Patent ID: 8726652

Claim:
A rotational actuator assembly comprising: a drive torque actuator having a first shape memory alloy (SMA) tube with a first trained twist direction and having a proximal end and a distal end; a return actuator having a second SMA tube with a trained twist direction opposite to the first trained twist direction and having a proximal end and a distal end, said return actuator collinear with the drive torque actuator with proximal ends; a central fitting joining the proximal ends and having a torque sensor; and, a control system employing a position sensor for the drive torque actuator and a torque sensor for the return actuator for combined antagonistic rotation of the central fitting, said control system including a first heater received in the SMA tube of the drive torque actuator and a second heater received in the SMA tube of the return actuator; and wherein the control system is responsive to an angular position command and provides a comparison to an output of the position sensor and an output incrementing or decrementing power to the first heater, said control system further providing an output incrementing or decrementing power to the second heater responsive to the torque sensor; and, wherein heating of the first SMA tube urges rotation of the central fitting in a first direction and heating of the second SMA tube urges rotation of the central fitting in a direction opposite the first direction.