Electronic parking brake system in vehicle and control method thereof

1. An electronic parking brake (EPB) system comprising:

a wheel speed sensor which senses a movement of a vehicle;

a vertical acceleration sensor which measures a vertical acceleration value;

an electronic control unit (ECU) which determines whether the vehicle is rolling based on the movement of the vehicle and the vertical acceleration value;

a parking brake which brakes the vehicle based on the determination of whether the vehicle is rolling by the ECU;

a comparator which determines whether an absolute value of the vertical acceleration value is greater than a reference value;

a counting portion which counts a number of times when the absolute value of the vertical acceleration value is greater than the reference value; and

a re-clamp restrictor which, while braking is applied by a driver, fastens the parking brake when the number is equal to or less than a reference counting number, and restricts fastening the parking brake when the number is greater than the reference counting number.

2. The EPB system in claim 1 , wherein the ECU further includes:

a rolling determination portion which determines that the vehicle is rolling when the number is equal to or less than the reference counting number; and

a shaking determination portion which determines that the vehicle is shaking when the number is greater than the reference counting number.

3. The EPB system in claim 2 , wherein when the shaking is determined, the ECU disables a rolling detection of the vehicle by the wheel speed sensor of the vehicle.

4. An EPB system comprising:

a vertical acceleration sensor which measures a vertical acceleration value;

an ECU which determines whether a vehicle is shaking based on the vertical acceleration value;

a parking brake which brakes the vehicle based on the determination of whether the vehicle is shaking by the ECU;

a comparator which determines whether an absolute value of the vertical acceleration value is greater than a reference value;

a counting portion which counts a number of times when the absolute value of the vertical acceleration value is greater than the reference value; and

a re-clamp restrictor which, while braking is applied by a driver, fastens the parking brake when the number is equal to or less than a reference counting number, and restricts fastening the parking brake when the number is greater than the reference counting number.

5. The EPB system of claim 4 , wherein the ECU further includes:

a rolling determination portion which determines that the vehicle is rolling when the number is equal to or less than the reference counting number; and

a shaking determination portion which determines that the vehicle is shaking when the number is greater than the reference counting number.

6. The EPB system of claim 5 , wherein the counting is performed when the vehicle is stopped.

7. A control method of an EPB system comprising:

sensing a movement of a vehicle by a wheel speed sensor of the vehicle;

measuring a vertical acceleration value by a vertical acceleration sensor of the vehicle;

determining whether the vehicle is rolling based on the vertical acceleration value and the movement of the vehicle; and

re-clamping a parking brake of the vehicle based on the determining of whether the vehicle is rolling,

wherein the determining of whether the vehicle is rolling includes:

counting a number of times when an absolute value of the vertical acceleration value is greater than a reference value;

determining that the vehicle is shaking when the number is greater than a reference counting number; and

determining that the vehicle is rolling when the number is equal to or less than the reference counting number, and

wherein the control method further comprises:

fastening the parking brake when the number is equal to or less than the reference counting number, while braking is applied by a driver; and

restricting the re-clamping of the parking brake when the number is greater than the reference counting number, while braking is applied by the driver.

8. The control method of claim 7 , further comprising disabling a rolling detection of the vehicle by the wheel speed sensor of the vehicle when the vehicle is determined to be shaking.