| This thesis explores milli- and meso-scale legged robot design and fabrication with compliant mechanisms. Our approach makes use of a process that integrates compliant flexure hinges and rigid links to form parallel kinematic structures through the folding of flat-fabricated sheets of articulated parts. Using screw theory, we propose the formulation of an equivalent mechanism compliance for a class of parallel mechanisms, and we use that compliance to evaluate a scalar performance metric based on the strain energy stored in a mechanism subjected to an arbitrary load. Results from the model are supported by experimental measurements of a representative mechanism. With the insight gained from the kinematic mechanism design analysis, we propose and demonstrate compliant designs for two six-legged robots comprising the robotic, autonomous, crawling hexapod (RoACH) family of robots. RoACH is a two degree of freedom, 2.4 gram, 3 cm long robot capable of untethered, sustained, steerable locomotion. RoACH's successor, DynaRoach, is 10 cm long, has one actuated degree of freedom and is capable of running speeds of up to 1.4 m/s. DynaRoACH employs compliant legs to help enable dynamic running and maneuvering and is three orders of magnitude more efficient than its milli-scale predecessor. We experimentally demonstrate the feasibility of a biologically-inspired approach to turning control and dynamic maneuvering by adjusting leg stiffness. While the result agrees qualitatively with predictions from existing reduced order models, initial data suggest the full 3-dimensional dynamics play an important role in six-legged turning. |
