Finite Element Modeling in the Design Process of 3D Printed Pneumatic Soft Actuators and Sensors

Abstract

<jats:p>The modeling of soft structures, actuators, and sensors is challenging, primarily due to the high nonlinearities involved in such soft robotic systems. Finite element modeling (FEM) is an effective technique to represent soft and deformable robotic systems containing geometric nonlinearities due to large mechanical deformations, material nonlinearities due to the inherent nonlinear behavior of the materials (i.e., stress-strain behavior) involved in such systems, and contact nonlinearities due to the surfaces that come into contact upon deformation. Prior to the fabrication of such soft robotic systems, FEM can be used to predict their behavior efficiently and accurately under various inputs and optimize their performance and topology to meet certain design and performance requirements. In this article, we present the implementation of FEM in the design process of directly three-dimensional (3D) printed pneumatic soft actuators and sensors to accurately predict their behavior and optimize their performance and topology. We present numerical and experimental results to show that this approach is very effective to rapidly and efficiently design the soft actuators and sensors to meet certain design requirements and to save time, modeling, design, and fabrication resources.</jats:p>

Finite Element Modeling of Soft Fluidic Actuators: Overview and Recent Developments

“…Once the design is complete and relevant geometries and material properties have been optimized, the final geometry can be fabricated for validation of the results. This can be achieved by directly 3D printing the geometry [51,131] or 3D printing molds for the desired shape. [9,82] Experimental characterization of SFAs can be performed using compressed air systems, [81,132,133] syringe pumps, [134][135][136] fluidic drive cylinders, [137,138] or simply by manually actuating a syringe.…”

“…Furthermore, the FEM is not limited to the slender structures required in the theory of Cosserat rods or the modeling of bending motion using the piecewise constant curvature assumption or Euler-Bernoulli beam theory. FEM has found many applications in soft robotics due to the following reasons: [51,[79][80][81] 1) FEM can cope with the large deformations and material nonlinearities during the pressurization of SFAs. 2) FEM can be used to predict performance and evaluate the capabilities and limitations of soft actuator designs under various inputs.…”

“…www.advancedsciencenews.com www.advintellsyst.com 6.2. Recommendations for Improved Convergence 1) According to Tawk and Alici, [51] as SFAs can undergo large deformations, a very fine mesh is not recommended, and a relatively coarse mesh instead is desired for convergence. However, a coarse mesh might result in lower deformations for the same pressure value.…”

“…Contact boundaries: frictional with symmetric option to minimize penetration, which results in more accurate results and realistic behavior. [51] Fiber reinforcement: under model, select the fiber and assign a beam model type. Under connections, assign a bonded contact region between the actuator and the fiber reinforcement.…”

Modeling of a Soft-Rigid Gripper Actuated by a Linear-Extension Soft Pneumatic Actuator

“…Therefore, sensors are necessary in controlling a soft gripper. At present, the types of sensors used on soft grippers include resistive sensors [ 28 , 31 , 32 , 33 ], capacitive sensors [ 34 , 35 ], flexible electronics [ 36 ], strain sensitive fabrics [ 37 ], magnetic sensors [ 38 , 39 ], and soft pneumatic sensors [ 40 , 41 ]. As previous studies described, most of the above sensors are directly attached to the surface of the finger or manufactured together.…”