While most current technological advances in robotics concern artificial intelligence, this time a team of Chinese researchers worked on a completely different area. Their research, recently published in
Proceedings of the National Academy of Sciences (PNAS), concerns the development of an ability to "feel" pain.
In other words, with this technology, robots could soon acquire a form of pain perception and the ability to develop autonomous reflexes, reacting to this pain with unprecedented speed. This evolution was made possible by a tactile interface inspired by the human nervous system.
Modular and neuromorphic electronic skin capable of actively perceiving pain and injury.
Credit: Xinge Yu, City University of Hong Kong A faster response than central processing
Current electronic skins generally function as networks of pressure sensors. They are capable of detecting contact, but the interpretation of its force (and thus the severity of the "injury") is processed in a central unit. This process, however fast, inevitably generates latency between contact detection and any subsequent action. This delay can have significant material consequences.
In humans, the reaction to a stimulation interpreted as harmful (a blow, extreme heat, injury) is much more direct. Indeed, the sensory neurons in the skin send an electrical signal to the spinal cord, which in turn orders the muscle contraction aimed at moving the affected body part away. This reflex is so fast that it occurs even before the brain perceives the pain. It thus constitutes a protection system optimized by millions of years of natural selection.
This is the system the scientists attempted to transpose. The neuromorphic skin they created generates distinct signals depending on the intensity of the pressure. If the measured intensity is below a certain threshold, the information is transmitted to the main processor for classic analysis. In the opposite case, a dedicated circuit triggers an immediate motor reaction.
An architecture inspired by living beings and modular
The structure of this artificial skin is organized in several layers. The outermost one imitates human epidermis, providing a protective envelope. Beneath this first layer, a matrix of sensors and microcircuits plays the same role as human nerve endings and transmission pathways. This layer is capable of generating electrical impulses, whose frequency and amplitude convey precise information.
The system also integrates a function of continuous self-monitoring: in the absence of contact, the skin emits weak impulses at regular intervals which are captured by the central controller, the latter thus interpreting that "all is well." This system allows for the detection of a malfunction or physical lesion: if the impulses cease in a specific spot, the robot can locate the damaged area and inform an operator, while adapting its behavior to compensate for this loss of sensitivity.
Finally, each section of the skin can be compared to a Lego piece, which can be detached and replaced individually in a few seconds. This system avoids the need for repairs or replacement of the entire tactile covering, thus improving long-term robustness and ease of use.
Article author: Cédric DEPOND