Mobile work machine and method for a work machine

A method for a mobile work machine where the mobile work machine includes

• a knuckle boom crane for lifting loads comprising at least two booms articulated to each other and actuators for moving the booms;
• a tool suspended from the knuckle boom crane for grabbing a load;
• a control system for controlling the knuckle boom crane at least partially automatically, wherein the control system includes a database comprising at least one control rule for protecting the knuckle boom crane from overloading, the method involving
• controlling of the knuckle boom crane at least partially automatically using the control system for grabbing a load;
• protecting the knuckle boom crane with the control system programmatically based on the control rule by limiting the operation of the actuators before the actual use of the knuckle boom crane for lifting or handling a load, wherein the control rule includes a tool-specific lifting force rule limiting a maximum allowable lifting force of the knuckle boom crane at each reach of the knuckle boom crane and the knuckle boom crane has a physical maximum reach and when following the reach rule, the control system is arranged to protect the knuckle boom crane by limiting the reach of the knuckle boom crane programmatically to less than the maximum reach.