WILMER Appealing Voluntary Closing Prehensor

The voluntary opening prostheses have a limited pinch force, limiting the performance of the users in their daily activities. The proprioceptive feedback provided by these prostheses is inverse and very counterintuitive. This is caused by the voluntary opening operating principle of these prostheses. In order to improve the functional performance of the WILMER appealing prehensor for toddlers, the Delft Institute of Prosthetics and Orthotics suggested to transform the operating principle of this split-hook from voluntary opening to voluntary closing. Conform this suggestion a new mechanism is designed and prototyped. Three concepts are proposed and the best among them is further elaborated into a prototype. This prototype is tested using an existing test bench. The energy dissipation is lowered with a factor of 2.5 in comparison with the best performing commercially available voluntary closing prosthesis, which shows the higher efficiency of the proposed design as compared to the currently available prostheses. The force transmission ratio of the prototype is 0.5, representing the ratio between activation force and pinch force. This is comparable with the best available voluntary closing prosthesis. Whereas the new design has no protruding mechanical parts out of the frame compared to the other voluntary closing prostheses, reducing damage to the clothing considerably. Conform the benefits of this new prosthetic device, it is a better performing voluntary closing prosthesis than the commercially available ones. Its performance together with its appearance makes it a promising alternative for the commercially available VC prostheses for the unilateral below-elbow amputees.BMEBioMechanical EngineeringMechanical, Maritime and Materials Engineerin