Digital Filter for Weigher Using Adaptive FIR Coefficients
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Solution Overview
Problem
Existing digital filters for digital weighers face challenges in reducing calculation time while maintaining weighing accuracy, especially in combination weighers, due to differences between preset and actual frequency ranges of oscillating components, leading to increased weighing time and reduced accuracy.
Innovation Solution
A digital filter comprising a FIR filter with a fixation section for removing predetermined oscillating components and an adaptive section for changing frequency ranges based on amplitude determination, reducing unnecessary calculations and improving damping efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the filter coefficient is re-calculated to remove oscillating components with varying frequency characteristics, then the oscillating components can be effectively removed, but the calculation time increases and weighing speed decreases
Solution Approach 1:
The patent pre-calculates and stores multiple filter coefficients corresponding to different frequency characteristics before actual weighing operations. When oscillating components are detected, the system quickly switches between pre-prepared coefficients without performing real-time calculations, thus removing oscillations effectively while maintaining fast weighing speed.
Solution Approach 2:
The system dynamically selects appropriate filter coefficients from a set of pre-calculated options based on the detected oscillation characteristics. This dynamic selection allows the filter to adapt to varying frequency characteristics without requiring time-consuming re-calculation during the weighing process.
2Measurement precision
If the filter order is increased to expand the frequency range of oscillating components to be removed, then more oscillating components can be removed, but the calculation amount increases and weighing time increases
Solution Approach 1:
The system dynamically adjusts the filter order based on the detected oscillation frequency characteristics. When oscillations are present, the filter order is increased to expand the frequency range; when oscillations are absent, the filter order is reduced to minimize calculation amount, thus maintaining weighing speed while ensuring adequate oscillation removal.
Solution Approach 2:
The patent changes the filter order parameter adaptively according to the oscillation situation. By adjusting this key parameter, the system expands or contracts the frequency range coverage of the filter, balancing between oscillation removal capability and calculation efficiency.
3Productivity
If a preset filter coefficient is used to reduce calculation time, then weighing speed increases, but the oscillating components may not be effectively removed if there is a great difference between preset and actual frequency ranges
Solution Approach 1:
The system performs preliminary detection of oscillation characteristics before using preset filter coefficients. Based on this detection, it selects the most appropriate pre-calculated coefficient that matches the actual frequency range, ensuring effective oscillation removal while maintaining fast weighing speed through quick selection rather than calculation.
Solution Approach 2:
The system continuously monitors the oscillation characteristics in the weighing signal and provides feedback for selecting appropriate filter coefficients. This feedback mechanism ensures that the preset coefficients being used are actually effective for the current oscillation conditions, maintaining both speed and accuracy.
Data Source
AI summary
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.