denotes the duration of the current pressure build up 25 see fig2 a q p max v p max u2212 v p min t up fig2 b reference number 20 q p mod v p mod u2212 v p min t up fig2 b reference number 17 finally the above variables of the volume flow error q error are calculated in the valve actuation process q error q p max u2212 q p mod q p mod fig2 b reference number 18 in the text which follows the current pressure build up cycle will be denoted by the value n the pressure build up cycle following said cycle is indexed with the value n 1 in the cycle n 1 the volume flow q req which is set at the valve is then corrected with the value of the calculated volume flow error q error in accordance with the following formula in which the absolute value of this variable q error is limited in particular to a maximum value q error lt q error max it can also be advantageous for the correction method according to aspects of the invention not to be carried out until a specific number of control cycles have already been carried out during a brake control process the control system is then in a steady state and more accurate correction values are therefore obtained according to a further preferred embodiment of the invention it is possible to determine q error over a larger number of cycles or over one complete abs control process and to determine a mean value from the individual cycles or over the entire abs control process it would also be appropriate in particular to store the correction values q error over the ignition run.