The disclosed invention makes use of slip related values to calculate friction related values and tire stiffness related values and feeds back an estimated tire stiffness relates value or a calculated friction related as a basis for further calculations. In particular, the disclosure relates to methods, apparatuses and computer program products to achieve the mentioned objective.

A rotation restriction control device comprises a selection unit that selects a rotation restriction state, on the basis of a road surface when parking a vehicle traveling on the road surface, and a control unit that controls a rotation restriction state of a restriction mechanism in accordance with a selection result from the selection unit when parking the vehicle.

A method and an apparatus for determining a road surface adhesion coefficient are provided. The method includes: determining, based on M state parameters of a vehicle on a target road section, M road surface adhesion coefficient estimation results respectively corresponding to the M state parameters, M being an integer greater than 1; selecting N road surface adhesion coefficient estimation results from the M road surface adhesion coefficient estimation results according to a traveling work condition of the vehicle on the target road section, N being a positive integer smaller than or equal to M; and determining a road surface adhesion coefficient of the target road section based on the N road surface adhesion coefficient estimation results.

An illustrative example method is for estimating a friction characteristic of a surface beneath a vehicle that has a plurality of wheels contacting the surface. The method includes determining a wheel speed of at least one of the wheels, determining a velocity of the at least one of the wheels separately from determining the wheel speed, determining a wheel slip of the at least one of the wheels based on the determined wheel speed and the determined velocity, and determining the friction characteristic based on the determined wheel slip. Determining the velocity separately from the wheel speed is accomplished using at least one detector that provides an output corresponding to a range rate, such as a RADAR or LIDAR detector.

An apparatus determines a road friction of a commercial vehicle. The commercial vehicle has a first axle and a second axle, a load distribution mechanism for changing a load on the first axle or on the second axle, and a slip sensor for determining a slip value for at least one wheel on the first axle or on the second axle. The apparatus includes an evaluation unit configured to control the load distribution mechanism to change the load of the first axle or on second axle, determine a change in the slip value in response to the change of the load, and evaluate the road friction based on the change in the slip value.

A method for controlling a hydraulic brake system for a motor vehicle to carry out a braking operation by means of at least one wheel brake includes, in a first step, a pressure buildup in the wheel brake, wherein hydraulic fluid is passed to a wheel brake via a normally open inlet valve. In a second step, a pressure reduction takes place in the wheel brake, wherein hydraulic fluid is discharged from the wheel brake via an energized normally closed outlet valve. The pressure reduction at the wheel brake is accomplished by means of control of the outlet valve in a predefined manner.

The invention pertains to a road condition determining system and a method for determining a condition of a road traversed by at least one vehicle. The road condition determining system comprises a vehicle position determination means for determining a position of the vehicle, a calibration parameter detection unit adapted to determine at least one calibration parameter of a part of the vehicle, a vertical acceleration sensor adapted to continuously sense a vertical acceleration of the vehicle, a calculation unit adapted to calculate a road condition value based on the vertical acceleration and on the calibration parameter, and to continuously monitor whether the road condition value exceeds a predefined schedule, and a data transmission unit adapted to provide maintenance data to at least one receiver, the maintenance data comprising at least an information about the vehicle position.

An apparatus for controlling a braking force of a vehicle is provided. The apparatus includes a sensor device that obtains information about an image in front of the vehicle and driving information of the vehicle and a controller that determines a road surface state including a left road surface state and a right road surface state based on the information about the image and the driving information and controls a braking force of left wheels of the vehicle and a braking force of right wheels of the vehicle respectively based on the left road surface state and the right road surface state of the vehicle.

A method includes obtaining creep measurements and tractive/braking measurements from at least one vehicle system at different locations along a route segment while the at least one vehicle system moves through the route segment. The method also includes calculating tribology characteristics of the route segment at the different locations. The tribology characteristics are based on the creep measurements and the tractive/braking measurements from the at least one vehicle system. The tribology characteristics are indicative of a friction coefficient of the route segment at the different locations. The method also includes determining an effectiveness of a friction modifier applied to the route segment based on the tribology characteristics.

A method is provided for determining an adhesion potential of a tire mounted on a wheel and travelling over ground. The method utilizes a database constructed to contain information obtained by evaluating experimental data on an evolution of a rolling radius of the tire as a function of predetermined rolling conditions of the tire on ground of variable and known adhesion. Based on the information in the database, an estimation model (M.sub.adpot) of an adhesion potential is established by determining a function linking an adhesion potential (μ.sub.max) of the tire to a rolling radius (RRt) of the tire and to vehicle parameters. The rolling radius (RRt) of the tire is determined while the tire is rolling. The adhesion potential (μ.sub.max) of the tire is evaluated by application of the estimation model (M.sub.adpot) and as a function of the vehicle parameters.