Deformation Analysis of TPU Structures and Actuation Using SMA Coils for a Prosthetic Finger

This thesis focuses on experimental study on the use of coiled shape memory alloy (SMA) and Peltier plates for robotic finger actuation, their manufacturing and design, and the relationships between input magnitudes and output results such as finger joint angles. A fundamental flexible structure based on cantilever beam that is 3D-printed using thermoplastic polyurethane (TPU) is studied both experimentally and via simulations. The experiments for robotic finger actuation with the use of coiled shape memory alloys and Peltier plates were all based on prior studies. However, here extensive open loop characterization study has been conducted to understand the system. First, we will go into the data that was acquired through characterization experiments for some pre-made cantilever beams. This will help give us a better understanding on the movement and characteristics of the robotic finger that is discussed in this work. Specifically, the bending properties of a robotic finger that is actuated by coiled SMA and its characteristics in response to change in amplitude of current and heating time. Next, TPU cantilever beams were simulated using CAD analysis software package, such as SolidWorks, to determine deflection in response to tip load. Structural analysis and frequency analyses were performed. The simulation results were compared with experimental results and good agreement in terms of the trend of the angles as the loads were varied. Instead of a solid geometry, we used a serrated structure that resembles the 3D printed structure. This modification was made because the advanced 3D printed used for the fabricated structures resulted in irregular surface finish of the structure. Finally, discussion on results and future improvements will be explained.