Authors:
Pavel Venev
;
Dimitar Chakarov
and
Ivanka Veneva
Affiliation:
Institute of Mechanics, Bulgarian Academy of Sciences, “Acad. G. Bonchev” str., Block 4, Sofia 1113, Bulgaria
Keyword(s):
Exoskeleton, Upper Limb, Transparency, Pneumatic, Cylinders, Stiffness, Torque, Air Pressure, Closed Chambers, Gravity Compensation.
Abstract:
The work studies an exoskeleton on the upper limb intended for rehabilitation and training. To meet the requirements of rehabilitation exoskeletons for transparency on the one hand and efficiency on the other, a pneumatic actuation with a wide range of control pressure is offered. The subject of the work is the development of a pneumatic drive that allows simultaneous adjustment of stiffness and torque in the joints of the exoskeleton. For this purpose, pressure in the cylinder chambers both higher and lower than atmospheric is used. The work presents the structure of the exoskeleton and a model of pneumatic actuation in the joints of the exoskeleton. Equations are derived for the torque and joint stiffness resulting from the elasticity of the air in the closed chambers of the pneumatic cylinders. The work proposes one approach to adjust the stiffness at certain joint position. In this position, the joint torque is varied by creating pressure profiles in the two chambers, so the join
t stiffness is adjusted in addition to the joint torque. The change in joint torque due to elastic deviations from the set position is also evaluated. An example of compensating gravity loads and providing transparency through pneumatic actuation is shown.
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