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Masaki Tauchi PhD, Kazuya Kuro-oka , Takabun Nakamura PhD

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, Japan. INTRODUCTION.

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Masaki Tauchi PhD, Kazuya Kuro-oka , Takabun Nakamura PhD

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  1. 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, TakabunNakamura PhD Okayama Prefectural University, Japan

  2. 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.

  3. The shape and the position of typical tipping lever

  4. 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.

  5. 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 levers, the experimental tipping lever holders aligned to the perpendicular to the direction of travel were attached.

  6. THE SHAPE OF TIPPING LEVER HOLDER (Large) The tipping lever holders, Large, were made allow to search wider range in the lower posterior part of the wheelchair In total 17 positions were examined. Distance from wheel axis (cm) 23.0 19.0 15.0 Wheel axis 11.0 17.5 Height from floor (cm) 15.0 The tip of TPL position of control 12.5 10.0 7.5 floor

  7. 10㎝ 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. 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

  8. The spatial distribution of the average effort of upper and lower limbs and load on lumber area Result 1 Distance from wheel axis (cm) 15.0 11.0 19.0 23.0 Effort or load 17.5 Large 15.0 Height from floor (cm) 12.5 10.0 Small control 7.5

  9. 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) 27.5 22.5 20.0 17.5 Control position 2 Wheel axis 15.0 The tip of TPL, control position 1 Height from floor (cm) 17.5 13.75 15.0 12.5 The shape of TPL holder used in Experiment 1 floor

  10. 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 limbs

  11. Result 2 Effect of distance from wheel axis to physical effort on lower limb ** 5 Position 1 ** ** ** p<0.001 Large 3 Physical effort Small 1 15.0 17.5 20.0 22.5 (cm) Distance from wheel axis

  12. Result 3 Effect of height from floor to physical effort on lower limb Distance from wheel axis Distance from wheel axis Distance from wheel axis 17.5 cm 20.0 cm 22.5 cm Large 5 3 Physical effort/load 1 Small 13.0 15.0 17.0 13.0 15.0 17.0 13.0 15.0 17.0 Height from floor (cm)

  13. Result 4 Lower limb Large 5 Comparison of physical effort on upper and lower limb and load on lumbar area to the distance from wheel axis 3 Physical effort Small 1 15.0 17.5 20.0 22.5 (cm) Upper limb Lumber 5 5 Large Large 3 3 Physical load Physical effort Small 1 1 1 Small 15.0 17.5 20.0 22.5 15.0 17.5 20.0 22.5 (cm) Distance from wheel axis Distance from wheel axis

  14. Result 5 Mapping of total average physical effort and load of tipping lever Distance from wheel axis (cm) 15.0 17.5 20.0 22.5 Large 17.5 Height from floor (cm) 15.0 Position 1 13.8 12.5 Small Total average physical effort and load: mean value of physical effort on upper and lower limbs and load on lumber

  15. 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.

  16. 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.

  17. Thank you for your attention

  18. 8.　結　論 ・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。

  19. 5.力学モデル 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 +θ1）　 －(1) (1)式を展開し、Fについて整理する F = M /（L2・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1.5 J = k・（M/（L2・sinθ + L1・cosθ）P K=k・MP = 定数とし、L2をhで表し整理する 車軸 L・sin(θ+θ1) O θ θ1 L L2 θ F TL H A B L1 h 床面 J = K・（（H－h）・sinθ + L1・cosθ）－P = K・（（27.7－h）・sinθ + L1・cosθ）－1.5

  20. 4-4.結果　ティッピングレバー位置と負荷*の分布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 負荷量 後輪軸からの水平距離（㎝） 大 20.0 22.5 17.5 15.0 17.5 床面からの高さ（㎝） 15.0 13.8 12.5 小 コントロール 非表示部分

  21. 6.負荷のモデルによる理論値 （B）床面からの高さと足への負荷の関係の （A）水平位置と足への負荷の関係の シミュレーション シミュレーション 床面からの高さ (cm) 水平距離（cm） 力の感覚 力の感覚 後輪軸からの水平位置（cm） 床面からの高さ（cm）

  22. Distance from wheel axis Height from floor Physical load on hand Physical load on foot Physical load on waist

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