Bag Weight Sensor Detects Missing Items
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Solution Overview
Problem
Existing solutions for detecting missing items from a bag, such as student backpacks, are ineffective due to their inability to account for the frequent removal and reinsertion of items throughout the day, leading to error-prone and annoying weight measurements.
Innovation Solution
A device coupled to a bag that measures the weight of items at designated times throughout the day, stores these weights as calibrated and measured values, and notifies the user if the measured weight is less than the calibrated weight, indicating a missing item.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If weight measurements are taken continuously to detect missing items, then detection accuracy is improved, but user frustration increases due to frequent false alarms from normal item removal and reinsertion
Solution Approach 1:
The system performs weight measurements at periodic intervals rather than continuously, with scheduled measurement times spaced throughout the day. This reduces the frequency of measurements to a manageable level that avoids user frustration while still providing adequate monitoring for detecting missing items.
Solution Approach 2:
The system establishes a baseline weight measurement at a scheduled time before the user typically removes items from the bag. By comparing subsequent measurements against this pre-established baseline, the system can distinguish between normal item removal and actual missing items without requiring continuous monitoring.
2Reliability
If weight measurements are taken at multiple scheduled times throughout the day, then false alarms from normal item removal are reduced, but device complexity increases
Solution Approach 1:
The system automatically manages its own measurement scheduling without requiring user intervention. The microcontroller autonomously determines when to perform measurements based on pre-programmed schedules, compares weights, and triggers notifications, making the system self-sufficient and reducing operational complexity.
Solution Approach 2:
The system combines multiple functions into a single integrated device: weight sensing (load cell), time management (schedule storage and execution), data processing (weight comparison), and user notification (alert generation). This consolidation reduces overall system complexity compared to having separate systems for each function.
3Ease of operation
If the system requires minimal user interaction to provide alerts, then ease of operation is improved, but the ability to handle dynamic item removal and reinsertion decreases
Solution Approach 1:
The system adapts its measurement schedule dynamically based on the bag's usage patterns. By detecting when the bag is being worn (via force-sensitive resistor) and adjusting measurement timing accordingly, the system remains responsive to dynamic item changes while maintaining ease of operation through automated adjustments.
Solution Approach 2:
The system uses feedback from weight measurements to automatically adjust its operation. When weight changes are detected at scheduled times, the system compares against baseline measurements and triggers notifications only when actual missing items are detected, rather than requiring user input or continuous adjustment.
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 allows for accurate detection of missing items with minimal user interaction, reducing errors and user frustration by considering the dynamic nature of item removal and reinsertion in a busy daily schedule.
Implementation Method 1
measuring at a first time with a load cell a first weight of the set of items
Implementation Method 2
determining with a force-sensitive resistor that the bag is being worn by a user
Data Source
AI summary
A method and system comprising a device coupled to bag containing a set of items includes measuring at a first time with a load cell a first weight of the set of items, storing the first weight as a calibrated weight, following a second time and after determining with a force-sensitive resistor that the bag is being worn by a user, measuring with the load cell a second weight of the set of items, storing the second weight as the measured weight, determining whether the measured weight is less than the calibrated weight, and, if so, notifying the user that at least one of the set of items is missing. A mobile device running bag application software coupled to the device may be further deployed to enhance the functionality described above by allowing the first and second times to be automatically updated from a class schedule.