If a robot is going to interact in close contact with human beings, it will be beneficial to have soft, pliant skin that is sensitive to pressure, temperature, and touch. Soft skin and the ability to detect the firmness of a grip will help prevent accidental injury to humans. JSK (Jouhou System Kougaku Lab, a department of Tokyo University) is making progress in this field with their robot named Macra.
The main problem is that individual sensors aren’t very accurate and cover a limited area. One solution is to cover the robot in hundreds of sensors in a grid-like mesh that wraps around the body. This technique is rather expensive due to the number of sensors required but provides the most accurate results. Macra uses fewer sensors distributed evenly throughout its body.
While these sensors provide important feedback during interactions with a human or its environment, equally important are the reactionary behaviors that must be programmed into the robot so that it can respond appropriately to external stimuli. This is a very difficult problem to solve in robots that have sensors covering their whole body.
For example, even standing still the robot is sensing the ground through its feet, as well as sensing its own body coming into contact with itself. When you add an extra stimuli, such as the robot picking up an object, the robot must know to hold on tightly enough not to drop the object but not so tight that it will crush it. Clearly, interpreting all of this data from the sensors and providing reactionary behavior is a monumental problem, and one that must be solved in the future for robots to truly interact with their environment.
Tokyo U. JSK Lab