Method and control system for applying defined tensile forces

Control system for applying defined clamping forces in a brake that is electrically operable by means of an actuator and includes a first friction surface (friction lining) and a second friction surface (brake disc) in between which a clearance is allowed, wherein the application of the first friction surface against the second friction surface is determined, and wherein a static correlation exists between its actuating travel or, respectively, the actuator position (jactual) and the clamping force (Factual), including a clamping force sensor for determining the clamping force (Factual) as well as a position sensor for determining the actuator position (jactual), with a first controller (force/travel controller) to which signals representative of a clamping force nominal value (Fnominal) and a clamping force actual value (Factual) as well as an actuator position actual value (jactual) are sent as input quantities, the output quantity of said controller corresponding to an actuator speed nominal value (nnominal), a second controller (speed controller) that is connected downstream of the first controller and to which signals representative of the actuator speed nominal value (nnominal) and an actuator speed actual value (nactual) are sent as input quantities, the output quantity of said controller corresponding to an actuator torque nominal value (Mnominal), as well as a third controller (current controller) that is connected downstream of the second controller and to which signals representative of the actuator torque nominal value (Mnominal) and an actual value (Iactual) of the current to be supplied to the actuator are sent as input quantities, the output quantity of said controller representing a correcting variable (U) for adjusting the actual value (Iactual) of the current to be supplied to the actuator,

• characterized in that a characteristic curve identification module (8) is provided, to which signals representative of the actual value of the position (jmeas) measured at the actuator (4) as well as of the actual value of the actuating force (Fmeas) measured at the actuator (4) are sent as input quantities, the output quantities of the module representing signals representative of a force sensor offset value (F0), a position sensor offset value (j0) as well as the gradient of a characteristic curve illustrating the correlation, wherein the signal representative of the clamping force actual value (Factual) is generated by subtracting the clamping force sensor offset value (F0) from the signal representative of the actual value of the clamping force (Fmeas) measured at the actuator, and the signal representative of the actuator position actual value (jactual) is generated by subtracting the position sensor offset value (j0) from the signal representative of the actual value of the position (jmeas) measured at the actuator.