Method of directing drilling pattern in curved tunnels, rock drilling rig, and software product

The invention relates to a method of determining a direction of a drilling pattern in tunnel curve calculation to be executed in a control unit of a rock drilling rig. The invention further relates to a software product implementing the method, and a rock drilling rig. A tunnel line (16) of a tunnel to be excavated is determined e.g. by using curve fitting. A location of a drilling site on the tunnel line is communicated to the control unit (11) and a navigation plane (19) of the drilling pattern (28) is positioned on the tunnel line. A start point (30) of a round is positioned on the tunnel line (16) and a length (L) of the round is provided. Further, an end point (31) of the round is positioned at a distance corresponding with the length of the round from the start point and a coordinate system (29) of the drilling pattern is directed such that one of its axes points from the start point to the end point. Finally, different coordinate systems are transformed.