Robotica

Proceedings of the 7th JFPS International Symposium on Fluid Power, TOYAMA 2008 September 15-18, 2008

P2-35

DEVELOPMENT OF PNEUMATIC WALKING SUPPORT SHOES USING POTENTIAL ENERGY OF HUMAN
Masahiro TAKAIWA* , Toshiro NORITSUGU* * The Graduate School of Natural Science and Technology, Okayama University 3-1-1 Tsushimanaka, Okayama, 700-8530, JAPAN E-mail: takaiwa@sys.okayama-u.ac.jptoshiro@sys.okayama-u.ac.jp
ABSTRACT Among the elderly person, most of their injuries are reported to be caused by falling down with stumbling. It is due to their shuffling walking style resulted from deterioration of their dorsiflexion muscle force along with aging. Walking plays an important role in their independent day life. In this study we aim at developing a wearable walking support equipment embeddedinto shoes for a purpose of fall prevention of elderly person. A commercial product of Ankle Foot Orthosis is introduced and newly developed wire type pneumatic actuator is equipped on to support dorsiflexion motion during swing period at walking motion actively. In generally, these kind of active supporting systems require power source. We propose a driving scheme with no use of electric power,but with only potential energy of the wearer. Required specifications for the equipment are derived and the validity of proposed walking support shoes is verified through some experiments. KEYWORDS Walking support, Pneumatic driving system, Energy autonomous

INTRODUCTION
Japan is about to face a super aging society where aged person will occupy 35 % in the total population in 2050[1]. In spitethat walking is indispensable for their independent day life, most of their injuries among aged person are reported to be caused by falling down with stumbling. It is supposed to be resulted from their shuffling walking style due to the deterioration of dorsiflexion muscle force along with aging. Once they fall down, they have higher possibility to break bones comparing to younger. Therefore it issignificant to develop a walking support equipment to keep their standard QOL. Some of these kind of equipment have been developed so far, such as, using ER actuator[2] as brake function by regulating viscosity for prevention

of drop of foot, using a pneumatic passive element to hold variable stiffness function to support walking[3], using a pneumatic cylinder to support knee joint moment[4][5],using an exoskeletal robot to support gait motion[6][7]. However these equipments generally require energy like an electric power, which may bring problems of cost, total weight and reliability, etc. Therefore we develop a walking support shoes holding a driving mechanism using no electric power at all but just human potential energy. In this paper, first of all, required specification for the equipmentis adjusted and the overview of the equipment is described. After mentioning a driving mechanism of a proposed walking support shoes, the validity of the equipment is verified through some experiments.

Copyright © 2008 by JFPS, ISBN 4-931070-07-X

Heal stance phase Foot Contact

Initial term of

Middle term of stance phase

Flat

Heal Off

Latter term of stance phase Toe OffSwing phase

Heal Contact

Force sensor

(a) Measurement situation
Foot moment [Nm]

(a) Walking aspect
20 35[deg] HO Foot angle [deg.] 10
20[deg]

2

foot moment 20 Foot angle [degree]

0

1.9[Nm] foot angle 0

−2

0 FF TO

HC
−4

FF

−20 16 20 time[s] 24

−10

(b) required moment
23 time [s] 24

−20

22

Figure 2: Measurement foot moment tally obtained. Asshown in Fig.2(a), an ankle joint is forced to move about 20 deg. repeatedly from the angle of TO in Fig.1 through a force sensor. Figure (b) shows the calculated moment around ankle joint and foot angle, which indicate about 2.0 Nm is required to obtain a dorsiflexion angle.

(b) Foot angle in the walking motion Figure 1: Foot angle trajectory

REQUIRED SPECIFICATION
Fig.1(a) shows the...