This paper reports on the continued development of a new concept for a personal vehicle called the 'personal riding-type wheeled mobile platform (PMP)' that consists of two wheels and a standing base for a human rider. The two wheels are driven independently, and forward and backward movement and steering are achieved by simply changing the relative position of the rider's center of gravity (COG) on the base. The vehicle has two distinct advantages: a reduction in total weight through its simple structure and a space-saving design that does not use a steering unit. We have already proposed the first prototype (PMP-1) and its posture stabilizing and running control methods, and we have achieved proper forward and backward movement according to the rider's intentions. This paper describes our proposed structure for detecting the rider's COG on the base and the steering control method in order to achieve steering control by changing the position of the rider's COG and the second prototype (PMP-2) whose weight is smaller than 12kg. We also investigated the steering control method to improve maneuverability in various estimated standing poses. Our experimental results demonstrate that natural steering control can be achieved using the rider's COG based on the rider's intentions.

We propose a new concept in personal vehicles called the 'Personal riding-type wheeled Mobile Platform (PMP)' consisting of two wheels and a standing base for a human. The two wheels are driven independently, and traveling and steering is achieved by simply changing the relative position of the rider's center of gravity (COG) on the base. The vehicle has two merits: reducing the total weight of the simple structure and saving space by not using a steering unit. In this paper, the mechanism of the first prototype, PMP-1, is introduced and its posture stabilizing and running control methods are proposed. The effectiveness of the posture stabilization control methods is demonstrated in computer simulations and human riding experiments. In the running control method, maneuverability by movement of the rider's COG is also investigated experimentally. The results demonstrate that the posture of the rider can be maintained and the velocity of forward and backward traveling can be controlled according to the rider's intentions.