Commercially available robotic hands are often expensive, customized for specific platforms, and difficult to modify. It is typically impractical to experiment with alternate end effector designs. This results in researchers needing to compensate in software for intrinsic and pervasive mechanical disadvantages, rather than allowing software and hardware research in manipulation to co-evolve.
The Yale OpenHand Project is a movement to advance the design and use of robotic hands designed and built through rapid-prototyping techniques in order to encourage more variation and innovation in mechanical hardware.
This project intends to establish a series of open-source hand designs, and through the contributions of the open-source user community, result in a large number of useful design modifications and variations available to researchers.
While advances in rapid-prototyping, shape deposition manufacturing (SDM), and dieless deposition manufacturing (DDM) have made it increasingly tractable to make custom parts expediently and on-demand, design choices must be made to make robotic hands suitable for repeated functional use, not just design prototyping. Hands developed through this project are designed to be minimalistic and rugged, especially appropriate for iterative design and operation in unstructured environments.
The released hand designs feature tendon-driven underactuated fingers. Underactuated hands have been shown to improve the generality of simple grippers by adaptively conforming to the surface of objects without the explicit need for sensors or complicated feedback systems. This design paradigm separates the actuation and finger elements, enabling a greater degree of customization.
The source CAD files allow for variable configurations, allowing users to quickly change functional parameters (ie. link lengths, transmission ratios) and manufacturing parameters (ie. shell thicknesses, hole dimensions) and have those changes propagate across all relevant parts.
Based on the original SDM Hand, the Model T is the OpenHand Project's first released hand design. the four underactuated fingers are differentially coupled through a floating pulley tree, allowing for equal force output on all finger contacts. All finger joints are flexure-based, made with Smooth-On polyurethane. An alternative design with pin-based base joints is also available.
Prof. Aaron M. Dollar
Assistant Professor of Mechanical Engineering
BS UMass Amherst, PhD Harvard University, Postdoc MIT
Dr. Lael U. Odhner
Associate Research Assistant
BS MIT, ScD MIT
Raymond R. Ma
BS Meche MIT, BS EECS MIT