Elevator Positioning via Accelerometer and Pressure Sensor Buffet Detection
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Solution Overview
Problem
Determining the vertical position of an elevator in a hoistway using accelerometers is challenging due to drift and integration errors, which increase with distance traveled and duration of the elevator journey, leading to positioning errors.
Innovation Solution
A method involving an accelerometer and a pressure sensor, both communicatively coupled to a monitoring controller, measures acceleration and pressure changes to detect buffets, allowing for the calculation of multiple estimated positions and updating the elevator's position, thereby correcting for drift and integration errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If double integration of accelerometer data is used to determine elevator position, then position information can be obtained, but positioning accuracy deteriorates due to cumulative drift and integration errors
Solution Approach 1:
The system uses pressure sensor feedback to detect buffets caused by door openings and uses this information to correct accelerometer-based position estimates. The controller continuously compares expected buffet timing with actual detections to identify and correct drift errors in the integrated position data, thereby maintaining positioning accuracy over extended travel distances.
Solution Approach 2:
The pressure sensor acts as an intermediary measurement device that detects physical buffets caused by door openings. These buffet detections serve as intermediate reference points that can be used to correct the accelerometer's cumulative position errors without requiring direct line-of-sight measurement or external positioning infrastructure.
2Quantity of substance
If accelerometer data is integrated over longer distances and durations, then more position data is available, but integration errors and drift increase
Solution Approach 1:
The system implements continuous feedback by monitoring pressure changes that indicate door openings. These buffet events provide periodic correction opportunities that reset the accumulation of integration errors. By using the timing and position of buffets as feedback signals, the system can correct drift at multiple points along the travel path, maintaining accuracy despite the quantity of data accumulated over long distances.
Solution Approach 2:
The system performs preliminary detection of buffet events using the pressure sensor before significant position errors accumulate. By detecting buffets at expected locations (such as door openings), the system can proactively correct position estimates before drift becomes problematic, effectively preparing the position data for continued accurate measurement over extended travel.
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 improves the accuracy of elevator position determination by using buffet-induced changes in acceleration and pressure to correct for drift and integration errors, enhancing the reliability of floor level detection.
Implementation Method 1
measuring an acceleration using the accelerometer for a run sequence of the elevator cab
Implementation Method 2
measuring a change in pressure using the pressure sensor and detecting at least one buffet
Data Source
AI summary
A method for determining the vertical position of an elevator cab in a hoistway comprising the steps of: providing an elevator cab positioned in a hoistway; providing an accelerometer attached to the elevator cab; providing a monitoring controller communicatively coupled to the accelerometer; measuring an acceleration using the accelerometer for a run sequence of the elevator cab; calculating a double integration of the acceleration determining a first estimated position of the elevator cab in the hoistway; measuring a change in acceleration using the accelerometer and detecting at least one buffet; determining a second estimated position of the elevator cab in the hoistway based upon the at least one detected buffet; comparing the first and second estimated positions; and updating a position of the elevator cab in the hoistway and determining a floor level. A pressure sensor may also be used to detect the buffet.