Travel over sloped terrain is difficult as an incline changes the interaction between each wheel and the ground resulting in an unbalanced load distribution which can lead to loss of traction and instability. This paper presents a novel approach to generating wheel rotation for primary locomotion by only changing its centre of rotation, or as a complimentary locomotion source to increase versatility of a plain centre hub drive. This is done using linear actuators within a wheel to control the position of the centre hub and induce a moment on the wheel from gravity. In doing so our platform allows for active ride height selection and individual wheel pose control. We present the system with calculations outlining the theoretical properties and perform experiments to validate the concept under loading via multiple gaits to show motion on slopes, and sustained motion over extended distance. We envision applications in conjunction to assist current motor drives and increasing slope traversability by allowing body pose and centre of gravity manipulation, or as a primary locomotion system.

This paper proposes a novel configurable wheel that exhibits desired properties of varied radius wheels. Positional manipulation of the centre hub is proposed and tested to achieve these desired characteristics of `virtual' wheels in a physical system. The centre hub is manipulated via the use of pneumatic actuators mounted to and constricted by the outer rim of the wheel, which allows for fast and accurate control to enable the vehicle ride height and gear ratio to be adjusted continuously and be maintained during the wheels' full rotation. Experiments are presented, validating this ability of the system. We envision uses for this system to extend from off-road robotics to space exploration as these wheels exhibit novel characteristics not demonstrated by other platforms.