Method and apparatus for filtering out signal components from output signals of a differential dosing scale using a fuzzy logic filter

An apparatus for filtering out measurement falsifying signal components from actual measured scale output signals of a differential dosing scale, comprising a differential dosing scale including a feed drive and weight sensors (3) for measuring actual scale output signal variations to provide size variations representing values, and a signal evaluating and control circuit (4) for processing said size variations representing values, said control circuit comprising a differentiating circuit (5) having an input connected to said weight sensors through a conductor (3A) for producing an actual feed rate signal at an output (5A, 5B) of said differentiating circuit (5), a time variable filter (6) having a first input (6A) connected to said output (5B) of said differentiating circuit (5), said time variable filter (6) having a first output (6B) providing a future prognosis value and a second output (6C) providing a current estimated value, a first comparator circuit (7) having a first input connected to said output (5A) of said differentiating circuit (5) to receive said actual feed rate signal and a second input connected to said first output (6B) of said time variable filter (6) to receive said future prognosis value for producing a first difference value (at 7A) between said future prognosis value and said actual feed rate signal at a signal sampling time, said signal evaluating and control circuit (4) further comprising a fuzzy logic circuit (9) having a first input (9A) connected to an output (7A) of said first comparator circuit (7) for evaluating said first difference value for its size to provide size variations representing values and for allocating said size variations representing values to different value groups representing the type and size of a disturbance that causes said measurement falsifying signal components, said fuzzy logic circuit producing a filter control signal at its control output (9B) in response to said value groups, said time variable filter (6) having a second control input (6D) connected through a conductor (9F) to said control output (9B) of said fuzzy logic circuit (9) for controlling said time variable filter (6) to filter out said measurement falsifying signal components in response to said filter control signal so that said estimated value at said second output (6C) of said filter (6) is free of said falsifying signal components.