Crossed four-bar mechanism for improved prosthetic grasp

Area of Science:

• Biomedical Engineering
• Rehabilitation Engineering
• Prosthetics

Background:

• Prosthetic terminal devices often lack the dexterity and intuitive control of human hands.
• Improving grasp functionality and reducing user input are key challenges in prosthetic design.

Purpose of the Study:

• To develop and evaluate passive linkages for prosthetic terminal devices.
• To enhance grasp stability and minimize user-controlled inputs.
• To compare the performance of the new mechanism against a normal hand and a commercial hook.

Main Methods:

• Development of passive linkages to aid grasp.
• Utilizing the Southampton Hand Assessment Procedure for performance evaluation.
• Comparative analysis of a prototype device, a normal hand, and a commercial hook.

Main Results:

• The prototype demonstrated improved heavyweight power and spherical grasps compared to the commercial hook.
• Prosthetic devices, including the prototype, were three times slower than the normal hand in task completion.
• Precision grasps were negatively impacted by the prototype's smooth distal surface.

Conclusions:

• Passive linkages can enhance specific grasp types in prosthetic terminal devices.
• Further development is needed to address limitations in precision grasps and overall task speed.
• The findings offer insights into optimizing prosthetic hand design for improved functionality.