LG 2000 Cellular Phone

Ergonomic Evaluation and Recommendations
Jeffrey A. Werner Student No. 0027662 SOCS-217 Ergonomics I Assignment 2 Emily Carr Institute of Art + Design March 6, 2007

Introduction

Table of Contents
1. Introduction (this page!) 2. Current Design of the device 3. Task Description of its use 4. Relevant Body Dimensions. User Profiles 6. Relevant Anthropometric Table 7. Clothing Considerations. Recommended Dimensions for redesign 9. New Design sketches Page 1 Page 2 Page 3 Page 4 Page 7 Page 9 Page 10 Page 11 Page 12

Purpose

This paper applies ergonomic principles and methodologies to a study of the design and use of an existing product, the LG 2000 Fido cellular telephone. The purpose is to determine what, if any, recommendations can be made to the physical design of the device in order to better fit its intended users. Measurements are taken of the device and then compared with existing anthropometric data tables, as well as an analysis of the various functions and tasks the phone and its users perform.

Terminology

Device User Open Closed The LG 2000 phone Target user group as specified in User Profile: Suggested Target Group The flipped open, or active, state of the device The closed, or passive, state of the device

Werner, page of 12

Current Design
Device Dimension Sketches

Task Description

Significant User Tasks
While the device can perform a number of functions it is found that many use the device to complete primary tasks like checking the time, the current communication status and voicemail messages. Other tasks include placing and receiving calls and sending and receiving text messages.

Task Summary

Task Storing device Grab device Open device Issues Possibly in pocket and bulky Few or none Too small to hold securely; positioning thumb between groove of clamshell difficult and increases chance of dropping; requires significant range of thumb motion Requires keying # (pound) key to confirm PIN: position of key puts thumb at extreme of range of motion and precarious grip for hand on device Must rotate arm and exert force to position and hold device near ear and mouth and compensate for shorter length of elbowear than elbow to phone grip; Buttons smaller than thumb breadth; lowest positioned buttons on keypad near bottom of device, puts strain on thumb and hand grip Thumb can coordinate with fingers to pry open clamshell High priority Notes Lower priority

Dial voicemail

Talk on device

Medium priority

Key buttons

Low & High Priority

All tasks are evaluated based on one-handed use of the device.

Relevant Body Dimensions

Overview
Device Dimension Open circumference Closed circumference Open length Keypad Keypad buttons (individual) Static/Dynamic Static Static Static Dynamic Static Relevant Body Dimensions Grip circumference, hand length, hand breadth Grip circumference, hand length, hand breadth Hand length, hand breadth, earmouth distance, elbowear distance Thumb breadth, thumb grip point, hand length, hand breadth, thumb range of motion Thumb breadth, thumb strength

All dimensions in millimetres and rounded to nearest whole digit.

Hand Width and Length

The measurement is relevant in determining how the user holds the device for use, including when it is open and closed. The width can dictate the smallest or largest object the users hand can accommodate. If the device is too wide or too narrow it will be cumbersome, or unusable.
Grip Width & Circumference
Again, this measurement is relevant in determining not only the maximum or minimum size of device the users hand can grip, but at what size does the user have the most power, control and comfort.

ElbowFingertip Distance

Because many of the devices functions dictate holding it to the ear and mouth, the users forearm length can determine the angle the device is held at, the relative strain on the users elbow joints, and the amount of power and stamina required to position the device to complete a task like placing or receiving calls.
Thumb Width and Grip Point
Larger thumb widths can often cause difficulty when dexterity and precision is required with small controls or keypads, such as the compact buttons of the device. The grip point, at which the thumb can exert the most control and power, also relates to the pressure required to active a button and the point at which activation or gripping becomes problematic.

Thumb Reach Envelope

The range in which the thumb can move while gripping the device greatly determines the level of usability presented by control positioning on the device.

User Profile

Current Target Group
The device is distributed in Canada exclusively through Fido Solutions Inc. and thus with a primary user base in Fidos cell phone user market: British Columbia, Canada. Taking into account the devices marketing, geographic penetration and current design, the following specific profiles are estimated as LG and Fidos target market for the device: Age Range 13-60 years old Gender Male and female Ethnic/Cultural Background Inclusive, though primarily English-speaking Size Various adolescent to adult to elderly. Body types ecto- to mesoto endomorph. Excludes infants and children, the physically disabled (blind or missing limbs/digits). Economic Standing Lower-middle class (the device is relatively lower-priced) to middle class. Geographic Location Urban dwellers in large city centres (based on marketing campaigns, majority Fido customer base, device aesthetics).

Suggested Target Group /Population Percentage
Because of the wide range of hand sizes and levels of dexterity found within the current target group, three user profile variationsand thus three device variationsare recommended over providing one device design that meets the needs of only the average or 50th percentile user and thus a small percentage of the target population. Except for age and gender, the following profiles assume the same demographics as the current target group: User Profile A 1318-year-old females User Profile B 1318-year-old males 1855-year-old females User Profile C 1855-year-old males In the interest of brevity and focus, only this target group will be addressed in this paper. User Profile D 5580-year-old males

Anthropometric Table

Relevant anthropometric data tables for all four user profiles should be consulted within a complete undertaking of the devices ergonomic redesign. Below, male-only population data is considered. This table is relevant because it is relatively recent (1989) and it considers Americans, a user group very similar in body dimensions to Canadians.
Body Dimensions of U.S. Civilian Adults, 1989 (excerpt, males only)
Dimension Grip circumference Hand length Hand breadth, metacarpal 5th %tile 84 50th %tile 90 95th %tile 98 SD 9.7 9.8 4.2 Relevance How far the hand can extend around the device. The min. or max length the device can be usably held. How the device is cradled and manipulated in the palm. Because thumb is used for keying, full hand width is not calculated. Manipulation of keypad buttons. Distance to position earpiece to ear. The larger the dimension the more the shoulder joint must be rotated and energy exerted. The optimum point on the thumb for keying buttons on the device. Related to elbowear distance, determines the reach needed to position device earpiece to ear as well as energy applied to hold device a comfortable distance from face.
Thumb breadth, interphalangeal Elbowear distance

22 533

24 561

27 590

Thumb grip point

Elbowfingertip distance

All dimensions in millimetres and rounded to nearest whole digit. Calculated by equating ear height to eye height and subtracting from this the elbow height. Both units measured from floor in standing position.
Source: The Anatomical and Mechanical Structure of the Human Body, page 27. Adapted from US Army data reported by Gordon, et. al. (1989). Werner, page of 12

Clothing Considerations

Handwear
Glove and other clothing worn on the hand have a significant effect on the usability of the device. However, the user profile suggests the urban dweller with a majority living in Canadas most temperate climate in Vancouver, where gloves are worn less than other target groups.

Torso and Legwear

Long sleeves on jackets or shirts, and small pockets on pants , have a bearing on the ergonomics of the device. For example, long sleeves could inhibit handling the device; small or nonexistent pockets would limit or determine the usable storage options for the user.
Based on demonstrations and observations of use (users tend not to exhibit a need for a device compatible with interfering wear) clothing is not considered a significant factor in this paper.

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Recommended Dimensions

(For User Profile C)

Device Measure Width Length open Current Dimension 35mm 175mm Current Percentile 5th95th 5th95th Recommend Dimension 60mm 225mm Percentile Accomm. 5th95th 5th95th Justification Same percentile range, but with greater comfort and control. Same percentile range, but with greater comfort and less exertion to hold it there; closer relationship between earpiecemicrophone distance and earmouth distance. Same percentile, but with more precision, control and comfort. Accommodates the greater range of thumb motion laterally than vertically; greater comfort; improved one-hand use. Better accommodates limited thumb extension; better grip on phone when keying bottom buttons
Individual numeric keypad buttons Overall keypad dimensions

50mm2 39x35mm

5th95th ~50th95th

100mm2 55x25mm

5th95th 5th95th
Keypad location from bottom

5th95th

Does not include antenna

Werner, page 11 of 12

New Design

Keys 100mm2 Keypad x2mm

Werner, page 12 of 12

A.V.Gerbessiotis lg lg n-depth Trees
CIS 668 09-11-2000 Doubly Logarithmic Depth Trees

Fall 2000 Handout 8

In a doubly-logarithmic depth tree, the number of level-i nodes is equal to 22

= 22 = 2 = 2

n1 (1+1/2+1/22 +.+1/2i1 ) 1/2i 1 1/21 1/2i 1 1/2

2n1 2n1

= 22 = 22 = 22

n(i+1)

n1 (21/2i1 ) n1 (22i+1 ) n 2ni
Each such node of level i has 22 children in level i + 1. Consider the square of this number which is 2(2n(i+1) ) and corresponds to the number of processors assigned to these children in algorithm MAX2. As the 2 n ni total number of level i nodes is the total number of processors assigned to level i + 1 nodes is then given by the following quantity. 22
)2 = 22 = 22 = 22 = 22 = N

n 2ni n 2ni

22(2 22

n(i+1) )

n 2ni +2ni n
Note: In class I used m for n and n for N.