ACTIVITY NO. 2
HANDGRIP STRENGTH TEST
SUMMARY:
INTRODUCTION:
OBJECTIVES:
1. To be familiar on the use of hand dynamometer.
2. To conduct actual laboratory trials using hand dynamometer.
3. To record and evaluate the results of the trials.
PROCEDURES:
1.
2.
3.
4.
5.
6.
7.
8.
The client should be in a seated position with the wrist supported by the opposite hand
and the elbow flexed to 90 degrees. Arm tested should be at side.
The wrist should be at 0 degrees of ulnar/radial deviation.
Starting in position one of the dynamometer, have the client squeeze maximally and
"hold" then "release."
Record the pounds or kilograms of force produced at each setting
The pounds measurements are on the outside of the force dial, while kilograms
measurements are on the inside of the force dial.
For a more accurate reading, it is recommended that three (3) readings be taken for each
position on each hand and the average of the results be used
Observe that the client is not using accessory movements of the wrist, arm, shoulder, or
trunk to produce additional effort during the performance of this evaluation.
Plot the forces onto the force grid provided on the Data Input Sheet.
a. Present your report via oral presentation of 30 minutes (including 10 minutes for
Q&A portion) creatively to your instructor and to other pre-selected stakeholders.
b. Submit the report on time.
Handgrip strength test results can vary depending
on the protocol used, so it is important to compare
results to norms derived using the same techniques. The
dynamometer handle is usually adjusted (if possible) to
fit the hand or set at the same setting for everyone. The
same setting should be used when retesting. The strength
of the left and right hand can also vary, so the tests
should be either be conducted on the same side, on the
dominant side, or done on both sides and averaged. Several attempts is usually required to get the
maximum score.
Results are expected to differ between male and females, between left and
right (dominant and non-dominant) hands, and with age. The results can also be
affected by the position of the wrist, elbow and shoulder, so these should be
standardized.
Variations: The position of the arm and hand can vary in different grip strength
protocols. Various positions include the elbow being held at right angles as per the
above procedure, the arm hanging by the side, and the extended arm being swung
from above the head to by the side during the squeezing motion.
Scoring: The best result from several trials for each hand is recorded, with at least
15 seconds recovery between each effort. The values listed below (in kg and lbs)
give a guide to expected scores for adults. These values are the average of the best
scores of each hand.
Reliability: the dynamometer may need to be calibrated regularly to ensure
consistent results. Having consistent technique and adequate rest is required to
ensure reliability.
o
The forearm muscles are easily fatigued, so the best scores are usually
achieved in the first or second trial.
Grip Strength Ratings for Males (in kg)
Grip Strength Ratings for Females (in kg)
TOOLS AND EQUIPMENT:
DISCUSSION:
Data Sheet
AGE:
SEX:
TRIALS
1
2
3
CONCLUSION:
LEFT HAND
RIGHT HAND
LABORATORY NO.3
ENGINEERING ANTHROPOMETRY
SUMMARY:
INTRODUCTION:
OBJECTIVES:
1. To provide the students with the fundamentals of deciding which anthropometric
measures are most important for a design case at hand, from where to obtain data and the
proper use of such data.
2. To develop an ergonomically design product.
PROCEDURES:
1.
2.
3.
4.
5.
6.
7.
Review the secretary’s chair with respect to ergonomic requirements.
Select thirty (30) respondents that will serve as the samples in the design.
Measures the body parts of the participants.
Calculate the percentile computations.
Collectively analyze and evaluate information
Plot the results.
Provide standard measurements (ergonomically).
a. Present your report via oral presentation of 30 minutes (including 10
minutes for Q&A portion) creatively to your instructor and to other preselected stakeholders.
b. Submit the report on time.
Anthropometry is the study of human body dimensions. Humans come in different body
sizes and builds. Engineering use of the available information and development of new
information for such use is called engineering anthropometry.
DESIGN APPLICATIONS
The primary areas of application of anthropometric data are:
1. Clothing design
2. Workspace design
3. Environment design
4. Design of equipment, tools and machinery
5. Consumer product design
Examples of these applications are socks, chairs, helmets, bicycles, kitchen counters,
hand tools, beds, desks, tables, car interiors, diving masks, production machinery and other
devices that people use.
In short, anthropometric data establish proper sizes of and the dimensional relationships
between the things people use.
The designer should accommodate the body dimensions of the population that will be
using the equipment. In general, universal operability is desired within a population. That is, at
least 90 to 95% of the population within a target user group must be able to use the design.
Universal operability objectives can be achieved by the adjustable designs,
Adjustability is a prerequisite of good designs, since equipment built according to one set
of dimensions seldom accommodates the entire range of body sizes in the user population.
Adjustability is also important in products intended for the exports, due to diverse human
body size around the world.
MEASUREMENT DEVICES AND TECHNIQUES
Simple devices exist for measuring body landmark distances. These include:
1. Spreading and sliding calipers to measure short distances.
2. Anthropometers: straight rod with one fixed and one movable arm with the distance
between the two arms indicated on a ruler.
3. Tapes to measure circumferences and contours.
4. Simple scales for weight measurements.
5. Cones and boards with holes for grip circumference and finger size measurement.
The conventional measurement techniques make use of simple devices. Using an
anthropometer, one can reach behind corners and tissue folds. Distances are read on a scaled rod
from a reference point fixed prior to measurement. A small sliding caliper measures short
distances, such as finger thickness and hand breadth.
Another conventional measurement technique is the Morant technique. Here, a set of
grids is used to aid in the measurements. The grids are usually attached on two vertical surfaces
that are positioned perpendicular to each other.
FACTORS THAT AFFECT ANTHROPOMETRIC DATA
Several factors affect body size. Designers must consider these factors and adjust their
designs accordingly. The most important factors are:
1. AGE
In general, body dimensions increase from birth to the early or late twenties.
Thus, it is important for the designer to define the user population as early in the design
cycle as possible and take the necessary steps.
2. SEX
Men are in general larger than women at any given percentile and the body
dimensions except for the hip and thigh measurements.
3. BODY POSITION
Posture affects body size. For this reason, standard position must be used during
surveys.
USING PERCENTILES
Most body dimensions are normally distributed. A plot of their individual measures falls
inside the well-known bell curve, shown in Figure 9.2. Only a few persons are very short, or very
tall, but many cluster around the center of the distribution (the mean or average). Figure 9.2
shows an approximate distribution of the stature of male Americans; only 2.5% are shorter than
approximately 1,620 mm, and another 2.5% are taller than 1,880mm. In other words: about 95%
of all men are in the height range of 1,620 to 1,880 mm, because the 2.5th percentile value is at
1,620 mm and the 97.5th percentile is at 1,880 mm. the 50th percentile is at 1,750 mm. (In a
normal – Gaussian – data distribution, mean (m), average, median, and mode coincide with the
50th percentile. The standard deviation (S) describes the peakedness or flatness of the data set.)
There are two ways to determine given percentile values. One is simply to take a
distribution of data, such as shown in Figure 9.2, and determine from the graph (measure, count,
or estimate) critical percentile values. This works whether the distribution is normal, skewed,
binomial, or in any other form. Fortunately, most anthropometric data are normally distributed,
which allows the second, even easier (and usually more exact) approach: to calculate percentile
values. This involves the standard deviation, S. If the distribution is flat (the data are widely
scattered), the value of S is larger than when the data cluster close to the mean, m.
To calculate a percentile value, you simply multiply the standard deviation S by a factor
k, selected from Table 9.2. Then you add the product to the mean,
STEPS IN DESIGN FOR FITTING CLOTHING, TOOLS, WORKSTATIONS, AND
EQUIPMENT TO THE BODY
Step 1: Select those anthropometric measures that directly relate to define design dimensions.
Step 2: For each of these pairings, determine whether the design must fit only one given
percentile (minimal or maximal) of the body dimensions, or a range along that body dimension.
Step 3: Combine all selected design values in a careful drawing, mock-up, or computer model to
ascertain that they are compatible.
Step 4: Determine whether one design will fit all users
If the desired percentile is above the 50th percentile, the factor k has a positive sign and
the product k * S is added to the mean, m; if the p-value is below average, k is negative and the
product k * S is subtracted from the mean. Examples:
1st percentile is at m-kS
2nd percentile is at m-kS
2.5th percentile is at m-kS
5th percentile is at m-kS
10th percentile is at m-kS
50th percentile is at m
60th percentile is at m+kS
95th percentile is at m+kS
with k = -2.33
with k = -2.05
with k = -1.96
with k = -1.64
with k = -1.28
with k = 0
with k = 1.28
with k = 1.64
Percentiles serve the designer in several ways. First, they help to establish the portion of a
user population that will be included in (or excluded from) a specific design solution. For
example, a certain product may need to fit everybody who is taller that 5th percentile and smaller
than the 60th percentile in hand size or arm reach. Thus, only the 5% having values smaller than
the 5th percentile, and the 40% having values larger than the 60th percentile, will not be fitted,
while 55% (60% - 5%) of all users will be accommodated.
ABLE 9.2 Percentile Values and Associated k Factors
BELOW MEAN
percentile factor k percentile factor k
percentile
0.001
-4.25
50
25
-0.67
0.01
-3.72
26
-0.64
51
0.1
-3.09
27
-0.61
52
0.5
-2.58
28
-0.58
53
1
-2.33
29
-0.55
54
2
-2.05
55
30
-0.52
2.5
-1.96
31
-0.50
56
ABOVE MEAN
factor k percentile
0
76
0.03
77
0.05
78
0.08
79
0.10
80
0.13
81
0.15
82
factor k
0.71
0.74
0.77
0.81
0.84
0.88
0.92
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
-1.88
-1.75
-1.64
-1.55
-1.48
-1.41
-1.34
-1.28
-1.23
-1.18
-1.13
-1.08
-1.04
-0.99
-0.95
-0.92
-0.88
-0.84
-0.81
-0.77
-0.74
-0.71
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
-0.47
-0.44
-0.41
-0.39
-0.36
-0.33
-0.31
-0.28
-0.25
-0.23
-0.20
-0.18
-0.15
-0.13
-0.10
-0.08
-0.05
-0.03
0
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
0.18
0.20
0.23
0.25
0.28
0.31
0.33
0.36
0.39
0.41
0.44
0.47
0.50
0.52
0.55
0.58
0.61
0.64
0.67
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
99.5
99.9
99.99
99.999
0.95
0.99
1.04
1.08
1.13
1.18
1.23
1.28
1.34
1.41
1.48
1.55
1.64
1.75
1.88
2.05
2.33
2.58
3.09
3.72
4.26
Any percentile value p can be calculated from the mean m and the standard deviation S (normal distribution assumed) by p = m + kS
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Illustrations of measured body dimensions
1. Stature: The vertical distance from the floor to the top of the head, when standing [99]. A
main reference for comparing population samples. Relates to the minimal height (clearance) of
overhead obstructions. Add height for more clearance, hat, shoes, stride.
2. Eye height, standing: The vertical distance from the floor to the outer corner of the right eye,
when standing [D19]. Origin of the visual field. Reference point for the location of vision
obstructions and of visual targets such as displays; consider slump and motion of the standing
person.
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3. Shoulder height (acromion), standing: The vertical distance from the floor to the tip (acromion)
of the shoulder, when standing [2]. Starting point for arm length measurements; near the center of
rotation of the upper arm (shoulder joint), reference point for hand reaches; consider slump and
motion of the standing person.
4. Elbow height, standing: The vertical distance from the floor to the lowest point of the right
elbow, when standing, with the elbow flexed at 90 degrees [D16]. Reference point for height and
distance of the work area of the hand and for the location of controls and fixtures; consider slump
and motion of the standing person.
5. Hip height (trochanter), standing: The vertical distance from the floor to the trochanter
landmark on the upper side of the right thigh, when standing [107]. Starting point for the leg length
measurement; near the center of the hip joint; reference point for leg reaches; consider slump and
motion of the standing person.
6. Knuckle height, standing: The vertical distance from the floor to the knuckle (metacarpal bone)
of the middle finger of the right hand, when standing. Reference point for lowest location of
controls, handles, and handrails; consider slump and motion of the standing person.
7. Fingertip height, standing: The vertical distance from the floor to the tip of the index finger of
the right hand, when standing [D13]. Reference point for lowest location of controls, handles, and
handrails; consider slump and motion of the standing person.
8. Sitting height: The vertical distance from the sitting surface to the top of the head, when sitting
[93]. The vertical distance from the floor to the underside of the thigh directly behind the right knee;
when sitting, with the knee flexed at 90 degrees. Relates to the minimal height of overhead
obstructions. Add height for more clearance, hat, trunk motion of the seated person.
9. Sitting eye height: The vertical distance from the sitting surface to the outer corner of the right
eye, when sitting [49]. Origin of the visual field; reference point for the location of vision
obstructions and of visual targets such as displays; consider slump and motion of the seated person.
10. Sitting shoulder height (acromion): The vertical distance from the sitting surface to the tip
(acromion) of the shoulder, when sitting [3]. Starting point for arm length measurements; near the
center of rotation of the upper arm (shoulder joint), reference point for hand reaches, consider slump
and motion of the seated person.
11. Sitting elbow height: The vertical distance from the sitting surface to the lowest point of the
right elbow, when sitting, with the elbow flexed at 90 degrees [48]. Reference point for height of an
arm rest, of the work area of the hand, and of keyboard and controls; consider slump and motion of
the seated person.
12. Sitting thigh height (clearance): The vertical distance from the sitting surface to the highest
point on the top of the right thigh, when sitting, with the knee flexed at 90 degrees [104]. Minimal
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clearance needed between seat pan and the underside of a structure, such as a table.; add clearance
for clothing and motions.
13. Sitting knee height: The vertical distance from the floor to the top of the right knee cap, when
sitting, with the knees flexed at 90 degrees [73]. Minimal clearance needed below the underside of a
structure, such as a table; add height for shoe.
14. Sitting popliteal height: The vertical distance from the floor to the underside of the thigh
directly behind the right knee; when sitting, with the knees flexed at 90 degrees [86]. Reference for
the height of a seat; add height for shoes, consider movement of the feet.
15. Shoulder elbow length: The vertical distance from the underside of the right elbow to the right
acromion, with the elbow flexed at 90 degrees and the upper arm hanging vertically [91]. A general
reference for comparing population samples.
16. Elbow-fingertip length: The distance from the back of the right elbow to the tip of the middle
finger, with the elbow flexed at 90 degrees [54]. Reference for fingertip reach when moving the
forearm in the elbow.
17. Overhead grip reach, sitting: The vertical distance from the sitting surface to the center of a
cylindrical rod firmly held in the palm of the right hand [D45]. Reference for height of overhead
controls to be operated by the seated person. Consider ease of motion, reach, and finger/hand/arm
strength.
18. Overhead grip reach, standing: The vertical distance from the standing surface to the center of
a cylindrical rod firmly held in the palm of the right hand [D42]. Reference for height of overhead
controls to be operated by the standing person. Add shoe height. Consider ease of motion, reach, and
finger/hand/arm strength.
19. Forward grip reach: The horizontal distance from the back of the right shoulder blade to the
center of a cylindrical rod firmly held in the palm of the right hand [D21]. Reference for forward
reach distance. Consider ease of motion, reach and finger/hand/arm strength.
20. Arm length, vertical: The vertical distance from the tip of the right middle finger to the right
acromion, with the arm hanging vertically [D3]. A general reference for comparing population
samples. Reference for the location of controls very low on the side of the operator. Consider ease of
motion, reach, and finger/hand/arm strength.
21. Downward grip reach: The vertical distance from the right acromion to the center of a
cylindrical rod firmly held in the palm of the right hand, with the arm hanging vertically [D43].
Reference for the location of controls low on the side of the operator. Consider ease of motion,
reach, and finger/hand/arm strength.
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22. Chest depth: The horizontal distance from the back to the right nipple [36]. A general reference
for comparing population samples. Reference for the clearance between seat backrest and the
location of obstructions in front of the trunk.
23. Abdominal depth, sitting: The horizontal distance from the back to the most protruding point
on the abdomen [1]. A general reference for comparing population samples. Reference for the
clearance between seat backrest and the location of obstructions in front of the trunk.
24. Buttock-knee depth, sitting: The horizontal distance from the back of the buttocks to the most
protruding point on the right knee, when sitting with the knees flexed at 90 degrees [26]. Reference
for the clearance between seat backrest and the location of obstructions in front of the knees.
25. Buttock-popliteal depth, sitting: The horizontal distance from the back of the buttocks to back
of the right knee just below the thigh, when sitting with the knees flexed at 90 degrees [27].
Reference for the depth of a seat.
26. Shoulder breadth, biacromial: The distance between the right and left acromion [10]. A
general reference for comparing population samples. Indication of the distance between the centers
of rotation (shoulder joints) of the upper arms.
27. Shoulder breadth, bideltoid: The maximum horizontal breadth across the shoulders between
the lateral margins of the right and left deltoid muscles [12]. Reference for the clearance requirement
at shoulder level. Add space for ease of motion, tool use.
28. Hip breadth, sitting: The maximal horizontal breadth across the hips or thighs, whatever is
greater, when sitting [66]. Reference for seat width. Add space for clothing and ease of motion.
29. Span: The distance between the tips of the middle fingers of the horizontally outstretched arms
and hands [98]. Reference for sideway reach.
30. Elbow span: The distance between the tips of the elbows of the horizontally outstretched upper
arms with the elbows flexed so that the fingertips of the hands meet in front of the trunk. Reference
for “elbow room.”
31. Head length: The distance from the glabella (between the browridges) to the most rearward
protrusion (the occiput) on the back, in the middle of the skull [62]. A general reference for
comparing population samples. Reference for head gear size.
32. Head breadth: The maximal horizontal breadth of the head above the attachment of the ears
[60]. A general reference for comparing population samples. Reference for head gear size.
33. Hand length: The length of the right hand between the crease of the wrist and the tip of the
middle finger, with the hand flat [59]. A general reference for comparing population samples.
Reference for hand tool and gear size. Consider changes due to manipulations, gloves, tool use.
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34. Hand breadth: The breadth of the right hand across the knuckles of the four fingers [57]. A
general reference for comparing population samples. Reference for hand tool and gear size, and for
the opening through which a hand may (or may not) fit. Consider changes due to manipulations,
gloves, tool use.
35. Foot length: The maximal length of the right foot, when standing [51]. A general reference for
comparing population samples. Reference for shoe and pedal size.
36. Foot breadth: The maximal breadth of the right foot, at right angle to the long axis of the foot,
when standing [50]. A general reference for comparing population samples. Reference for shoe size,
spacing of pedals.
37. Weight: Nude body weight taken to the nearest tenth of a kilogram. A general reference for
comparing population samples. Reference for body size, clothing, strength, health, etc. Add weight
for clothing and equipment worn on the body.
TOOLS AND EQUIPMENT: Large and small anthropometer
DISCUSSION:
CONCLUSION:
LABORATORY NO.4
NOISE LEVEL MEASUREMENT
SUMMARY:
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INTRODUCTION:
OBJECTIVES:
1. To determine the importance of safety inside the company for a best human
performance and the effects of noise on the body.
2. To determine the physical environmental stressors.
3. To optimally structuring of the work environment to help improve comfort and
performance and reduce potential risks due to environmental factors particularly
noise.
PROCEDURES:
1. Using a sound - level meter, take five readings of sound pressure level in your
environment.
2. Collectively analyze and evaluate information
3. Compare results with recommended maximums.
4. Discuss differences.
a. Present your report via oral presentation of 30 minutes (including 10 minutes for
Q&A portion) creatively to your instructor and to other pre-selected stakeholders.
b. Submit the report on time.
WHAT IS NOISE POLLUTION?
Sound that is unwanted or disrupts one’s quality of life is called as noise. When there is
lot of noise in the environment, it is termed as noise pollution.
Sound becomes undesirable when it disturbs the normal activities such as working,
sleeping, and during conversations.
It is an underrated environmental problem because of the fact that we can’t see, smell, or
taste it.
World Health Organization stated that “Noise must be recognized as a major threat to human
well-being”.
Health Effects
According to the USEPA, there are direct links between noise and health. Also, noise
pollution adversely affects the lives of millions of people.
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Noise pollution can damage physiological and psychological health.
High blood pressure, stress related illness, sleep disruption, hearing loss, and productivity
loss are the problems related to noise pollution.
It can also cause memory loss, severe depression, and panic attacks.
Sources of Noise Pollution
Transportation systems are the main source of noise pollution in urban areas.
Construction of buildings, highways, and streets cause a lot of noise, due to the usage of
air compressors, bulldozers, loaders, dump trucks, and pavement breakers.
Industrial noise also adds to the already unfavorable state of noise pollution.
Loud speakers, plumbing, boilers, generators, air conditioners, fans, and vacuum cleaners
add to the existing noise pollution.
Decibel (Loudness) Comparison Chart
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Solutions for Noise Pollution
Planting bushes and trees in and around sound generating sources is an effective solution
for noise pollution.
Regular servicing and tuning of automobiles can effectively reduce the noise pollution.
Buildings can be designed with suitable noise absorbing material for the walls, windows,
and ceilings.
Workers should be provided with equipment such as ear plugs and earmuffs for hearing
protection.
to automobiles, lubrication of the machinery and servicing should be done to minimize
noise generation.
Soundproof doors and windows can be installed to block unwanted noise from outside.
Regulations should be imposed to restrict the usage of play loudspeakers in crowded
areas and public places.
Factories and industries should be located far from the residential areas.
Community development or urban management should be done with long-term planning, along
with an aim to reduce noise pollution.
Social awareness programs should be taken up to educate the public about the causes and effects
of noise pollution.
TOOLS AND EQUIPMENT:
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DISCUSSION:
CONCLUSION:
LABORATORY NO.5
Qualitative and Quantitative Display
SUMMARY:
INTRODUCTION:
OBJECTIVES:
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1.
2.
3.
To visit a power plant, manufacturing firm, service industries and observe two displays:
one quantitative and one qualitative;
Analyze the existing displays;
Evaluate each display and propose improvements.
PROCEDURES:
a.
b.
c.
d.
e.
Form a working team with 3 members and organize the necessary activities you will need
to do in order to complete the laboratory. Note that your team identifies clear roles and
responsibilities.
Visit a power plant, manufacturing firm, service industries and observe two displays: one
quantitative and one qualitative.
Collectively analyze and evaluate information.
Present your project via oral presentation of 30 minutes (including 10 minutes for Q&A
portion) creatively to your instructor and to other pre-selected stakeholders.
Submit the laboratory project on time.
Perceptual and Cognitive Factors and their Applications
DISPLAYS
Any display must give the operator information about the functional status of technology
and/or processes.
3 classes of information:
Need to know - warnings, orders etc.
Nice to know - advisory, messages etc.
Historical - miles traveled, time elapsed etc.
Purpose of Displays
Convey information about a certain entity in our environment or surrounding.
•
•
•
Displays: Functional Requirements
Speed - how quickly can the information be acquired?
Accuracy - is information interpretation unambiguous and error free?
Sensitivity - can changes in the displayed variable be detected at the relevant magnitude?
Displays: Design criteria
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•
•
•
Detection - can the user detect the displayed information and any changes in this in context (e.g.
see a visual display, hear an auditory display)?
Recognition - can the user extract the relevant information from the display?
Comprehension - can the user understand the displayed information?
Displays: Basic Types
•
•
Static display - display content remains unchanged with time (label, traffic sign, graph, symbol
etc.).
• Graphic symbols
• Labels
• Instruction signs
• Industrial and Consumer Safety Signs
Dynamic display - display content changes with time (speedometer, fuel gauge, radar, watch
etc.).
•
Quantitative display - displays the quantity of some variable (time, speed, temperature etc.).
Fixed scale with a moving pointer is preferred is not digital, more attention getting,
allows you to see a trend in performance or in the data.
•
Qualitative display - displays qualitative information (brake light, battery gauge etc.).
• Use color to enhance meanings
• Use shape coding to enhance meaning
• Use zone coding to enhance meaning
Displays: Types of Information
•
•
•
•
•
•
Status - system conditions (on/off).
Warnings - unsafe conditions (brake light).
Representations - (pictures, maps, graphs).
Identification - (traffic lanes, color-coded wires).
Symbolic - (alphanumeric, music, math).
Time-phased - signal duration/interval (flashers, heart beat monitor)
Safety Signs: 6 characteristics
•
•
•
•
•
•
Sign should be in the immediate vicinity of the hazard
Sign should contrast with background.
Sign should identify the nature of the hazard.
Sign should indicate the hazard consequences.
Sign should identify the seriousness of the hazard.
Sign should indicate how to avoid the hazard.
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TOOLS AND EQUIPMENT:
DISCUSSION:
CONCLUSION:
LABORATORY NOS.6 & 7
APPLICATION OF RULA / REBA
SUMMARY:
INTRODUCTION:
OBJECTIVES:
1. Have a basic understanding of RULA and REBA.
2. Explain the differences between RULA and REBA.
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3. Be able to analyze a task using RULA and REBA.
PROCEDURES:
1.
2.
3.
4.
5.
6.
7.
Observe the task in a certain manufacturing or service industries (photos vs video)
Collectively analyze and evaluate information
Select postures for assessment.
Score the postures.
Process the scores.
Determine the final score.
Confirm action level.
a. Present your report via oral presentation of 30 minutes (including 10 minutes
for Q&A portion) creatively to your instructor and to other pre-selected
stakeholders.
b. Submit the report on time.
RULA









Survey method assess postures of neck and upper limb loading
Best for sedentary, seated tasks
Final risk assessment score combines arm/wrist risk with neck, trunk, leg risk
Final score magnitude (between 1 and 7) overall injury risk due to musculoskeletal loading
One of most popular ergonomic assessment tools in industry
User-friendly, charts can be confusing
Not as good for determining risk due to repetition
No major calculations needed, quick
Validated
RULA
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RULA Action Level
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REBA




Same principles as RULA, validated .
Better tool for whole body static, dynamic, unstable or rapidly changing postures
User-friendly, tables used to compute scores .
Good for health care & service industries Not as useful for production line work.
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TOOLS AND EQUIPMENT:
DISCUSSION:
CONCLUSION:
LABORATORY NO.8
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NIOSH Lifting
SUMMARY:
INTRODUCTION:
OBJECTIVES:
1. To visit a manufacturing firm, service, construction and other related industries and
observe lifting activities.
2. Analyze the lifting activities performed by the workers;
3. Evaluate the lifting tasks using NIOSH Lifting Guide and propose improvements.
PROCEDURES:
a. Form a working team with __ members and organize the necessary activities you will need to
do in order to complete the project. Note that your team identifies clear roles and
responsibilities.
b. Collectively analyze and evaluate information.
c. Present your project via oral presentation of 30 minutes (including 10 minutes for Q&A
portion) creatively to your instructor and to other pre-selected stakeholders.
d. Submit the project on time.
Step-by-Step Guide: NIOSH Lifting Equation
Introduction
The NIOSH Lifting Equation is a tool used by occupational health and safety professionals to
assess the manual material handling risks associated with lifting and lowering tasks in the
workplace. This equation considers job task variables to determine safe lifting practices and
guidelines.
The primary product of the NIOSH lifting equation is the Recommended Weight Limit
(RWL), which defines the maximum acceptable weight (load) that nearly all healthy employees
could lift over the course of an 8 hour shift without increasing the risk of musculoskeletal
disorders (MSD) to the lower back. In addition, a Lifting Index (LI) is calculated to provide a
relative estimate of the level of physical stress and MSD risk associated with the manual lifting
tasks evaluated.
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NIOSH Lifting Equation Outputs
Recommended Weight Limit (RWL): Answers the question… “Is this weight too heavy for
the task?”
Lifting Index (LI): Answers the question… “How significant is the risk?”
A Lifting Index value of less than 1.0 indicates a nominal risk to healthy employees. A
Lifting Index of 1.0 or more denotes that the task is high risk for some fraction of the population.
As the LI increases, the level of low back injury risk increases correspondingly. Therefore, the
goal is to design all lifting jobs to accomplish a LI of less than 1.0.
The NIOSH lifting equation always uses a load constant (LC) of 51 pounds, which
represents the maximum recommended load weight to be lifted under ideal conditions. From that
starting point, the equation uses several task variables expressed as coefficients or multipliers (In
the equation, M = multiplier) that serve to decrease the load constant and calculate the RWL for
that particular lifting task.
NIOSH Lifting Equation: LC (51) x HM x VM x DM x AM x FM x CM = RWL
Task variables needed to calculate the RWL:






H = Horizontal location of the object relative to the body
V = Vertical location of the object relative to the floor
D = Distance the object is moved vertically
A = Asymmetry angle or twisting requirement
F = Frequency and duration of lifting activity
C = Coupling or quality of the workers grip on the object
Lifting Index (LI): Weight ÷ RWL = LI
Additional task variables needed to calculate the LI:


Average weight of the objects lifted
Maximum weight of the objects lifted
The RWL and LI can be used to guide lifting task design in the following ways:
1) The individual multipliers the determine the RWL can be used to identify specific weaknesses
in the design. 2) The LI can be used to estimate the relative physical stress and injury risk for a
task or job. The higher the LI value, the smaller the percentage of workers capable of safely
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performing these job demands. Thus, injury risk of two or more job designs could be compared. 3)
The LI can also be used to prioritize ergonomic redesign efforts. Jobs can be ranked by LI and a
control strategy can be implemented based on a priority order of the jobs or individual lifting
tasks.
The Frequency-Independent Recommended Weight Limit (FIRWL) and the FrequencyIndependent Lifting Index (FILI) are additional outputs of the NIOSH lifting calculator. The
FIRWL is calculated by using a frequency multiplier (FI) of 1.0 along with the other task
variable multipliers. This effectively removes frequency as a variable, reflecting a weight limit
for a single repetition of that task and allows equal comparison to other single repetition tasks.
The Frequency-Independent Lifting Index (FILI) is calculated by dividing the weight lifted by
the FIRWL. The FILI can help identify problems with infrequent lifting tasks if it exceeds the
value of 1.0.
How to Use the NIOSH Lifting Equation
Step 1: Measure and Record Task Variables
The first step is to gather the needed information and measurements for lifting task
variables, and record the data to be used later to calculate the RWL and LI for the tasks being
evaluated.
The evaluator should prepare by interviewing and observing workers to gain a complete
understanding of all required lifting tasks. Selection of the lifting tasks to be evaluated should be
based on the most significant and demanding manual material handling tasks.
If the job requires a wide variety of lifting tasks, a multi-task evaluation can be
performed using a composite of all single-task lifting assessments performed. More on that later,
but for now let’s focus on single-task assessments.
For each lifting task analyzed, the evaluator will need to determine the task variables as
outlined above. We have developed the following worksheet to assist you with data collection:
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The following task variables are evaluated to calculate the multipliers that are used in the
NIOSH equation to determine the RWL. Here are some quick explanations and guidelines that
you can use to gather the needed measurements:
1) Horizontal Location of the Hands (H) – Measure and record the horizontal location of the
hands at both the start (origin) and end (destination) of the lifting task. The horizontal location is
measured as the distance (inches) between the employee’s ankles to a point projected on the
floor directly below the mid-point of the hands grasping the object as pictured below:
2) Vertical Location of the Hands (V) – Measure and record the vertical location of the hands
above the floor at the start (origin) and end (destination) of the lifting task. The vertical location
is measured from the floor to the vertical mid-point between the two hands as shown below. The
middle knuckle can be used to define the mid-point.
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3) Vertical Travel Distance (D) – The vertical travel distance of a lift is determined by
subtracting the vertical location (V) at the start of the lift from the vertical location (V) at the end
of the lift. For a lowering task, subtract the V location at the end from the V location at the start.
4) Asymmetric Angle (A) – Measure the degree to which the body is required to twist or turn
during the lifting task. The asymmetric angle is the amount (in degrees) of trunk and shoulder
rotation required by the lifting task. Note: Sometimes the twisting is not caused by the physical
aspects of the job design, but rather by the employee using poor body mechanics. If this is the
case, no twisting (0 degrees) is required by the job. If twisting is required by the design of the
job, determine the number of degrees the back and body trunk must twist or rotate to accomplish
the lift. (i.e. 90° as pictured below)
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5) Coupling (C) – Determine the classification of the quality of the coupling between the
worker’s hands and the object as good, fair, or poor (1, 2, or 3). A good coupling will reduce the
maximum grasp forces required and increase the acceptable weight for lifting, while a poor
coupling will generally require higher maximum grasp forces and decrease the acceptable weight
for lifting.
1 = Good – Optimal design containers with handles of optimal design, or
irregular objects where the hand can be easily wrapped around the object.

2 = Fair – Optimal design containers with handles of less than optimal
design, optimal design containers with no handles or cut-outs, or irregular
objects where the hand can be flexed about 90°.
A. 3 = Poor – Less than optimal design container with no handles or cut-outs, or
irregular objects that are hard to handle and/or bulky (e.g. bags that sag in the middle).

6) Frequency (F) – Determine the appropriate lifting frequency of lifting tasks by using the
average number of lifts per minute during an average 15 minute sampling period. For example,
count the total number of lifts in a typical 15 minute period of time and divide that total number
by 15.


Minimum = 0.2 lifts/minute
Maximum is 15 lifts/minute.
7) Load (L) – Determine the weight of the object lifted. If necessary, use a scale to determine
the exact weight. If the weight of the load varies from lift to lift, you should record the average
and maximum weights lifted.
8) Duration (Dur) – Determine the lifting duration as classified into one of three categories:
Enter 1 for short-duration, 2 for moderate-duration and 8 for long-duration as follows:
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


1 = Short – lifting ≤ 1 hour with recovery time ≥ 1.2 X work time
2 = Moderate – lifting between 1 and 2 hours with recovery time ≥ 0.3 X lifting time
8 = Long – lifting between 2 and 8 hours with standard industrial rest allowances
Step 2: Enter Data / Calculate RWL and LI

In step 1, we determined and recorded the lifting task variables in our worksheet. The
following is an example of a completed worksheet:
Now we are ready to input the collected data into our calculator to determine the RWL and LI:
Origin and Destination Calculations:
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TOOLS AND EQUIPMENT:
DISCUSSION:
CONCLUSION:
LABORATORY NO.9
Computer (VDT) Workstations
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SUMMARY:
INTRODUCTION:
OBJECTIVES
1. To make the students more familiar about computer visual display terminal;
2. Analyze the given task considering workstation seating, work surfaces, computer
monitor, keyboard, input devices, VDT accessories, work practices, office lighting and
glare and environment.
3. Propose possible improvements.
PROCEDURES:
a. Form a working team with 3 members and organize the necessary activities you will need to
do in order to complete the project. Note that your team identifies clear roles and
responsibilities.
b. Collectively analyze and evaluate information.
c. Present your project via oral presentation of 30 minutes (including 10 minutes for Q&A
portion) creatively to your instructor and to other pre-selected stakeholders.
d. Submit the project on time.
When using the checklist:
• A “no” response indicates that an ergonomic risk factor may be present which requires further
analysis. Refer to the list of possible solutions for ideas to improve the situation.
• A “yes” response indicates acceptable ergonomic design conditions.
• This checklist is not all-inclusive and may not cover all topics that are relevant for the
workstation that you are evaluating.
• It is important to note that if more than one person uses a workstation, this checklist should be
applied to each individual to ensure that the
workstation is usable by all the individuals that work at it.
• No posture is perfect for an individual to remain in indefinitely – frequent changes in posture
are the best.
• If you are unsure about how to best apply these suggestions to the work environment or if an
individual continues to experience discomfort after changes have been made to his/her
workstation, please consult an ergonomist.
HUMAN COMPUTER INTERFACE
Nowadays, many human tasks are being allocated to machines. Transition to machine
task from human tasks is called automation. Especially in an office environment, automation
project take the form of computerization of routine human functions in terms of information
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documentation, entry, retrieval, and processing. In addition to the hardware functions, an
ergonomist must be concerned with effective human-computer interface for best human
performance in such occupations. A user-friendly interface will be much more positively
responded to by humans than an interface that does not address user needs and characteristics.
The potential benefits of improved user interfaces are reduced human-initiated errors,
reduced training requirements, increased efficiency and increased job acceptance.
METHODOLOGY FOR EFFECTIVE INTERFACE DESIGN
1.
DEFINE AND KNOW THE USERS
Users have to be involved with the design early in the design process. Ergonomist design with
the user, not for the user. The designer should have direct and ongoing contact with the users.
Personal interviews, questionnaires, and users on the design team are the best ways to accomplish
these objectives.
2.
DEFINE SYSTEM REQUIREMENTS
Before any development, a detailed definition of system requirements is necessary. This includes
the detailing of an operations plan together with a function definition. What the system objectives
are and how they will be achieved are the questions to be answered.
3.
DEFINE TASK REQUIREMENTS
For each operational function, a detailed investigation of user tasks is necessary. Task analyses
are also valuable in allocating functions to the computer and to the user. Skill requirements and
hence training needs are other results of task analysis.
4.
UTILIZE EXISTING DESIGN GUIDELINES/DEVELOP NEW ONES
Research may be carried out to solve unknowns. Design guidelines describe conventions
and practices for developing effective user interfaces.
5.
DESIGN THE USER INTERFACE
This step includes dialogue design, display screen design, equipment selection and design, and
training process design, including the training documents. This is the step where all design
guidelines and work area design suggestions are put into use.
6.
DEVELOP PROTOTYPES
It is an early version of the system being designed. Their use is primarily in the early design
cycle, to reveal flaws in the design and let the user evaluate the requirements firsthand. More
often than not, the user may make modifications after a good review of the prototype.
7.
CONDUCT USER ACCEPTANCE TESTING
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User acceptance testing (UAT) is the full scale testing of the software, with all functionality,
screens, and dialogues. The user conducts this testing with help from the developer.
8.
TRAIN THE USERS
This is mass training of all the users on the system structure and each feature, including the
dialogue screen.
9.
CONDUCT FOLLOW-UP EVALUATIONS AND ENHANCEMENTS
Once a system has been designed and put into use, follow-up evaluations reveal mismatches
between assumption and the functionality built into the system.
INTERFACE DESIGN GUIDELINES
GENERAL PRINCIPLES:
1.
Reduce Mental Processing Requirements
The computer must aid the user in performing tasks rather than complicate the responsibility.
Designers must build procedures into computer systems to reduce the frequency of mental
processing.
2.
Allocate Functions to the User and the Computer Based on Their Relative Strengths
The implication of all research done along these lines is that the human being is best in
controlling, decision making, and responding to unexpected events. The computer is best for
storing and retrieving data, processing information using prespecified procedures and presenting
options and supporting data to users.
3.
Allow the User to Develop Effective Mental Models of System Operation
Extensive rules and syntax, no underlying overall framework, or internally inconsistent
conventions can lead to frustration.
4.
Build in as much consistency as possible
If a consistent set of convention is not decided upon, documented, and incorporated into all
phases of the system, the resulting interface will appear to have a different set of interaction rules
for each affected transactions. This will significantly increase mental stress.
5.
Use as many physical analogies as logical
In this respect, icons are very effective. Direct manipulation of pictorial representations of
objects of interest seems more friendly than otherwise.
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6.
Build interfaces that capitalize on expectations and stereotypes
These will minimize requirements to learn new and unfamiliar associations. If the product is to
be used only by a specialized group of users, their expectations and stereotypes must be
considered. For example, a computer system designed for the Arabic speaking countries needs to
present information in right-to-left-order.
7.
Consider stimulus-response compatibility
It is sufficient to say that specific features of control-display compatibility in a computer system
must be observed. For example, to move the cursor to the right, the right arrow key should be
presented.
8.
Provide an appropriate balance of ease of learning, ease of use and functionality
This could be accomplished by designing for experts and intermittent users, avoiding excess
functionality, providing multiple paths for option selection, and minimizing the consequences of
errors through reversible actions.
TOOLS AND EQUIPMENT:
DISCUSSION:
CONCLUSION:
LABORATORY NO. 10
DESIGNING AN INDIVIDUAL EXPERIMENT
“DEVELOPMENT OF AN ERGONOMICALLY DESIGNED HAND TOOLS”
SUMMARY:
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INTRODUCTION:
OBJECTIVES:
1. Determine the parts of the hand tool that needs to redesign or for improvement;
2. Collectively analyze and evaluate information
3. Evaluate the existing dimensions of the hand tool that needs to redesign or for
improvement;
4. Apply the knowledge learned in ergonomics to come up with the proposed design;
5. Explain the ergonomic benefits of the new design;
6. Produce an actual ergonomically designed hand tool; and
7. Conduct cost analysis.
PROCEDURES:
1.
2.
3.
4.
5.
6.
Select a hand tool for redesigning or improvement;
Measure the existing dimensions of the hand tool;
Apply the principles of ergonomics in the redesigning of hand tool;
Formulate an ergonomic standard;
Evaluate the ergonomically designed hand tool; and
Explain the ergonomic benefits of the new design
a. Present your report via oral presentation of 30 minutes (including 10 minutes
for Q&A portion) creatively to your instructor and to other pre-selected
stakeholders.
b. Submit the report on time.
TOOLS AND EQUIPMENT:
DISCUSSION:
CONCLUSION:
REFERENCES
Herczeg, M. and Stein, M. (2012). Human Aspects of Information Ergonomics.
McCormick, E. J. & Sanders, M. S. Human Factors Engineering and Design, 6th Edition.
National Engineering Center, UP Diliman, Quezon City. Human Factors Engineering, 2006
Pulat, M. B. Fundamentals of Ergonomics.
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http://www.usabilitybok.org/physical-ergonomics