Electro-hydraulic steering system and a method of controlling an electro hydraulic steering system

A computer implemented method of controlling an electro-hydraulic steering system for a vehicle comprising a steering wheel and a steered wheel, the method comprising:

• determining an angular misalignment between the angular position of the steering wheel and the angular position of the steered wheel;
• and
• carrying out a realignment procedure, the realignment procedure comprising:
• calculating a compensation angle based on the angular misalignment;
• and
• outputting a control signal for controlling the steering ratio of the vehicle based on the compensation angle;
• the method further comprising:
• receiving a steering demand for rotating the steered wheel through a rotation angle;
• determining a turning direction of the steering demand;
• and;
• determining an aligned angular position (L*) of the steered wheel in relation to an angular position (D) of the steering wheel, wherein the realignment procedure comprises:
• determining if an angular position of the steered wheel (L) is ahead of or behind the aligned angular position (L*) of the steered wheel in the turning direction;
• and
• if the angular position (L) of the steered wheel is ahead of the aligned angular position (L*) of the steered wheel in the turning direction, adjusting the steering ratio of the electro-hydraulic steering system to decrease the rotation angle of the steered wheel by the compensation angle, so as to rotate the steered wheel by a compensated rotation angle;
• or
• if the current angular position (L) of the steered wheel is behind the aligned angular position (L*) of the steered wheel in the turning direction, adjusting the steering ratio of the electro-hydraulic steering system to increase the rotation angle of the steered wheel by the compensation angle, so as to rotate the steered wheel by a compensated rotation angle.