A method can be used to control a steer-by-wire steering system for a motor vehicle that has two axles each with two wheels. Two front wheels can be steered by front-wheel steering and two rear wheels can be steered by rear-wheel steering. The motor vehicle includes a single wheel drive that is assigned to one of the two axles and drives the two wheels of the corresponding axle via a differential. The motor vehicle comprises an inboard braking system. The method involves checking the motor vehicle speed and activating rear-axle steering when a motor vehicle speed should be slower than 40 km/hr. With rear-axle steering active, the following steps are performed: deactivating front-wheel steering and rear-wheel steering, determining a reference position of a first steering rod via a reference wheel steering angle, determining a differential drive torque between the rear wheels to reach the reference position via a control unit.

A method of controlling a vehicle includes obtaining a linear representation of a vehicle dynamics model that includes actuator dynamics u integrated with vehicle dynamics x. The actuator dynamics u include a road wheel angle at rear wheels δr and a torque Mz. The method also includes obtaining an objective function based on a function of the vehicle dynamics x and the actuator dynamics u and formulating a cost function to minimize the objective function. The actuator dynamics u including the torque Mz are determined for a next time sample based on minimizing the objective function. The vehicle is controlled to implement the torque Mz.

A method and device for controlling a rear-axle steering system, in particular a rear-axle steering system of a motor vehicle, determines a current physical condition of the rear-axle steering system on the basis of a detected current operating state and a pre-determined reference operating state of the rear-axle steering system. The method defines a maximum permissible steering angle of the rear-axle steering system depending on the estimated physical condition of the rear-axle steering system and depending on at least one of the operating parameters of driving speed, steering angle and steering angle speed of the vehicle, and actuates the rear-axle steering system such that the steering angle of the rear-axle steering system does not exceed the assigned defined maximum permissible steering angle for the current operating parameter(s) of the vehicle.

A vehicle steering system is applied to a vehicle including wheels including at least turning wheels and includes a steering member, a reaction actuator, a turning device, and an electronic control unit. The electronic control unit is configured to: control the turning device based on a target turning angle corresponding to an amount of steering of the steering member; control the reaction actuator such that a steering reaction force based on a first turning axial force corresponding to the target turning angle and a second turning axial force corresponding to an output current or an output torque of the turning device is generated; and change a first proportion of the first turning axial force distributed to the steering reaction force and a second proportion of the second turning axial force distributed to the steering reaction force based on a slip rate of the wheels.

A four-wheel independent steering system and a method of controlling the four-wheel independent steering system. The four-wheel independent steering system includes a front/rear-wheel-angle-ratio calculation unit to calculate a ratio Kss between front and rear wheel angles that allows a body slip angle to converge to ‘0’ and allows a yaw angle and a yaw rate to maintain target values, and a control unit to perform four-wheel steering control based on the ratio Kss between the front and rear wheel angles.

A method for controlling a wheel axle assembly of a vehicle. The vehicle comprises a vehicle body with a longitudinal axis extending in a longitudinal direction, a transversal axis extending in a transversal direction and a vertical axis extending in a vertical direction. The longitudinal axis, the transversal axis and the vertical axis are perpendicular to each other.

The longitudinal direction corresponds to an intended direction of travel of the vehicle and the vertical direction being parallel to a vertical line when the vehicle is positioned on a flat horizontally extending surface. The vehicle body comprises a vehicle body centre plane extending along the longitudinal axis and the vertical axis and separating the vehicle body into two body halves.

A method can be used to control a steer-by-wire steering system for a motor vehicle that has two axles each with two wheels. Two front wheels can be steered by front-wheel steering and two rear wheels can be steered by rear-wheel steering. The motor vehicle includes a single wheel drive that is assigned to one of the two axles and drives the two wheels of the corresponding axle via a differential. The motor vehicle comprises an inboard braking system. The method involves checking the motor vehicle speed and activating rear-axle steering when a motor vehicle speed should be slower than 40 km/hr. With rear-axle steering active, the following steps are performed: deactivating front-wheel steering and rear-wheel steering, determining a reference position of a first steering rod via a reference wheel steering angle, determining a differential drive torque between the rear wheels to reach the reference position via a control unit.

An apparatus for estimating a friction coefficient of a road surface is provided. The apparatus includes a current sensor configured to measure a control current value of a rear wheel steering (RWS) motor, a stroke sensor configured to measure a stroke value indicating a movement amount of a rear wheel steering link, and a controller configured to estimate the friction coefficient of the road surface based on the control current value measured by the current sensor and the stroke value measured by the stroke sensor.

A steering assembly for a vehicle comprising a first, a second, a third, and a fourth wheel, a first steering actuator comprising a first actuating member, and a second steering actuator comprising a second actuating member. The first actuating member is connected to each of the first wheel and the second wheel. The second actuating member is connected to each of the third wheel and the fourth wheel. The steering assembly comprises a connection arrangement. The first and second steering actuators are connected to each other via the connection arrangement such that the first actuating member and the second actuating member move independently of each other when a relative movement parameter is within a predetermined relative movement range and the connection arrangement transfers movement between the first actuating member and the second actuating member when the relative movement parameter is outside the predetermined relative movement range.

A rear wheel steering motor generates rotational force. A movement converter has a converting portion coupled to the wheel steering motor and configured to convert the rotational force transmitted from the rear wheel steering motor into a linear movement. An MR fluid is applied on the converting portion. An inverter controls driving of the rear wheel steering motor. A magnet switch works in concert with the inverter to change a magnetic field to selectively provide the magnetic field to the MR fluid of the movement converter.