Artificial muscles for jaw movements

Facial expressions in humanoid robots play an important role in improving the interactions between human beings and machines. Jaw movements are key components in facial expressions especially during talking and singing activities. In this paper we develop artificial muscles for jaw movements, using dielectric elastomer actuators with embedded plastic fibers. The soft actuator can avert electromechanical instability and achieve a linear strain of 48%. The actuators are installed in a robotic skull to drive jaw movements, at the positions similar to those of the masseters in a human jaw. The experiments show that these artificial muscles can achieve periodic jaw movements with displacements and velocities comparable to those achieved by natural muscles. The actuators can also achieve jaw movements with various amplitudes and frequencies, mimicking the human singing (or talking) activities. The present studies demonstrate that dielectric elastomer actuators are capable of achieving accurate and controllable deformations/movements, which is significant in the applications to soft and biomimetic robots.