Masaki Tauchi PhD Kazuya Kurooka Takabun Nakamura PhD Okayama Prefectural University Japan INTRODUCTION Because of Aged Society the use of manual wheelchairs for physically disabled is rapidly increasing Many of the elderly persons who use wheelchairs are no ID: 530426
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Slide1
The relationship between physical workload and the position of tipping lever of wheelchair while accompanied helper lift up and down wheelchair front
Masaki
Tauchi
PhD, Kazuya
Kuro-oka
,
Takabun
Nakamura
PhD
Okayama Prefectural University, JapanSlide2
INTRODUCTION
Because of ‘Aged Society,’ the use of manual wheelchairs for physically disabled is rapidly increasing. Many of the elderly persons who use wheelchairs are not able to maneuver freely by themselves but need assistance of care workers.
One of the major problems when they encounter in the mobile environment in the town is to clear differences in heights on floor or road surface.
For this problem, tipping levers are equipped in the rear of the wheelchair to lift up the front of wheelchair. But the shape and position may not be appropriate for the assistance by less powerful persons.Slide3
The shape and the position of typical tipping lever Slide4
PURPOSE
The tipping
lever of
manual wheelchair to
lift up and down the
casters is
not always easy to use
because of the
present shape
and/or position.
To find out appropriate position of the tipping lever, we
investigated the relationship between the power needed to lift up and down casters and positions of the tipping lever
in this study.
For this purpose, an introspection of the effort on upper and lower limb and load on lumber area when the subjects lift up the front of wheelchair at the various tipping lever position was measured.Slide5
METHODS
SUBJECTS
Eleven
subjects
having certain skill for wheelchair assistance participated. Four of them were males and 7 were women, mean age 27.6 +/- 3.8yrs, body weight
57.8 +/- 10.9kg
and height
165.8 +/- 10.2cm
SETTING OF EXPERIMENTAL TIPPING LEVER
On both sides of the tip of the tipping l
evers,
the experimental tipping lever
holders aligned to the perpendicular to the direction of travel were attached. Slide6
17.5
Distance
from wheel
axis
(cm)
19.0
7.5
10.0
12.5
15.0
15.0
11.0
23.0
Height from floor
(cm
)
Wheel axis
The tip of TPL
position of control
floor
THE SHAPE OF TIPPING LEVER HOLDER (
L
arge)
The tipping lever holders,
L
arge, were made allow to search wider range in the lower posterior part of the wheelchair In total 17 positions were examined.Slide7
10㎝
EXPERIMENTAL PROCEDURE
①
Lift up the front of the loaded wheelchair and step forward to put caster on the of 10cm high platform slowly
②
Ask ‘how heavy it was’ for the work
③
Lift up front again, then land on floor stepping backward slowly
④
Ask ‘how heavy it was’ for the work
10㎝
THE LOAD ON THE WHEELCHAIR
The concrete slab was used as a dummy load of wheelchair user. The weight placed on the seat was as much as 70% of the weight that the individual subjects can manage to lift up the front.
The subjective physical load felt by the subjects on their upper and lower limb and lumbar area was measured when they lift up and down the casters.
The weight on the seat of the wheelchair was set at 70% of maximum weight that the subjects can lift up.Slide8
Result 1
The spatial distribution of the average effort of upper and lower limbs and load on lumber area
11.0
23.0
19.0
15.0
Distance from wheel axis (cm)
17.5
15.0
12.5
10.0
7.5
Height from floor (cm)
control
Effort or load
Small
LargeSlide9
THE SHAPE OF TIPPING LEVER HOLDER (S) The tipping lever holders S
allow to take 14 different positions in total including two control positions at foremost and rearmost locations. The pits for four different heights and three distances were installed on the holder.
Distance
from wheel
axis (cm)
floor
17.5
20.0
22.5
15.0
27.5
15.0
17.5
13.75
T
he shape of TPL holder used in Experiment 1
Height from floor (cm)
Wheel axis
The tip of TPL, control position 1
Control position 2
12.5Slide10
EVALUATION 1) Effort on lower limb and upper limb
Need very small power (1pt)
~Need large power (5pts)
The effort of position 1 (the tip of tipping levers) was set at 5 points and the position 2 at 1pt. The subjects answered their effort by taking numbers at intervals of 0.5.
2) Load on lumber area
Feel very small load( 1pt)
~ Feel large load (5pts)
Measurement was the same as lower and upper limbsSlide11
15.0 17.5 20.0 22.5 (cm)
Distance from wheel
axis
1
3
5
Physical effort
Small
Large
Result 2
Effect of distance from wheel axis to physical effort on lower limb
**
**
p<0.001
**
**
Position 1Slide12
Distance from wheel
axis
17.5 cm
Physical effort/load
Small
Large
1
3
5
13.0 15.0 17.0
Distance from wheel
axis
20.0 cm
Distance from wheel
axis
22.5 cm
13.0 15.0 17.0
Height from floor (cm)
13.0 15.0 17.0
Result 3
Effect of height from floor to physical effort on lower limbSlide13
Result 4Comparison of
physical effort on
upper and lower limb and
load on lumbar area to the distance from wheel axis
Upper limb
Lower limb
Lumber
1
Distance from wheel
axis
5
3
15.0 17.5
20.0 22.5
Distance from wheel
axis
5
3
15.0 17.5
20.0 22.5
(cm)
5
3
Physical effort
Large
15.0 17.5
20.0 22.5
(cm)
1
Small11
Physical effort Large
Small
Physical load
LargeSmallSlide14
15.0
22.5
20.0
17.5
17.5
13.8
15.0
12.5
Height from floor
(cm)
Distance from wheel axis
(cm)
Position 1
Mapping of total average physical
e
ffort and load of tipping lever
Total
average physical effort and load: mean value of physical effort on upper and lower limbs and load on lumber
Small
Large
Result 5Slide15
SUMMARY
The
amounts
of
effort of subject’s lower and upper limbs and physical
load on
lumber
area decreased linearly
toward lower distal direction from the present tipping lever position.
The effort and the load decreased
when the height of the tipping lever decreased, though the relationship was not
linear. The effort and the load were almost the same for both for both lifting up and lifting down wheelchair front.
By searching the appropriate space for tipping levers behind wheelchair, it was found that the
area around 12.5cm height and 22.5cm distance from the axis of rear wheel fulfill the purposes.Slide16
CONCLUSION
By elongating and lowering the tipping levers of
the manual wheelchair
certain amounts, to lift up or down the casters become
much easier
for
assistance
with low physical
strength persons.Slide17
Thank you for your attentionSlide18Slide19
・現状のティッピングレバー位置を、やや低く、水平位置を介助者側により近づけることで、車いす前輪上げ動作時における介助者の身体的負荷を軽減することが可能であることが分った。・実用化には、ティッピングレバーの踏む部分の形状に関する検討が必要である。
8.
結 論Slide20
ティッピングレバーを鉛直線からθ
の角度で踏むと仮定する
M
：回転モーメント、
F
：ティッピングレバーを踏む力
M = F
・
L
・
sin(θ +θ
1
） －
(1)
(1)式を展開し、
F
について整理する
F = M /
（
L
2・sinθ + L1・cosθ
） －(2)Stevensの式に従い、力の感覚量で表すJ：力の大きさ感覚J = k・FP k：定数、P：重さの場合は1.5J = k・（M/（L
2・sinθ + L1・cosθ
） P
K=k・MP = 定数とし、
L2をhで表し整理する
L1
L2
H
h
L
F
θ
1
θ
A
OB
θ
床面
J = K
・（（
H
－
h
）・
sinθ + L
1
・
cosθ
）
－
P
= K
・（（
27.7
－
h）・sinθ + L1
・cosθ）－
1.5
5.
力学モデル
L・sin(θ+θ1)
TL
車軸Slide21
コントロール
負荷量
非表示部分
小
大
15.0
22.5
20.0
17.5
後輪軸からの水平距離（㎝）
床面からの高さ（㎝）
17.5
13.8
15.0
12.5
4-4.
結果
ティッピングレバー位置と負荷*の分布
＊負荷量は下肢・上肢・腰それぞれの負荷の平均としたSlide22
後輪軸からの水平位置（
cm
）
力の感覚
床面からの高さ
(cm)
（
A
）水平位置と足への負荷の関係の
シミュレーション
床面からの高さ（
cm
）
力の感覚
（
B
）床面からの高さと足への負荷の関係の
シミュレーション
6.
負荷のモデルによる理論値
水平距離（
cm
）Slide23
Distance from wheel axisHeight from floor
Physical load on hand
Physical load on foot
Physical load on waist