A Novel Compliant Joint for Robotic Prosthetic Fingers

open_access
Open Access
Author:
Vreeland, Owen
Area of Honors:
Engineering Science
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
Xiaogang Hu, Thesis Supervisor
Patrick James Drew, Thesis Honors Advisor
Keywords:
compliant mechanism
robotics
prosthetic hand
DIP
PIP
Abstract:
The complexity of the human hand poses many engineering challenges in the design of a robotic counterpart. One such complexity lies in the proximal and distal interphalangeal joints. Said joints exhibit a moving center of rotation during flexion-extension; this provides the tendons with a variable moment arm. Current designs in literature do not prioritize kinematic accuracy, thereby losing this biomechanical property. In order to address said gap in the literature, this thesis presents a novel design for a compliant, robotic prosthetic finger joint. Central to the design is a pair of compliant mechanisms. A program was developed to predict the deformation behavior of the compliant members. The prediction is fit to an input curve representing the desired joint path. Three test curves, each with different center of rotation behavior, were used to generate six test joints. The kinematics of each joint were simulated using finite element methods. Accuracy with respect to the predicted joint path was quantified using the Fréchet distance. Of those tested, the best performing joints had neutral angles at the center of their range of motion and were generated from test curves with an increasing center of rotation. The performance of the overall design approach is discussed and possible manufacturing methods speculated. Multiple avenues for future work are also proposed. Overall, the presented design represents a crucial first step towards resolving the current gap in the literature.