Washing Drum Imbalance Detection with Calibration Compensation
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Solution Overview
Problem
Existing washing machines face challenges in accurately determining and compensating for imbalances during centrifugal operation, leading to inaccuracies in measuring the position and size of imbalances due to inherent asymmetries in rotating parts and measuring devices.
Innovation Solution
Incorporating a memory to store calibration values, specifically no-load measured values, which allows the controller to offset measured values and eliminate inaccuracies by calculating corrected values through quotient formation, and storing phase shifts between measured values and imbalance positions as a function of rotational speed for precise imbalance determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If measured values are taken during centrifugal operation to detect imbalance, then imbalance detection is enabled, but measurement accuracy deteriorates due to inherent asymmetries in rotating parts and measuring device
Solution Approach 1:
The patent applies preliminary action by performing calibration measurements during idle operation (without laundry load) before actual imbalance detection. The controller stores calibration values representing the baseline behavior of the measuring device and rotating parts. During centrifugal operation, these pre-stored calibration values are used to compensate for inherent asymmetries, thereby improving measurement accuracy while maintaining reliable imbalance detection capability.
2Measurement precision
If calibration values are stored and used to offset measured values, then measurement accuracy is improved, but device complexity increases due to additional memory and calculation requirements
Solution Approach 1:
The patent applies parameter changes by utilizing the controller's existing computational capabilities to perform quotient formation and value offsetting operations. Instead of adding complex hardware compensation mechanisms, the solution changes the processing parameters - storing calibration values and mathematically adjusting measured values by dividing by calibration values or subtracting offsets. This approach improves measurement accuracy while minimizing increases in device complexity, as it leverages the existing controller rather than adding substantial new hardware.
Data Source
Figure 1
Figure 2~5
AI summary
To measure the imbalance of the drum (1) during spinning, acceleration sensors (7) and an angular velocity sensor (8) are provided on the drum (1) and/or on the oscillating system of the device. The angle-resolved velocity signals of the angular velocity sensor (8) are compensated with calibration values obtained from measurements on an empty drum (1). The measurements of the acceleration sensors (7) are compensated with calibration values that reflect the phase shift of the displacement of the oscillating system as a function of the rotational speed of the drum (1). Using these calibration values improves the measurement accuracy of the device.