Hyperelastic Modeling and Validation of Hybrid-Actuated Soft Robot with Pressure-Stiffening

Abstract

Soft robots have gained popularity, especially in intraluminal applications, because their soft bodies make them safer for surgical interventions than flexures with rigid backbones. This study investigates a pressure-regulating stiffness tendon-driven soft robot and provides a continuum mechanics model for it towards using that in adaptive stiffness applications. To this end, first, a central single-chamber pneumatic and tri-tendon-driven soft robot was designed and fabricated. Afterward, the classic Cosserat’s rod model was adopted and augmented with the hyperelastic material model. The model was then formulated as a boundary-value problem and was solved using the shooting method. To identify the pressure-stiffening effect, a parameter-identification problem was formulated to identify the relationship between the flexural rigidity of the soft robot and internal pressure. The flexural rigidity of the robot at various pressures was optimized to match theoretical deformation and experiments. The theoretical findings of arbitrary pressures were then compared with the experiment for validation. The internal chamber pressure was in the range of 0 to 40 kPa and the tendon tensions were in the range of 0 to 3 N. The theoretical and experimental findings were in fair agreement for tip displacement with a maximum error of 6.40% of the flexure’s length.

Quasi-Static Modeling Framework for Soft Bellow-Based Biomimetic Actuators

“…The calculated with respect to the corresponding circumferential stretch is further recorded for the analytical relationship between the input pressure and deformation of the bellow actuator. Reference [ 17 ] provides further details on the numerical approach used for solving this mathematical relationship.…”

“…Developing a motion prediction model for soft actuators is crucial to guide efficient design processes [ 15 ]. Earlier investigations focused on modeling the behavior of PneuNets and fiber-reinforced soft actuators under pressurization [ 16 , 17 ], specifically examining the correlation between angle–pressure and force–pressure relationships. However, the deformable nature of these systems presents a challenge as soft bodies can have infinite degrees of freedom (DOF), limiting the effectiveness of analytical methods.…”

Cosserat Rod-Based Dynamic Modeling of a Hybrid-Actuated Soft Robot for Robot-Assisted Cardiac Ablation

“…A key contribution of this study lies in the derivation of a set of dynamic partial differential equations (PDEs) for a soft robot that is actuated simultaneously by air pressure and tendons. The principal distinction from the prior research [13] lies in the incorporation of the time-dependent parameter within the Cosserat rod model. Furthermore, despite differences in the intended surgical application, the kinematic, material modeling, and governing equations of motion differ from the previous study.…”

“…Previous research has demonstrated that the efficacy of RFA is closely related to maintaining the catheter-tissue contact force within a range of 10 to 30 grf [12]. To address this challenge, recent studies have shown that soft robots can provide a range of stiffness options during an intervention, thereby ensuring the procedure's safety [13][14][15].…”

Design Optimization of a Hybrid-Driven Soft Surgical Robot with Biomimetic Constraints

“…Similarly, Shahid et al [ 38 ] developed a soft composite finger with an adjustable joint stiffness using a hybrid actuation approach combining cable tension and air pressure. Furthermore, Roshanfar et al [ 39 , 40 , 41 , 42 ] developed a continuum model of a tendon–air hybrid actuated soft robot based on the Cosserat rod model that was specifically designed for applications in the RAMIS.…”