China develops humanoid robot with realistic expressions

In order to increase the emotional interaction between robots and users, experts seek to increase the number of motors and expressions on the robot's face.

Professor Liu Xiaofeng talks with a graduate student studying humanoid robots at Hehai University. Photo: Xinhua

Liu Xiaofeng, a professor at Hehai University in eastern China's Jiangsu Province, and his research team are developing a humanoid robot with a highly expressive face, Xinhua reported on August 2. The new research, published in the international journal IEEE Transactions on Robotics, aims to optimize the technology for emotional interaction between humans and robots.

Humanoid robots often struggle to convey complex and realistic facial expressions typical of humans. This can hinder their ability to interact with users, Liu said. "To address this challenge, we introduce a comprehensive two-stage approach to empower our autonomous and emotional robots to express rich, natural facial expressions," he said.

Liu explains that in the first phase, their method generates images of robot facial expressions as directed by Action Units (AUs). In the next phase, they realize an emotional robot with a wide range of freedom of facial movements, allowing the robot to express detailed expressions.

People may be more familiar with “digital humans” and “virtual editors” that can create a variety of real-time expressions, according to Ni Rongrong, a researcher at Changzhou University and co-author of the study. However, humanoid robots face certain limitations, such as size and number of motors, which make this more difficult. “For example, the humanoid robot we used before only had nine micromotors under its face, which is much less than the number of muscles in a human face,” Ni said.

Therefore, the team divided the nine motors on the humanoid robot's face into 17 AUs to enable richer expressions and smoother transitions through coordinated movements. They plan to continue increasing the number of AUs on the face and equip the robot with sophisticated automatic expression capabilities.

Liu believes that as the emotional interaction capabilities of humanoid robots continue to advance, robots with both high emotional quotients and intelligence will be widely used in nursing homes, kindergartens, special education schools and other facilities. "Humanoid robots will not only assist or replace humans in completing some tasks, but also bring more emotional value," he said.