In a method for controlling a vehicle with a drive system comprising a power unit configuration adapted to provide output for the vehicle's operation, and further comprising a planetary gear and a first and second electrical machine, connected to components in the planetary gear via their rotors, a locking means is moved from a locked position, in which two of the planetary gear's components are locked together, so that the three components of the planetary gear rotate with the same speed, to a release position, when the vehicle is driven with the locking means in a locked position, by carrying out the following method steps. The power unit configuration is controlled in order to achieve torque balance between the components that are locked together by the locking means, and such locking means are moved into a release position, when said torque balance prevails.

The control device of a four-wheel drive vehicle is applied to a four-wheel drive vehicle having a differential restriction device which can change a differential restriction degree between a front wheel rotary shaft and a rear wheel rotary shaft, a braking device can separately change a braking force of the front wheels and a braking force of the rear wheels. The control device determines whether a specific state which has a high possibility that a state where a rear wheel slip ratio becomes larger than a front wheel slip ratio is generated occurs assuming that the differential restriction degree is set to a first degree when the differential restriction degree is set to a second degree so as not to allow the differential operation and change the differential restriction degree from the second degree to the first degree when it is determined that the specific state has occurred.

Methods and systems are provided for operating a driveline of a hybrid vehicle that includes an internal combustion engine, an electric machine, and a transmission are described. In one example, regenerative torque and torque of an electronically controlled differential clutch are adjusted to increase utilization of a vehicle's kinetic energy.

A drive device for an all-wheel drive, two-track motor vehicle, in the drive train of which a first motor vehicle axle and, via a center clutch, a second motor vehicle axle are driven permanently by a drive assembly in driving operation. In the closed state of the center clutch, the second vehicle axle is engaged with the drive train, and, in the open state of the clutch, the second vehicle axle is decoupled from the drive train. In a driving situation with engaged all-wheel drive as well as with axle friction coefficients of varying size, a greater wheel torque can be taken up at the vehicle axle with a large axle friction coefficient than at the vehicle axle with a small axle friction coefficient, and a control instrument is provided, which, for engine torque limitation, limits the drive assembly to a maximum allowed engine torque.

A slip control system for an off-road vehicle includes a control system configured to output a signal indicative of a first action if a magnitude of slippage of the off-road vehicle relative to a soil surface is greater than a first threshold value and less than or equal to a second threshold value. Furthermore, the control system is configured to output a signal indicative of a second action, different than the first action, if the magnitude of slippage is greater than the second threshold value.

In a method for controlling a vehicle with a drive system comprising an output shaft of a combustion engine and a planetary gear with a first and a second electrical machine, connected via their rotors to the components of the planetary gear, the combustion engine is started while the vehicle is driven by ensuring that the rotor of the second electrical machine is connected with the output shaft of the combustion engine, and controlling such electrical machine's rotational speed towards the combustion engine's idling speed, whereupon fuel injection into the combustion engine is carried out to start the latter.

A method and system for controlling the stability and yaw response of a vehicle being equipped with a front axle (24), a rear axle (26), a controllable differential (22) and a control unit (50) arranged for locking and unlocking the differential (22), the method includes: selectively locking or unlocking the differential (22) depending on the operation of the vehicle; measuring at least the longitudinal vehicle speed (v); comparing the measured vehicle speed (v) with a predetermined first reference speed (v.sub.H); and locking the differential (22) if the measured vehicle speed (v) exceeds the first reference speed (v.sub.H).

A method to control a road vehicle with steering rear wheels when driving along a curve. The control method comprises the steps of: determining an actual attitude angle of the road vehicle; determining a desired attitude angle; and changing the steering angle of the rear wheels based on the difference between the actual attitude angle and the desired attitude angle.

In a method for controlling a vehicle with a drive system comprising an output shaft in a combustion engine, a planetary gear and a first and second electrical machine connected to the planetary gear, the turning off of the combustion engine is achieved when the vehicle is driven with the combustion engine running, and a transition to operation of the vehicle with the electrical machines is achieved by ensuring that the second electrical machine's rotor is connected with the combustion engine's output shaft, that injection of fuel into the combustion engine is interrupted and that the second electrical machines rotational speed is controlled towards and until a standstill, whereupon the combustion engine's output shaft is disconnected from the second electrical machine and the planetary gear.

In a method for controlling a vehicle with a drive system comprising a power unit configuration adapted to provide power for the vehicle's operation, and further comprising a planetary gear and a first and second electrical machine, connected to components in the planetary gear via their rotors, a locking means is moved from a release position, in which the planetary gear's components are free to rotate independently of each other, to a locked position, in which two of the planetary gear's components are locked together, so that the three components in the planetary gear rotate with the same speed. The power unit configuration is controlled in order to achieve a synchronous, or substantially synchronous, rotational speed between the input and output shaft of the planetary gear, and the locking means are then moved to the locked position.