Shape memory alloy (sma) actuators and devices including bio-inspired shape memory alloy composite (bismac) actuators

Abstract

An actuator comprising a flexible spring affixed at a separation distance from a shape memory alloy or artificial muscle element amplifies strain developed by the shape memory alloy or artificial muscle element while maintaining a substantial fraction of the force developed during activation of the shape memory alloy or artificial memory element. A plurality of such actuators positioned relative to each other by encapsulation or attachment to a body of material such as a terminal hub can emulate a wide variety of biological movements such as for providing gripping in the manner of an opposed human thumb or propulsion in the manner of a jellyfish.

1 . An actuator comprising, in combination,
 a flexible spring beam,   a shape memory alloy or artificial muscle element, and   a connection between said flexible spring beam and said shape memory alloy or artificial muscle element maintaining a separation distance therebetween over a length of said actuator.   
     
     
         2 . The actuator as recited in  claim 1 , further including stand-off structures for establishing said separation distance. 
     
     
         3 . The actuator as recited in  claim 1 , wherein stiffness of said beam is locally modified to control shape of said actuator when said shape memory alloy or artificial muscle element is activated. 
     
     
         4 . The actuator as recited in  claim 3 , wherein said beam is modified in thickness or width to control stiffness. 
     
     
         5 . The actuator as recited in  claim 4 , wherein said beam is shaped to control shape of said actuator when said shape memory alloy or artificial muscle element is not activated. 
     
     
         6 . The actuator as recited in  claim 5 , wherein said shape memory alloy or artificial muscle element has a parent shape, when activated, such that activation from an unactivated state emulates a biological motion. 
     
     
         7 . The actuator as recited in  claim 5 , wherein a combination of said bean and said shape memory alloy or artificial muscle element has a parent shape, when activated, such that de-activation from an activated state emulates a biological motion. 
     
     
         8 . The actuator as recited in  claim 1 , wherein said beam is modified in thickness or width to control stiffness. 
     
     
         9 . The actuator as recited in  claim 8 , wherein said beam is shaped to control shape of said actuator when said shape memory alloy or artificial muscle element is not activated. 
     
     
         10 . The actuator as recited in  claim 9 , wherein said shape memory alloy or artificial muscle element has a parent shape, when activated, such that activation from an unactivated state emulates a biological motion. 
     
     
         11 . The actuator as recited in  claim 9 , wherein a combination of said bean and said shape memory alloy or artificial muscle element has a parent shape, when activated, such that de-activation from an activated state emulates a biological motion. 
     
     
         12 . An apparatus comprising
 a plurality of actuators, wherein an actuator of said plurality of actuators comprises
 a flexible spring beam, 
 a shape memory alloy or artificial muscle element, and 
 a connection between said flexible spring beam and said shape memory alloy or artificial muscle element maintaining a separation distance therebetween over a length of said actuator, and 
   a body for locating said plurality of actuators in a desired relationship to each other.   
     
     
         13 . The apparatus as recited in  claim 12 , wherein said body is a rigid body. 
     
     
         14 . The apparatus as recite inn  claim 12 , wherein said body is a terminal hub. 
     
     
         15 . The apparatus as recited in  claim 14 , further including an umbrella shaped bell and said plurality of said actuators are arranged to contract said umbrella-shaped bell. 
     
     
         16 . The apparatus as recited in  claim 15 , wherein said umbrella-shaped bell encapsulates said plurality of actuators. 
     
     
         17 . The apparatus as recited in  claim 12 , wherein said shape memory alloy or artificial muscle element has a parent shape, when activated, such that activation from an unactivated state emulates a biological motion. 
     
     
         18 . The apparatus as recited in  claim 12 , wherein a combination of said bean and said shape memory alloy or artificial muscle element has a parent shape, when activated, such that de-activation from an activated state emulates a biological motion.