US 12,415,521 B2
On-board road friction estimation
Mats Jonasson, Partille (SE); Leo Laine, Härryda (SE); and Leon Henderson, Härryda (SE)
Assigned to Volvo Truck Corporation, Gothenburg (SE)
Appl. No. 17/777,752
Filed by Volvo Truck Corporation, Gothenburg (SE)
PCT Filed Dec. 10, 2019, PCT No. PCT/EP2019/084337
§ 371(c)(1), (2) Date May 18, 2022,
PCT Pub. No. WO2021/115561, PCT Pub. Date Jun. 17, 2021.
Prior Publication US 2022/0402498 A1, Dec. 22, 2022
Int. Cl. B60W 40/068 (2012.01); B60W 60/00 (2020.01)
CPC B60W 40/068 (2013.01) [B60W 60/001 (2020.02); B60W 2520/125 (2013.01); B60W 2520/14 (2013.01); B60W 2530/10 (2013.01); B60W 2530/20 (2013.01); B60W 2540/18 (2013.01); B60W 2552/40 (2020.02)] 10 Claims
OG exemplary drawing
 
1. A method of estimating a road friction coefficient of a vehicle, the method comprising:
obtaining substantially contemporaneous values associated with a steering angle (δ) for a steered axle of the vehicle, a lateral acceleration (ay), a yaw acceleration (dωz/dt), an alignment torque (Mz), and an axle load (mf) on the steered axle;
estimating a lateral tire force (Fy) on the basis of the steering angle, lateral acceleration, and yaw acceleration;
deriving a pneumatic trail (tp) from the alignment torque (Mz) and the estimated lateral tire force (Fy); and
estimating a road friction coefficient (μ) from the lateral tire force, the axle load, and the pneumatic trail,
wherein the method further comprises at least one of:
i) estimating the road friction coefficient by evaluating a predetermined nonlinear function of the pneumatic trail, wherein the nonlinear function is at least equal to any of:

OG Complex Work Unit Math
or scaled versions thereof, where g is gravitational acceleration, 2a is a tyre contact length, Fy is lateral tyre force and tp is the pneumatic trail;
ii) deriving a tolerance range (μ−, μ+) associated with the road friction coefficient; and
iii) evaluating the lateral tire force and alignment torque with respect to threshold values (Fy,lim, Mz,lim) for the lateral tire force and the alignment torque.