Bioinspired Soft Actuators for Eyeball Motions in Humanoid Robots

Technological progress in advanced materials and artificial intelligence has given an impetus to the development of humanoid robots that can mimic human appearance and interact with people effectively. Eyeball motions play a key role in facial expression of humanoid robots, and can greatly improve the relationship between the robots and the users. In this paper, we develop soft actuators which can achieve horizontal, vertical, and circular motions, for the application of robotic eyeballs. Inspired by nature, this soft actuator combines three linear dielectric elastomer actuators (DEAs). By controlling voltages applied to the three DEAs, this soft actuator is capable of realizing the horizontal, vertical, and circular motions. Each DEA is developed with optimal designs to achieve large voltage-induced deformation. The calculations on the optimal prestretches of the DEA are qualitatively consistent with the experiments. By combining two DEAs together, the soft actuator can mimic the horizontal motion of human eyeballs. By combing three DEAs together, the soft actuator can track desired motion trajectories effectively. This project can contribute to the development of humanoid robots with bioinspired design, lightweight, and low cost. The humanoid robot based on soft actuators can also improve the interaction with the users, due to its natural appearance, excellent safety and adaptability, and quiet operation.