Drum Motor Torque Sampling for Fast Laundry Load Estimation
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Solution Overview
Problem
Current methods for determining the laundry load in washing machines are either time-consuming, inaccurate due to fabric type variations, or limited to specific washing programs, and do not provide a simple, quick, and precise solution.
Innovation Solution
A method involving controlling the electric motor to change the rotational speed of the drum according to a prefixed reference speed profile, sampling torque values during acceleration and constant speed phases, and calculating an integral value to determine the laundry load, which includes acceleration and deceleration ramps, and using these values to estimate the load index.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If water absorption method is used to estimate laundry load, then the method is simple to implement, but the accuracy is low due to fabric type variations
Solution Approach 1:
The patent replaces the water absorption method with a motor parameter-based measurement system. During the drum acceleration phase, the controller measures motor current, voltage, and rotational speed to calculate torque and power consumption. These mechanical/electrical parameters directly reflect the laundry load without being influenced by fabric type, thereby improving measurement accuracy while maintaining implementation simplicity through existing motor control circuits.
Solution Approach 2:
The patent changes the measurement parameter from water absorption quantity to motor electrical parameters (current, voltage, speed, torque). By measuring how the motor performs during drum acceleration instead of how much water the laundry absorbs, the system achieves accurate load estimation independent of fabric material properties.
2Measurement precision
If water loading procedure is performed to complete estimation, then the estimation can be obtained, but the time consumption is excessive (more than 15 minutes)
Solution Approach 1:
The patent performs load estimation during the initial drum acceleration phase before the main washing cycle begins. By measuring motor parameters during this brief acceleration period (typically just a few seconds to a minute), the system obtains load estimation results much faster than the water loading method, eliminating the 15+ minute delay while still achieving accurate measurements.
Solution Approach 2:
The patent skips the time-consuming water loading procedure entirely and rushes through the estimation process by utilizing the necessary drum acceleration phase. Instead of waiting for water to be loaded and absorbed over many minutes, the system quickly measures motor parameters during the acceleration ramp-up, achieving fast estimation without sacrificing accuracy.
3Measurement precision
If fabric-type specific algorithms are used to correct estimation, then accuracy for specific fabrics improves, but the device complexity increases
Solution Approach 1:
The patent replaces complex fabric-type-specific correction algorithms with a universal motor parameter-based measurement approach. Since motor torque and power consumption during acceleration directly reflect the actual physical load regardless of fabric composition, the system eliminates the need for multiple correction algorithms for different fabric types, thereby reducing device complexity while maintaining or improving accuracy across all fabric types.
4Measurement precision
If motor in generator mode is used to determine load, then the measurement can be performed, but additional electrical components and complexity are required
Solution Approach 1:
The patent uses the motor in motor mode (not generator mode) during the drum acceleration phase. By measuring electrical parameters (current, voltage, speed) during the normal acceleration operation, the system calculates torque and power consumption without requiring the motor to operate as a generator. This approach eliminates the need for additional electrical components while achieving accurate load measurement using the existing motor control system.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for quick and precise determination of the laundry load without additional electrical components, improving accuracy and applicability across various washing programs.
Implementation Method 1
an electric motor for rotating said drum
Implementation Method 2
controlling the electric motor to cause said drum to change the rotational speed according to a prefixed reference speed profile comprising at least an acceleration ramp
Data Source
AI summary
A method to control a laundry machine. The method includes: controlling an electric motor to rotate a drum to change the rotational speed according to a prefixed reference speed profile comprising an acceleration ramp from a low speed to a prefixed high speed and a constant speed phase at the high speed, sampling first torque values generated by the motor during the acceleration ramp according to a first sample time, sampling second torque values generated by the motor during the constant speed phase according to a second sample time, calculating a third value indicative of an average torque being calculated on the basis of the second torque values, determining a fourth value by performing an integral function with respect to the first torque values less the third value, and determining the amount of laundry load on the basis of the fourth value.