Electronic skin: “Body sensation” for robots

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In industry, robots are already working safely alongside humans without any protective fences. However, more “feeling” is desired for robots that work in homes or in health care. New honeycomb-shaped skin cells could be the answer in the future.

You don’t often encounter care robots such as Pepper from Softbank in aged care facilities. But where they are used in this field, they entertain the elderly with memory games. On the other hand, they are not yet permitted to carry out more active work, such as delivering meals or moving a resident to another bed. One of the reasons for this is that in the case of direct body contact the “human-machine interface” has to fulfill much higher safety standards than, for example, in an industrial environment.

The basic requirement is that robots “sense” their surroundings and the humans in real time. But this needs an enormous number of sensors that can very easily push the system’s calculating capacity to its limits.

To avoid this, researchers at the Technical University of Munich (TUM) in Germany are using biological models. Their artificial robot skin consists of individual hexagonal cells each the size of a two euro coin.

Each of these contains a microprocessor and a range of different sensors that measure touch, acceleration, approach, and temperature. This enables robots to perceive their environment in much more detail and with more sensitivity. This supports their own sequence of movements and also ensures “sensitive” interaction with humans.

Electronic skin imitates our nervous system

To reduce the computational effort by up to 90 percent, the cells are not monitored continuously but only in an event-based manner. The individual cells pass on the sensor information only when there are changes in the measured values. Our nervous system works similarly. For instance, we feel a hat as soon as we put it on. Then we forget about it and remember it only if it falls off. This always leaves us enough capacity to respond to new impressions.

For the human-sized autonomous robot H-1 from the Technical University of Munich with its 1,260 cells and more than 13,000 sensors on its upper body, arms, legs and soles of its feet, this concept creates a completely new “body sensation.” The robot is now able to react to unevenness on the floor and even balance on one foot, but can also hug a person safely. When it does this, the robot has contact to the person at many different points and from this complex information must calculate its correct movements and the appropriate amount of force very quickly. While this may not be so important in industry, in areas such as health care, service robots must be designed in such a way that they can have very close contact to humans.

The e-skin system from the TUM is also very robust and variable. Since the skin is not in one piece but consists of cells, it can still function if individual cells stop working. The system is designed to work with all types of robots quickly and without problems.

The National University of Singapore recently presented “Asynchronous Coded Electronic Skin” (ACES), a sensor system that responds a thousand times faster than the human sense of touch.

 

 

 

Electronic Skin (Image: TUM).

The first skin consisting of individual cells for a human-sized autonomous robot. (Image: TUM).