Vehicle travel assistance system

A vehicle travel assistance system which controls a difference in braking force between a left wheel and a right wheel of the vehicle when causing the vehicle to perform a yawing motion on the basis of a set target yawing moment, comprising:

• at least one processor configured to:
• distribute half of the target yawing moment to an inner wheel and distribute the rest of the target yaw moment to an outer wheel, the inner wheel being a wheel, among the left wheel and the right wheel of the vehicle, located on an inner side at a time of the yawing motion, and the outer wheel being a wheel, among the left wheel and the right wheel of the vehicle, located on an outer side;
• increase an amount of increase of a braking force of the inner wheel as the target yawing moment distributed to the inner wheel increases;
• increase an amount of decrease in a braking force of the outer wheel as the target yawing moment distributed to the outer wheel increases;
• execute a moment control which increases the braking force of the inner wheel in accordance with the amount of increase of the braking force of the inner wheel, and decreases the braking force of the outer wheel in accordance with the amount of decrease of the braking force of the outer wheel;
• execute a deceleration control to decelerate the vehicle by applying the braking force to avoid a collision between the vehicle and an obstacle when the obstacle is present in front of the vehicle;
• determine whether or not a relative speed can be set to “0 (zero)” or less in front of the obstacle, on the basis of a relation between the relative speed based on the obstacle and a predicted value of the time until the relative speed becomes equal to “0 (zero)” by the execution of the deceleration control, when both the deceleration control and the moment control are executed;
• determine whether or not there is a wheel that will skid on the basis of the braking force of the wheel, a driving force of the wheel, and a lateral acceleration of the vehicle;
• increase and correct the braking force of the outer wheel, when it is determined that it is possible to set the relative speed to “0 (zero)” or less in front of the obstacle, and it is determined that there is a wheel that will to skid;
• and
• decrease and correct the braking force of the outer wheel, when it is not determined that it is possible to set the relative speed to “0 (zero)” or less in front of the obstacle, and it is determined that there is a wheel that will skid, and wherein,
• when the at least one processor executes the moment control together with the deceleration control, the at least one processor is configured to:
• make the braking force of the inner wheel equal to a sum of the braking force applied to the inner wheel by the deceleration control and an amount of increase of the braking force of the inner wheel, and
• make the braking force of the outer wheel equal to a difference obtained by subtracting the amount of decrease of the braking force of the outer wheel from the braking force applied to the outer wheel by the deceleration control.