study of ergonomics should be seen clearly to include the variation in human
sizes; articulation of the human body; strength and fatigue; bodily needs
and tolerances; emotional responses."
"Ergonomics should be considered in everyday situations with which the candidate would normally have first-hand experience, including the candidates' practical work, and in the context of the chosen Specified Topic."
[Taken from syllabus]
[from erg meaning energy; heat; work.]
Ergonomics has been used to inform about factory layouts, instrument layouts on cars etc. Recommendations include; noise and pollution limits, operating times, lighting levels.
Terminology: Problems associated with human factors are essentially interdisciplinary and there are four particular disciplines on which designers will commonly need to draw: physiology, psychology, anthropometrics and ergonomics.
Physiology is concerned with the study of the systems within the human body, their responses, limitations and capabilities. Reaction times, responses to temperature changes, visual acuity and colour perception, strength, fatigue and muscle control and hearing thresholds are just some of the areas with which a designer may be concerned.
Psychology is concerned with the study of the human mind. Human senses are continually
being stimulated and sending corresponding signals to the brain.
Anthropometrics concerns the measurement of the physical characteristics of humans and
in particular the determination of their physical dimensions, although
other data on, for example, how far people can reach, how much space they
need and how much force they can exert is also determined.
Ergonomics is concerned with the relationships between people and the equipment and environments they use. Its origins were in the 1930s as part of the drive towards increased efficiency in manufacturing, and the term ergonomics was coined by Professor Hywel Murrell in the 1940s. (The term human factors is now used more or less interchangeably with ergonomics, particularly in the USA). Prior to this time most industrial equipment had been designed without reference to the requirements of the operator who, it was assumed, would adapt. Humans are, of course, extremely capable of adapting but it was realised that the limits of this approach had been reached and that further progress depended on improving the design of the equipment so that operators could use it more efficiently. It is evident that ergonomics will be dependent on much of the information gained from physiological psychological and anthropometrics studies but its uniqueness lies in the application of this knowledge to equipment design. There is now a wealth of information concerning the relationship between people and products which has grown up as a result of ergonomic studies. Safety in the use of products and systems is now primarily thought of in the context of ergonomics. Consider the following extracts from an article by Duncan Hopwood concerning ergonomics and safety issues.
People cut hedges with rotary lawnmowers They stand on chairs They use fridge doors as stepladders to climb up to change lightbulbs Believe it or not that case reached the US law courts Also in the States, several people died from putting petrol in washing machines to clean dirty overalls They died horribly when the machines burst into flames At Three Mile Island, banks of instruments on each side of the control room were mirror images of each other, a natty design concept but hardly usable Staff distinguished two vital levers which had entirely different functions by placing different brands of beer cans over each lever The slowness in shutting down the reactor has been blamed on control room confusion. Ergonomics testing of the control equipment at Three Mile Island could have averted a nuclear disaster.
There is all
element of predictability in the way humans misuse products and systems.
It was not just one person who put petrol in a washing machine.
Statistics and design decision-making Dreyfuss first publication concerning anthropometric data for designers recognised the need to define small average and large for men and women and the statistical approach now adopted represents a formalisation of this concept. Figure 2.12 shows a normal (or Gaussian) distribution curve. This distribution has been found to be the one which most commonly applies and is sometimes named after the mathematician Gauss.
The normal or Gaussian distribution curve.
The horizontal axis represents the range of the variable you are considering, perhaps peoples' heights, with the smallest height value on the extreme left and the largest value on the extreme right. You can imagine generating the curve shape by making a cross for each individual of your target population with a particular height as is illustrated for part of the curve. If human heights follow a normal distribution then the most common height, known as the mode or the modal height, will be in the middle. The value where there is 50% of the population with a greater value and 50% with a lesser value is also known as the median. For a normal distribution the mode and the median can be seen to have the same value. As the curve is symmetrical this will also be the same as the arithmetical average or mean.
Anthropometric data are usually based on a normal distribution and gaps in the information are often filled in on this basis. The information given usually refers to percentiles. The 1st percentile, for instance, is the value reached by all but 1%, of the population and the 5th percentile is the value exceeded by 95%, of the population. manikin models of 5th percentile, 50th percentile and 95th percentile individuals which were made up to test a scale model of an exercise bicycle. Although such an investigation can often be carried out mathematically or graphically a physical model can make a thorough investigation of the total movement easier.
Link to an excellent website about ergonomics, click here
For Link to website about Anthropometric Data, click here
To Download Excel Spreadsheet containing Anthropometric Data, click here
For Exam questions on this subject, click here