Circling turning locomotion of a new multiple closed-chain-legs robot with hybrid-driven mechanism

A multi-legged robot based on a hybrid-driven mechanism is presented in this paper as an improvement of the legged robot based on crank-driven linkage mechanism. A hybrid-driven mechanism containing a full-rotational degree of freedom (DOF) and a linear translational DOF was obtained after a series of foot trajectory analyses on the Jansen mechanism. The stance phase trajectory of this hybrid-driven mechanism can maintain horizontality regardless of the length adjustment of the linear DOF. A turning gait of a hexapod robot based on this hybrid-driven mechanism was proposed, such that all of the legs had an identical crank angular speed, and the robot turned its orientation through different linear servo controls on the legs of the two sides. Simulation and experimental results showed that the hexapod robot could realize the turning gait when the legs of the two sides applied different length adjustments. The body center trajectories in all cases were approximate to a circle, and the smallest turning radius was close to the length of the robot. Moreover, the magnitude of the pitch and roll angles, and body center fluctuation in the simulations was all small, indicating that the hexapod robot based on the hybrid-driven mechanism was stable during the turning locomotion.