Vehicle steering control without mechanical connection between steering wheel and steered wheels

A path controller for controlling a path of a vehicle, comprising a steering control system for determining control angles,

• wherein the steering control system is for a land vehicle that includes at least one front wheel and one rear wheel, the vehicle including a control member available to a driver for steering the vehicle, the control member delivering a requested steering signal quantified in terms of amplitude and direction,
• wherein the steering control system includes:
• a first actuator configured to act on a steering angle of a front steered wheel;
• a second actuator configured to act on a steering angle of a rear 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 of the first and second actuators, a control angle according to which the actuator is controlled for steering the vehicle, wherein the controller:
• determines an equivalent steering angle of a steered wheel of an equivalent bicycle model according to the requested steering signal and to determine a transverse coordinate of an instantaneous center of rotation of the vehicle,
• determines a longitudinal coordinate of the instantaneous center of rotation of the vehicle to be determined from the speed of the vehicle, a maximum transverse acceleration parameter of the vehicle, and a rule characteristic of a dynamic equilibrium of the vehicle, and
• determines the respective control angles of the steered wheels from the longitudinal coordinate of the instantaneous center of rotation of the vehicle and the transverse coordinate of the instantaneous center of rotation of the vehicle,
• wherein the maximum transverse acceleration parameter of the vehicle is fixed for the vehicle or is variable based on conditions of operation of the vehicle,
• wherein the rule characteristic of the dynamic equilibrium of the vehicle includes a calculation of a connection curve between an initial center of rotation at zero speed and a transition instantaneous center of rotation at a transition speed, the connection curve being tangent to a straight line parallel to an axle of the vehicle, and
• wherein the longitudinal coordinate of the instantaneous center of rotation of the vehicle is determined by reading a transverse coordinate at a site that includes the connection curve and the straight line parallel to an axle of the vehicle for a speed of the vehicle below the transition speed, and the longitudinal coordinate of the instantaneous center of rotation of the vehicle is equal to a longitudinal coordinate that is a function of a speed of the vehicle above the transition speed, and
• wherein the path controller superimposes corrections determined by a control function and determines a corrected steering angle for each of the wheels, each corrected steering angle including a component resulting from the requested steering signal and a correction component.