Page 28 - Mechatronics for Safety, Security and Dependability in a New Era

Ch03-I044963.fm Page 12 Tuesday, August 1, 2006 12:24 PM
Ch03-I044963.fm
12 12 Page 12 Tuesday, August 1,2006 12:24 PM

5 5
• κ=0.83
=0.83
Right wrist torque T R [N • m] -2.5 0 Rightwrist torque T R [N • m] 0 -dBBKS j=jTnmiiiHH • Κ=0.83
E
0.47
% 2.5 - 0.47 2.5 2.5 sssa
2.5
2.5
0.33
0.33
κ=0.83
-2.5
-2.5
0.47
0.33
0.33
-5 -5 V £ Q: -2.5 D 0.47
-5 -5
-50 -25 0 0 25 50 -50 -25 0 0 25 50
-25
-50
25
50
-25
50
25
-50
Steering angle θ S [deg] Steering angle θ S [deg]]
Steering angle θ S [deg]
Steering angle θ S[deg
(a) Conventional oval handle
(a) Conventional oval handle (b) Link type handle
(b) Link type handle
Figure 4: Relationship between steering angle and right wrist torque
DISCUSSION
Most electric carts have employed oval steering handle mechanism. On the conventional oval handle,
bending motion of wrist was forcused as a major problem. On the other hand, the amount of arm
motion was substantially reduced by using link type handle. Therefore, new type handle was efficient
not only to decrease the burden, but also to make operator's operation convent. Finally, it was
become clear that there was little bending of wrist and no movement of center of gravity of body by
the use of link type handle. Therefore, a seating position posture always would be held in the stable
state, and comfortable operation could be performed by improvement in operativity.
CONCLUSION
The link type handle mechanism, which was proposed in this report, has not required the rotation of
wrist which causes the large torque at the wrist. Since a seating position posture has been held in the
natural and stable state, it turns out that run stability could be improved.
ACKNOWLEDGEMENT
Some parts of this report have been helped by the research fund on "Living Assistance Technology for
Improvement of Quality of Life" supported by ORD1ST (Organization for Research and Development
of Innovative Science and Technology) in Kansai University.

REFERENCES

Mussa-Tvaldi FA, Hogan N, Bizzi E (1985). Neural, mechanical and geometric factors
subserving arm posture in humans. J Neurosci 1985:5, 2732-2743
Dolan JM, Friedman MB, Nagurka ML (1993) Dynamic and loaded impedance components in
the maintenance of human arm posture. IEEE Trans Sys Man Cybern 1993:23, 698-709
Tsuji T, Morasso PG, Goto K, Tto K (1995). Human hand impedance characteristics during
maintained posture. Biol Cybern 1995:72, 475-485
Flash T, Mussa-lvaldi F (1990) Human arm stiffness during the maintenance of posture.
Exp Brain Sci 1990:82, 315-326