An arrangement and a method for controlling at least one
drill parameter when drilling in rock with a rock
drill, comprising an impulse-generating device arranged to induce shock
waves in a tool acting against the rock with a percussive force generated via a
shock wave-generating pressure. The arrangement also comprises a rotation-generating device arranged to supply a torque to the
impact device with a rotation generated via a rotation pressure, and a pressurisable damping chamber arranged to at least partially regulate the rock
drill's contact with the rock via the prevailing pressure in the damping chamber, in which connection the
shock wave-generating pressure is regulated depending on the rotation pressure. The arrangement comprises a
control system arranged to: determine a first parameter value representing the damping pressure or
feed pressure, determine a second parameter value representing the
drill bit's rotation pressure, determine a deviation between the above second parameter value and a rotation pressure reference value, determine a parameter reference value depending on the above deviation and regulate the percussion pressure based on a function of the above deviation and the above parameter reference value.