Abstract: An articulated tracked vehicle that has a main section, which includes a main frame, and a forward section. The main frame has two sides and a front end, and includes a pair of parallel main tracks. Each main track includes a flexible continuous belt coupled to a corresponding side of the main frame. The forward section includes an elongated arm. One end of the arm is pivotally coupled to the main frame near the forward end of the main frame about a transverse axis that is generally perpendicular to the sides of the main frame. The arm has a length sufficiently long to allow the forward section to extend below the main section in at least some degrees of rotation of the arm, and a length shorter than the length of the main section. The center of mass of the main section is located forward of the rearmost point reached by the end of the arm in its pivoting about the transverse axis.

Abstract: A resilient wheel structure having a rim and a hub interconnected by spokes, wherein the rim is sufficiently stiff to distribute a load to all of the spokes, and wherein the wheel is able to absorb loads in both the radial and axial directions. The rim comprises an inner and outer rim portion supported by ribs, that are located co-radially with curved spokes that allow tension and compression. The wheel structure being optimally used on a mobile robot.