Abstract: An unpowered wadding duck robot based on the non-smooth dynamics with friction and impact effects is designed. The duck robot can walk stably and periodically along the slope down through the contact state transformation of detaching, sliding and sticking without any external drives and controls. It is very difficult to accurately determine the instantaneous contact state between feet and slope because there are multiple points of friction and collisions in the robot. The dynamic model of the robot system is proposed and its movements are studied by three-dimensional simulation and principle prototype experiment. Simulation and experimental results show that the movement of duck robot in one cycle can be divided into nine processes. The changes of the initial position and posture do not alter the stable movement behavior of the robot. The dynamics characteristics of the robot are investigated and the time history of the dynamic parameters simulations show an obvious cyclical variation, which verifies the robot is able to achieve cyclical, stable passive mobile and the dynamics model is reasonable.

Key words: passive robot;non-smooth dynamics;stability analysis;dynamic simulation