Abstract: A robotic vehicle is provided with a novel wheel design and a virtual differential transmission. The novel wheels are generally rounded with scallops along the outer periphery permitting secure engagement of irregular terrain structures, such as the rungs of an inclined ladder. The virtual differential transmission employs rotational sensors in independently driven wheels to maintain information on the relative rotational position of left- and right-side wheels. When necessary, the relative rotational position information is used to selectively drive the left- or right-side wheel until the scallops in a left-side wheel are horizontally aligned with the scallops in a right-side wheel. Thus, the virtual differential transmission can realign the scallops in left- and right-side wheels to facilitate their mutual engagement with a terrain structure, such as a ladder rung.

Abstract: A drink system comprising a platform configured to extend between supporting members. The drink system comprises a body configured to traverse a plane between the two supporting members when attached to the platform, the body comprising an interior space configured to store liquid. The drink system optionally comprises a tube to draw the liquid from the body. The tube comprising a first portion configured to fit within the body and a second portion configured to extend outside the body. The drink system optionally includes a clip configured to attach to the second portion of the tube for placement of the tube relative to a user to draw the liquid from the body.

Abstract: A robotic vehicle is provided with a novel wheel design and a virtual differential transmission. The novel wheels are generally rounded with scallops along the outer periphery permitting secure engagement of irregular terrain structures, such as the rungs of an inclined ladder. The virtual differential transmission employs rotational sensors in independently driven wheels to maintain information on the relative rotational position of left- and right-side wheels. When necessary, the relative rotational position information is used to selectively drive the left- or right-side wheel until the scallops in a left-side wheel are horizontally aligned with the scallops in a right-side wheel. Thus, the virtual differential transmission can realign the scallops in left- and right-side wheels to facilitate their mutual engagement with a terrain structure, such as a ladder rung.