Actuator assembly

An actuator assembly comprising:

• first and second parts, wherein a primary axis is defined with reference to the second part;
• a plurality of lengths of shape-memory alloy wire connected between the first and second parts, wherein the lengths of wire are configured, when selectively powered, to cause three-dimensional movement of the first part relative to the second part, the three-dimensional movement including translational movement in three translational degrees of freedom;
• and
• a mechanism configured, when the lengths of wire are unpowered, to hold the first part in at least one position and/or orientation relative to the second part against the force of gravity for any orientation of the second part.