Fully embedded actuators in elastomeric skin for use in humanoid robots

Humanoid robot head designs that have embedded actuators within the elastomeric skin solve most of the problems of hardware integration and space requirement of perepheral elements. Presently, most humanoid robotic heads use actuators such as servo motors and pneumatic actuators to achieve head movements and facial expressions. These actuators are expensive, bulky, heavy in weight, and take up a lot of space. The use of embedded actuators will closely mimic the natural human head that consists of numerious muscles and sensors. Here, we present soft actuators based on twisted and coiled polymer (TCP) muscles within elastomeric skin for the robot face design and development. The TCPs are made of silver-coated nylon 6,6 following the common fabrication process: twisting, coiling, annealing and training. The fabricated skin was mounted on a 3D printed humanoid head and facial expressions were tested. We showed several head movements and the six basic facial expressions. It is for the first time such significant improvement is shown in humanoid robots with facial expressions due the embedded actuators in the silicone skin.