Load Cell Data Validation Using Door Sensor Correlation

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Solution Overview

Problem

In materials handling facilities, load cell data used for inventory management is often contaminated by erroneous weight changes due to air movement and thermal effects when doors are opened, leading to inaccurate interaction data and increased resource utilization.

Innovation Solution

The implementation of door sensors and analysis techniques to determine the validity of weight data by correlating data from multiple shelves, analyzing trajectory data, and using machine learning to distinguish between valid and invalid weight changes, ensuring accurate interaction data is derived.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If door sensors and analysis techniques are implemented to determine weight data validity, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improveweight data accuracyVSAvoidsystem complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system performs preliminary validation of weight data by checking door sensor status before processing load cell measurements. By determining whether the door was open or closed at the time of weight measurement, the system can pre-filter erroneous data points caused by air movement, thereby improving measurement precision without requiring complex post-processing algorithms

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The door sensor acts as an intermediary indicator that mediates between the physical environment (door state) and the measurement system (load cell data). By using the door sensor status as an intermediate validation criterion, the system can identify and exclude invalid weight measurements caused by air movement when the door is open, improving measurement accuracy through a simple binary state check rather than complex analysis

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If multiple shelves' weight data are correlated to determine validity, then reliability is improved, but loss of time increases

Engineering Contradiction:
Improveinteraction data reliabilityVSAvoiddata processing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The system segments the validation process into independent shelf-level assessments. Instead of performing complex global correlation analysis across all shelves simultaneously, the system evaluates each shelf's weight data independently against its door sensor status and local consistency criteria, then combines results. This segmentation reduces computational complexity and processing time while maintaining reliability through distributed validation

Inventive Principle:
Principle #1Segmentation

3Measurement precision

If machine learning techniques are used to distinguish valid and invalid weight changes, then measurement precision is improved, but use of energy increases

Engineering Contradiction:
Improveweight change classification accuracyVSAvoidcomputational energy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The system uses the door sensor status as a self-service validation mechanism that automatically identifies invalid weight measurements without requiring energy-intensive machine learning models. By leveraging the inherent information from the door sensor (open/closed state), the system can self-determine which weight changes are erroneous due to air movement, achieving accurate classification with minimal computational energy consumption

Inventive Principle:
Principle #25Self-service

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 approach effectively filters out invalid weight data, reducing errors and resource consumption by providing reliable interaction data for inventory management systems, allowing for precise tracking of item interactions.

Implementation Method 1

A plurality of load cells at the shelf are configured to generate weight data

Methodology Applied
Scientific EffectForce detection: Force

Implementation Method 2

A door sensor in the fixture is configured to provide door sensor data indicative of a configuration of the door at a particular time

Methodology Applied
Scientific EffectPosition detection:

Data Source

PatentUS10520353B1System to process load cell data
Publication Date: 2019.12.31 AMAZON TECH INC
  • US10520353B1 patent drawing
  • US10520353B1 patent drawing
  • US10520353B1 patent drawing

AI summary

Shelves or other fixtures may be used to hold items at a facility. Load cells at the fixtures may be used to acquire weight data indicative of changes to the fixture as items are added or removed from the fixture. The fixtures, such as a freezer case, may include a door that when opened or closed results in air movement with respect to the shelves. This air movement may produce weight data that is erroneously indicative of a false event, such as a pick or place, even when no actual event has taken place. Weight data from load cells in the shelves may be analyzed to determine a correlation in the data from multiple shelves. If there is a high correlation in the changes to the weight data at multiple shelves, the weight data may be disregarded as being due to air movement.