Inspired by human skin, a system was developed that combines artificial skin with control algorithms. The system was used to create the first autonomous humanoid robot with full-body artificial skin.
The artificial skin consists of hexagonal cells about one inch in diameter. Each is equipped with a microprocessor and sensors to detect contact, acceleration, proximity, and temperature. Such artificial skin enables robots to perceive their surroundings in much greater detail and with more sensitivity. This not only helps them to move safely but also makes them safer when operating near people, giving them the ability to anticipate and actively avoid accidents.
The biggest obstacle in developing robot skin has been computing capacity. Human skin has about 5 million receptors. Efforts to implement continuous processing of data from sensors in artificial skin soon ran up against limits. Previous systems were quickly overloaded with data from just a few hundred sensors.
To overcome this problem, researchers do not monitor the skin cells continuously but rather with an event-based system, reducing the processing effort by up to 90 percent. The individual cells transmit information from their sensors only when values are changed. This is similar to the way the human nervous system works. A human can, for example, feel a hat when it is first put on but quickly gets used to the sensation. There is no need to notice the hat again until it is taken off. This enables the human nervous system to concentrate on new impressions that require a physical response.
With the event-based approach, the researchers applied artificial skin to a human-size autonomous robot not dependent on any external computation. The H-1 robot is equipped with 1,260 cells (with more than 13,000 sensors) on its upper body, arms, legs, and even the soles of its feet. This gives it a new bodily sensation; for example, with its sensitive feet, H-1 is able to respond to uneven floor surfaces and even balance on one leg.
With its special skin, H-1 can safely give a person a hug. During a hug, two bodies are touching in many different places — the robot must use this complex information to calculate the right movements and exert the correct contact pressures. In potential appliations such as nursing care, robots must be designed for very close contact with people.
The robot skin system is also highly robust and versatile. Because the skin consists of cells and not a single piece of material, it remains functional even if some cells stop working.