Method to control, while driving along a curve, a road vehicle with a variable stiffness and with rear steering wheels

A method to control, while driving along a curve, a road vehicle (1) with a variable stiffness and with rear steering wheels (3);

• the road vehicle (1) comprises:
• a frame (12), four wheels (2, 3), at least one first actuator (14), which is designed to change a distribution of the stiffness of a connection of the four wheels (2, 3) to the frame (12), and at least one second actuator (15), which is designed to change a steering angle (α) of the rear wheels (3);
• the control method comprises the steps of:
• determining an actual attitude angle (β) of the road vehicle (1);
• establishing a desired attitude angle (βTGT);
• determining an actual yaw rate (dψ/dt) of the road vehicle (1);
• establishing a desired yaw rate (dψ/dtTGT);
• changing, in a simultaneous and coordinated manner, the steering angle (α) of the rear wheels (3) and the distribution of the stiffness of the connection of the four wheels (2, 3) to the frame (12) depending on a difference (εβ) between the actual attitude angle (β) and the desired attitude angle (βTGT) and depending on a difference (εψ) between the actual yaw rate (dψ/dt) and the desired yaw rate (dψ/dtTGT);
• and
• controlling as a priority, while driving along the curve and when a lateral acceleration is smaller than 4-6 m/s2, a steering action of the rear wheels (3) in order to maximize a dynamic response of the road vehicle (1) to a command of steering of the front wheels (2) requested by a driver, adjusting accordingly the distribution of the stiffness of the connection of the four wheels (2, 3) to the frame (12) by means of the first actuator (14).