High power/weight ratio braking device based on shape memory material technology

A friction brake assembly to act between a main actuator and a linear shaft relatively moveable with respect to said main actuator, comprising:

• a linear shaft;
• a brake member connected to said linear shaft,
• a carrier connected to said main actuator;
• a friction pad attached to said carrier for removable engagement with said brake member;
• a first actuator comprising a plurality of shape memory alloy rods arranged in parallel, said first actuator being operatively coupled to said carrier and actuatable to move said friction pad into engagement with said brake member to apply a braking force on the brake member, wherein the engagement of said friction pad with said brake member inhibits movement of said linear shaft;
• a second actuator comprising a plurality of shape memory alloy rods arranged in parallel, said second actuator operatively coupled to said carrier and actuatable to move said friction pad away from said brake member to remove said braking force, wherein the moving away of said friction pad from said brake member allows movement of said linear shaft;
• and
• a control circuit to operate selectively said first and second actuator,
• wherein the first and second actuators are configured to change in length only when an electric current is applied thereto such that the length of the first and second actuators remains unchanged upon removal of the current, thereby allowing the friction pad and brake member to remain in a stable position without the continued application of electrical power to the first and second actuators.