ABML2011

O2-8

2011年11月3日-5日 東京（芝浦工業大学）

片流れ検知・軽減走行技術による簡易形電動車いすの操作負担変化の評価
Evaluation of Changes in Power Wheelchair Maneuvering Induced by a Detection and Prevention
System of Downhill Turning on Cross Slope Surfaces

Jun SUZURIKAWA, Takafumi KINOSHITA, Takenobu INOUE, Research Institute of National Rehabilitation Center for
Persons with Disabilities
Mitsuhiro KAMO, Norikazu IIDA, AISIN SEIKI Co., Ltd.
Kakuya IWATA, Osamu MATSUMOTO, National Institute of Advanced Industrial Science and Technology
Abstract: In order to improve safety of wheelchairs we have developed a detection and prevention system of downhill
turning on cross slope surfaces. The effect of the system on wheelchair maneuvering, however, has not been wellclarified. In this study we quantitatively characterized changes in maneuvering strategies induced by the downhill turning
prevention control (DTPC). Six subjects with physical disabilities that normally use a power wheelchair drove a test
wheelchair on an 8-degree cross slope with and without DTPC under measurement of joystick excursions. Among
several evaluation measures calculated from the joystick logs, the x-axis joystick displacement amount was found to besignificantly decreased by DTPC, while other measures remained unchanged with DTPC. This observation means thatthe subjects themselves compensated for the downhill turning tendency by their joystick inputs. This result strongly
suggests that DTPC can reduce the burden of maneuvering on cross slope surfaces.
Key Words: Smart wheelchair, Cross slope, Safety, Evaluation
1. はじめに((yaw rate))

0(1)

(2)
2-2 被験者
(2)

62
1

1

1

1
2-3 走行実験
1B

(3)

1589m

4m(2)

40 Hz
2. 方法

2-4 データ解析(22-100)(10-01)2-1 片流れ検知・軽減走行技術を搭載した電動車いす
1A(JIS T 9203:2010)●(joystick displacement amount, JDA)
(joystick displacement variation amount, JDVA)
O2-8-12(())Tgoal

JDAx = ∫TstartJS x (t ) dtdJS x (t ) dt
Tstart dt

JDVAx = ∫Tgoal

JSx(t)

── (1)(d(JSx)/dt = JSx’)── (2)
3()

Tstart15
Tgoal

2(3D(i))(p= 3.45 × 10-4; two sided t-test)
3
14m
( 3B)
0.05)

●
(yawangular displacement amount, YDA)
(yaw rate amount, YRA)

(3A)
(p <(1) (2)

i)
ii)
iii)

2

Matlab (Mathworks Inc.)(4)

3. 結果と考察
3-1 走行・操作指標の比較
2(JSx)

Fig. 2 Time courses of x-axis joystick angular displacements.
Angular displacements (black, left axis) and the displacement
variations (red, right axis) are shown for typical trials with (toppanel) and without (bottom) the downhill turning prevention
control by the same subject. Joystick inputs for the downward
direction of the cross slope (leftward to the travelling directionin Fig. 1B) are defined as positive.

Fig. 1 (A) Developed power wheelchair with the downhill
turning detection and prevention system. (B) Test cross slopewith the angle of 8°.
O2-8-2

Fig. 3 Comparison of evaluation measures obtained in trials with and without the downhill turning prevention control (DTPC).
(A) Absolute lateral displacement of the wheelchair. (B) Time to complete the 4-m test course. (C) Yaw angle displacement
amount (i) and yaw rate amount (ii). (D) X-axis joystick displacement amount (i) and variation amount (ii). (E) Y-axis joystickdisplacement amount (i) and variation amount (ii). Results of a two sided t-test are shown with p values or “n.s.” (no significance,
when p≥0.05). Each line indicates mean values for a subject. Colors of the dots and lines correspond with the subjects (n=6).
3-2 評価指標の線形判別
Sorrent(4)2XY

3-3 重回帰分析による負担軽減幅の予測

240.1164
3
1O2-8-3

p5%

Table 1 Multiple regression analysis of JDAx improvement
on measures without the DTPC (sorted with p-values).
Explanatory variables
R2
p*JDAx

0.843

0.0098JDAx, YRA, YDA
JDAx, YRA

0.99240.91590.01130.0244

JDAx, JDVAy, YRA
JDAx, JDVAy

0.98130.90240.028
0.0305JDAx, YDA
0.86550.0493: F-test.
JDA: Joystick displacement amount, YRA: Yaw rate amount,
YDA: Yaw-angular displacement amount, JDVA: Joystickdisplacement variation amount.
*Simpson(smart wheelchair)(5)

4. おわりにFig. 4 Linear discriminant analysis of the trials with andwithout the downhill turning prevention control. Two
dimensional plots of the evaluation measures were analyzed
with the x-axis of JDAx and the y-axis of JDVAy (A), YDA (B)and JDVAx (C). The classification results are shown as areacolors (red: w/ control, blues: w/o control). Misclassification
rates are shown on the top of the panels. Colors of the dots
correspond with the subjects (n=6). Open and closed dots
indicate the trials with and without the control, respectively.

(4)

参考文献
(1) Brubaker CE, McLaurin CA, McClay IS, Effects of sideslope on wheelchair performance, J. Rehabil. Res. Dev.,
vol. 23, pp. 55-57, 1986.
(2),,22, 2011.
(3),,,,,,,,25, pp. 229-230, 2010(4) Sorrento GU, Archambault PS, Routhier F, Dessureault D,Boissy P, Assessment of Joystick control during theperformance of powered wheelchair driving tasks, J.
NeuroEng. Rehabil., vol. 8, art. # 31, 2011.
(5) Simpson RC, Smart wheelchairs: A literature review, J.
Rehabil. Res. Dev., vol. 42, pp. 423-436, 2005.
O2-8-4