Soft Robots with Densely Reinforced Chambers: A Design, Modelling and Evaluation Framework

Minimally invasive surgeries (MIS) rely on precise and adaptable tools to navigate the intricate confines of human anatomy. Soft manipulators, with their flexibility and bio-compatibility, are ideal for such tasks. However, their non-linear material properties and complex kinematics pose significant challenges to accurate modeling and control. This project focused on developing an analytical model for the kinematics of soft manipulators, incorporating non-linear material properties and formulating an optimization framework. The goal was to enhance their functionality while ensuring safety and efficiency in surgical applications.

Methodology

• The analytical modeling began with studying the mechanical behavior of non-linear materials used in soft manipulators, specifically their tensile, compression, and elastic properties. The following steps were undertaken: Kinematic Model Development: Based on continuum mechanics, we derived equations to capture manipulator behavior under external forces and boundary conditions.
• Optimization Framework: An optimization problem was formulated to minimize deviations between the predicted and actual behavior of the manipulator, ensuring robust performance across various surgical scenarios. Validation and Testing: Simulations were conducted to test the model’s accuracy, comparing it against experimental data for validation.

Results

• To evaluate materials, we incorporated flammability constraints and ranked them based on their non-linear properties and suitability for surgical environments. Key material indices considered included elasticity, toughness, fatigue resistance, and cost. Silicone Elastomers: These materials exhibited excellent flexibility but were prone to significant deformation under load, making them unsuitable for high-precision tasks.
• Polymer Composites: These provided better strength-to-weight ratios but introduced challenges in manufacturability and cost.
• Final Selection: After iterative optimization, we selected a composite blend of polymer and elastomeric materials, with a high toughness-to-weight ratio and bio-compatibility.
• The optimized design achieved a 25% reduction in manipulator mass while maintaining structural integrity under surgical loads. The optimized model minimized positional errors to within 1 mm, making it highly suitable for precision surgery.

The final analytical model and material selection provide a reliable framework for soft manipulator design in minimally invasive surgeries. The optimization-based approach ensures the model is both accurate and practical, paving the way for improved surgical tools that enhance patient outcomes.