Page 73 - Mechatronics for Safety Security and Dependability in a New Era

Ch12-I044963.fm Page 56 Tuesday, August 1, 2006 9:08 PM
Ch12-I044963.fm
56 56 Page 56 Tuesday, August 1, 2006 9:08 PM

Y

R W
ρ d
β
Assistance dog
Assistance dog
O d
Trajectory of wheelchair
Trajectory of wheelchair
X
(a) Explanatory diagram for evaluation function P
V d =2.5[km/h]
V d =2.5[km/h] K =0.277 [-] 7.5 8 V d =2.5 [km/h] K K =0.277
=0.277 [-]
[km/h]
V d =2.5
=0.277
l K l
l l
9
Evaluation function P [-] 8 4 1.75 2 2 —1 Evaluation function P [-] 7 , / 1.75 2 2 ....
ρ d =1.5[m]
5[m]
ρ d =1 .5[m]
ρ d =1.5[m]
f
7.5
.75
1
1.75
2
2.5 5
3
* 7 7 k —J- - 6.5 \ -A
6.5
2.5
3
§ 6 6 5 5 I 5.5 6 5 5
5.5
Left rota ion
Rightt rotation
5 Right rotation 5 Left rotation
0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1
0.4
0.8
0.8
0.6
0.2
0.4
0.2
0.6
gian
Rotational
Rotational gain
Rotational gain K φ [-] Rotational gian K φ [-]
(b) Right rotation (C) Lett rotation
Figure 4 Simulation results to fix the rotational gain K
fi
electric wheelchair would turn inside an assistance dog. Both trajectories of them were overlapped at
^=0.33 in left rotation and ^^=0.25 in right rotation. These condition on K^ results the fluctuation
of evaluation function shown in figure 4(b) and 4(c). The smaller evaluation function P implies the
better condition of rotational gain K . From the minimum points of these results, the rotational gain
f)
^=0.25 in right rotation and A^,=0.25~0.3 in left rotation might be determined. We evaluated
driving trajectories in practical route many times and determined the optimum rotational gain K^=0.3.
DISCUSSION AND CONCLUSIONS
We proposed the device and control system for an assistance dog guiding an electric wheelchair. And
we can expect the mitigation of assistance dog's corporal burden by using this device and system. In
addition, matching of Guidance unit and conventional driving system of electric wheelchair was
copleted with only a fundamental gain adjustment system. In present situation of the development of
electric wheelchair, major company develops all elements of electric wheelchair, body of wheelchair,
driving system, control system, and input device. Moreover, if input device is changed, they tend to
redesign most part of electric wheelchair. But, if consider about only input device and its compliance
for conventional driving system of electric wheelchair, we can reduce the cost of development.
Ultimate of this concept is standardization of connecting system between input device and driving
system of electric wheelchair. And we can develop suitable input device for each user.
References
Maeda M and so on (2002), Evaluation of Traveling performance and Optimal Adjustment of
an Electric wheelchair employing Bi-state Operation, Mechanical Engineering Congress Japan,
2002:7, 167-168
Maeda M and so on (2003), Performance estimation of the Electric Wheelchair on Guidance
control with Service dog, Mechanical Engineering Congress Japan, 2003: 5, 147-148
Uemoto T and so on (2003), Driving characteristics of Electric Wheelchair by the Binary
controller detecting motion of head, Mechanical Engineering Congress Japan, 2003:5, 149-150
Coppinger R(1995), Dog Studies Program and Lemelson, Center for Assistive Technology
Development, Hampshire College, 3-11