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.
In this paper, we present a new design of head immobilization system for head and neck (H and N) cancer radiotherapy. The immobilization system consists of a radio-translucent 3D printed thermoplastic, helmet-like structure open partially in the front and custom-made fluidic actuators. The system can be actuated using compressed air to induce pitch and roll rotations. The mechatronic components of the system include two valves for each chamber, a microcontroller, airflow sensor, power supply, a compressed air source, and one pump to remove air. All of these are kept away from the patient's head so as not to interfere with the radiation beams, and radiation transparent tubing are connected with the chambers to the mechatronic components. The design provides comfort to patients due to curvature fit of patient head/neck and the use of soft actuators. The material used for custom-made actuators is silicone elastomer Eco-Flex 30. The main design variables are air chamber size, air pressure, volume flow rate, number of chambers, layers of sealing and shore hardness of the elastomer. Various arrangements of actuators and designs are investigated. The fabricated new actuators specifically designed for the positioning system were characterized using a humanoid robot head that mimics an actual patient’s head. We hope that the new device will give comfort to patients due to curvature fit of patients’ head/neck and the soft compliant actuators.
The potential applications of humanoid robots in social environments, motivates researchers to design, and control biomimetic humanoid robots. Generally, people are more interested to interact with robots that have similar attributes and movements to humans. The head is one of most important part of any social robot. Currently, most humanoid heads use electrical motors, pneumatic actuators, and shape memory alloy (SMA) actuators for actuation. Electrical and pneumatic actuators take most of the space and would cause unsmooth motions. SMAs are expensive to use in humanoids. Recently, in many robotic projects, Twisted and Coiled Polymer (TCP) artificial muscles are used as linear actuators which take up little space compared to the motors. In this paper, we will demonstrate the designing process and motion control of a robotic head with TCP muscles. Servo motors and artificial muscles are used for actuating the head motion, which have been controlled by a cost efficient ARM Cortex-M7 based development board. A complete comparison between the two actuators is presented.
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