Shape Control of Hose-Like Flexible Arm by Wire's Constrains

Abstract

When a positioning mechanism is used with human such as the case of human care machine, safety is the most important factor. To improve the safety, it is desirable that the mechanism has elasticity in itself. Authors have proposed a flexible positioning mechanism using wire constrains for such purpose. However, the mechanism does not realize multiple degrees of freedom motion. The paper thus proposes new positioning mechanism by multiple wires' constraints. The paper describes a motion analysis of the positioning mechanism which enables to form complex shapes of the mechanism. The mechanism consists of a flexible structure, support disks and multiple wires. As the flexible structure, a pneumatics hose is used. By changing the wire's length of the mechanism, the tip of the flexible mechanism can be positioned in three dimensional space. And also, intermediate points of the mechanism can be also controlled by manipulating wire's length. The relationship between wire's length and the position of flexible mechanism is complicated. In this paper, therefore, displacement of reference points of the mechanism is analyzed based on beam bending theory. Theoretical analysis is verified by an experimental flexible mechanism using pneumatic hose.