Design of Ergonomic Computer Workstation

using Anthropometry for an Educational

Institution

Chintan H. Trivedi

M.Tech Scholar (Industrial Engineering)

Shri Ramdeobaba College of Engineering and Management Nagpur.

Dr. R.B. Shahu

Associate Professor (Industrial Engineering)

Shri Ramdeobaba College of Engineering and Management Nagpur

Abstract- This paper focuses on developing design which considers an ergonomic aspect in computer

workstation for an educational institution. However, in order to design of an ergonomic computer

workstation anthropometric parameters were considered which include student body measurements which

has its projection in design selection. Based on subjects body measurements data is tabulated into mean

standard deviation and percentiles values. A model of ergonomic computer workstation is proposed in this

paper for subjects under study of Educational Institution.

Keywords – Anthropometry , Ergonomics, Computer Workstation.

I. INTRODUCTION

Every day, people spend much time in seated posture, while eating, driving, meeting, watching television, etc.

Researchers found that sitting required less muscular work than standing . Since the anthropometric database has

been established, the anthropometric database is completely based on students of educational institution of age

group 18-25 years of Gondia district (Maharashtra). How to apply anthropometric database in the use of design of

product is an important objective. The objective of this study focuses on the application of an anthropometric

database of student, in use of designing of computer workstation. This study focus on the application of an

anthropometric survey of student and finally, with the help of anthropometric database, the designing of computer

workstation is been done.

In order to design for an ergonomic product one need understand “for whom and for what concept” in order to ease

the design process of product. “For whom” defines what will be the population accommodated and “For what”

concept defines the need of the product. Normally design is divided in three categories. “Extremely design” which is

considering the application for extremely aspects, “Average people and adjustable design” is for ordinary people,

actually average people is not existed. Therefore “Average people design” is constrained for people whom are not

suitable for extremely design and adjustable design. In order to design an ergonomic computer chair this three

categories are been taken into consideration for study. Anthropometry is the study which deals with the

measurement of the physical features and functions of the human body, including linear dimensions, weight, range

of movements etc. Structural dimensions are measured with the body of the persons in fixed or static standardized

positions. Functional dimensions are taken of body positions which results from its motion are called functional

body dimensions.

The rest of the paper is organized as follows. Section II includes Methodology used for this study. Analysis of Data is presented in section III. Results are shown in section IV. And Conclusion is given in SectionV.

II. METHODOLOGY

A. Sample, procedure, measuring method

Study considers students of different age group from various departments from Gondia Education Society

Colleges, Gondia. In order to carry out the research authorization was obtained from the director, principal and

Professors of the colleges. About 200 students were selected randomly for the various anthropometric measurements

of the students out of which 100 were male and 100 were female. Twelve Criteria for anthropometric measurement

were selected. Students were categorized according to their level of study: first-year, second-year, third-year, and

final-year undergraduate. Their ages ranged from 18 to 25 years with a mean age of 19.3 years and a standard

deviation of 1.6 years.

Various anthropometric measurements of normal healthy students were taken in standard sitting and standing

positions having barefoot and light normal dress with empty pockets. The demographic details like age, gender, and

grade level of each participating student were also collected. A standard measuring tape was used to measure body

dimensions. A statistical-software named Microsoft Excel spread sheet was used to calculate the mean values,

standard deviation value, and also the percentile value.

B. Anthropometric Measurement

Figure 1. Anthropometric Measurement Parameters

Anthropometric measurements are obtained as the basis for the design of Computer Chair ergonomically. Thus,

for its designing, the following anthropometric measurements have been considered. However it is assumed that the

participant sits fully erect with thighs fully supported and the person is supporting the flat feet on the floor.

Fig. 1 shows anthropometric dimensions have been measured belonging to the age group of 18-25 years in this

study. It Includes: 1= Stature, 2 = Sitting height 3 = Sitting mid shoulder height 4 = Popliteal height 5= Hip breadth

6 = Elbow rest height 7 = Buttock popliteal length 8 = Buttock knee length 9 = Thigh clearance 10 = Sitting eye

height 11 = Shoulder breadth 12 = Knee height as shown in Figure 1 2 3. These Anthropometric dimensions have a

direct impact on the design of Computer workstation including Table and Chair for the users.

Stature: Distance measured vertically from the footrest to the vertex while the participant stands fully erect with feet

together looking straight ahead.

Sitting height: Distance measured vertically from a horizontal sitting surface to the vertex.

Sitting shoulder height: Distance measured vertically from a horizontal sitting surface to the acromion. Shoulders

are relaxed, with upper arms hanging freely

Popliteal height: Distance measured vertically from the floor to the popliteal angle at the inner side of the knee and

supports the feet flat on the floor.

Hip breadth: Maximum horizontal distance across the hips in the sitting position while the participant keeps his

knees together. Measurements were taken without pressing into the flesh of the hips.

Sitting elbow height: Measured with the elbow flexed at 90º as vertical distance from the seat surface to the

underside of the Elbow. Upper arms hang freely downwards and forearms are horizontal.

Buttock popliteal length: Distance measured horizontally from the back of the uncompressed buttocks to the

popliteal angle. At the back of the knee, where the back of the lower legs meets the underside of the thigh while

the Participant sits fully erect with thighs fully supported and sitting surface extending as far as possible Into the

hollow of the knee, supporting the feet flat on the floor freely. The position of the rearmost Point of the buttock is

vertically projected onto the sitting surface by means of a measuring block, which touches the buttocks. Distance is

measured from the measuring block to the forward edge of the sitting surface.

Buttock knee length: Distance measured horizontally from the back of the uncompressed buttock to the front of the

kneecap. The position of the rearmost point of the buttock was vertically projected onto the sitting surface by means

of a measuring block which touches the buttocks.

Sitting eye height: Distance measured vertically from the footrest to the inner canthus (corner) of the eye.

Thigh clearance: Distance measured vertically from the seat surface to the top of the uncompressed soft tissue of the

thigh as its thickest point, generally where it meets the abdomen.

Shoulder breadth: Horizontal distance across the lateral surfaces of the shoulder spread is measured.

Knee height: Vertical distance from the footrest to the top of the knee quadriceps muscle.

III.DATA ANALYSIS

Table 1: Anthropometric Data for Male students

Dimension (mm) Average Std. Deviation 5th

Percentile 95th

Percentile Male

Stature 1714.5 72.17 1624.33 1854.2

Back Waist length 457.2 33.72 406.4 508

Shoulder breadth 457.2 42.16 379.73 508

Hip breadth, sitting 457.2 44.361 355.6 433.87

Arm reach forward 838.2 48.597 736.6 889

Forearm–hand length 469.9 20.248 431.8 495.3

Buttock–knee length 533.4 40.665 495.3 609.6

Buttock–popliteal

length 457.2 29.27 418.338 508

Sitting height 863.6 41.148 800.1 914.4

Sitting eye height 762 39.159 711.2 812.8

Sitting shoulder

height 584.2

25.55

558.8

635

Sitting elbow height 234.95 38.76 190.5 304.8

Shoulder–elbow

length 330.2

23.24

292.1

368.3

Knee height 533.4 18.533 508 558.8

Popliteal height 457.2 22.23 406.4 482.6

Thigh clearance 114.3 21.765 101.6 152.4

Weight 57 6.478889651 45.665 68.3

Table 2: Anthropometric Data for Female students

Dimension Average Std. Deviation 5th

Percentile 95th

Percentile Girls

Stature 1549.4 92.4839 1371.8 1676.4

Back Waist length 406.4 41.6077 355.6 508

Shoulder breadth 406.4 33.77 355.6 482.6

Hip breadth, sitting 384.58 38.1 321.73 447

Arm reach forward 762 55.1586 685.8 870

Forearm–hand length 431.8 39.99 355.6 508

Buttock–knee length 508 35.3898 482.6 558.8

Buttock–popliteal

length 431.8 51.1175 381 508

Sitting height 787.4 39.13 711.2 838.2

Sitting eye height 685.8 43.9369 609.6 736.6

Sitting shoulder height 533.4

28.9737 482.6

584.2

Sitting elbow height 203.4 28.25 177.038 279.4

Shoulder–elbow length

330.2

29.718

304.8

381

Knee height 457.2 41.097 405.13 533.4

Popliteal height 412.75 31.80588 381 483.87

Thigh clearance 190.5 24.1401 152.4 228.6

Weight 37.95 5.0661 45 56

Measured Anthropometric Dimensions of subjects are analysed in Microsoft Excel. Dimensions are measured in mm

and then tabulated stating 5th Percentile, 95th

Percentile, 50th

Percentile Values also with standard deviation value.

Tables 1 and 2 show the average, standard deviation, 5th percentile and 95th percentile of anthropometric

dimensions collected for Indian male & female students respectively of Gondia district.

The Design parameters for designing computer workstation are as follows:

A. Seat height: The chair sitting height is the vertical distance from the floor to the highest point on the front of the

seat. The seat height is calculated for 5th to 95th percentile.

Seat height = 95th percentile of Sitting Popliteal height of male

B. Seat depth: The chair seat depth is the horizontal distance from the back of the sitting surface of the seat to its front. The chair seat depth is calculated from the Buttock popliteal depth. There must be a clearance

between the back of the knees and the front of the seat. The clearance should exist for approximately 4 to 5 inches,

measured from the leading edge of the chair. That means seat depth will be 4 to 5 inch less then Buttock popliteal

depth.

Seat depth = 50th percentile of Buttock popliteal length

C. Seat width: The chair width is the horizontal distance from the outer left side of the sitting surface of the seat to

the outer right side. Hip breath is the considerable measure in case width.

Seat width = 95th percentile of hip breath

D. Backrest height: The backrest height is the vertical distance from the top side of the seat surface to the highest

point of the backrest. The backrest height is calculated from sitting shoulder height.

Backrest height = 50th percentile of shoulder height

E. Backrest width: The American National Standard Institute (ANSI) recommended backrest should be at least

30cm wide in the lumber region.

Backrest Width = 95th

percentile of shoulder breadth

F. Backrest angle: Backrest angle is adjusted between 90- 105° according to ANSI.

G. Keyboard tray height: The Keyboard tray height is the vertical distance from the top side of the seat surface to

the highest point of the tab surface. Elbow height and thigh clearance are the considerable measure in case tab

height.

Keyboard tray height = 95th

percentile sitting elbow height

Table 3 gives the result of workstation dimension of anthropometry.

Table 3: Workstation Dimension using Anthropometry

Specification Measurement Criteria Value (cm.)

Seat height Popliteal height 52

Seat depth Buttock popliteal depth 45

Seat width Hip breadth 45

Backrest height Sitting shoulder height 55

Backrest width 95th

percentile of shoulder

breadth

46

Keyboard tray height sitting elbow height 20

IV. Proposed Design

The results obtained based on the anthropometric dimensions of students are basis for the design each component of

chair say from backrest to armrest of chair. Suitable percentile Percentiles values of each anthropometric dimension

are selected to accommodate user with ease. Fig shows the sketch of Chair which is being developed. Design of

Chair and Table is been developed in Sketch Up 2016 Make. Sketches made give an exact resemblance of final

developed Working Chair and Table after Fabrication.

Fig 2: Three Dimensional View of Chair Fig 3: Three Dimensional View of Table

Design of Worktable is been done keeping in view the students. However as compared to chair worktable design is

has lesser aspect of anthropometric dimension. Along with that the utility or need of student is also been considered

while the designing the work table. Design of worktable is also been developed in Sketch up 2016 Make. Figures

below shows various view of worktable which is to be fabricated.

Table 4.Dimensions of Work Table

S. No Component Dimension (inches)

1.

2.

3.

4.

Table Top Platform

Bottom Platform

Keyboard Tray

Sideway Plat form

18×24

14×18

14×18

8×14

V. CONCLUSION

The results obtained from anthropometric dimension of students are important substance in design of computer

workstation. Anthropometric Dimensions obtained were classified into 5th

Percentile, 50th

Percentile and 95th

Percentile. Based on Design Specifications appropriate percentiles were used. Results helped us to specify in the

design which principles of anthropometry parts should be used (e.g. design for adjustable range, or design for

extreme or design for average). The anthropometric data collected in this study shows that 90%.. The Workstation is

designed and fabricated to suit majority of the user population therefore it should be concentrated between 5th

percentile female to 95th percentile male which covers majority of the user population. Even though it is difficult to

design for all the users but a product that matches majority of the user population can be designed and the problems

solved up to a considerable extent.

V. REFERENCES

[1] C.O. Anyaeche , A. O. Adeodu , “Anthropometry as an Ergonomic Design Factor in an Open Plan Selected

Computer Operator Work Station: Cyber Cafés Perspectives”, International Journal of Scientific & Engineering

Research, Volume 4, Issue 7, July-2013 2379 ISSN 2229-5518 .

[2] Shahrukh Ansari, Dr. M I Khan, “Ergonomic Design of VDT Workplace for Indian Software Professionals”,

International Journal of Technical Research and Applications e-ISSN: 2320-8163 Volume 2, Issue 4 (July-Aug

2014), PP. 62-66.

[3]Samuel A. Oyewole , Joel M. Haight “The Ergonomic Design of Classroom Furniture/Computer Workstation for

first graders in an elementary school”, International Journal Of Industrial Ergonomics · July 2010.

[4] Kemal Lale , Orhan Korhan , “An Anthropometric Computer Workstation Design to Reduce Perceived

Musculoskeletal Discomfort”, International Conference on Industrial Engineering and Operations Management

Istanbul, Turkey, July 3 – 6, 2012.

[5]Angsumalin, H. L. (2010). “The Application of Anthropometric Design for University Desk and Seat Heights”

The 11th Asia Pacific Industrial Engineering and Management Systems Conference Bangkok, Thailand:

Chulalongkorn University.

[6] Ashraf, M. (2007). “Office Ergonomics: Deficiencies in Computer. International Journal of Occupational Safety

and Ergonomics” (JOSE) , 13,2,215-223.

[7] Callahan, J. L. (2004). “Effects of different seating arrangements in higher education computer lab classroom on

student learning, teaching style,and classroom appraisal”.

[8]Castellucci, P. A. (2010). “Mismatch between classroom furniture and anthropometric measures in Chilean

schools. Applied Ergonomics” 41, 563-568.

[9] Gouvali, B. (2006). “ Match between school furniture dimensions and children’s anthropometry”. Applied

Ergonomics. pp 37, 765-573.