Robot thumbs: better grip with the sixth
An additional, artificial thumb should be able to improve the gripping ability of the human hand. Researchers have tested this on test subjects.
The robotic thumb allows more gripping options.
(Image: Dani Clode Design & The Plasticity Lab)
A research team at the University of Cambridge has developed a robotic thumb that is designed to improve the gripping abilities of humans. The additional thumb makes it possible to pick up larger and more complex objects. In addition, tasks that previously required two hands can now be carried out with one hand.
The robotic thumb, which the researchers describe in their study "Evaluating initial usability of a hand augmentation device across a large and diverse sample", published in Science Robotics, is strapped to the human hand so that it is located next to the little finger. The researchers built the artificial thumb using parts from a 3D printer. It is moved by an electric motor via a cable and has three movable joints.
The control of the second thumb is somewhat tricky: it is controlled via the wearer's left and right toes. To do this, the scientists have attached a pressure sensor under each toe. If pressure is applied with the right big toe, the thumb is pulled across the entire hand. When pressure is applied with the left toe, the thumb is pulled upwards back towards the fingers. The movement can be controlled quite precisely, as the thumb moves in proportion to the amount of pressure exerted. When the pressure is released, the thumb returns to its starting position.
The scientists tested the robotic thumb over a period of five days on 596 test subjects aged between 3 and 96 years. Children used a smaller version adapted to their hands. Only four of the testers were unable to control the thumb at all, for example because it could not be securely strapped to the hand or because the pressure sensors did not react sufficiently with lightweight children and were therefore not suitable for them.
The test subjects had around one minute to familiarize themselves with the robotic thumb on their right hand, the scientists write. During this time, the researchers explained to them which tasks they had to perform with the artificial thumb.
Robot thumb in the test
The first task was to move as many pins as possible from a pegboard into a basket within 60 seconds. This was achieved by 333 of the 596 participants. In a second task, the test subjects were asked to use the robotic thumb together with their hand by manipulating variously shaped foam objects and placing as many as possible in a basket within 60 seconds. This was achieved by 246 participants.
The researchers recorded that although there were different skill levels among the participants, gender and whether someone was right-handed or left-handed had no influence on this. It also turned out that having a special talent for craftsmanship or playing a musical instrument had no significant influence on the operation.
However, older adults found it more difficult to use the artificial thumb with increasing age than younger adults due to the decline in sensorimotor and cognitive performance. Otherwise, performance was at a similar level. Younger children found it very difficult to use the robotic thumb. Six of the 13 participants who were unable to solve the task were under 10 years old. Overall, it was found that older children also had more problems with the application.
The scientists analyzed the results and came to the conclusion that various aspects need to be taken into account when using this technology. These include age, weight, lifestyle, physical impairments, cultural background and the user's openness to technology. However, a larger-scale study is still required in order to draw precise conclusions.
(olb)