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Human Factors and Ergonomics - Coggle Diagram
Human Factors and Ergonomics
Anthropometrics: Study measurements of the human body, knowing peoples sizes aids designers to make comfortable products
Dynamic/Functional
Human body measurements taken when the subject is in motion
Exaples: Reach, clearance, volumetric
More useful, harder to obtain
Static/Structural
Human body measurements taken when the subject is still
Tools: stadiometer, head calliper, measuring tape, skinfold calliper
Examples: Height, weight, skinfold thickness, circumference
Easier to obtain, easier, accurate, more reliable
What makes them unreliable?
Tools used, 2. Personnel Training, 3. Time of Day, 4. Body Shape, 5. Users carry tasks differently, 6. Obtaining static data is straightforward but users interact dynamically
Types of Data
Primary
Collecting data that doesn't exist
Specific purpose, field research, but measurements may not be reliable
Secondary
Collecting data by someone other than the user
Desk research, involves, summation of data, synthesis of existing data
Percentile and Percentile Ranges
Percentile Range: Proportion of the population with a dimension at or less than a given value
5, 50, 95th percentile
5th: Smallest/weakest population. Example: Airplane cockpit, can opener
95th: Tallest population. Example: Door height
50th: Average population. Example: Chair height
5-95th
90% majority, used for adjustability
2.5-97.5th
Methods of extremes
Range of Sizes vs. Adjustability
Range of sizes
Making a product fit everyone isn't ergonomically possible, based on percentile ranges
Selection of sizes that caters for majority of the market
Example: Clothng (S,M,L)
Adjustability
Multivariate accommodation, fitting in several variables means 5% designed out
Adjusted for the majority
5th female - 95th male
Example: Iron board, car driver seats
Clearance
Minimum distance to enable user into/through an area
Designed for 95th percentile
Example: Safety hatches, emergency exists, construction sites
Reach
Workspace envelope, 3D space where you can carry out physical activities at a fixed area
Primary (closest) and secondary (furthest)
Psychological Factors: Human factor data related to psychological interpretations caused by light, smell, sound, taste, temperature and texture.
Environmental factors
Light
Determines visual sharpness of an object
At night, red and blue: Increase alertness
Brightness: increase alertness
Noise
Excessive noise can cause workers to lose their hearing and suffer from tinnitus
Additional noise: decrease alrtness
Loud: 85hz or more, quiet: 50hz or less, ambient: 50-70hz
Spatial Issues
Open office plan encourages communication
Defensible spaces: focused thinking
Air Quality
Ideal: Cool dry air
Factors that contribute to thermal comfort in an office
air temp, radiant temp, air velocity, NO humidity
Methods of collecting data
Ordinal
Labelling w/o quantitative value
Example: yes or no
Nominal
Non-numeric and numeric. Order of values matter, but difference between them dont.
Example: happiness and satisfaction levels
Interval
Numeric scales. Order of values and difference between them matter. No zeroes.
Example: Celsius temp
Ratio
Everything including absolute zero.
Example: rulers
Interviews, surveys/questionnaires, observation, standardised test, case studies
Human information processing system
Input, sensory, central, motor, output
An automatic system that a person uses to interpret information and react. It is normally comprised of inputs, processes (which can be sensory, central and motor), and outputs.
Breakdown
Occurs when information input is incompatible w/ sensory receptors, central processing stage is incorrect, and output unable to perform
Human error
Primary cause in disasters and accidents
Flow process broken due to: age, skill, level, disability, fatigue
Example: Drinking and driving, plane crash, chernobyl
Alertness and perception
Alertness: level of vigilance in an individual
Aware of surroundings to understand how information, events, and action impact the future
In depth sense of situation awareness has high knowledge and understanding -> skilled drivers
Lack of alertness is a main factor in accidents
Perception: Way something is understood.
Understanding the environment has 3 levels
Comprehension: Understanding meaning of what is perceived: Interpret significnace
Projection; Predict situation in advance based on the env
Perception
Physiological factors: Human factor data related to physical characteristics used to optimise the user's safety, health, comfort and performance (motor processes).
Collection of data
Performance testing, user trials/observation, collecting anthropometric data
Comfort and fatigue
Comfort: A person's sense of physical or psychological ease.
Determines how effective the design is and how well a human can interact
Physical
Product intuitive and comfortable. Increases utility.
Psychological
Quality should feel it is made out of good materials. Comfort found in feedback,
Example: Lightweight and flimsy isn't comfortable
Fatigue: Person's sense of physical and psychological tiredness
Biomechanics
Force
Excessive impact joints and causes muscles to tense
Example: Wheelchair where users snap arms in the end of a push, puts force on shoulder joints
Duration
Continuous muscle effort
Pressure
Position held upright while standing, sitting, laying down
Example: Wheelchair optimal posture is more upright
Repetition
High task repetition with other risk factors such as high force and awkward posture -> musculoskeletal disease
Repetitive if 30 sec or more
Example: Wheelchair coasting and going slower bc takes less pushes to maintain speed