Homework 3 Total Points: 5 Due Date: May 29, 2019 1. (2.5 points) Should HFE specialists advise on how to accommodate obese workers or just tell them to lose weight? 2. (2.5 points) Describe the statistical terms- Mean and Standard Deviation. How these parameters are used in anthropometric design and why are they important? CHAPTER 3: ANTHROPOMETRY, WORKSTATION AND FACILITIES DESIGN 1 General requirements for humans in systems ⚫ Where human physical variability places constraints on the design, the system shall be designed to accommodate the majority of operators on all relevant user dimensions for males and females in the target population. ⚫ The design solution shall fit the at least the 5th percentile female to 95th percentile male on that dimension. ⚫ The physical characteristics of the target population of users must be identified and planned for in advance ⚫ Subgroups with special anthropometric needs such as pregnant females, the disabled or obese employees must be catered for: either in the design solution; or in bespoke arrangements to enable them to work safely and efficiently. Anthropometry: The measurement of man 2 ⚫ Anthropos: Man ⚫ Metron: Measure ⚫ In ergonomics, systems are designed to accommodate an identified population of users of workers ⚫ The emphasis is on designing to fit at least 90% of users ⚫ The focus is on identifying the constraints the user variability places on the design Avoid Anthropometric Mismatches 3 The Normal Distribution: N is Small 4 Number measured xx 8 XXXXXXXXXX 1 | XXXXXX XXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX 1.40m Short people 1.70m 2..00m Tall people | | | | | | Normal Distribution Where N is Large 5 Mean and Standard Deviation 6 Anthropometric Data 7 ⚫ Databases are available containing information on a range of human bodily dimensions ⚫ We will focus on those dimensions that are most useful for ‘person-workspace fit’ Examples of Anthropometric Variables: Heights in Sitting 8 Length and Reach 9 Standing 10 Reaches and Breadths 11 Finding areas Under the Normal Curve: 5th and 95th percentiles 12 Tables of the Standard Normal Deviate - Z 13 ⚫ Normal distributions differ in the values of their mean and standard deviation ⚫ However, the relationship between the mean and the standard deviation is ALWAYS the same ⚫ We can find the area under the normal curve from tables of a statistics known as ‘Z’ Definition of Z 14 _ Z= (X – X)/sd _ Where X = Mean X = A value of the variable of interest sd = standard deviation The value of Z tells us the ‘distance’ of a value from the mean in terms of standard deviations Example 15 ⚫ Sarah is a UK female. She is 1580mm tall. How does she compare with the rest of the UK population of adult females? Assume: _ X = 1620mm sd = 64mm Example 16 Z = (1580-1620)/64 = -40/64 = -0.625 From the tables of Z, the area under the normal curve for a value of Z of -0.625 is 0.2643. So, approximately 26% of the area under the curve lies to the left of this value In other words, Sarah is taller than 26% of the UK female population. She has 26th Percentile stature Functional Movement Ranges 17 www.rsbridger.com Inclinometer for Measuring Ranges 18 Anthropometric Data on Strength 19 ⚫ Grip and pinch strength ⚫ Pushing ⚫ Pulling ⚫ Wrist twisting ⚫ Handle turning Quick Estimates from Stature when there is no Anthropometric Database 20 Uses of Anthropometric Data: Define the Posture: Palm pinch, key pinch, tip pinch 21 Anthropometry in Design: Identify the constraints 22 ⚫ Maximum dimension – what is the largest dimension of the product so that small people can still use it? ⚫ Minimum dimension – how small can it be and still be usable by tall people ⚫ What’s the average size that will suit most people? ⚫ Define ‘usability’ Minimum Allowable Dimensions 23 Maximum Allowable Dimensions 24 Assessing Fit: Questions to Ask 25 ⚫ Is equipment difficult to operate? Why? ⚫ Does it require too much force? ⚫ Are parts difficult to grip? ⚫ Do you have to reach too far forward, up or down? ⚫ Do you have to stand or sit in an awkward posture? ⚫ Can you see all you need to see? ⚫ Is equipment too bulky? ⚫ Can you get access? ⚫ Can you get out in an emergency? Consult Users: Controls too Low 26 How it Should Be 27 Digital Human Models: Meet SAMMIE and JACK 28 Modelling Head Clearance in Bunks 29 Digital Human Models in Virtual Environments 30 Applying the Data: Defining Zones of Convenient Reach 31 Standing Reach 32 Dynamic Anthropometry: Moving Around a Workplace 33 Anthropometric Data in Engineering Design and Practice 34 ⚫ ISO has several standards on engineering anthropometry ⚫ They are useful as part of engineering management, accreditation and contractually ⚫ When designing new systems, the ergonomics requirements are subsumed into procurement requirements ⚫ We can make it a requirement that contractors design for the 5 th to the 95th percentile of our employees ⚫ This applies to workstations, offices (chairs etc.) control rooms and so on Understand the Context of Use: Allowances for Personal Protective Equipments (PPE) 35 Links with Space Planning 36 ⚫ In the design of any large facility, the optimum use of space has enormous economic benefits. Floor space costs money to build or rent, so we want to maximise the occupancy rate while ensuring that the facility is an effective workplace Overview of Space Planning Steps 37 1. 2. 3. 4. 5. Determine the number of people who will use the office Determine the organisational structure Describe the main activities Determine the equipment needed Detailed layout: 1. 2. 3. 4. Allow 50cm free space in front of window Allow 3m at the front and 1m at the side of the main entrance Allow 1.5m in front and 0.5m to the side of all doors Allow 0.5m in front of A/C units Overview of Space Planning Steps 38 6. Free space around desks Allow 55cm in front for passage Allow 50cm along sides for ingress and egress Allow 75cm at the back for seating space Allow 1m at the back if there are cabinets behind the desk 7. Determine the requirements for proximity. Physical separation should be compatible with task separation. Place highly interactive units in the centre of the space 8. Arrange individual workstations in accordance with anthropometric and other health and safety requirements Volumetric Models Based on Anthropometry 39 Example of Good Design 40 Adjustability: Victorian School Desk 41 Footrests 42 Desk Heights 43 Future Challenges 44 ⚫ Obesity epidemic in many countries – girth and width ⚫ ⚫ ⚫ ⚫ data suspect Secular increases as some countries become wealthier Ageing populations change in size and mobility Populating the digital databases and modelling the effects of these changes Designing for a global customer base Aim for Compatibility Between Task Requirements and User-Characteristics 45
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