Brazil Seat Ergonomics & Vibration Talk
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Transcript of Brazil Seat Ergonomics & Vibration Talk
8/20/2019 Brazil Seat Ergonomics & Vibration Talk
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Driver Ergonomics and
Whole Body Vibration
Eckardt Johanning M.D. M.Sc.
8/20/2019 Brazil Seat Ergonomics & Vibration Talk
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The problem – The Aching Back
• Risk analysis:
• Repetitive mechanical stress:
vibration and shock• Posture: Seat
• Exposure duration & break time: Schedule
• Health complaints/disorders and injuries
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Where do you find Vibration?
Hand-ArmWhole Body
In Buildings
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Tested yard switcher GP40-2 - January 27, 2004
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DEFINITION OF WHOLE BODY
VIBRATION
• Mechanical
v ibrat ion that, when
transm it ted to the
who le body , entai ls
r isks to the heal th
and safety o f
workers, inpart icular low er
back morb id i ty and
traum a of the sp ine.
Eckardt Johanning M.D. M.Sc.
8/20/2019 Brazil Seat Ergonomics & Vibration Talk
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VIBRATION
• Began with the
Industrial Revolution.
• Humans exposed to
oscillatory motions
(vibration) for the firsttime when working
with powered
equipment.Eckardt Johanning M.D. M.Sc.
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WHAT IS SHOCK & VIBRATION?
Eckardt Johanning M.D. M.Sc.
Simples vibration
Two dominant frequencies
Complex vibrations:
multiple dominant frequencies
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WHAT IS SHOCK & VIBRATION?
Eckardt Johanning M.D. M.Sc.
8/20/2019 Brazil Seat Ergonomics & Vibration Talk
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What is Whole Body
Vibration (WBV)?• Energy transmitted to the body as a whole,
through a supporting surface
• Important Factors:
– magnitude
– direction
– frequency
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Measuring Vibration
• Acceleration: measure of vibration
• Vibration: magnitude and direction
• Measurements: three directions:
– x, y, z
• Units: meters per second squared
(m/s2)
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Eckardt Johanning M.D. M.Sc.
The concept of Resonance effects: Magnification
Resonance is the tendency of a system to oscillate with larger amplitude at
some frequencies than at others.
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CRITICAL
RESONANCE
RANGES OF
THE HUMAN
BODY.Eckardt Johanning M.D. M.Sc.
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Vibration and Resonance Effects of Internal Organs of Humans
Eckardt Johanning M.D. M.Sc.
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Eckardt Johanning M.D. M.Sc.
8/20/2019 Brazil Seat Ergonomics & Vibration Talk
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AGINGCROSS
ANATOMY &
MRI IMAGE
Eckardt Johanning M.D. M.Sc.
8/20/2019 Brazil Seat Ergonomics & Vibration Talk
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Spine aging and vibration related
degenerationMore and earlier damage
Eckardt Johanning M.D. M.Sc.
8/20/2019 Brazil Seat Ergonomics & Vibration Talk
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RISK FACTORS
Posture.
ExposureDuration.
RestPeriods.
Eckardt Johanning M.D. M.Sc.
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MTA test bus – March 8, 2004
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TWU test driver – WBV seat
test pad
Orion CNG Bus – built 5/03 9938 miles –
Seat: Recaro air suspension (ergo-metro)
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Seat air suspension
adjustments
Problem: in extreme position – suspension impaired
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MTA – controls….
Seat back support
adjustment problem
–restricted & hits
wall
MTA vibration
sensor
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The Seat of old New York City Buses
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Vertical Axis – Seat levelTime Sample
t
hh:m
m:ss aweq MTVV VDV
VDV/aw*T1/
4
MTVV/awe
q CF14:11:45 300 0:05:00 0.364 1.77 2.87 1.89 4.85 10.75
14:16:45 300 0:05:00 0.514 1.79 3.54 1.65 3.48 6.57
14:21:45 300 0:05:00 0.533 2.25 3.78 1.70 4.22 10.08
14:26:45 210 0:03:30 0.508 1.45 3.04 1.57 2.86 5.71
14:33:30 300 0:05:00 0.437 1.57 3.03 1.67 3.59 7.50
14:38:30 300 0:05:00 0.605 2.64 3.95 1.57 4.36 7.58
14:43:30 300 0:05:00 0.350 1.49 2.84 1.95 4.25 13.11
14:48:30 300 0:05:00 0.244 1.38 2.03 2.01 5.66 14.36
14:53:30 300 0:05:00 0.245 0.81 1.70 1.67 3.29 7.46
15:05:15 300 0:05:00 0.243 1.06 1.77 1.75 4.34 8.48
15:10:15 45 0:00:45 0.454 1.05 1.79 1.52 2.32 6.07
15:11:15 120 0:02:00 0.378 1.45 2.15 1.72 3.84 7.86
3075 0:51:15 0.42 2.64 5.59 1.79 6.28 12.79
Tri axial vibration bus (vs train) compared
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Tri-axial vibration bus (vs. train) compared(seat and floor) (ISO 2631, 1997)
Vibration (aw rms) (mean) :
Fore-aft (x) 0.21 (0.18) m/s2,
Lateral (y) 0.19 (0.28) m/s2Vertical (z) 0.42 (0.32) m/s2.
Frequent and high shock levels:
The Crest factors (CF): 9-16 (>9)
Maximum Transient Vibration Value (MTVV/aw):5.13 (5. 26) (x),
4.34 (5.12) (y)
6.28 (4.81) (z)
Vibration Dose Value (VDV/aw T 1/4)
1.63 (1.32 to 2.3) (x-axis)1.7 (1.33 to 1.7) (y-axis)
1.79 (1.38 to 1.86) (z-axis)
Seat transmission factors (SEAT):
x:1.44 y:1.01 z:0.71 (1.44,1.2, 1)
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STANDARDS
Eckardt Johanning M.D. M.Sc.
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Summary and RxVibration and shock are recognized risk factors
for ergonomic stress and back disordersPreliminary and comparison testing of bus
operator seat shows that WBV are in asimilar range
New study of Railroad engineers reveals highlevel of back complaints and disorders
Transit workers study recommended based onpreliminary analysis of test data of “modelbus”
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Summary and Rx
• Transit workers study
recommended based on preliminary
analysis of test data of “model bus” • Collaborative and participatory
principle
• Intervention study
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How Do We Control Exposure
to Whole Body Vibration ?u Redesign or
engineering controls
u Maintain seatingsystems
u Administrative controls
u Anti-vibration seatcushions
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Key Check Points –
Healthy Driving1. Seat adjustment (length)
2. Seat angle adjustment
3. Back support adjustment
4. Pedal angle adjustment
5. Seat height and pedal reach6. Knee angle (110-120 degree)
7. Leg/Thigh support easy
8. Steering wheel and
instruments (slightly angled
elbow)
9. Good back support without
pressure?
10. Head support (top above eye
level?)Eckardt Johanning M.D. M.Sc.
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New Generation Bus Seats• Suspension seat adjustment
1. Height
2. Lumbar support
3. Lateral support
4. Backrest
5. Heater/ventilation6. Armrest
7. Armrest adjustment
8. Seat pan angle
9. Seat depth adjust.10. Fore/aft adjust.
11. Swivel
12. Vertical shock
absorber adjust.
Eckardt Johanning M.D. M.Sc.
Source: Grammer, Germany
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•Change seatingposture frequently:
– Dynamic sitting –
move and change
posture• Inform yourself about
the bus seat and
driver adjustments
• Sit slightly backwardswith good contact to
back support
Eckardt Johanning M D M Sc
Think of
yourback
Take a break and move around!
Good sitting posture!