| 摘要 |
A positioning device (19) or actuator assembly comprises an actuator (2) constructed from a shape-memory effect (SME) alloy which has a pre-set memorised shape such that, from another shape, the actuator (2) generates a first force when heated above a transition temperature, heat supply means (4, 12) connected to the actuator (2), urging means (24) arranged to exert a second force acting in a direction opposite to the first force, a positionable member (20) moveable between first and second positions under the influence of the first and second forces, and sensing means (53, 54) for detecting the position of the positionable member (20) relative to a reference point. Control means (44) are operably connected with the heat supply means (4, 12) and the sensing means (53, 54) for controlling of the temperature of the actuator (2). Above an elevated temperature above the transition temperature, the positionable member (20) is moved towards its first position against the action of the urging means (24), and below the elevated temperature, the positionable member (20) is moved towards its second position by the urging means (24). |
