Method for determining whether or not ground contact loss is imminent for a wheel of a vehicle

A control unit for a vehicle, the control unit being adapted to determine whether or not ground contact loss is imminent for a wheel of the vehicle, the vehicle comprising a vehicle body having a vertical extension in a vertical direction, the wheel being allowed to be subjected to a relative vertical displacement, in the vertical direction, in relation to the vehicle body, wherein the vehicle further is such that a maximum value of a vertical displacement of the wheel relative to the vehicle body is limited to a relative vertical displacement limit, the control unit being adapted to:

• determine an actual relative vertical displacement of the wheel relative to the vehicle body,
• determine a limit margin as the difference between the actual relative vertical displacement and the relative vertical position limit,
• determine that ground contact loss is imminent for a wheel if the limit margin is within a predetermined vertical threshold range,
• upon determining that ground contact loss is imminent, reduce torque that is transmitted to the wheel,
• wherein the vehicle comprises a bogie system, the bogie system comprising a plurality of wheels and the bogie system being such that each one of the wheels is allowed to be subjected to a relative vertical displacement in relation to the vehicle body.