (SEMG)▫12 electrodes placed on the upper body to

measure muscle activity during testing Bilateral - flexor, extensor, trapezius, deltoid,

thenar and hypothenar Mean and Standard deviation of RMS of SEMG

Subjective Measures

•Modified Body Discomfort Diagram▫17 body parts and muscle groups for

participants to rate (primarily looking at the upper body)

•Open-ended questions▫Participants’ computer usage▫Their comfort or discomfort after each

session

Goals•Obtain objective and subjective ratings from

participants for the 4 touch screen devices ▫Gather data with different input styles (single

and mixed use) where applicable▫Gather data in the different postures that apply

to each device•Better understand the risks involved for these

4 products •Provide valuable information to minimize risks

in current and future technologies

Appendix:Timeline

Appendix:Budget

Appendix:Data Analysis

•Primarily exploratory and descriptive analyses:▫ANOVA’s calculated for each dependent

measure on each device (and by environment where appropriate) subjective: BDD objective: S-EMG

▫Summary of comments on open ended questions

Analyses-Subjective

• BDD: difference in ratings by • device, posture, muscle, session

• free choice• input device, posture

• free response• most uncomfortable task, how uncomfortable

were they with the posture• did counterbalance seem to matter with any of

these?

Analyses-Objective• SEMG:

• Mean EMG: by device, task, muscle, posture• SD EMG: by device, task, muscle, posture

• Motion Capture• 3 angles: shoulder abduction (?), elbow extension,

torso lean (?)• per device and posture (two prescribed postures):

• Typical worst posture• how long until participants assume that posture• how long they maintain the posture

• per device - free choice: • Typical worst posture• how long until participants assume that posture• how long they maintain the posture