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38 Pages·2009·1.8 MB·English

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ACKNOWLEDGEMENT 

I am thankful to my supervisor Dr. Jerard J Gouw for giving me a real life project to work on
Ergonomic design of a car seat. This project definitely helped me to gain better learning and
understanding of different type of seating position and its impact on human comfort and injury. I
would also like to thank him for rendering all his efforts, supports and encouragement to complete the
project.

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ABSTRACT 

Passenger car seating design and arrangement for driver plays significant role on drivers comfort and
safety while driving. Most drivers are in a high-risk group for spinal disorders including back pain,
neck pain, sciatica, degeneration, and herniated discs, etc. A proper ergonomics design can solve these
problems or reduced the problem significantly, therefore as an engineer we must have to know about
the structure of the vehicle seat. It is necessary to establish ergonomic models of the seating and
analyze the position of the segments of the body when the driver holds a posture of driving.

This project based on popular software CATIA V5 and provides details on human builder and human
measurements components. Major role of the software is to create mankind with different percentile
using Human Builder and Human Measurement Workbench with additional analysis of different
posture. Before designing and analyzing an ergonomic car seat its prime need to design a 3D model of
mankin with necessary view which explains work activities with different posture, including reach
envelop, vision analysis and posture activity. Additionally; and ergonomic car seat and steering wheel
also modeled and assembled with the design. Furthermore; apart from the software recent
technological aspect to design an ergonomic car seat also discussed and analyzed. Based on necessity
and habit, most of the cases a driver is bound to drive a car for long time, therefore because of long
term sitting movement of different body segments such as hand, forearm, leg and eyes are affected
which are the cause of light injuries and affected the task of driver. Because, the postures should be
studied in the research and the designer of the vehicle seat should emphasized on it. The position of
the segment of the body of the driver in driving is also an important parameter in the design of the
vehicle seat. It decides the dimension of the seat and makes the seat more comfort and can be used by
the 95 percent people. An ergonomic seat also designed and compared with flat type back seat. The
result shows ergonomic seat has less impact in trunk than regular seat.

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TABLE OF CONTENTS 

Section Title Page
1. Introduction and Literature Review …………………………………………………. 01
1.1 Ergonomics In The Automotive Industry ………………….…………..….….. 02
1.2 Standards, Guidelines And Recommendations …………..……………………. 02
1.3 Anthropometry And Fundamental Fallacies ………………..……….…………. 03
1.4 Seat Feature Design Assessment ……………………………………………….. 04
1.4.1 Road Test ……….……………………………………………..…………. 05
1.4.2 Simulation ………………………………………………………..……… 05
2 Design Consideration …………………………………………………….…………. 06
3 Designing Passenger Car Seat Travel ………………………………………..……… 06
4 Model Development, Analysis and Discussion ……………..……………..……….. 09
4.1 Create Mankin ……………………………………………………..…………. 10
4.2. Create Different % Ile Mankin …..……………………………………….…... 10
4.3. Steering Wheel Design …..………………………………………………….... 11
4.4. Chair Design ……..…………………………………………………………… 11
4.5. Human Measurement Edition ..………………….……………………………. 12
4.6. Load Parameters ………………………………………………………………. 13
4.7. Create Constraint ……………………………………………………………… 14
4.8. Posture Editor ……………………………………………….………………… 15
4.9. Angular Limitations To Percentage Setting …………………………………… 16
4.10. Object Attachment With The Mankin ………………………………………… 17
4.11 Mankin Reach Envelop ……………………………………………………….. 18
4.12 Inverse Kinematics (IK) ………………………………………………………. 19
5 Ergonomic Analysis ………………………………………………………………… 20
5.1. Vision Analysis ………………………………………………….................... 20
5.2 RULA Analysis using CATIA ………………………………………………… 21
5.2.1. Setting Ergonomics Analysis in CATIA ……………………….. 22
5.2.2. Perform RULA Analysis ……………………………………… 22
5.2.3.1 Posture Related to RULA Analysis …………………... 23
6 REBA Analysis ………………………………………………………………………. 24
7 Biomechanics Single Action Analysis ……………………………………………… 25
7.1. Biomechanics Analysis Result ………………………………………………… 26
8 Comparing Ergonomic And No Ergonomic Seat Effects On Trunk …………….….. 28
9 Some Recommendations Of Correct Sitting, Seat Design And The Drivers …..…… 29
10 Discussion ………………………………………………………..…………..…….. 31
11 Conclusion ………………………………………………………..…………..…….. 32
12 References ……………………………………………………………………..……. 33

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LIST OF FIGURE 

FIGURE No SHORT TITLE PAGE NO
1 Experimental Driving Rig 5
2-4 Seat Travel Distance 6-7
5-8 Mankin 9-10
9 Steering Wheel Design 10
10-12 Chair Design 10-11
13-16 Human Measurement 12-13
17-19 Load Definition 13-14
20-23 Posture 15-16
24 Angular Limitation 17
25-30 Object Attachment 17-18
31 Reach Envelop 19
32 Inverse Kinematics 19
33-34 Vision Analysis 20-21
35-37 RULA Analysis 21-22
38 REBA Analysis 24
39 Biomechanics 27
41-42 Comparing Correct Seating 30
43-44 Recommendation of Seating 31

LIST OF TABLE 

TABLE No SHORT TITLE PAGE NO
1 Result Of Summary Data Tab 28
2 Result of Joint Moment Strength Data Tab 28
3 Result of Segment Positions Tab 28
4 Result of Reaction Forces And Moments 29

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1.  INTRODUCTION AND LITERATURE REVIEW 

Ergonomics has a wide application in human society nowadays. Humans need more comfortable
environment of living and safer working condition. The goal to apply ergonomics technology on the
design of the equipments and systems is to ensure humans with them in complete harmony. So
engineers always put ergonomics in the more important position in the design. The purpose of this
project is to develop a CATIA tutorial to make a full human activity analysis in a sitting position of
vehicle driver. This project deals with developing a step by step CATIA tutorial explaining how the
Ergonomic Design and Analysis module along with its Human Builder and Human Measurements
components are used for creating a manikin with different percentile while changing joint angles
reflecting postural change. These changed postures are then viewed in different planes including in 3D
and analyzed for the driving activity which must include viewing at the display terminal while sitting
on a driving sit.

Firstly, a model is realized using the Human Builder tool available in Ergonomics Design and
Analysis. The model is then tailored to different percentiles using Human Measurements components.

Secondly, two major different percentile models are studied in a step by step tutorial form for their
different postures performing the driving vehicle. The study here means the information generated by
CATIA corresponding to a particular posture of particular model are gathered and observed carefully
to see whether any sitting position for driver performed over a long period of time per day could cause
any health injury resulting from awkward posture.

Finally; the driver can adjust the height of the seat and the angle of the rest back and also can move the
seat along the sliding rack to let it to suit the different size of the drivers. The position of the segments
of the body and posture of driving are most important parameters that the designer should consider and
designed the seat based on the posture so that it can provide a good lumber support of driver. From the
above parameters the designer can find the best posture to reduce the risk of the ergonomic problem
significantly.
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1.1 ERGONOMICS IN THE AUTOMOTIVE INDUSTRY 

Tools and techniques used by ergonomists in the automotive industry are based on statistical data, Test
drive, and Simulation and computer software. Statistical data analysis and test drive are the primitive
but not considered that much in now a days. In case of simulation and computer software they are
using the same data sources and CAD tools and some simulative hardware. Simulative hardware runs
user trials to evaluate their products; in some cases using only company staff as subjects, in other cases
with members of the general public. They have good correspondence with universities and the
organization is involved in research projects. Normally if there are no ergonomists then the data
sources considered as out of date and user evaluations are rarely conducted. Overall Ergonomics
evaluation depends on the quality of product and the price therefore only few model cars come with
proper ergonomic design of car seat.

1.2 STANDARDS, GUIDELINES AND RECOMMENDATIONS [3]    

Many areas of ergonomics those are pertinent to automotive design. In case of occupant
accommodation there is wide range of standards, guidelines and recommendations available those are
extremely useful in the early stages of concept design because they are readily available. Some of the
major giant company use their own or modified standard. Some of the standards and their associated
procedures have already been developed or in developing process in the field of ergonomics. USA:
The Society of Automotive Engineers (SAE) has been particularly active in the generation of such
Standards and many of these form part of the legislation which covers automotive design. In case of
human body parts with their relevant posture SAE recommendation to Ergonomist are give below:

SAE J826 H-point (ISO 6549)
SAE J1100 Seating reference point
SAE J1100 H-point travel path
SAE J1517 Driver selected seat position
SAE J941 Eye llipse (ISO 4513/BS AU 176)
SAE J1052 Driver and Passenger head position contours
SAE J287 Hand controls reach envelopes (ISO 4040/BS AU 199)
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1.3 ANTHROPOMETRY AND FUNDAMENTAL FALACIES [3 ]  

Design and development of vehicles still now many automotive companies did not have a formalized
structure to identify and deal with ergonomics issues. The main reason behind this is several
misconceptions about ergonomics and lack of knowledge to justify the necessity of it. Pheasant (1996)
and Porter and Porter (1997) in their own experience found that ergonomics in automobile industry
eight fallacies exist to design and implement a product.

1. Ergonomics is expensive and since products are actually purchased on appearance and styling,
ergonomics considerations may conveniently be ignored.

2. The design is not satisfactory for me – it will, therefore, be unsatisfactory for everybody else (a
variation on fallacy 1 above).

3. Percentiles are a very clear and simple way to present and use information concerning body size.

1-3 Fallacies is ignored because we are designing ergonomics sitting.

4. The design is satisfactory for me – it will, therefore, be satisfactory for everybody else.
Not recommended fallacies for this project because the design should fit wide range of people.

5. This design is satisfactory for the average person – it will, therefore, be satisfactory for everybody
else.
Not recommended fallacies for this project because unfortunately for automotive designers, there is no
such thing as an average man or woman, or child for that matter.

6. The variability of human beings is so great that it cannot possibly be catered for in any design – but
since people are wonderfully adaptable it doesn’t matter anyway.
Not recommended fallacies for this project because though we know people are adaptable but we have
to does research has to come up with result that meet requirement for most people.

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7. Ergonomics is an excellent idea. I always design things with ergonomics in mind, but I do it
intuitively and rely on common sense so I don’t need tables of data.

Not recommended fallacies for this project because manual design without using table and standard
data may not fulfill all the requirement of ergonomics car seat design.

8. Designing from 5th percentile female to 95th percentile male dimensions will accommodate 95%
of people.

Recommended and considered fallacies for this project. This will be true if only one dimension is
relevant to the design solution. However, some vehicle requires simultaneous accommodation on a
large number of dimensions because of lot of extra features than regular vehicle. There are poor
correlations between body dimensions it follows that those males who are designed out because of
limited headroom will not necessarily be the same 5% who are designed out for having arms that are
too long or the 5% with legs that are too long, hips too broad etc. Similarly, those females who are not
considered in design their relevant data too small will not just constitute 5% of the females. Therefore
5th percentile stature is a value whereby 5% of the population are shorter and 95% are taller; 50th
percentile stature is the median stature.

Finally; depending on the situation higher and median value conceded for this for this project. For
example, In case of car height definitely we have to consider the highest value of mankin therefore; we
must have to consider 95% ile male height.

1.4 SEAT FEATURE DESIGN ASSESMENT [3]  

In case operation of a seat and drivers comfort, visual requirement and correct posture depends on
optimum design. A good design does not necessarily make sure that the design is correct in terms
drivers ergonomic requirement until it’s not tested or assessed .To asses a design it a challenge for
manufacturer because the result come from mass group of driver after a certain period of use.
Therefore; design should be tested very accurately before marketing. Most cases testing can be
performing by two major ways: 1. Road test 2. Simulation
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1.4.1 ROAD TEST 

One of the experiments of road test conducted by Porter and Gyi (1998) [3]. According to the Vehicle
Ergonomics Group instruction they performed two test videos of 2.5 hour (60 mile) drive in their road
trials. During this test they give driver’s view of the road, with a voice-over of instructions about the
route to guide the driver of when to change gear, slow down other driving instruction. After driving
they collect necessary data from drivers. In this way mental and physical effect of driver can be
assessed before and after the test.

1.4.2 SIMULATION 

Another ways the car manufacturer tests a design by simulation. To accomplish this: Porter and Gyi
(1998) [3] used a highly adjustable driving rig (Figure 01) to identify driving postures and its effects
on a family type driving car. The simulation carried out to obtain the preferred driving
posture of driver. For this with respect to the
seat they vary the height and horizontal
location of the steering wheel and pedals.
The seat tilt angle was also adjustable. For
each of these adjustments the component
travelled by the experimenter at discrete
increments throughout its range of travel
from one extreme to the other. Then they
temporarily fixed the component and back
again the adjustment in a balanced order
F i g u r e - 0 1 An Experimental Driving Rig.

and perform the test again and again to achieve a satisfactory position. Until get a satisfactory result
they fine tuned the adjustment of all controls and positions again and again. Each adjustment a 10–15
minute driving simulation at the rig was then carried out to further confirmation that this posture was
optimum. Each result they document the relevant measures regarding the positions of the controls
from a fixed reference point. To get accurate result they placed the hands on the steering wheel and
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