Rotary Encoder Bearing Fault Detection at Varying Speeds
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Solution Overview
Problem
Existing methods for detecting faults in rotary bearings are complex, require offline data processing, and are ineffective at varying speeds, leading to increased costs and system complexity.
Innovation Solution
A method using a rotary encoder coupled to a bearing to generate a position-speed-signal, which is processed by an integrated circuit to determine instantaneous angular speeds, filtered, and decimated for fault detection during operation, allowing detection at varying speeds with high resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If data are gathered at high speed for precise fault analysis, then measurement precision is improved, but device complexity and processing complexity increase
Solution Approach 1:
The patent segments the high-speed data stream by selecting only specific samples based on instantaneous angular position thresholds. Instead of processing all high-speed data points, the system divides the data collection into angular segments and selectively samples from these segments, reducing processing complexity while maintaining fault detection precision.
Solution Approach 2:
The patent extracts only the necessary data points from the high-speed data stream by applying angular position-based selection criteria. The controller identifies and extracts samples that fall within specific angular ranges relative to the bearing's rotation, discarding redundant data while preserving fault-related information.
2Measurement precision
If data are gathered at high speed for precise fault analysis, then measurement precision is improved, but loss of time increases due to offline processing requirement
Solution Approach 1:
The patent performs preliminary organization of data during the acquisition phase by tagging samples with their instantaneous angular positions. This preliminary action prepares the data in advance for efficient processing, allowing the system to skip time-consuming offline analysis steps and enable real-time or near-real-time fault detection.
3Measurement precision
If separate detection device is used for bearing fault analysis, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the fault detection functionality into the existing motor controller by integrating the encoder signal processing and fault analysis algorithms into the controller's existing architecture. This consolidation eliminates the need for separate detection devices while maintaining fault detection precision through the angular position-based sampling method.
Solution Approach 2:
The motor controller is designed to perform multiple functions: it controls motor operation, processes encoder signals for position feedback, and simultaneously performs bearing fault detection by analyzing the same encoder data with angular position-based sampling. This multi-functionality reduces system complexity by eliminating dedicated fault detection hardware.
4Measurement precision
If fault analysis is performed at constant speed, then measurement precision is improved, but adaptability decreases for varying speed operations
Solution Approach 1:
The patent implements a dynamic sampling strategy where the selection of data samples is based on instantaneous angular position rather than fixed time intervals or constant speed assumptions. The controller continuously adjusts which samples to collect based on the current rotational position, allowing accurate fault detection across varying speeds by maintaining the angular position reference frame.
Data Source
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AI summary
A method for detecting a fault of a bearing (6) is described. The method comprises: receiving a position-speed-signal (29), wherein the position-speed-signal (29) is representative of instantaneous angular speeds (vi) of teeth (12) of a wheel (10) of a rotary encoder (8) and of unique numbers (i) of corresponding encoder pulses (28) from the rotary encoder (8); determining the instantaneous angular speeds (vi) and the corresponding unique numbers (i) from the position-speed-signal (29) several times; generating a speed signal comprising consecutive ones of the instantaneous angular speeds (vi); shifting the generated speed signal depending on a predetermined shifting frequency (fshift); applying a low pass filter on a correspondingly shifted speed signal (vshifted); determining a decimated speed signal (vshifted_filtered_downsampled) from a correspondingly shifted and filtered speed signal (vshifted_filtered), wherein the decimated speed signal (Vshifted_filtered_downsampled) is representative for a subset of the realigned instantaneous angular speeds (vn) represented by the shifted and filtered speed signal (vshifted_filtered); and detecting the fault of the bearing (6) depending on the determined decimated speed signal (vshifted_filtered_downsampled).