FlexLegs: Flexible Legs Actuated by Shape Memory Alloy

A flexible leg (FlexLeg) design using BiFlex actuators was designed, fabricated and characterized. BISMAC actuators are unidirectional flexible actuators capable of exhibiting high curvature. These actuators were modified to achieve bidirectional deformation. The new bidirectional actuators termed as “BiFlex” actuators, have proven the capability to achieve large deformation in two directions. The FlexLegs consist of six segments which can be actuated individually. Two different sets of legs were constructed to determine the effect of size. The small legs measure 35.8 mm in height and 63.2 mm in width and the large legs were 97.4 mm in height and 165.4 mm in width. The small FlexLegs achieved a maximum deformation of 12% and 4% in the x- and y-direction respectively using a power of 0.7 W while producing a maximum force of 0.023 N. They were also able to withstand a load of 1.18 N. The large FlexLegs had a maximum deformation of 57% and 39% in the x- and y-direction respectively using a power of 3 W while producing a force of 0.045 N. They were able to withstand a load of 0.25 N. The legs were also able to perform several walking algorithms consisting of stepping, crabbing and yawing.