A novel one-legged robot: cyclic gait inspired by a jumping frog

A novel construction of planar one-legged robot is proposed, which, unlike previous one-legged robot with springy legs, consists of three revolute joints, two links and two feet. On some conditions, it can be modeled as a two-degree-of-freedom manipulator. Inspired by our observation of a jumping frog, we design a cyclic gait for this one-legged robot. The gait is divided into four phases. During takeoff only two phases are actively controlled and exerted on the knee joint. The trajectory planning of the four phases is formalised as a problem of optimization subject to several constraints, including the ZMP constraint