Patent ID: 8078381

Claim:
A vehicle speed control system comprising: means for calculating instantaneous curvature; and means for controlling a vehicle speed; wherein, a vehicle is controlled to reduce the vehicle speed when the instantaneous curvature tends to increase and to enhance the vehicle speed when the instantaneous curvature tends to decrease; the means for calculating instantaneous curvature includes means for instantaneously detecting a positional coordinate (x(t), y(t)) of the vehicle in a plane defined by at least two axes perpendicular to each other; and the instantaneous curvature (κ(t)) is calculated on the basis of the following expression; κ ⁡ ( t ) = x . ⁡ ( t ) ⁢ y ¨ ⁡ ( t ) - x ¨ ⁡ ( t ) ⁢ y . ⁡ ( t ) ( x . ⁡ ( t ) 2 + y . ⁡ ( t ) 2 ) 3 2 .