Patent ID: 8036793

Claim:
A steering control system with variable ratio for a land vehicle that includes two or more wheels, at least one of which is steered, the vehicle including a control member available to a driver for steering the vehicle, the control member being maneuverable within a maximum range between a leftward stop and a rightward stop and delivering a requested steering signal quantified in terms of amplitude and direction, the steering control system comprising: at least one actuator configured to act on a steering angle of the at least one steered wheel; and a controller that uses as input variables at least a speed of the vehicle and the requested steering signal in order to determine, for each actuator, a control angle according to which the actuator is controlled for steering the vehicle, wherein the controller includes: a first unit configured to determine, at least according to the speed of the vehicle and a parameter characteristic of an equilibrium of the vehicle, a maximum steering angle on a steered wheel of an equivalent bicycle model of the vehicle, a second unit configured to determine a gearing-down ratio according to the maximum range of the control member and the maximum steering angle, wherein the gearing-down ratio is determined according to RD=θ max /β max , in which RD represents the gearing-down ratio, θ max represents the maximum range of the control member, and β max represents the maximum steering angle, and wherein the gearing-down ratio is utilized to prevent the parameter characteristic of the equilibrium of the vehicle from being exceeded, and a third unit configured to determine a steering angle according to the gearing-down ratio and the requested steering signal.