Chaos study of a vibratory micro-robot in hybrid motion

In this paper, motion of a micro-robot with two perpendicular vibrational actuators is studied. In this work, separation of the micro-robot body from the substrate of motion is modeled. If the applied vertical force to the micro-robot body is greater than its weight, body of the micro-robot jumps apart from the substrate and then returns to it. This motion will continue intermittently until it is damped. In this condition, the motion mechanism of stick-slip is not valid, and a hybrid motion according to stick-slip-jump mode is governed. By increasing the applied vertical force, the motion velocity of the micro-robot becomes disordered and unrepeatable. By numerical solving of the equation of motion and investigating the dynamic response, we find the micro-robot motion is chaotic, related to the restitution factor of the motion substrate and the ratio of vertical force to micro-robot weight.