US 11,904,861 B2
Apparatus and method for estimating friction coefficient of road surface
Min Ji Chae, Incheon (KR); and Hyun Su Kim, Uiwang-si (KR)
Assigned to HYUNDAI MOTOR COMPANY, Seoul (KR); and KIA CORPORATION, Seoul (KR)
Filed by HYUNDAI MOTOR COMPANY, Seoul (KR); and Kia Corporation, Seoul (KR)
Filed on Aug. 9, 2021, as Appl. No. 17/397,229.
Claims priority of application No. 10-2020-0103412 (KR), filed on Aug. 18, 2020.
Prior Publication US 2022/0055623 A1, Feb. 24, 2022
Int. Cl. B60W 30/18 (2012.01); B60W 40/09 (2012.01)
CPC B60W 30/18109 (2013.01) [B60W 40/09 (2013.01); B60W 2520/28 (2013.01); B60W 2520/30 (2013.01); B60W 2552/20 (2020.02); B60W 2552/35 (2020.02)] 17 Claims
OG exemplary drawing
 
1. A road surface friction coefficient estimation apparatus comprising:
one or more sensor configured to obtain an information of a speed of a vehicle and driving torque at wheels of the vehicle; and
a processor coupled to the one or more sensor, and configured to:
determine a driving state of the vehicle by collecting information for grasping a driving situation of the vehicle, and to determine whether to estimate a road surface friction coefficient according to a result of determining the driving state of the vehicle;
arbitrarily add a braking force, which causes a wheel speed difference, to an axle of the vehicle to which the braking force is applied, and to add a driving force canceling the braking force to an axle of the vehicle, to which the driving force is applied, when the processor determines that the driving state of the vehicle is an inertial driving state; and
estimate a state of the road surface friction coefficient by the wheel speed difference caused by the arbitrarily added braking force,
wherein the processor is further configured to:
obtain wheel speeds of the vehicle from a wheel coupled to the axle, to which the braking force is applied, among the wheels and a wheel coupled to the axle, to which the driving force is applied, among the wheels;
determine a magnitude of the wheel speed difference between the wheel speeds; and
determine a value of the wheel speed difference as a corrected wheel speed difference index value by multiplying the determined wheel speed difference by a predetermined correction coefficient, depending on a magnitude of a target driving torque acting on the axle, to which the driving force is applied.