The Korea Institute of Machinery and Materials has achieved technological innovation by developing an ultra-light robotic prosthetic hand that can precisely grasp the fingertips and adaptively grasp objects according to their shape using a simple control method. In particular, it has achieved world-class user convenience and lightness by applying a groundbreaking mechanism that individually controls the two-degree-of-freedom movements of the thumb with a single actuator. This is expected to contribute to strengthening the competitiveness of domestic technology-based products in the electric prosthetic limb market, which is dependent on foreign products.

The research team led by Shin Min-ki, a senior researcher at the Medical Robotics Laboratory of the Daegu Convergence Technology Research Center of the Korea Institute of Machinery and Materials, under the National Research Council of Science and Technology, announced on the 29th that they have developed an ultra-light robotic prosthetic hand that allows amputees to stably grasp various objects with simple commands by applying a linkage-wire composite actuation method and a trivial actuation mechanism, and have completed a test evaluation targeting actual users.

The existing four-section linkage type robotic hand had difficulty stably grasping objects of various shapes due to the fixed grasping trajectory, and the wire method was effective in adapting to the shape of the object, but had limitations in implementing fingertip grasping movements or natural grasping.

In contrast, in this study, a linkage-wire composite actuation mechanism was developed that combines the advantages of both methods to realize a natural grasping motion capable of strong fingertip grasping and object shape adaptation.

In this study, we also developed a trivial actuation-based thumb mechanism that can individually control the internal/abducted and flexed/extended movements of the thumb with a single actuator by utilizing the intermittent actuation characteristics of the Geneva mechanism. While existing commercial products have limited usability or increased weight due to the use of passive joints or two actuators, this technology satisfies both lightness and usability by enabling independent two-degree-of-freedom control with a single actuator.

This technology helps amputees, who have difficulty controlling precise movements, to easily grasp various objects with simple manipulation. In addition, it is expected that the burden on the user will be greatly reduced by weight reduction through the lack of drive mechanism, and that it will contribute to extending the battery usage time by reducing energy consumption through the shape-adaptive grip function.

Currently, a patent application for the core mechanism of this technology has been completed, and the technology transfer and commercialization procedures are in progress.

Shin Min-ki, a senior researcher at the Korea Institute of Machinery and Materials, said, “The newly developed prosthetic hand is expected to operate in a similar way to the detailed hand movements that people perform unconsciously when grabbing objects, allowing users to use it more naturally as if it were their own body.”

He also said, “If applied to future humanoid robots, it is expected to show excellent performance in terms of efficiency, response speed, and versatility by reducing the amount of computation.”

This study was conducted with the support of the Basic Project of the Korea Institute of Machinery and Materials (Development of Human Enhancement Medical Technology for Restoring Upper and Lower Extremity Motor Function) and the Reserve Fund Project (Development of a Lightweight Multi-DOF Robotic Hand Capable of Tactile Information Feedback).