Manufacturing of artificial muscle actuators

A method of manufacturing an artificial muscle actuator fiber, the method comprising:

• providing a tube having one or more continuous heating sections along a length of the tube;
• and
• in a continuous process,
• threading an untwisted fiber along the axis of the tube and inside the tube from a first end of the tube towards and passing an opposite second end of the tube;
• providing a tension on the untwisted fiber;
• twisting the untwisted fiber while the fiber is within the tube by applying a rotational force to the untwisted fiber such that the fiber is continuously twisted at a twisting point that is intermediate the first end of the tube and the opposite second end of the tube,
• advancing twists, formed by twisting the previously untwisted fiber, towards the opposite second end of the tube,
• wherein the tube is configured to prevent snarling during the twisting of the untwisted fiber,
• providing an inner diameter of the tube to be 10% to 20% larger than a diameter of the untwisted fiber, and
• wherein the tube is further provided as a heater to raise the localized temperature of a cross-section of the tube to a predetermined temperature.