Area Sensor Weighing Scale for Uneven Load Accuracy
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Solution Overview
Problem
Existing electronic weighing scales face inaccuracies when loads are unevenly positioned, as different load cells sense varying forces, leading to offset weight calculations, and existing solutions can only estimate the center of mass or count similar-weight items, failing to accurately determine the position and weight of multiple objects or changes in load distribution.
Innovation Solution
A weighing scale with a platform supported by force transducers and an area sensor that outputs force signals, allowing a processor to determine the weight and location of the load by measuring transducer force signals and area force signals, enabling accurate weight determination and center of mass calculation, even under asymmetrical loads, and monitoring changes in weight and location over time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple load cells are used at the corners of the platform, then the scale can support larger loads and provide broader measurement range, but measurement precision deteriorates when the load is unevenly positioned on the platform
Solution Approach 1:
The platform surface is divided into multiple discrete sensing zones using an array of capacitive sensors (e.g., 4x4 grid or more), allowing independent measurement of load at each location. This segmentation enables the system to detect not only total weight but also the spatial distribution of the load, thereby resolving the contradiction between supporting large loads and maintaining precision under uneven positioning.
Solution Approach 2:
The invention transitions from traditional single-dimensional weight measurement to two-dimensional spatial-weight measurement by incorporating area sensors that detect load position across the platform surface. This dimensional expansion allows the system to simultaneously determine total weight and center of mass location, correcting for uneven load distribution while maintaining measurement precision.
2Device complexity
If load cells are positioned at specific locations to simplify the structure, then device complexity is reduced, but the ability to accurately detect load position and center of mass deteriorates
Solution Approach 1:
Instead of using a few complexly positioned load cells, the invention employs numerous simple capacitive sensors arranged in a regular grid pattern across the platform. This segmentation approach simplifies individual sensor placement while collectively providing comprehensive spatial and weight information through signal processing algorithms that calculate center of mass from the distributed sensor readings.
3Quantity of substance
If traditional load cells are used to detect force, then the scale can measure weight, but the ability to detect load position and monitor changes over time deteriorates
Solution Approach 1:
The capacitive sensor array serves multiple functions simultaneously: it measures total weight through summation of all sensor signals, determines load position through spatial analysis of signal distribution, tracks center of mass movement over time through sequential measurements, and even detects the presence and number of separate objects. This multi-functionality eliminates the need for separate sensing systems for each measurement type.
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 solution provides improved accuracy in weighing and counting items by precisely determining the load's position and weight, correcting for non-ideal load positions and detecting gradual changes, suitable for diverse applications including diet management and inventory monitoring.
Implementation Method 1
The load cells can detect load using, e.g., variable resistance or variable capacitance. For example, U.S. Publication No. 2010/0307839 by Bradley describes capacitive load cells at the corners of the scale.
Implementation Method 2
one or more sensor elements bonded thereto. When a load is applied to the load cell, the sensor plate mechanically bends and the sensor elements bonded thereto produce an electrical output signal
Data Source
AI summary
A weighing scale includes a platform supporting a load. Force transducers beneath the platform output respective transducer force signals of the load. An area sensor above the platform outputs area force signals of load forces applied to respective spatial areas of the platform. A processor is configured to determine the load's weight and location on the platform based on the transducer force signals and the area force signals. A method of weighing the load is also described. A method of monitoring the load includes measuring first transducer force signal(s) and first area force signal(s) of the load, and then repeatedly measuring second force signal(s) of the load using the transducer(s) or area sensor until the first and second signal(s) indicate a change in a weight or location of the load. A changed weight or changed location of the load is then determined using the measured second force signal(s).