SMA actuator assembly

A shape memory alloy (SMA) actuator assembly comprising:

• a support structure;
• a movable part;
• one or more SMA wires arranged, on contraction, to tilt the movable part relative to the support structure about two orthogonal axes that are perpendicular to a primary axis of the support structure;
• axial translation constrainers configured to limit axial translation of the movable part relative to the support structure along the primary axis of the support structure;
• wherein the axial translation constrainers comprise endstop surfaces of the support structure against which complementary endstop surfaces of the movable part can abut so as to limit movement of the movable part relative to the support structure;
• and
• wherein the endstop surfaces and/or the complementary endstop surfaces are curved such that the distance between the endstop surfaces of the support structure and the complementary endstop surfaces of the movable part remains substantially constant over the range of possible tilt of the movable part relative to the support structure.