In a method for computing a target setting value—which is adapted to a harvesting process—for a control parameter of a working unit of a harvesting machine, operating-result curves are plotted for a plurality of different operating-result parameters as a function of the related control parameter, a target setting value of the control parameter is subsequently computed based on a combination of the plotted operating-result curves, and a method and a corresponding control unit for controlling a working unit of a harvesting machine, and a harvesting machine with a control unit of this type are also provided.