ClosedForm Equations and Experimental Verification for Soft Robot Arm Based on Cosserat Theory * Compared with conventional robots, soft structures such as living octopus arms and various softrobot arms have more degrees of freedom (DOFs) and greater flexibility. Soft robot arms have a considerable range of applications. However, it is arduous to establish a mechanical model for them, because of the hyperredundant DOFs, and the hyperelasticity and nonlinearity of the soft material. In this study, to investigate the deformation of soft octopus robot arms, the simplified closedform analytical equations for the curvature and torsion were derived according to the Cosserat theory. A closedform model for axial constriction was developed. The analytical equations were experimentally validated, and a dynamical simulation of the multiflexible bodies was performed for a cabledriven softrobot arm inspired by the octopus. The results show satisfactory accuracy.

Modeling, Simulation and Experimental Validation of a Tendondriven Softarm Robot Configuration  A Continuum Mechanics Method This paper presents the mathematical derivation and experimental validation of a computational model, which accurately predicts static, largestrain deformations of tendon driven nonslender softarm manipulators subjected to gravity. The large strain behaviors are captured by employing the GreenLagrange strain and by deriving analytical expressions for the variation of the equivalent Young modulus of the structure due to the large strains. No simplifying assumptions are made regarding the curvature of the structure, the stretching or the compression. Furthermore the paper proposes an iterative method for numerically solving the resultant nonlinear system of coupled differential equations and demonstrates a number of application scenarios. The model is experimentally validated using a setup comprising one segment of tendon driven softarm, which integrates stretchable and compressible hyperelastic (rubbertype) materials into its nonhomogeneous back bone structure.