Ime 3420 - Exam 2

Front 1

• What are 2 objective evaluation techniques?

Back 1

o Physiology - Heart rate, oxygen consumption, electromyography
o Biomechanics - Applied forces, posture

Front 2

• What are the subjective evaluation techniques?

Back 2

o Body Assessment Map
o BORG Scale
o Checklist for analysis of workplace
o Rapid Upper Limb Assessment (RULA)
o Rapid Entire Body Assessment (REBA)
o Strain Index (SI)
o Quick Exposure Checklist (QEC)

Front 3

• What is the purpose of the body map assessment?

Back 3

o To subjectively determine aches and pains

Front 4

• What is the purpose of the BORG scale?

Back 4

o To subjectively determine perceived exertion or to rate workload

Front 5

• How is the BORG scale used?

Back 5

o Scale rating ranges from 6 to 20 with 6 having a Verbal Anchor of No Exertion At All and 20 having a verbal Anchor of Maximum Exertion. Users or workers are asked to verbally rate their perceived level of exertion using the Verbal Anchor Ratings

Front 6

• What is the relationship between the BORG rating and heart rate?

Back 6

o Typically the rating *10 = approx. current heart rate

Front 7

• What does RULA stand for?

Back 7

RULA: Rapid Upper Limb Assessment

Front 8

• What does the RULA assessment help to identify?

Back 8

RULA help identify contributors to Repetitive strain injuries (RSI's)

Front 9

• What are the main contributors to Repetitive Strain Injuries (RSI's)?

Back 9

o Postures of the Neck, Trunk, and Upper limbs (upper limbs = upper extremeties)
o Forces experienced by the body
o Muscle activities

Front 10

• What does REBA stand for?

Back 10

REBA: Rapid Entire Body Assessment

Front 11

• What are the 3 types of postures that REBA is designed to evaluate?

Back 11

o Dynamic
o Static
o Gross changes in position

Front 12

• What types of information does REBA collect?

Back 12

o Body postures
o Forces
o Type of movement or action
o Repetition

Front 13

• What are the advantages to using REBA?

Back 13

o Identify exposure to risk factors associated with MSD's and determine magnitude and severity of exposure
o Provide a postural analysis system that is sensitive to musculoskeletal risks in a variety of occupational tasks
o Provide a scoring system for muscle activity caused by the 3 types of postures
o Give an action level with an indication of urgency

Front 14

• What does the Job Strain Index help to evaluate?

Back 14

o Job's level of risk for developing MSD's in the:
 Hand, wrist forearm, and elbow
 Task variables, such as:
 Intensity of exertion
 Duration of exertion
 Hand/wrist postures
 Speed of work
 Duration of task per day

Front 15

• What do the different SI scores mean?

Back 15

o 0 - 3 = Jobs are probably safe
o 4 - 5 = Jobs associated with distal upper extremity disorders
o 7 - above = Jobs are probably hazardous

Front 16

• What are the limitations of the Job Strain Index?

Back 16

o Does not evaluate segmental vibration (doesn't predict risk of hand-arm vibration syndrome)
o Does not evaluate contact trauma (doesn't predict risk of hypothenar hammer syndrome)
o Limited to predicting the risk for distal upper extremity neuromusculoskeletal disorders
o 3 of the 6 (50%) task variables are subjectively evaluated by the analyst
o No mathematical relationship between the task variables
o Strain index tested on only 25 jobs in one industry

Front 17

• What does QEC stand for?

Back 17

QEC: Quick Evaluation Checklist

Front 18

• What do the questions in the QEC help to evaluate?

Back 18

o Postures
o Frequency of movement in the back, wrist/hand, shoulder/arm, and neck

Front 19

• What do the questions in the QED help to assess/what are the advantages?

Back 19

o Exposure to risks for work related MSD's
o Provides a basis for ergonomic interventions
o Assesses the 4 main body areas
o Involves both practitioners and workers in the assessment

Front 20

• What are some of the areas assessed through questions in the Motion Economy Checklist? (for details, look at page 5 of the notes)

Back 20

o Suboperations
o Holds
o Delays
o Movements
o Cycles
o Machine Time

Front 21

• What are the 2 main types of questions asked about the areas?

Back 21

o Can it be eliminated/shortened?
o Can it be made easier?

Front 22

• What are some of the MSD's?

Back 22

o Tendinitis
o Tenosynovitis
o bursitis
o Ganglionic cyst Tendinitis
o Carpal Tunnel Syndrome
o Vibration Syndrome
o Low back pain

Front 23

• What are 3 types of controls or changes?

Back 23

o Engineering Controls
 Equipment Design
 workstation design/redesign
 document holder, footrest, etc
o Administrative Controls
 training
 worker selection
 work pace/frequency
o Personal Protective Equipment (PPE) - Required
 safety glasses
 hard hats
 back belts and wrist splints are NOT PPE's

Front 24

• When it comes to root cause analysis, what is the question to ask?

Back 24

The question to ask in root cause analysis is: WHY?
(Human Problems vs. Workplace Solutions)

Front 25

• What are the types of hand tools?

Back 25

o Power tools (electrically powered)
o Hand tools (manually powered)

Front 26

• What are the situational strength factors?

Back 26

o Motivation, ego involvement
 will succeed or fear of injury
o Skill and experience
o Body motion, or lack thereof
o Ability to brace body against support structure
o Body posture
 Allowing use of strong muscles at advantageous leverage
o Body site used for exertion
 Eg. one foot or both feet, shoulder, hand or hands
o Coupling between body and object

Front 27

• What are the individual strength factors?

Back 27

o Age
o Gender
o Muscle cross section
o Length of muscle
o Speed of motion
 Static or dynamic exertion
o Fatigue
o Hand anthropometry
o Hand dominance

Front 28

• Notes on Hand dominance?

Back 28

o Majority of people are right-handed
o 10% of people are left-handed
 Most workstations and equipment is designed for right-handed users
o More natural feeling

Front 29

• How does hand strength vary?

Back 29

o Age
o Gender
o Exercise
 May be strengthened by use
 May be weakened by disuse
o Grip span
o Injury and/or disease

Front 30

• What is the hand strength design guideline?

Back 30

o If the force exerted continuously for a period of time -> Do not exceed 10-15% of maximum force
o If the force exerted over short duration or at frequent intervals -> Do not exceed 30% of maximum force
o If the force exerted occasionally & for a brief moment -> Do not exceed 60% of maximum force

o Apply caution while using these guideliens while designing for elderly individuals
o Insufficient information available about tolerance to force exertions (Imrhan, 1994)

Front 31

• What are the types of grips? (see page 2 for pictures)

Back 31

o Power Grip
 Fingers and sometimes thumbs are used to clamp
o Precision Grip
 Object is manipulated between fingers
 Thumb
 Pulp 2-5 (thumb with any other finger)
 Tip Pinch
 Key Pinch or lateral Pinch
 Chuck Pinch

Front 32

• How can hand strength be measured?

Back 32

o Hand dynamometer
o Pinch dynamometer

Front 33

• What are the fundamentals of handle design?

Back 33

o Force is exerted most effectively in compression rather than shear (what does shear mean?)
 Better to exert thrust perpendicular to handle axis
o Eliminate all pressure hot spots on gripping handle
 Finger shaping
 Unless designed with anthropometric factors
 The end of the toold
 Eg. End of pliers which may dig into the palm if handle is short
 Edges of raised surfaces
 Eg. Application of labels or logos
 Pinch points between moving points
o Shaping tool handle to provide high friction
 Gloves
 Be cautious with form fitting handles
o Facilitate secure holding & transfer of energy
 Provide mechanical interlocking between hand & handle
 Eg. Groves, bulges and serrations
o Maintain straight wrist
 Avoid overexertion of connective tissue
 Prevent compression of median nerve in carpal tunnel
 Bent wrist reduces the force that may be applied
 Bend the tool, not the wrist (Learning curve becomes an issue as people are not used to bend the tool)
o Force is exerted most effectively in compression not shear
o All sharp edges should be eliminated
 Finger shaping
 The end of the tool
 Edges of raised surfaces
 Pinch points
o If hand must fit in aperture? appropriate clearance should be provided
o Handle shape should reflect the curve of the hand
o Support surfaces at appropriate points
o Tools should be used equally for left and right hand users
o Use a power grip for tasks requiring force
o Power Grip
 Force line of action can vary with
 Force parallel to forarm (sawing)
 Force at an angle to forearm (hammering)
 Force acting on a moment arm (screwdriver)
 Used for power of holding heavy objects
 Inline grip vs. pistol grip (see page 3 for pictures)
o Pinch Grip
 Used for tasks requiring precision
 Used for control and precision
 Item held between distal ends of one or more fingers

Front 34

• Notes on design guidelines?

Back 34

o Avoid prolonged static muscle loading
o Perform twisting motions with elbows bent
o Maintain straight wrist
o Avoid tissue compression
o Avoid repetitive finger action
o Use the strongest working fingers
 Middle finger
 Thumb
o Design 1.5 in handle diameters for power grips
o Design a 3 in grip span for two-handled tools
o Decision grip surface to be compressible & nonconductive
o Keep the weight of the tool below 5 lbs
o Use gloves
o Use power tools such as nut & screwdrivers instead of manual tools
o Choose a power tool with the proper characteristics
o Use reaction bars & tool balancers for power tools
o Use the prove configuration & orientation of power tools

Front 35

• How is information measured?

Back 35

o Information is measured in bits.

Front 36

• What is meant by bit?

Back 36

o Bit is the amount of information needed to decide between 2 equally likely alternatives
 H = log2N
 H = Amount if information
 N = The # of equally likely alternatives
o If information is not weighted equally,
 H = Sum(pi*log2(1pi))
 P = Probability of the event
 i = alternatives from 1 to n
(MUST SEE PPT NOTES)

Front 37

• What is band width?

Back 37

o Band width is the maximum information processing speed of a given communication on channel
 Motor Processing Tasks 6-7 bits
 Speech communication 50 bits

Front 38

• What is perception?

Back 38

o Perception is the comparison of incoming stimulus information w/ stored knowledge to categorize information

Front 39

• What is signal detection?

Back 39

o Signal detection is determining whether a signal is present or not

Front 40

• What are the different types of memory?

Back 40

o Short-term memory
o Long-term memory
o Working memory

Front 41

• What is the working memory? What is its capacity? How often does it decay?

Back 41

o The working memory is a short term storage of memory
o The capacity of the working memory is approximately 7 +-2 items
o Working memory decays very quickly

Front 42

• What are the recommendations for minimizing error for tasks requiring working memory?

Back 42

o Minimize memory load
o Utilize chunks
 Eg. 12125551212 -> 1-212-555-1212
o Keep chunks small (less than 3 or 4 items)
o Keep numbers separate from letters
o Minimize confusion of similar-sounding items
 Eg. The number zero versus the letter "o"

Front 43

• Can information in working memory be transferred to long term memory for later use?

Back 43

o Yes, information in working memory can be transferred to long term memory for later use

Front 44

• Notes on decision making and response selection?

Back 44

o Humans are not optimal decision makers
o Humans have biases that influence outcomes:
 Limited amount of information used
 Undo weight is given to early cues
 Inattention is given to later cues
 Prominent cues are given greater weight
 A limited number of hypotheses are generated
 Small amount of responses are chosed

Front 45

• What are they different types of attention?

Back 45

o Focused attention (Eg. Assembler)
o Divided attention (Eg. Air traffic control)
o Sustained attention - Vigilance decremation with time
 More frequent rest
 Task variation
 Task feedback
 Appropriate levels of stimulation

Front 46

• What does the identification of appropriate controls (coding methods) depend on?

Back 46

o The identification of appropriate controls (coding methods) depend on:
 Detectability,
 Discriminability,
 Meaningfulness,
 Standardization, and
 Compatibility

Front 47

• What do primary coding methods include?

Back 47

o Shape
o Texture
o Size
o Location
o Operational Method
o Color
o Labels

Front 48

• Explain the detectability of codes?

Back 48

o A stimulus must be detected by human sensory mechanisms under the environmental conditions anticipated
 Eg. Color coded control knobs on underground mining equipment would not be detectable in low levels of light

Front 49

• Explain the discriminability of codes?

Back 49

o Every code symbol, even though detectable, must be discriminable from other codes symbols
 Eg. If 20 different levels of size are used to distinguish controls, it is highly likely that they will be confused

Front 50

• Explain the meaningfulness of codes?

Back 50

o Codes must be meaningful to the user (tribalism)
 Eg. Bent arrow on traffic sign means bend in the road ahead

Front 51

• Explain the standardization of codes?

Back 51

o When a coding system is to be used by different people in different situations, it is important that the codes be standardized & kept the same from situation to situation
 Eg. Red should mean the same on all signs (Red means danger)

Front 52

• Explain the compatibility of codes?

Back 52

o The compatibility of codes refers to the degree to which relationships are consistent human expectations
 Spatial, Movement are types of compatibility

Front 53

• Regarding compatibility of control-machine movement, what should the direction of control movement be compatible with?

Back 53

o The direction of control movement should be compatible with response movement of controlled machine

Front 54

• Regarding control-effect relationships, how should the relationships between control action & resulting effects be?

Back 54

o Relationships between control action & resulting effects should be made apparent through common sense, habitual use, similarity, proximity & grouping, coding, labeling, etc.

Front 55

• Regarding shape coding of controls, what does the discrimination of shape-coded controls essentially involves?

Back 55

o The discrimination of shape-coded controls essentially involves tactual sensitivity

Front 56

• Regarding texture coding controls, can control devices vary in surface texture?

Back 56

o Yes, control devices can vary in surface texture

Front 57

• When determining the arrangement of the controls, what are some "operational rules" to keep in mind?

Back 57

o Locate for the ease of operation
o Primary controls first
o Group related controls together
o Arrange for sequential operation
o Dead man control (a control that has a default setting that it reverts to automatically once you release it. ie. your steering wheel returns to a position that keeps you moving straight once you release the wheel)
o Feedback
o Guard against accidental activation
o pack tightly, but do no crowd
o be consistent

Front 58

• When considering the location coding of controls what are some key things to keep in mind?

Back 58

o For toggle switches, vertical arrangements are more accurate than horizontal
o The minimum distance between vertically arranged switches should be 2.5"
o The minimum distance between horizontally arrange switches should be 4"

Front 59

• What is an operational method of coding? Give an example.

Back 59

o Operational method of coding is when each control has its own unique method of operation. An example would be the windshield wipers in a car. Although every car has windshield wipers, the way they operate can vary greatly.

Front 60

• What are the advantages and disadvantages to color coding of controls?

Back 60

o Advantage - Colors can be picked that are meaningful (ie, red means stop and green means go)
o Disadvantage - The user must look at the control, in poor lighting colors are hard to detect, and dirt/wear may impede its effectiveness

Front 61

• When considering labeling coding of controls...

Back 61

o It should be the minimum coding requirement for any control
o It should not be used excessively, especially in environments when users are subject to quick speeds

Front 62

• Redundant codes...

Back 62

o Combine coding methods such as location, size and color, when it is unnecessary to use all 3.

Front 63

• What are the types of displays?

Back 63

o Dynamic displays
o Static displays

Front 64

• How can information be classified?

Back 64

o Quantitative (temperature, speed)
o Qualitative (direction, trend such as low or high)
o Status: limited conditions (on/off, stop/caution/go)
o Representational information (photos, maps, wastebasket for deleted files)
o Alphanumeric & symbolic information (signs, labels, braille)
o Time-phased information (Morse Code or blinking lights)

Front 65

• What the display modalities?

Back 65

o There are 5 display modalities (5 senses)
 Vision
 Hearing
 Touch
 Taste
 Smell

Front 66

• Which display modalities or senses are the most popular?

Back 66

o Vision
o Hearing

Front 67

• Where is tactile generally used?

Back 67

o Tactile is generally used in control design

Front 68

• Give examples of how some display modalities are being used to warn or prevent people from danger?

Back 68

o Odors used to warn homeowners of gas leaks
o Sour taste (medicine) to prevent children from accidentally swallowing it

Front 69

• What needs to be considered to choose between a visual or an auditory display?

Back 69

o Condition
o Purpose

Front 70

• When are visual displays more appropriate?

Back 70

o Environment is noisy
o Operator stays in place
o Message is long & complex and will be referred to later
o deals with spacial locations

Front 71

• When are auditory displays more appropriate?

Back 71

o Environment is dark
o Operator moves around
o Message is short and simple and requires immediate attention
o deals with events in time

Front 72

• What is the range of frequency for auditory displays?

Back 72

o 500 - 3000 Hz

Front 73

• What does the frequency of the auditory display depend on?

Back 73

o Use frequencies below 1000 Hz if signals need to travel long distances
o Use frequencies below 500 Hz if signals have to bend around objects

Front 74

• How often do we need to use a modulated signal?

Back 74

o 1 to 3 times per second

Front 75

• To minimize the masking of signals, what can be done?

Back 75

o Use signals with frequencies different than those that dominate any background noise

Front 76

• What are the variables in design and selection of visual displays?

Back 76

o Task-related considerations
 Consider the way each item on the display will be used and its importance
 Consider when the item on the display will be used
 Consider specific characteristics of users visual acuity and/or skill level
 Consider the use of same display during normal operation & emergency situations
o Type of display (based on the information the user needs to know)
o Information content & format
o Physical characteristics

Front 77

• Give some recommendations of the locations of the displays?

Back 77

o Within normal viewing area of an operator, with their surfaces perpendicular to the line of sight (line of sight = 0 +-15 degrees?)
o The more critical the display, the more centered it should be within the operator's cone of sight
o Avoid glare
o Group alignment

Front 78

• What is the purpose of visual displays?

Back 78

o Providing information either of a qualitative kind or providing exact quantitative information

Front 79

• What are the different types of displays?

Back 79

o There are 4 types of displays, they are:
 Moving pointer (fixed scale) example: spedometer (you should not have a moving scale with a moving pointer!!)
 Moving scale (fixed pointer) example compass or scale
 Counters
 Pictorial displays (Eg. seatbelt sign that turns on when the seat belt is not fastened)

Front 80

• When are digital displays better than analog displays?

Back 80

o A precise numeric value is required
o The values being read remain visible long enough to be read

Front 81

• When are analog displays better than digital displays?

Back 81

o Values are subject to frequent or continual change
o The direction of rate of change of the values is important

Front 82

• Which of the followings is preferred: Moving point or fixed scale?

Back 82

o Moving pointer

Front 83

• What pattern should numerical increases follow?

Back 83

o Numerical increases should match natural interpretation
 Eg. off, low, then high instead of low, off, high

Front 84

• Should mix pointer scale indicators be mixed?

Back 84

o No, mix pointer scale indicators must not be mixed

Front 85

• What is the purpose of light signals?

Back 85

o Indicating status of a system
o Alerting an inoperative system (or a part of the system) & indicating that action is required

Front 86

• What are the common color coding systems?

Back 86

o White
o Green
o Yellow
o Red
o Flashing red

Front 87

• How does an alert start?

Back 87

o An alert starts w/ an auditory warning signal accompanied by a flashing light

Front 88

• When should alerts be used?

Back 88

o To warn of an actual or potential dangerous situation

Front 89

• How many warning lights should be used?

Back 89

o Usually one

Front 90

• Which type of alerts should be used: steady state or flashing?

Back 90

o If event is continuous, use steady light
o If new conditions occur or emergencies, use flashing light

Front 91

• What is the recommended flash rate?

Back 91

o 3-10 per second (4 is best)
o If flash rates are to represent different levels of a variable then no more than 3 rates

Front 92

• Where should the warning light be location?

Back 92

o Within 30 degrees of operator's normal line of sight

Front 93

• How about the warning light intensity or color?

Back 93

o The light should be twice as bright as immediate background
o Red means danger (yellow means caution)
o With low to signal-to-background brightness contrast, red is best followed by green, yellow, & white.