A Method for Controlling the Position of a Blade Lifting Yoke and a Blade Lifting Yoke for a Rotor Blade for a Wind Turbine

A method for controlling the position of a blade lifting yoke for a rotor blade for a wind turbine, said blade lifting yoke comprising:

• a yoke unit and a suspension unit, said yoke unit including a base section and a holding device, and said suspension unit being connected to a crane at a crane attachment point;
• wherein the holding device comprises a lower clamping member configured for supporting the rotor blade and an upper clamping member configured for pressing the rotor blade against the lower clamping member and being arranged at a distance from the lower clamping member in a height direction, which is perpendicular to the longitudinal direction;
• and
• wherein the suspension unit comprises a plurality of actuators each being attached to the yoke unit at a yoke attachment point and extending from said yoke attachment point towards the crane attachment point, and said yoke attachment points being distanced from each other so that the actuators are angled in relation to each other;
• the method comprising:
• changing a length of at least one of a first actuator, a second actuator, and a third actuator of the plurality of actuators, wherein each of the first actuator, the second actuator and the third actuator is controlled individually via a control unit;
• and
• moving a position of the lower clamping member relative to the crane attachment point, wherein the yoke attachment points at which said first actuator and said second actuator are attached are arranged at a distance from each other in the longitudinal direction, and wherein the yoke attachment points at which said third actuator is attached is arranged at a distance in a width direction from a least one of the yoke attachment points at which said first actuator and said second actuator are attached, said width direction being perpendicular to the longitudinal direction and to the height direction.