Development of Posture Analysis Software for Continuous Farm Work

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Development of Posture Analysis Software for
Continuous Farm Work

• Masafumi Mitarai1, Hironori Matsuoka1, Julius
  Caesar Sicat2,Tomohiro Mino1, Sayaka Hosoyamada1
• 1Faculty of Agriculture,Miyazaki
  University,Miyazaki City,Japan
• 2Department of Science and Technology Regional
  Office No.3, Pampanga, Philippines

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Background and Objective of the Study
Manual farm work is often accompanied by intense
work load. Aging farmers doing agriculture in
present-day Japan are gradually increasing in
number. As a result, problems of accumulated
physical stress and weariness increase as well.
Therefore, to solve these problems, it is
necessary to improve farm working postures as
related to the amount of work loads. To date,
various ways of evaluating working postures were
developed. Examples are OWAS, RULA, NIOSH and
Bless Pro. However, evaluation of work processes
and working moments using these softwares is a
bit complicated. Also, they are not able to
measure the forces and bending moments associated
with continuous farm work operations.
A software which analyzes work posture and
determines the optimum working posture was
developed to solve the problems mentioned above.
It can evaluate continuously the forces and
bending moments acting on critical body parts of
the worker. The body angle data were continuously
measured using a work posture monitor VM12-512.
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Work Posture Monitor (VM12-512)
Mac Enaduo (VM12-512) made by VINE company was
used as work posture monitor. It was developed
to measure the posture of the worker moving
continuously. It can measure the inclination
angle of each part of the body (body trunk, upper
arm, forearm, thigh and portion below the thigh)
by angle sensors. The angle sensors detect the
angular change of measured part relative to the
vertical line.
Figure 1. The angle sensors Table 1.
Specification of work posture monitor
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Work Posture Display and Analysis
The posture analysis software assumes farm work
to be two-dimensional. Also, the study focuses on
the L5/S1 joint where waist ailment called
lumbago frequently occurs. The software analyzes
a load that divides the body into two the upper
part of the body trunk and the lower part of the
body trunk. (1) The work posture display (2)
Joint bending moment analysis (3)
Estimation of forces on lumbar vertebrae
L5/S1
Figure 2. The human body model for calculating
the various forces and moments on the different
joints
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Forces Acting on L5/S1
Shearing force at L5/S1 disc Fs
Force at erector spinal Fm
Compression force at L5/S1 disc Fc
Abdominal pressure Fa
L5/S1
Figure 3. Biomechanical model of lumbar loads
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Calculation of Lumbar Loads
Angle between L5/S1 and the thigh joint -
shoulder joint line ?b59.255-0.33339H-0.0
02562H2-0.00072369K20.003309HK
???(3) Angle between L5/S1 and the shoulder joint
- thigh joint line
?asin-1(L30sin?b)/L31 ???(4) Inclination
angle of lower body trunk?p?3-?b
???(5) Inclination angle of upper body
trunk?q?3?a ???(6) Force at erector spinalFm
(pmp 9.807 - Fa D) / e ???(7) Compression
force at L5/S1 discFc Twp 9.807 Cos(Ra)
Lw 9.807 Cos(Ra) - Fa Fm ???(8) Shearing
force at L5/S1 discFs Twp 9.807 Sin(Ra)
Lw 9.807 Sin(Ra) ???(9) where?
pmpBending moment at L5/S1 FaAbdominal
pressure D Lever arm of L5/S1 (abdominal
pressure) eLever arm of the force at
erector spinal TwpWeight above L5/S1
RaInclination angle of L5/S1 joint surface
LwWeight of hand load
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Posture Analysis Software
START?
Figure 4. the menu screen of the posture analysis
software
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Conclusion

• The work posture analysis software was
  found effective in the following conditions
• Continuous analysis and evaluation when the work
  positions of legs and hands are different and
  loads on both hands are different as well.
• Evaluation and improvement of work posture which
  bends forward and down and momentary overloaded
  postures such as in manual farm work.
• Evaluation and improvement of difficult farm work
  such as carrying and lifting heavy load.
• Analysis and improvement of unstable farm work in
  inclined places.