Speeding-up of passive combined rimless wheel using active wobbling mass

It was clarified that a passive combined rimless wheel (CRW) that consists of two identical eight-legged rimless wheels can increase the walking speed either by adjusting the phase difference or by using a passive wobbling mass that vibrates up-and-down in the body frame. This paper then investigates the effect of an active wobbling mass driven by an actuator for the purposes of further speeding-up and investigating the effect of indirect excitation control. First, we develop the mathematical model and numerically show that the CRW generates walking motion in synchronization with the up-and-down motion of the active wobbling mass at high frequencies. Several interesting nonlinear phenomena are also reported. Second, we describe the experimental results using our prototype CRW machine.