Ergonomics in the Automotive Design Process

13

2

Engineering Anthropometry

and Biomechanics

INTRODUCTION

The process of vehicle design begins with a discussion on the size and type of the vehicle and the

number of occupants that the vehicle should accommodate. To assure that the required number of

occupants can be accommodated, the designers must consider the dimensions of drivers and the

passengers and their posture in the vehicle space. Therefore, in this chapter, we will review basic

concepts, principles, and data related to human anthropometric and biomechanical characteristics,

along with the considerations used in vehicle design, with an emphasis on occupant package and

seating design.

Anthropometry and biomechanics are related elds in the sense that both depend on the dimen-

sions of humans and the ability of humans to assume different postures while working or using

vehicles. The two elds can be dened as follows.

Engineering anthropometry is the science of measurement of human body dimensions of differ-

ent populations. It deals with skeletal dimensions (which are measured from certain reference points

on the bones that are less exible as compared with skin tissues), shape, contours, area, volumes,

centers of gravity, weights, and so forth, of the entire human body and body segments. Engineering

anthropometry involves applications of the anthropometric measurement data to design and evalu-

ate products to accommodate people.

Biomechanics deals primarily with dimensions, composition, and mass properties of body

segments, joints linking the body segments, muscles that produce body movements, mobility of

joints, mechanical reactions of the body to force elds (e.g., static and dynamic force applications,

vibrations, impacts), and voluntary body movements in applying forces (torques, energy/power) to

external objects (e.g., controls, tools, handles). It is used to evaluate if the human body and body

parts will be comfortable (e.g., internal forces well below strength and tolerance limits) and safe

(avoidance of injuries) while operating or using machines and equipment (or vehicles).

USE OF ANTHROPOMETRY IN DESIGNING VEHICLES

The very rst step in designing a vehicle is to determine the user population(s) and their anthropo-

metric and biomechanical characteristics. The anthropometric data of the user population will help

in determining many basic dimensions of the vehicle. The biomechanical data will help design the

vehicle such that the users will not be required to exert or be subjected to forces that are above their

tolerance or comfort levels.

Figure 2.1 shows some basic dimensions of people in standing and seated postures. A number of

populations from different countries and different types of vehicles are measured (available in many

human factors books, e.g., Pheasant and Haslegrave, 2006). Such data are also obtained by automo-

tive companies by measuring dimensions of participants invited to attend market research clinics to

evaluate new vehicle concepts or early prototypes.

Table 2.1 provides anthropometric data on U.S. adults for dimensions that are useful in accom-

modating occupants and in evaluating interior spaces and clearances. The table presents 5th, 50th,

and 95th percentile values and standard deviations of various anthropometric dimensions of females

and males compiled from different sources. It should be noted that these values do not take into