2023 Author: Bryan Walter | [email protected]. Last modified: 2023-05-21 22:24
American and Japanese engineers have created an artificial analogue of the finger, relatively accurately repeating its structure, including the annular ligaments and flexor tendons. The peculiarity of this development is that it was printed in one operation using a 3D printer that works with different materials. The article was presented at the UR 2020 conference.
Robots with a human body-like design are used both on their own and as arm or leg prostheses. In robotic arms, the brushes often outwardly and functionally repeat the work of real brushes, but from the inside they are arranged differently: they often have electric motors between each pair of phalanges. In humans, the fingers bend in a different way. In them, on the phalanges or between them, there are circular ligaments through which the flexor tendons pass. Above, in the forearm, these tendons pass into the muscles - the deep and superficial flexors of the fingers. There are robotic arms in which this mechanism is repeated with the help of cables passing through the fingers, but in design they are still not completely analogous to a real hand.
A team of engineers led by Shinichi Hirai of Ritsumeikan University has created a more anatomically correct artificial finger using a 3D printer. It consists of three phalanges, three tendons, and several connecting elements that mimic cartilage and other tissues. The authors created models of these elements based on data on the structure of real fingers.
One of the features of the finger is that, although it consists of different functional elements with different mechanical properties, in fact it is a single monolithic part. This was achieved thanks to a 3D printer capable of printing with two materials at once. The engineers printed the phalanx bones with hard and hard plastic, the cartilage was made of a soft and elastic polymer, and the rest of the elements were printed with a mixture with a certain ratio of the two materials, which allows them to achieve properties as close to real tissues as possible.
Artificial finger components
As a result, they obtained a finger flexed by polymer analogs of the tendons passing through the analogs of the annular ligaments. They connected one actuator to the ends of the tendons, which can move up or down, changing the tension of the tendon. The engineers also performed a simulation and found that the behavior of a real finger is fairly accurately described by the model. They suggested that the method developed by them in the future will make it possible to create more affordable, but at the same time, artificial hands for prostheses or robots with more similar properties.
In addition to imitating the structure of the hands, the developers of prostheses are also trying to recreate the sense of touch, which is one of the main ways of studying the surfaces of objects during everyday interaction. For example, Swiss engineers have created a finger with piezoresistive sensors that read surface irregularities and send impulses to the median nerve of the hand.
