Engineering Anthropometry - Comprehensive Study Notes

OBJECTIVES

  • Define anthropometry

  • Discuss the importance of anthropometry

  • Identify the necessary anthropometric data for a given design

  • Differentiate static to dynamic measurements

  • Accurately measure body dimensions (in steady and action state)

  • Identify the best design principle for a specific application

  • Correctly compute for the necessary statistics in an anthropometric design

  • Identify the effects of poorly-designed systems

  • Identify real-life applications of engineering anthropometry

BRIEF HISTORY

  • An outgrowth of Physical Anthropometry

    • Initially an attempt to differentiate among fossils to distinguish among races and ethnic groups of humans, identify criminals and aid in making medical diagnoses

  • More recently used in industrial settings

    • Development of engineering requirements and evaluation of vehicles, worksites and clothing

WHY ANTHROPOMETRY?

  • To design workplaces, equipment and the physical environment to fit the characteristics and capabilities of most people in a complex task

  • Poorly designed equipment or environment may lead to injuries

EXAMPLES OF POORLY DESIGNED WORKPLACES

  • Sinks that are too low

  • Handrails that are too high

  • Pants that fit the hips but are too loose at the waist

  • Falling face shields

  • Hand rails in MRT

ANTHROPOMETRY

  • The science of measurement and the art of application that establishes the physical geometry, mass properties, and strength capabilities of the human body

  • Derived from the terms anthropos (human) and metrikos (pertaining to measurement) – Adolphe Quetelet

  • One of the basic tools for the analysis and development of engineering design requirements

  • Analysis of forces and torques during manual material handling, accommodation, comfort and general human performance

  • Influences many Human Factors and Ergonomics aspects of physiology and psychology of comfort

ANTHROPOMETRIC CONSIDERATIONS

  • Sizes

  • Proportions

  • Mobility

  • Strengths

  • Other factors that define human beings physically

USES OF ANTHROPOMETRY

  • Evaluate postures and distances to reach controls

  • Specify clearances separating the body from hazards such as surrounding equipment

  • Identify objects or elements that constrict movement

KNOWLEDGE AND SKILLS REQUIRED – ANATOMY

  • Locations, names and shapes of bones and muscles

  • How to read measurement scales, measure weights and how to handle instruments

  • For advanced technologies, understanding of principles of electronics, lasers, photography, and video devices

KNOWLEDGE AND SKILLS REQUIRED (Anatomy – Body Planes and Orientation)

KNOWLEDGE AND SKILLS REQUIRED – ADDITIONAL

  • Statistical principles and methodologies

  • Mathematics, concepts of mass properties, forces and torque

  • Planning and organizing time and processes

  • Good language skills and facility in writing scientific material

ANTHROPOMETRIC MEASURES

  • Static (Structural Dimensions)

  • Dynamic (Functional Dimensions)

BASIS OF MEASUREMENTS

  • Baseline Definitions

    • Body segment lengths and heights

    • Breadths, depths and circumferences

    • Surface contours

    • Body volumes, densities and areas

    • Envelopes of reach

  • Postures

    • Standard sitting and strength

    • Standard upright sitting

    • Leaned against a wall with back flattened and buttocks facing the wall

    • Lying on the back

    • Other postures depending on task being analyzed

BASIS OF MEASUREMENTS (posture examples)

  • Posture definitions include standard sitting, upright sitting, leaning against a wall, lying on the back, and other task-specific postures.

DEVICES AND PROCEDURES

  • Manual Anthropometrical Instruments

    • Grip board and blocks

    • Anthropometers

    • Calipers

    • Flexible tapes

    • Goniometers

  • Indirect Methods

    • Photography

    • Video Recording

  • Lasers and Optical Surface Scanning Methods – Internal Imaging

    • X-rays

  • Methods of measuring mass properties

    • Weighing Scales

ANTHROPOMETRIC INFORMATION

  • US Soldiers were measured extensively for uniforms, armor and equipment

  • Represents one of the most extensively documented human groups

  • Studies have been done in other Asian countries such as Taiwan, Japan, Hong Kong, etc., most of which are industry-specific

STATISTICS AND ANTHROPOMETRY

  • Most data are normally distributed

  • Most parametric statistics procedures are applicable

  • Issues on variability include:-

    • Measurement

    • Intra-individual

    • Inter-individual

    • Secular

  • Heavy use of percentiles

  • Establishes exclusions

  • Selection of subjects for fit tests

  • Any dimension can be located exactly

  • Selection of users of products

ANTHROPOMETRIC DESIGN PRINCIPLES

  • Design for All

  • Design for Adjustment

  • Design for Several Sizes

  • Design for Extreme Individuals

KNOWLEDGE AND SKILLS REQUIRED – THE SKELETAL SYSTEM

  • The human skeleton is normally composed of 206 bones, with connective tissues and articulations

  • The skeletal bone provides an internal framework for the whole body

THE SKELETAL SYSTEM

  • Connective Tissues

  • MUSCLES are the organs that generate force and movement

  • TENDONS are strong elastic tissues connecting muscles to bones

  • LIGAMENTS connect bones and provide capsules around joints

  • CARTILAGE is a translucent, viscoelastic, flexible material, as articulation surfaces at the joints

  • Joints are body links that determine the human mobility

  • Maximal displacements of the body define the range of motion

RANGES OF MOTION

  • Flexion

  • Hyperextension

  • Extension

  • Outward rotation

  • Abduction

  • Adduction

  • Inward rotation

  • Outward rotation

  • Inward rotation

  • (Additional entries listed in the transcript cover variations like dorsal flexion, ulnar/radial deviation, pronation/supination, plantar flexion, lateral flexion)

RANGES OF MOTION (expanded)

  • Extension, Hyper-extension, Dorsal flexion, Ulnar deviation, Supination, Flexion, Radial flexion, Pronation, Plantar flexion, Lateral rotation, etc.

THE SKELETAL SYSTEM – SPINAL COLUMN

  • The spine consists of 24 movable vertebrae arranged in fused groups of rudimentary bones

  • The spine protects the spinal cord

  • The spine is capable of withstanding loads, yet flexible enough to allow a large range of motion

BACK PAIN

  • The spinal column is often the location of injury, pain and discomfort because it continuously transmits internal and external strains

  • Back pain results from a combination of repetitive trauma and the normal aging process

  • Overexertion injuries have been traced to the compression of spinal discs, particularly the lumbar area

HUMAN STRENGTH

  • Muscle Strength – maximal tension or force that a muscle can develop voluntarily between its origin and insertion

  • Body Segment Strength – force or torque that can be applied by a body segment to an object external to the body (e.g., hand, elbow, shoulder, back or foot)

HUMAN STRENGTH ASSESSMENT

  • Strength is influenced by motivation and the physical conditions under which it is exerted

  • Body strength is measured using analog or digital dynamometers

  • Example reference: Digital Hand Dynamometer

RECENT TRENDS IN ANTHROPOMETRY

  • Use of computer modeling to model humans; shift in measurement goals

  • New electronic imaging technology impacting anthropometric methods

  • Determination of true percentage accommodation is favored over common percentile manikins

APPLICATIONS OF ENGINEERING ANTHROPOMETRY

  • Automotive Vehicle Interiors: body posture selection and foot location; eye position; reach envelopes; human and cabin dimensions

  • Airplane Cockpits: design specification layout; clearance and adjustment envelopes

  • Aircraft Passenger Accommodations: shin clearance for seating; shoulder clearance; design of lavatories for handicapped people

  • Computer