Apparatus and method for positioning rock drilling rig

A method of drilling angular drill holes, the method comprising:

• providing a drilling a rock drilling rig including a mobile drilling platform, a drilling mast, at least one rock drilling unit supported by the drilling mast and a drilling tool connected to the drilling unit, the drilling mast, the drilling unit and the drilling tool being arranged to move vertically;
• determining a target drill hole to be drilled;
• tilting the drilling mast relative to the drilling platform to set an angle of the drilling tool to correspond with a drilling angle of the target drill hole and in response to the drilling platform;
• positioning the rock drilling rig by tramming the drilling platform to a drilling position in accordance with a start point of the target drill hole;
• leveling the drilling platform after the tramming vertically from the initial vertical tramming position to a levelled vertical drilling position, whereby also;
• drilling a drill hole by means of the drilling tool;
• receiving sensing data on position and orientation of the drilling tool;
• determining a first aiming line passing along the drilling tool at an initial vertical tramming position of the drilling platform;
• determining data on vertical levelling requirement for levelling the drilling platform from the initial vertical tramming position to an estimated levelled vertical drilling position;
• determining a second aiming line passing along the drilling tool at the estimated levelled drilling position;
• determining intersection points between the aiming lines and a reference plane;
• calculating an estimated displacement between the aiming lines on the reference plane in response to the determined vertical levelling requirement;
• indicating the estimated displacement for providing positioning information;
• and
• moving by means of the tramming the drilling tool at the displacement distance from the target drill hole until initiating the leveling.