In an article published in the journal Science Robotics, engineer Renan Bao (Zhenan Bao) and her team claim that technology has brought the day closer when robots will be equipped with the same tactile abilities that human skin gives. Sensors at the ends of the gloves measure pressure intensity and direction simultaneously. Researchers recognize that the technology of automatic control of these sensors still needs to be improved, but even now the robot in such a glove is dexterous enough to hold the egg between the thumb and forefinger, without breaking it or allowing it to slip out.
The outer layer of human skin also has sensors for determining pressure, heat and other parameters, and especially in this regard, our fingers and palms stand out. These sensors work in conjunction with the component of the epidermis (Stratum spinosum). When our finger touches the subject, the outer layer of the skin touches the stratum spinosum, whose sensors are incredibly sensitive. The more intense the pressure, the stronger our sensations.
However, the pressure force is not everything. This sublevel also helps to reveal the pressure vector and shear force. For example, a finger, squeezing the upper part of a chicken egg, creates stronger signals in the sensors located below, which allows us to gently but firmly hold the egg between the thumb and forefinger.
© Stanford University School of Engineering
Clementine Boutry and Marc Negre, Stanford employees, have been developing electronic sensors that mimic this human mechanism. Each sensor at the fingertip of the robotic glove is made of three flexible layers that work together. The upper and lower layers are electrified. The researchers laid a grid of electrical lines on each of the two facing each other surfaces and turned these rows perpendicular to each other to create a dense array of small sensitive pixels, repeating the structure of the stratum spinosum.
A rubber insulator separated the top and bottom layers of the electrodes from each other. When the robotic finger pressed on the object, pressing the upper electrodes closer to the base, the stored energy increased, and the structure of the lower layer made it possible to compare the intensity and direction of pressure with specific points on perpendicular grids, like human skin.
The researchers placed their three-layer sensors on the fingers of a rubber glove and put them on a robotic arm. In one experiment, they programmed the robot to gently touch the berry without damaging it. In another case, a gloved hand gently lifted and moved the ping-pong ball, using a sensor to determine the appropriate shear force to grab the ball and not lower it.
According to scientists, with proper programming, a robotic hand in a modern touch glove can perform various routine tasks: for example, remove eggs from a conveyor belt and put them in cardboard boxes. In addition, the technology can be used in robotic surgery. However, their main goal, scientists see the development of an improved version of the glove, which independently calculates the required amount of force for safe contact with the object without prior programming.