Evolving Robotic Soft Skin

Recently, a new type of intelligent, stretchable and highly sensitive soft sensor has been developed, which is expected to become the new skin of robots . Its arrival has brought new changes to the application of robot appearance and machine prostheses. This is a new product jointly developed by Honda, one of the earliest humanoid robot developers, and the University of British Columbia.

When this sensor skin is applied to the surface of a prosthetic or robotic limb, it can provide the robot with touch sensitivity and flexibility, allowing the machine to perform previously difficult tasks, such as picking up soft fruits with ease. At the same time, because the tactile properties of the soft sensor are similar to those of human skin, it helps make the interaction between robots and humans safer and more realistic.

The UBC team, one of the leading institutions in robotics research in Europe, developed the technology in collaboration with Frontier Robotics at Honda Research Institute, which has been innovating in humanoid robotics since the 1980s, developing the famous ASIMO robot, other assisted walking devices and the emerging Honda Avatar robot.

The sensor is made of silicone rubber, a material commonly used to create skin textures in movie special effects, and its unique design allows it to bend and wrinkle like human skin. The sensor uses weak electric fields to sense objects, even at a distance, just like a touchscreen. But unlike traditional touchscreens, this sensor is soft and can detect the force of objects entering and moving along its surface. This unique combination is necessary to realize robots that can interact with humans.

The sensor uses the sum and difference of signals from four deformable capacitors to distinguish between normal and shear forces applied simultaneously. The crosstalk between shear force and normal force is less than 2.5%, and the crosstalk between shear axes is less than 10%. The normal stress and shear stress sensitivities are 0.49 kPa and 0.31 kPa, respectively, and the minimum displacement resolution is 40 μm. In addition, the detection range of finger proximity can reach 15 mm.

"Dr. Madden's lab at UBC has extensive expertise in the field of flexible sensors, and we are excited to be working with them to develop this tactile sensor technology for robotics," said Ryusuke Ishizaki, one of the lead authors of the study and a principal engineer at Frontier.

The researchers noted that the new sensor is relatively simple to manufacture, so it can be easily expanded to cover large areas and mass-produced. Dr. Madden stressed that the continuous development of sensors and intelligent technology has made robots more powerful and realistic, and people are able to collaborate and interact with them more.

However, soft sensors can do much more than that. Dr. Madden said: "Human skin has 100 times more sensory points than our current technology, which makes it easier for robots to perform more delicate tasks, such as lighting a match or sewing. As sensors get closer to the properties of human skin and can also detect temperature and damage, robots need to be smarter about understanding which sensors to focus on and how to respond. The development of sensors and artificial intelligence needs to advance in parallel."