Piezoelectric actuation and sensing for facial robotics

Electromagnetic actuators have been commonly deployed in robotics technology for obtaining expressions and other motion. However, the current technology is unable to meet the requirement of space limitation and at the same time provide high displacement and force (22-25 mm and force 2-7 N). The loss of space due to bulky motors prohibits the possibility of installing processing and control cards inside the skull of humanoid robot which is required to realize a smart expressive face. Our study shows the feasibility of utilizing piezoelectric ultrasonic motors and fiber matrix composites as an alternative to electromagnetics. The results are very promising and clearly demonstrate the promise of piezoelectric technology. A sample skin was developed from artificial room temperature vulcanized silicone material with piezoelectric unimorphs embedded inside it. For actuation, ultrasonic motors were implemented to drive anchor points of our humanoid robot-Albert to demonstrate facial expressions like opening and closing of eyes, smiling and squinting. Characterization of macro fiber composite for both sensing and actuation was also conducted and results are highly encouraging.