A method for operating a steering mechanism (12) of a motor vehicle, wherein a steering rod (27) can be held or displaced along its longitudinal axis (a) by an electric motor (22) so that the wheel steering angle (8, 9) of at least one wheel (5, 6) on at least one vehicle axle (1) can be maintained or changed. When a force (F.sub.ext) acts essentially axially on the steering rod (27), displacement of the steering rod (27) is at least inhibited by a detent torque (RM) of the electric motor (22) and/or by a self-induced torque (M.sub.sip) of the electric motor. The invention also relates to a device for carrying out the method and to a steering mechanism, which is preferably in the form of a steer-by-wire steering system. A control unit is provided for carrying out the method.

A travel control device includes a turning control unit configured to execute turning support control causing a turning state quantity to follow a target turning state quantity by causing at least one of a front wheel steered angle adjustment device, a rear wheel steered angle adjustment device, and a braking device to be driven, and a steering instruction unit configured to, when steering is not being performed during the execution of turning support control, derive a holding torque and instruct a steering device to apply the holding torque to a steering wheel. The turning control unit causes the rear wheel steered angle adjustment device and/or the braking device to be driven but causes the front wheel steered angle adjustment device not to be driven when steering is not being performed. The turning control unit causes the front wheel steered angle adjustment device to be driven when steering is being performed.

A travel control device includes a turning control unit configured to execute turning support control causing a turning state quantity to follow a target turning state quantity by causing at least one of a front wheel steered angle adjustment device, a rear wheel steered angle adjustment device, and a braking device to be driven, and a steering instruction unit configured to, when steering is not being performed during the execution of turning support control, derive a holding torque and instruct a steering device to apply the holding torque to a steering wheel. The turning control unit causes the rear wheel steered angle adjustment device and/or the braking device to be driven but causes the front wheel steered angle adjustment device not to be driven when steering is not being performed. The turning control unit causes the front wheel steered angle adjustment device to be driven when steering is being performed.

A wheel suspension includes an axle limb which supports a wheel. The axle limb includes a first steering axle which provides a first steering angle in a specified range for the wheel, and components for connecting the axle limb to a support structure. At least one of the components includes a second steering axle which is selectively releasable in order to provide a steering angle which is different than the first steering axle. The components for connecting the axle limb to the support structure form a McPherson suspension.

A wheel suspension includes an axle limb which supports a wheel. The axle limb includes a first steering axle which provides a first steering angle in a specified range for the wheel, and components for connecting the axle limb to a support structure. At least one of the components includes a second steering axle which is selectively releasable in order to provide a steering angle which is different than the first steering axle. The components for connecting the axle limb to the support structure form a McPherson suspension.

A four-wheeled vehicle includes: a frame; two front suspension assemblies and two rear suspension assemblies connected to the frame; two front wheels operatively connected to corresponding ones of the two front suspension assemblies; two rear wheels operatively connected to corresponding ones of the two rear suspension assemblies; a motor connected to the frame; a front differential and a rear differential operatively connecting the motor to the two front wheels and the two rear wheels respectively; and a steering system. The steering system includes a front steering assembly for steering the front wheels and a rear steering assembly for steering the rear wheels. The front steering assembly includes a user-operated steering input device. The rear steering assembly includes an actuator operatively connected to the rear wheels and operable to modify a steering angle thereof. The actuator is mounted to the frame and is disposed completely rearward of the rear differential.

A scalable tractive power system for vehicles (car, truck, bus, semi-trailer), integrated with all-wheel steering system which leverage synergies between plurality of differently designed electric traction-motors and all-wheel electric steering-motors is configured with plurality of sensors to virtually eliminate wheel-dragging and EPS, as part of virtually 100% dynamic efficiency. A fully automated electronic clutch-system attached to selected electric traction motors is configured to carry out above 90% traction efficiency by coupling to wheels selected electric traction-motors in their high efficiency range of operation, and de-coupling and replacing electric traction-motors with another electric traction-motors while the vehicle is changing speed or when the vehicle requires higher or lower tractive-power, from forward-motion start to top-rated speed of the vehicle. A holistic controller is configured with multi-objective optimization design (MOOD) procedures computing complex variable values and parameters, finding the required trade-off among design objectives, and improving the pertinence of solutions, while complying with NHTSA's ‘fail operational systems’ for steer-by-wire.

A dual-mode active rear-wheel steering device, including: a steering motor, a main shaft, an intermediate gear, a transmission gear, a planetary gear coupling mechanism and a mode switching assembly. An output end of the steering motor is provided with a first input gear. An end of the main shaft drives a first rear wheel to rotate by a two-stage gear transmission system and a first rear-wheel motion conversion mechanism, and the other end of the main shaft drives a second rear wheel to rotate by the planetary gear coupling mechanism and a second rear-wheel motion conversion mechanism. The intermediate gear, the transmission gear and a sun gear of the planetary gear coupling mechanism are provided on the main shaft. The intermediate gear meshes with the first input gear.

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 steering actuator comprising a shaft having an input coaxial with an output, wherein the output is in drivable communication with one or more wheels of a vehicle, and a locking mechanism configured to enable the shaft to rotate in both a first direction and a second direction in response to torque provided at the input, and prevent the shaft from rotating in both the first direction and the second direction in response to torque provided at the output.