Model-based design of a pneumatic actuator for a dynamically reconfigurable socket for transtibial amputees

Area of Science:

• Robotics
• Biomaterials Engineering
• Biomechanics

Background:

• Prosthetic sockets often cause localized pressure and discomfort for users.
• Developing adaptable interfaces for prosthetics requires accurate modeling of soft actuator behavior.

Purpose of the Study:

• To introduce a cost-effective, scalable pneumatic silicone actuator array for dynamic skin conformance.
• To systematically identify, parameterize, and validate constitutive models for finite element analysis of these actuators.
• To investigate the relationship between actuator design, material properties, and surface deformation for pressure relief.

Main Methods:

• Finite element analysis (FEA) was used to model actuator behavior under realistic loads.
• 270 design variations were simulated to examine surface deformation fields.
• A novel speckle imaging technique was employed for accurate non-linear deformation measurements.

Main Results:

• FEA achieved predictive accuracies within 70 µm for surface deformation.
• Speckle imaging provided displacement measurements with ~40 µm accuracy.
• The Ogden N3 model accurately predicted actuator deformation (16% accuracy).

Conclusions:

• Design factors significantly influence actuator surface deformation and pressure distribution.
• The validated modeling strategy and imaging technique are crucial for optimizing soft actuator arrays.
• Findings are transferable to various robotics applications requiring deformable, load-bearing interfaces.