Method performed by a control device for controlling the feeding distance and feeding rate in a rock drilling unit, a rock drilling unit and a rock drilling rig

A method performed by a control device for controlling a feeding distance and a feeding rate in a rock drilling unit, the rock drilling unit comprising:

• a feeding device for feeding at least one drill rod and a drill bit in an axial direction;
• a rotating device configured to generate a rotational movement of the at least one drill rod and the drill bit;
• a hose drum rotatably driven by a motion of the feeding device, wherein in an event of feeding the feeding device in first direction, hoses are unwound from the hose drum and the hose drum rotates in a first rotational direction, and wherein in an event of feeding the feeding device in a second direction, the hoses are winded up on the hose drum and the hose drum rotates in a second rotational direction;
• and
• a distance and rate measuring device comprising at least one rotational target wheel configured to be driven by the feeding device and at least one sensor device connected to the control device, wherein the at least one sensor device is configured to sense a rotational motion of the at least one rotational target wheel;
• wherein the at least one rotational target wheel is connected to the hose drum, the at least one rotational target wheel being arranged directly on a rotational axis of the hose drum, or being arranged at distance from the hose drum and connected to the hose drum by a transmission;
• wherein the at least one rotational target wheel is arranged to follow a rotational motion and rotational direction of the hose drum;
• the method comprising:
• controlling the feeding device to move in the axial direction;
• determining the feeding distance from a first position and the feeding rate of the feeding device from the rotational motion of the at least one rotational target wheel;
• determining an axial direction of the feeding device based on the rotational motion of the at least one rotational target wheel;
• controlling the feeding device based on the determined feeding distance, feeding rate, and axial direction of the feeding device.