19 - Compliant Finger Mechanism
Team Members:
Mark Helwig, Evan Kuo, Faith Lee, Matthew Na
Summary/Overview:
Robotic hand design has progressed rapidly, particularly in regard to prosthetics and assistive robotics where devices interact with a wide range of everyday objects. Despite these advancements, many current systems face a tradeoff between simplicity and dexterity. Basic grippers are mechanically simple and reliable but struggle to conform to objects with varying shapes. In contrast, highly articulated robotic hands achieve greater dexterity at the cost of increased complexity, control requirements, and actuator count.
This project focuses on bridging this gap by investigating a mechanically adaptive finger design that can achieve compliant grasping with limited actuation. The objective is to allow the finger mechanism to conform around different objects without requiring independent motors at each joint.
To address this challenge, the design uses an under-actuated finger mechanism that switches between two four-bar mechanisms using a torsional spring. This configuration allows the mechanism to change its motion behavior once contact with an object occurs, enabling sequential bending of the finger segments using a single actuator. Through this approach, the system aims to achieve more natural finger closure and improved grasping ability while maintaining a relatively simple mechanical structure.
The compliant finger mechanism prototype underwent several iterative updates to improve performance and robustness. Design refinements were guided by both CAD simulations and physical testing, allowing us to identify and address issues such as excessive distal bending in the first stage of motion. Link lengths and geometries were adjusted to achieve more natural, finger-like behavior, and the system was prepared for the torsional spring’s implementation. Kinematic analysis of positions, velocities, and accelerations supported these efforts by visualizing and quantifying motion profiles. This iterative process of simulation, fabrication, and testing ensured that design changes were validated in practice, leading to a more reliable and effective prototype.
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