Digital filter for digital weigher, digital weigher including digital filter for digital weigher and wave filtering process method

Patent metadata

Field	Value
Publication number	US-9970809-B2
Application number	US-201013820130-A
Country	US
Kind code	B2
Filing date	Sep 8, 2010
Priority date	Sep 8, 2010
Publication date	May 15, 2018
Grant date	May 15, 2018

Abstract

A digital filter for a digital weigher reduces a calculation time in an adapted filter while maintaining weighing accuracy, a digital weigher includes the filter for the weigher, and a wave filtering process method uses the digital filter for the digital weigher. A fixation section of a FIR filter removes an oscillating component in a predetermined frequency range, from a digital weighing signal. A determination device determines whether an amplitude of an oscillating component contained in a digital weighing signal derived by performing a wave filtering process falls within a predetermined damping range. A control device changes a frequency range of an oscillating component to be removed by an adaptive section of the filter based on a result of the determination. The adaptive section of the filter performs the wave filtering process with respect to the oscillating component in the frequency range changed by the control device.

First claim

The invention claimed is:

1. A digital filter for a digital weigher, comprising:
a FIR filter configured to perform a wave filtering process with respect to a digital weighing signal to remove oscillating components from the digital weighing signal, the FIR filter including:
a fixation section configured to remove an oscillating component in a predetermined frequency range, without performing calculation for the predetermined frequency range within one weighing cycle, and
an adaptive section for removing an oscillating component in a changeable frequency range;

a determination device for determining whether or not an amplitude of an oscillating component falls within a predetermined allowable damping range, in every predetermined sampling of the digital weighing signal within the weighing cycle;
a control device configured to change the frequency range of the oscillating component in the changeable frequency range which is to be removed by the adaptive section, based on a result of the determination performed by the determination device; and
wherein both of the fixation section and the adaptive section of the digital filter sequentially perform the wave filtering process with respect to the digital weighing signal input to the digital filter.

2. The digital filter for the digital weigher according to claim 1 ,
wherein the control device is configured to change a filter coefficient of the adaptive section to change the frequency range of the oscillating component which is to be removed by the adaptive section.

3. The digital filter for the digital weigher according to claim 2 , wherein the control device is configured to calculate the filter coefficient based on the digital weighing signal which has been subjected to the wave filtering process in the fixation section.

4. The digital filter for the digital weigher according to claim 1 ,
wherein the control device is configured to change a filter order of the adaptive section by a predetermined number to change the frequency range of the oscillating component which is to be removed by the adaptive section.

5. The digital filter for the digital weigher according to claim 1 ,
wherein the fixation section is configured to remove a character frequency of a weight sensor of a digital weigher which weights objects, from the digital weighing signal input to the FIR filter.

6. The digital filter for the digital weigher according to claim 1 ,
wherein the adaptive section includes lattice FIR filters of a predetermined number which are connected together.

7. The digital filter for the digital weigher according to claim 1 ,
wherein the fixation section includes lattice FIR filters of a predetermined number which are connected together.

8. The digital filter for the digital weigher according to claim 1 ,
wherein the fixation section is configured to perform the wave filtering process with respect to the digital weighing signal input to the FIR filter; and
wherein the adaptive section is configured to perform the wave filtering process with respect to the digital weighing signal derived by performing the wave filtering process by the fixation section.

9. A digital weigher comprising the digital filter for the digital weigher according to claim 1 .

10. A wave filtering process method using a digital filter for a digital weigher, including a FIR filter, sequentially by configured to perform a wave filtering process with respect to a digital weighing signal to remove oscillating components from the digital weighing signal; a determination device configured to determine whether or not an amplitude of an oscillating component contained in a digital weighing signal derived by performing the wave filtering process by the FIR filter falls within a predetermined allowable damping range, in every predetermined sampling of the digital weighing signal within one weighing cycle; and a control device; wherein the FIR filter includes a fixation section configured to remove an oscillating component in a predetermined frequency range without performing calculation for the predetermined frequency range within the weighing cycle, and an adaptive section configured to remove an oscillating component in a changeable frequency range; and wherein the control device is configured to change a filter coefficient of the adaptive section, based on a result of the determination performed by the determination device, the method comprising the steps of:
calculating a filter coefficient of the fixation section based on a sine wave corresponding to a character frequency of a weight sensor of a digital weigher;
calculating a filter coefficient of a lattice filter of the adaptive section based on a predetermined integrated weighing signal;
inputting the digital weighing signal to the digital filter for the digital weigher; and
performing a wave filtering process with respect to the weighing digital signal input to the FIR filter, sequentially by the fixation section and the adaptive section, based on the filter coefficient calculated in the fixation section and the filter coefficient calculated in the adaptive section;
wherein when the determination device determines that the filter coefficient should be changed after a specified weighing cycle, the control device calculates and updates the filter coefficient of the adaptive section based on the digital weighing signal in a previous weighing cycle.

Assignees

• Ito Sachie
• Nagai Takayuki
• Shimizu Ryo
• Yamato Scale Co Ltd

Inventors

• Ito Sachie
• Nagai Takayuki
• Shimizu Ryo

Classifications

• G01G23/10

  by electric or magnetic means · CPC title

• G01G3/16

  measuring variations of frequency of oscillations of the body · CPC title

• G01G3/142

  Circuits specially adapted therefor · CPC title

• G01G23/01 Primary

  Testing or calibrating of weighing apparatus · CPC title