Patent ID: 7644782

Claim:
A method for correcting positioning errors in rock drilling occurring in a drilling rig comprising a boom and a rock drill, the boom attached at one end thereof to a carrier and being turnable in relation to it about one or more joint axes of one or more respective joints, the rock drill being turnably mounted to another end of the boom, the apparatus arranged in a drilling position for drilling a hole in a way that the boom is controlled using control devices of the drilling rig wherein the boom is subjected to various movements until the boom is in a desired set position, wherein a deviation of the boom's actual turning angle about one of said joint axes from a desired turning angle about said one of said joint axes is measured using a movement sensor, and the boom's position is corrected on the basis of the measured deviation, the method comprising the steps of: A) storing, in a memory, a first set of deviations obtained by turning the boom through incremental turning angles about said one of said joint axes from a reference position to predetermined angularly spaced intervals about said one of said joint axes, and measuring using a movement sensor, for each such interval, a deviation of the boom position from a desired incremental turning angle, and B) using the stored first set of deviations during a subsequent drilling operation as correction values for locating the boom at the desired incremental turning angles corresponding to the respective predetermined angularly spaced intervals about said one of said joint axes.