Patent ID: 7188473

Claim:
A linear actuator comprising: a shape memory alloy actuator, said shape memory alloy actuator changing length upon application of a temperature change to said shape memory alloy actuator, a first end of said shape memory alloy actuator being fixed to a structure and a second end moving freely in response to length change of said shape memory alloy actuator, creating a controlled displacement at the second end; a plurarity of heating segments for changing temperature of said shape memory alloy actuator; a backing plate to maintain contact between said shape memory alloy actuator and said heating segments; said shape memory alloy actuator being slidably disposed between said heating segments and said backing plate while said shape memory alloy maintains contact with said heating segments; a control device for selectively changing the temperature of each of said heating segments to predetermined temperatures, wherein a first predetermined hot temperature reduces the length and a second predetermined cold temperature increases the length of said shape memory alloy actuator; wherein the displacement of said second end of said shape memory alloy actuator can be controlled by activating a selectable quantity of heating segments; wherein the shape memory alloy actuator comprises a material such that the material expands and contracts as the temperature changes.