1. Introduction to Ergonomics

2. Engineering Definitions Process: Problem symptom or need
Problem Definition,
Statement of Desired Outcome
Analysis (Experimentation?)
Synthesis of Alternative
Solutions
Decision (Selection)

3. Process Example
What are the design considerations for a prosthetic Leg?

4. 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

5. Ergonomics - Introduction
Worker Capacity <= Job Demands
Methods:
Workplace and Equipment Design
Tool Design
Design of Work Methods
Matching Capabilities and Limitations of Worker

6. 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

7. Ergonomics and Physiology
Relevant Subject Areas
Muscular
Nervous
Circulatory
Digestive
Psychosocial
Cognitive
Sensory

8. Ergonomics and Physics
Force
Regularly exerted ON the body and BY the body
F=ma
Acts in a linear direction
Muscles generate force

9. 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.

10. Ergonomics and Physics
Pressure
Imparted BY the body and ON the body
P=F/A
Examples

11. Occupational Injury Difference between Ergonomics and Safety?
Cumulative Trauma Disorders (CTD)
Definition: Bodily injury associated with repeated biomechanical stress over time.

12. Occupational Injury
Risk Factors for Cumulative Trauma Disorders

13. 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.

14. Cumulative Trauma Disorders
De Quervain’s Disease
Tenosynovitis in the tendons at the base of the thumb.
Finkelstein Test

15. 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

16. 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.

17. 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

18. 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

19. Tool Design Guidelines
Types of Grip
Power
Precision
Design for Population
Gender
Left/Right Handedness

21. Tool Design Guidelines
Handle
Diameter
Length
Shape
Surface (material)
Angulation
Grip Span
Weight

22. Examples
Pliers
Knives
Scissors

26. Engineering Design Constraints
Example: The Vibration Dilemma

27. The Future
Workplace and Equipment Design