  Continuum arms, such as trunk and tentacle robots, lie between the two
extremities of rigid and soft robots and promise to capture the best of both
worlds in terms of manipulability, dexterity, and compliance. This paper
proposes a new kinematic model for a novel constant-length continuum robot that
incorporates both soft and rigid elements. In contrast to traditional
pneumatically actuated, variable-length continuum arms, the proposed design
utilizes a hyper-redundant rigid chain to provide extra structural strength.
The proposed model introduces a reduced-order mapping to account for mechanical
constraints arising from the rigid-linked chain to derive a closed-form curve
parametric model. The model is numerically evaluated and the results show that
the derived model is reliable.
