Design Technology- Topic 1: Human Factors and Ergonomics

Human Factors

The way humans interact with and behave with products.

Ergonomics

The application of scientific information concerning the relationship between human beings and the design of products, systems and environments.

What are the aims of considering human factors in design?

- Reduce stress and fatigue in people, as they can do things faster, easier, safer and with fewer mistakes.
- Increase safety
- Increase ease of use
- Enhance operational comfort
- Improve system performance, reliability and maintenance

What are the human factors?

Anthropometrics, Physiological factors, Psychological factors

Anthropometrics

Knowing the size of people, their body parts and movements.

Ensuring that products are designed in the right size for the user and therefore comfortable to use.

How is anthropometrics important in design?

They aid designers in developing products and services that are comfortable and adjustable

Designers have access to data and drawings which state measurements of humans of all ages, from all regions.

They increase ease of use, ensure safety and an error-reduced experience

Static Data

Measurements of skeletal structures and soft tissue.

Dynamic Data

The measurements of the human body in motion.

Dynamic Data: Clearance

Minimum distance required to enable a user group into or through a space.

Dynamic Data: Reach

The body's range of motion and the reach of various limbs (how far can they reach).

Instruments for collecting anthropomorphic data

Stadiometer, Sitting height table, Skin fold calliper, Soft tape measure, Ruler

Why might there be limitations with collecting anthropometric data?

Unreliability with tools used to measure

Person's body shape: problems with collecting data from nude or clothed people

Inadequate personnel training

Time of day: spine discs compress throughout the day (22mm shorter in the evening)

Users not carrying out tasks in the same way: Unreliable when observing user behaviour

Adjustability

The ability of a product to be changed in size to increase the range of percentiles that a product is appropriate for.

Range of sizes

A selection of sizes a product is made in that caters for the majority of a market. [for comfort and safety] [but more expensive]

5th Percentile

The lower limiting anthropometric measurement.

95th Percentile

The upper limiting anthropometric measurement.

Psychological factors

Ensuring that products (and services) are designed with the human's complex psychological makeup in mind and understanding that there are many different reactions to consider.

Smell, light, sound, taste, texture and temperature

Sight

Readability-> Health and safety warnings, labels, instructions

Light level-> Related to level of precision work required

Perception-> Lighting can change user's perception

Kind of lighting-> Fluorescent light vs rotating machines: strobe effect (objects appear to be not moving)

Sound

Warning sounds-> Must be audible

Feedback-> Response to user's input

Quality of sound-> Volume/pitch/frequency

Ambient noise-> Positive: In cafe, elevator, toilets.

Negative: Office

Touch

Texture-> Addition (or removal) of texture to enhance usage of a product

Grip-> Addition of texture to increase grip, so that there is more friction and better transmission of force

Temperature-> Choice of material can affect the perceived temperature of objects, changing the perception (warmth vs. coolness, cosy vs. clean)

Taste

Flavour/appeal-> Good taste for food (to make it appealing, obviously)

Bad taste-> Warning for toxins

Tastelessness-> Lack of taste in objects that are neither encouraged nor discouraged to be ingested

Smell

Warnings-> Presence of dangerous chemicals

Ambience-> Can change the perception of the user.

Aroma-> Perfume, deodorant, laundry detergent, candles, incense

Nominal

Classified by name into discrete groups.

The "scale" does not provide measurement within and between groups.

Ordinal

Order or positioning of items in a hierarchy, but no quantitative comparison.

Interval

Data is organized into equal divisions or intervals.

No true zero.

Ratio

Equal divisions with true zero.

Can compare differences between numbers.

Human information processing system

Input (stimulus) -> Sensory Processes -> Central Processes -> Motor Processes -> Output (reaction)

Environmental Factors

Noise, Lighting, Temperature, Humidity, Vibrations, Aroma, Space

Space, vibrations

Environmental Factors: Aroma

- Some researchers believe that aromas like peppermint, pine and citrus can make people more alert.

- Lavender, meanwhile, seems to have a sedative effect.

Environmental Factors: Light

Bright light tends to increase alertness, particularly during the night hours.

Dim light or darkness set the stage for falling asleep.

Environmental Factors: Sound

A tool for promoting sleep and increasing alertness.

Eg. the soft hum of computers in the middle of the night might lull you into sleep and fast paced music might make you exercise better.

Environmental Factors: Temperature and humidity

- Cool, dry air, especially on your face, makes it easier to stay alert, while heat and humidity make you drowsy.

- Similarly, a cold shower is invigorating, while a warm bath prepares you for sleep.

Alertness

The level of vigilance, readiness or caution of an individual.

Perception

Perception is the organization, identification, and interpretation of sensory information in order to represent and understand the environment

Link between alertness and perception

Humans have evolved to recognise patterns using perception to spot repeating things and allow us to be less alert to save energy for noticing new things.

Physiological Factors

Muscle strength, stamina/endurance, balancing, visual acuity, hand-eye coordination, fatigue + comfort, tolerance to extreme temperatures, frequency of hearing.

Comfort + Fatigue

Ensuring that individual physical characteristics are taken into consideration when designing.

Comfort

A person's sense of physical or psychological ease.

Fatigue

A person's sense of physical or psychological tiredness.

Mental vs. Physical fatigue

Link between comfort and fatigue

When users interact with products, they may put stress on their bodies.

If something is uncomfortable, it may cause fatigue.

Biomechanics in human factors

The research and analysis of the mechanics of the human body.

Strength, Grip, Repetition, Duration, Posture

Biomechanics: Strength

The quality of being physically strong;

Biomechanics: Grip

To take a firm hold of something;

Biomechanics: Repetition

Any action or influence that moves an object; doing the same motion or movements time after time.

Biomechanics: Duration

The length of time that a muscle is in continuous use

Biomechanics: Posture

The position of a person's body parts.

Outline the biomechanical factors important in the design of a wheelchair

Grip: The wheelchair should provide adequate grip for the user to manoeuvre and propel the wheelchair effectively. This includes the design of the hand rims on the wheels, which should offer a firm and ergonomic surface to facilitate gripping and propulsion.

Force: Excessive impact jolts the user's joints and causes their muscles to tense in response. Some wheelers snap their arms at the end of a push, which puts force on the shoulder joints. If the user is able to do a wheelie over a curb, they have to decide whether they land with impact or allow themselves to go over the edge gently. Going over a significant bump at too great a speed in a powered wheelchair or scooter can result in unnecessary impact.

Repetition: How many pushes does it take them to travel a given distance? It is advised that it would be a better advantage to carry out coasting (which means keeping the tyres inflated and the wheelchair well maintained) and consider going a little slower (it takes more pushes to go faster).

Duration: Continuous muscular effort. It does not have to be heavy lifting. Small exertions continuously held are as stressful to the human tissues as brief, heavy effort. Leaning on armrests - often because of a poor relationship to the seat and back - putting a continuous load on shoulders is an example of doing "static" exertions.