US Patent 10532787 Compact mobile device having adjustable drive mode

A compact mobility device has an adjustable drive mode. The device includes a base panel and a number of drive wheels rotatably provided at opposite ends of the base panel. The drive wheels are configured to rotate by receiving torque from a driving unit. A column is constituted by a plurality of links connected in series to be foldable and is configured such that a lower end of a lower link is rotatably coupled to the base panel with an upper end of an upper link being provided with a steering handle. An auxiliary wheel is provided between the links constituting the column and is configured to roll along with the drive wheels by coming into contact with a ground when the links are folded.