A downforce system for a vehicle includes: a restrictor configured to restrict a flow of air into a region that is defined at least in part by the restrictor and a ground surface, a rim disposed on the restrictor and configured to form at least a partial seal with the ground surface; a dedicated pressure source disposed outside the restrictor and connected to the restrictor via an air flow path, the pressure source being configured to generate a pressure differential across the restrictor; and a dust and debris removal system configured to prevent dust and debris from exiting the downforce system via the air flow path. By generating a pressure differential across the restrictor, a downforce which acts on the vehicle may be generated. The downforce may result in an improved grip or traction of the vehicle, which may improve handling and safety of the vehicle.

Provided is a mobile device 10 with a spherical drive system that moves over a travel surface G and comprises four or more rotors 15, 15, 16, 16, 17, 17, 18 and 18 that are rotationally driven by driving sources 20, 22, 24 and 26 while in contact with four driving spheres 11, 12, 13 and 14 from two different directions, thereby causing the driving spheres to rotate, wherein the centers P1, P2, P3 and P4 of the driving spheres are positioned at the side edges S1, S2, S3 and S4 of a virtual inverted hip roof pentahedron H having a base e disposed at a position higher than the center of each driving sphere and a ridge O disposed at a position lower than the center of each driving sphere, respectively.

Provided is a mobile device 10 with a spherical drive system that moves over a travel surface G and comprises four or more rotors 15, 15, 16, 16, 17, 17, 18 and 18 that are rotationally driven by driving sources 20, 22, 24 and 26 while in contact with four driving spheres 11, 12, 13 and 14 from two different directions, thereby causing the driving spheres to rotate, wherein the centers P1, P2, P3 and P4 of the driving spheres are positioned at the side edges S1, S2, S3 and S4 of a virtual inverted hip roof pentahedron H having a base e disposed at a position higher than the center of each driving sphere and a ridge O disposed at a position lower than the center of each driving sphere, respectively.