Compliant four-bar linkage mechanism for a robotic finger
Inventors
Akhtar, Aadeel • Bretl, Timothy • Choi, Kyung Yun
Assignees
Publication Number
US-11974930-B2
Publication Date
2024-05-07
Expiration Date
2039-04-29
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Abstract
A system and method for a compliant four-bar linkage mechanism for a robotic finger that includes: a monolithic bone structure comprised of a compliant joint region and an input link segment and a coupler link segment, wherein the input link segment and the coupler link segment are connected through the compliant joint; an output link; a ground structure; wherein the monolithic bone structure, output link, and ground structure are connected through a set of joints in a configuration of a compliant four-bar linkage mechanism which comprises: the output link on a first end and the coupler link segment connected through an output joint, the output link on a second end connected to a ground joint on the ground structure, and the monolithic bone structure connected to an input joint connected to the ground structure; and an actuation input coupled to the input joint.
Core Innovation
The invention provides a compliant four-bar linkage mechanism for a robotic finger that includes a monolithic bone structure with a compliant joint region connecting an input link segment and a coupler link segment. This compliant joint region is made from a compliant material, such as thermoplastic polyurethane, and replaces the traditional rigid input and coupler links, as well as the typical pivot joint, found in conventional four-bar linkage mechanisms. The system further comprises an output link and a ground structure, with these components connected by a set of joints in a specific configuration to form the compliant four-bar linkage.
The problem addressed by this invention arises from the limitations of existing prosthetic fingers, which rely on small, rigid components prone to breakage during normal use, particularly due to lateral impacts. Traditional designs make repairs laborious and expensive, and the pin joints commonly used are frequent sites of mechanical failure. There is a need for a new system and method that enhances durability, impact resistance, and overall usability in actuated prostheses, especially in the context of prosthetic fingers.
By integrating compliance into key components, the mechanism absorbs lateral forces, reducing the likelihood of breakage and extending the prosthesis's usability. This design also enables easier fabrication and assembly, by allowing construction through methods such as 3D printing and reducing the number of required parts. In addition, the compliant four-bar linkage mechanism maintains a range of motion comparable to rigid mechanisms, ensuring functional finger-like actuation for prosthetic hands and potentially other robotic or actuating devices.
Claims Coverage
The patent contains three independent claims, each outlining inventive features for a compliant four-bar linkage mechanism in prosthetic fingers or hands.
Compliant four-bar linkage mechanism with a monolithic bone structure for a prosthetic finger
A system comprising: - A monolithic bone structure with a compliant joint region, an input link segment, and a coupler link segment, where the input and coupler segments are connected through the compliant joint made of compliant material. - An output link and a ground structure. - Connection of the monolithic bone structure, output link, and ground structure through joints forming a compliant four-bar linkage: - The output link and coupler link segment connect through an output joint. - The output link connects to a ground joint on the ground structure at its second end. - The monolithic bone structure connects to an input joint on the ground structure. - An actuation input coupled to the input joint.
Compliant four-bar linkage mechanism for a prosthetic finger with a compliant proximal interphalangeal joint
A system comprising: - A monolithic bone structure with a compliant proximal interphalangeal joint, an input link segment, and a coupler link segment, where the input and coupler link segments are connected via the compliant proximal interphalangeal joint made of compliant material. - An output link and a prosthetic hand structure. - Connection in a compliant four-bar linkage configuration: - Output link and coupler link segment connected through an output joint. - Output link connected to a ground joint on the prosthetic hand structure. - Monolithic bone structure connected to a metacarpophalangeal input joint on the prosthetic hand structure. - An actuation input coupled to the compliant metacarpophalangeal input joint.
Compliant four-bar linkage mechanism for a prosthetic hand with multiple prosthetic fingers
A system comprising: - A base palm body integrated with a set of worm gear actuation systems. - Multiple compliant four-bar linkage mechanisms configured as prosthetic fingers, each including: - A monolithic bone structure with a compliant joint region, input link segment, and coupler link segment, with the input and coupler connected through the compliant joint region made of compliant material. - An output link. - The output link and coupler link segment connected through an output joint. - The output link connected to a ground joint on the base palm body at its second end. - The monolithic bone structure connected to an input joint on the base palm body. - Each worm gear actuation system is mechanically coupled to the input joint of each four-bar linkage mechanism.
The inventive features focus on a prosthetic finger or hand utilizing a compliant four-bar linkage with a monolithic bone structure, compliant joint regions, and specific mechanical linkages, providing the benefits of compliance and simplified integration with actuation systems.
Stated Advantages
Enhanced impact resistance and durability of prosthetic fingers by replacing rigid joints with compliant joints.
Reduction in energy loss due to friction from link rotation, and elimination of parts requiring lubrication and maintenance.
Simplified fabrication, assembly, and maintenance enabled by reduced part count and suitability for molding or 3D printing.
Reduction in weight and increased compactness of the prosthetic mechanism compared to traditional rigid linkages.
Ability for the prosthetic hand to withstand and recover from loads beyond maximum capacity due to elastic deformation.
Prosthetic fingers can more effectively conform to different object shapes, improving grasp versatility.
Reduction in hysteresis, resulting in a more responsive prosthetic finger.
Documented Applications
Use in fabrication and operation of prosthetic fingers for prosthetic hands, providing impact resistance and finger-like motion.
Integration into prosthetic hands comprising multiple prosthetic fingers using the compliant four-bar linkage mechanism.
Application in other fields such as robotics or automated mechanisms needing actuating limbs, levers, or mechanisms.
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