Patent ID: 8876046

Claim:
A rotational actuator assembly comprising: a first torsion actuator mounted to a control surface and having a shape memory alloy (SMA) tube with a first trained twist direction and having a first proximal end and a first distal end; a second torsion actuator mounted to the control surface and having a SMA tube with a second trained twist direction opposite to the first trained twist direction and having a second proximal end near the first proximal end and a distal end opposite the second proximal end, said second torsion actuator collinear with the first torsion actuator with the first and second proximal ends engaged to one another; a first heater received in a bore in the first torsion actuator and a second heater received in a bore in the second torsion actuator; a central fitting joining the first and second proximal ends; and a control system having a position control module responsive to an angular position command providing a low temperature command as an input to a temperature control loop adjusting temperatures of the first heater and second heater about an average control temperature, the control system operable to control a temperature of the first torsion actuator and the second torsion actuator about the average temperature, to cause torsion of the first torsion actuator and torsion of the second torsion actuator in an opposite direction.