Conveyance Motion Monitoring With Pressure-Triggered Accelerometer Analysis
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Solution Overview
Problem
Existing conveyance systems face challenges in accurately determining the start and stop times of conveyance apparatuses, especially in systems without direct access to drive machinery, leading to inaccurate attribution of vibrations to door or roller health, and requiring intense processing that consumes significant power.
Innovation Solution
Combining pressure sensors to detect robust motion changes and accelerometers to analyze accelerometer data only when necessary, using a low pass filter and threshold-based analysis to determine the precise start or stop time efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If accelerometer data is continuously analyzed to determine start and stop times, then measurement precision is improved, but use of energy increases significantly
Solution Approach 1:
The pressure sensor performs preliminary detection of motion changes (start/stop events) before triggering intensive accelerometer data analysis. This preliminary action filters out periods when detailed analysis is unnecessary, significantly reducing overall energy consumption while maintaining detection accuracy when events occur.
Solution Approach 2:
The pressure sensor acts as an intermediary between the continuous motion state and the intensive accelerometer analysis. It mediates by detecting coarse motion changes and only triggering detailed accelerometer processing when these changes occur, thus reducing the frequency of high-energy operations while preserving measurement precision for actual events.
2Ease of operation
If pressure sensor data is used to detect motion changes, then ease of operation is improved, but measurement precision deteriorates due to ±0.5m accuracy limitation
Solution Approach 1:
The system merges pressure sensor data and accelerometer data to achieve both ease of operation and measurement precision. The pressure sensor provides simple motion change detection triggers, while the accelerometer provides precise position and motion analysis during these events, combining the advantages of both sensors.
Solution Approach 2:
The detection process is segmented into two stages: coarse detection using the pressure sensor to identify when motion changes occur, and fine detection using the accelerometer to precisely characterize the motion. This segmentation allows each sensor to operate in its optimal mode.
3Measurement precision
If accelerometer data is analyzed at high sampling rates, then measurement precision is improved, but use of energy increases due to intensive processing
Solution Approach 1:
Instead of continuous high-rate accelerometer processing, the system uses periodic action triggered by pressure sensor events. The accelerometer is processed at high sampling rates only during brief periods when motion changes are detected, rather than continuously, dramatically reducing total processing energy while maintaining precision for actual events.
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 provides accurate and energy-efficient detection of conveyance apparatus motion, enabling better health analysis of systems by separating door and car vibrations, and extending battery life in independently powered devices.
Implementation Method 1
acquire pressure sensor data by sampling the pressure sensor; determine from the pressure sensor data that a start or stop of the conveyance apparatus has occurred
Implementation Method 2
acquire accelerometer data by sampling the accelerometer; analyse the accelerometer data to determine a first position within the accelerometer data
Data Source
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AI summary
A monitoring system for a conveyance system, comprising:a pressure sensor mounted on a conveyance apparatus; an accelerometer mounted on the conveyance apparatus; and a controller arranged to: acquire accelerometer data by sampling the accelerometer; store the accelerometer data in a buffer; acquire pressure sensor data by sampling the pressure sensor; determine from the pressure sensor data that a start or stop of the conveyance apparatus has occurred; and upon said determination, analyse the accelerometer data to determine a first position within the accelerometer data, wherein the first position is a position at which the start or stop of the conveyance apparatus occurred. Both pressure and acceleration readings are combined to determine a point in time at which motion started or stopped. The pressure sensor is used first to determine a robust indication that the motion state has changed (started or stopped). Upon making that determination, the accelerometer data is then analysed to make an accurate determination of when the motion state changed (i.e. when the conveyance apparatus started or stopped). The processing that is required to extract an accurate start or stop time from the accelerometer data is sufficiently intensive and power consuming that it cannot be run continuously on a low power (e.g. battery powered or energy harvesting) device. However the pressure sensor detection part of the process is low powered and is used to trigger the accelerometer processing only when necessary, such that the overall detection process is energy efficient as well as accurate.