Introduction to Ergonomics
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Transcript Introduction to Ergonomics
Introduction to Ergonomics
Engineering
Definitions
Process:
Problem symptom or need
Problem Definition,
Statement of Desired Outcome
Analysis (Experimentation?)
Synthesis of Alternative
Solutions
Decision (Selection)
Process Example
What are the design
considerations for a
prosthetic Leg?
Ergonomics - Introduction
Derived from the Greek “nomos” – natural
laws, “ergon” – work
Definition – discipline that uses knowledge
of human abilities to design systems, jobs,
tools, and products for the safe and efficient
execution of work.
Ergonomic Objective:
Worker Capacity <= Job Demands
Ergonomics - Introduction
Worker Capacity <= Job Demands
Methods:
Workplace and Equipment Design
Tool Design
Design of Work Methods
Matching Capabilities and Limitations of Worker
Ergonomics – Introduction
Why Important?
Specialization / Automation
Diversity of Workforce / Labor Laws
Gender
Aging Population
Injured, Disabled workers
Increase Productivity / Competitive Advantage
Prevent Injury / Reduce workers Comp Costs
Societal Quality of Life
Ergonomics and Physiology
Relevant Subject Areas
Muscular
Nervous
Circulatory
Digestive
Psychosocial
Cognitive
Sensory
Ergonomics and Physics
Force
Regularly exerted ON the body and BY the body
F=ma
Acts in a linear direction
Muscles generate force
Ergonomics and Physics
Torque
M=F*D
Acts as a moment about a fixed point
Muscles in conjunction with tendons, joins, and
ligaments generate torque.
Ergonomics and Physics
Pressure
Imparted BY the body and ON the body
P=F/A
Examples
Occupational Injury
Difference between Ergonomics and Safety?
Cumulative Trauma Disorders (CTD)
Definition: Bodily injury associated with
repeated biomechanical stress over time.
Occupational Injury
Risk Factors for Cumulative Trauma
Disorders
Cumulative Trauma Disorders
Bursitis
Tendonitis
Tenosynovitis
Tendon injury involving the synovial sheath,
caused when excessive amounts of synovial fluid
are created due to extreme repetition. Sheath
becomes swollen or painful.
Cumulative Trauma Disorders
De Quervain’s Disease
Tenosynovitis in the tendons at the base of the
thumb.
Finkelstein Test
Cumulative Trauma Disorders
Trigger Finger (Flexor Tendonitis)
Tendon swelling interferes with the normal
movement of the tendons through the synovial
sheath and can cause the finger to click, catch, or
lock in position
Cumulative Trauma Disorders
Carpal Tunnel Syndrome
Impaired nervous function in the first three digits
manifested as numbness, tingling, pain, and loss
of dexterity.
Median nerve inside the wrist becomes
compressed due to inflammation or thickening of
adjacent tendon sheaths. Inflammation may be
caused by overexertion or repeated unsafe wrist
orientations.
Tool Design Guidelines
Improper Tool Design May Cause:
Increased grip forces (CTD)
Unwanted postures (CTD)
Acute Trauma (Burns, cuts, lacerations,
abrasions, fractures, strains, sprains, dislocations,
etc.)
Reduced Productivity
Tool Design Guidelines
Situations to avoid
Sustained Ulnar/Radial Wrist deviation
Excessive or repeated flexion/extension of hand and
wrist
Excessive force
Impact shocks
Tissue compression from sharp edges or misdirected
forces
Ischemia – obstruction of blood flow to the tissues and eventual
numbness or tingling
Tool Design Guidelines
Types of Grip
Power
Precision
Design for Population
Gender
Left/Right Handedness
Tool Design Guidelines
Handle
Diameter
Length
Shape
Surface (material)
Angulation
Grip Span
Weight
Examples
Pliers
Knives
Scissors
Engineering Design Constraints
Example: The Vibration Dilemma
The Future
Workplace and Equipment Design