Carl Schenck Ag

Hans Werner

Gerhard Jost

Volker Tews

Josef Wehhofer

The accuracy of the output feed rate or output feed quantity of a differential dosing scale is increased by eliminating from the respective feed rate signal or output quantity signal measuring disturbance that can adversely influence the output accuracy. For this purpose, the size of the output signal variations or of the feed rate variations are processed in a fuzzy logic circuit (9) which allocates the respective signals to fuzzy sets, e.g. 'small', 'medium', 'large' in accordance with type and size of the disturbance or interference. The fuzzy logic circuit (9) forms a filter control signal that corresponds to a filtering degree or filter factor. The filtering control signal controls the time constant of a time variable filter (6) through which the differentiated signal coming from the dosing scale load cells is passed prior to processing in the fuzzy logic circuit (9).

Method and apparatus for filtering out signal components from output

In a method and system for controlling a differential dosing scale having a weighing device and a control for the delivery rate especially of loose bulk material achieved by comparison of rated and actual weight values, measures are taken to eliminate the effects of disturbances of the output signal of the weighing device. Improvements are achieved in that an estimated or predicted value (G) for the next measured weight value is derived from previously measured values (G.sub.i) of the output signal (G) of the weighing device. The predicted value (G) is compared with the next actual measured value (G.sub.i) to determine a difference. If this difference exceeds a prescribed tolerance range or value, the control of the delivery rate continues at the unchanged previous actual value (P) of the delivery rate. Thus, the effects of disturbances are greatly reduced or even completely eliminated. Changes in the rated value of the delivery rate can also be taken into account. A differential dosing scale for carrying out the method includes appropriate hardware components or software for achieving the described control.

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Darmstadt, Germany

Hans Werner