Bed Check Sensor Calibration for Low-Weight Detection
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Solution Overview
Problem
Existing bed monitoring systems, particularly those using Force Sensing Resistors (FSR), face challenges in accurately detecting small changes in weight, such as a child's presence, due to issues like drift, sensitivity to noise, and false alarms, especially when placed on carpets or in environments with movement.
Innovation Solution
A bed check device incorporating a Force Sensing Resistor, a resistor divider, a microprocessor, an analog-to-digital converter, a power supply, and a wireless transmitter, which automatically calibrates to compensate for drift and uses threshold-based voltage analysis to differentiate between 'in bed' and 'out of bed' states, reducing false alarms and providing accurate alerts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Force Sensing Resistor is used to detect small weight changes, then the device can detect child's weight, but the measurement precision deteriorates due to drift and noise
Solution Approach 1:
The system performs preliminary calibration by measuring the bed's initial weight before the child enters. This baseline measurement is stored and used for subsequent comparisons, allowing the system to detect only changes in weight rather than absolute weight values, thereby improving precision while compensating for drift
Solution Approach 2:
The system continuously monitors the FSR output and compares it against the calibrated baseline. When weight changes exceed a threshold, the system triggers an alert. This feedback mechanism filters out minor fluctuations and noise while reliably detecting actual weight changes
2Measurement precision
If the detection circuitry is made sensitive to detect small weight differences, then it can detect child's presence, but false alarms increase due to noise and vibrations
Solution Approach 1:
The system takes preliminary anti-action by establishing a baseline measurement and setting threshold criteria before actual detection begins. This preparation allows the system to distinguish between normal noise/vibrations and actual weight changes, preventing false alarms while maintaining sensitivity
Solution Approach 2:
The system uses feedback by continuously comparing current FSR readings against the calibrated baseline and only triggering alerts when changes exceed predetermined thresholds. This feedback loop filters out noise and vibrations while reliably detecting actual weight changes
3Measurement precision
If continuous calibration is performed to compensate for drift, then measurement accuracy is maintained, but device complexity increases
Solution Approach 1:
The system performs calibration as a preliminary one-time action before use, measuring the bed's initial weight and storing it as a baseline. This preliminary calibration compensates for drift without requiring complex continuous calibration mechanisms, maintaining accuracy while minimizing complexity
Solution Approach 2:
The system performs self-calibration by automatically measuring the baseline weight and using it for subsequent comparisons. This self-service approach maintains measurement accuracy without requiring external calibration equipment or complex manual procedures
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
The device effectively differentiates the child's weight from the bed's weight, reduces false alarms by continuous calibration and noise filtering, and sends alerts via wireless transmission, ensuring reliable monitoring of a child's presence in bed.
Implementation Method 1
a force sensing resistor; a resistor divider... wherein the force sensing resistor is in mechanical contact with a bed, such that a change in force to the bed corresponds to a change in its resistance
Data Source
AI summary
A bed check device having a force sensing resistor; a resistor divider; a microprocessor; an analog to digital converter; a power supply; a wireless transmitter; and an antenna wherein the force sensing resistor is in mechanical contact with a bed, such that a change in force to the bed corresponds to a change in its resistance and voltage, which is analyzed and acted upon by the resistor divider, microprocessor, analog to digital converter, power supply, wireless transmitter, and antenna.