Multi-stage actuation for an active materials-based actuator

A mechanical system for selectively moving a load a motive distance, the mechanical system comprising:

• an actuator operable for applying a force to the load, the actuator including a first active material element having a variable property;
• a controller connected to the actuator and operable for determining a priming stimulus level to shift the actuator from a first state to a second state associated with detecting the onset of actuation for the actuator;
• wherein the controller is operable to send the priming stimulus level to the actuator to shift it to the primed state;
• wherein the controller is operable for sending a second stimulus to the actuator to shift the actuator to a third state, such that the actuator is applying the force to the load to move the load the motive distance;
• and
• wherein the actuator includes a priming device operable for determining the onset of actuation of the first active material element.