Normally-Closed Flexy-Hand Terminal Device 1.0

youmagine

Developing a hand for a terminal device that is "Normally-Closed" or "Voluntary Opening" has proven to be a difficult challenge for the e-NABLE volunteers. The flexor tendons made of elastic material and extension tendons could be made of non-stretch materials, but there's too much friction and not enough mechanical advantage in the hands for this to work. The present design avoids this problem by having the extensor cable pull against an elastic cable rather than against the finger extension tendons directly. The e-NABLE volunteers are currently testing a Normally-Closed Flexy-Hand Terminal Device, which is an experimental design for a component of an upper limb prosthesis known as the Monette Trans-Radial System v1.0. However, this design is not yet ready for use by e-NABLE volunteers. It's a remix of https://www.youmagine.com/designs/flexy-hand-terminal-device and has the same assembly except for the pulley and elastic flexing cable. This hand provides an adaptive-grip hand with a 1/2 inch - 20 thread bolt to be attached to an arm prosthesis component such as the Monette Socket by Jeff Erenstone http://www.thingiverse.com/thing:724815. The Flexy-Hand TD is similar to other Voluntary Opening (VO) terminal devices like the Hosmer Hook http://hosmer.com/products/hooks/pdfs/PR108-Hooks_Brochure.pdf. This experimental device isn't ready for use by e-NABLE Volunteers because it hasn't been thoroughly tested and debugged. When it's ready, it will be published on http://enablingthefuture.org/upper-limb-prosthetics with full instructions for fabrication. The development of this technology involved a collaborative effort that included contributions from Jeff Erenstone, Jeremy Simon, Steve Wood, the RIT e-NABLE Lab, and many other volunteers. The STL files are scaled to match digits of the 90% scaling of the Flexy-Hand. However, these files are not scalable parametric designs, so scaling them in a slicer will cause the hex bolt to not fit properly. Parametric designs will be published after the design is mature. Jeremy Simon has done a nice video review of the Flexy-Hand TD reference, and you can also see the Socket by Jeff Erenstone at http://www.thingiverse.com/thing:724815/#files. We'll publish more information in coming days on the Arms Forum: http://forums.enablingthefuture.org/viewforum.php?f=8&sid=1bd15d72a6059580e3828f82213dba2e. The Normally-Closed Flexy-Hand TD is a remix of several designs, including: * The Flexy-Hand TD https://www.youmagine.com/designs/flexy-hand-terminal-device * Flexy-Hand by Gyrobot http://www.thingiverse.com/thing:242639 * Flexy-Hand 2 by Gyrobot http://www.thingiverse.com/thing:380665 * Balancer for Adaptive Grip Prosthetic by Gyrobot http://www.thingiverse.com/thing:392970 * Adaptive Grip Mechanism for Prosthetic Hand by SkipMeetze https://www.youmagine.com/designs/adaptive-grip-mechanism-for-prosthetic-hand * Wilhe's Raptor Adaptor (Terminal Device for Existing Prosthesis) by SkipMeetze https://www.youmagine.com/designs/wilhe-s-raptor-adaptor-terminal-device-for-existing-prosthesis * Raptor Reloaded Adaptor v1.0 left 100% by SkipMeetze https://www.youmagine.com/designs/raptor-reloaded-adaptor-v1-0-left-100