MRI compatibility, which often is a requirement for the new medical soft robot projects, greatly reduces available actuation methods and sensors. An example of such project is STIFF-FLOP, which aims to develop a soft silicone manipulator actuated by pressure. The current arm construction and method of actuation cause several undesirable effects, which pose problems for actuation and sensing. In this paper, the authors identify the source of those negative effects and propose improvements over the current construction to eliminate or limit their influence. The new construction concept is tested and compared with the current one. Possible ideas for further development are also proposed

Background: For some surgical interventions, like the Total Mesorectal Excision (TME),

Various methods based on hyperelastic assumptions have been developed to address the mathematical complexities of modelling motion and deformation of continuum manipulators. Here, we propose a quasi-static approach for 3D modelling and real-time simulation of a pneumatically actuated soft continuum robotic appendage to estimate the contact forces and the overall pose. Our model can incorporate external load at any arbitrary point on the body and deliver positional and force propagation information along the entire backbone. In line with the proposed model, the effectiveness of elasticity vs. hyperelasticity assumptions (Neo-Hookean and Gent) are investigated and compared. Experiments are carried out with and without external load, and simulations are validated across a range of Young's moduli. Results show best conformity with Hooke's model for limited strains with about 6% average normalized error of position; and a mean absolute error of less than 0.08N for force applied at the tip and on the body; demonstrating high accuracy in estimating the position and the contact forces.