A first vehicle autonomous brake-apply system includes a vehicle hydraulic brake assembly, a vacuum booster assembly operatively connected to the vehicle hydraulic brake assembly, a solenoid valve operatively connected to the vacuum booster assembly, and an automatic controller including an output signal operatively connected to the solenoid valve. A second system uses a lateral-acceleration-sensor assembly in place of the automatic controller. A third system includes a braking controller, an electrical braking device, and at least one distance sensor. A method for assisting driving of a vehicle includes applying a braking force to stop the vehicle before the vehicle strikes an obstacle whose distance to the vehicle is measured using at least one distance sensor.