Since 2017, Will Cogley has been on a mission to lend a helping hand – quite literally. His groundbreaking work revolves around the development of a mechanical hand and forearm that replicate the intricate movements of the human hand. However, his goal wasn’t just to achieve perfection in movement; rather, he aimed to create a robust baseline design that could serve as a platform for further development.
Designing a hand is no small feat, considering the complexity involved. The human hand comprises 27 bones, 34 muscles, and over 100 ligaments. Cogley tackled this challenge by employing Fused Deposition Modeling (FDM) 3D printing for the “bones” and a wire-and-sheath design, akin to a bicycle brake cable, for the “muscles”. This approach ensured both strength and flexibility. Servo motors provided the motive force, albeit with modifications to the feedback mechanism. By bypassing the typical rotary potentiometer feedback and focusing on precise finger joint angles, Cogley optimized the hand’s performance. Additionally, installing the servos on the forearm, instead of the hand’s base, maximized available space for hardware.
Iterative refinement is crucial in the development of prehensile hand designs, and Cogley’s bio-mimetic hand was no exception. Supported through Patreon and affiliate marketing since 2017, Cogley has shared his development journey, incorporating improvements and design changes along the way. This collaborative approach has laid the groundwork for crowd-sourced engineering in artificial hand development.
A key metric for success in this endeavor is the Southampton Hand Assessment Procedure (SHAP), which outlines six standard grips that a prosthetic hand should achieve. These include the Tip Grip, Tripod Grip, Extension Grip, Lateral Grip, Power Grip, and Spherical Grip. Cogley demonstrates the effectiveness of his hand in achieving these grips in a comprehensive YouTube video.
Cogley’s commitment to collaboration and open-sourced projects is evident throughout his work. In his own words, “education should be accessible,” and he believes that as a community, greater achievements are possible. His vision entails producing “living designs” that anyone can access, download, modify, and experiment with.
In line with his philosophy, Cogley has released his design files and plans to provide a step-by-step assembly guide in a follow-up video. By transparently sharing his knowledge and experience, he challenges the wider community to learn and contribute, fostering continuous improvement in the design and functionality of the Cogley hand.
Website – Nilheim Mechatronics