Elevator Car Positioning via Laser Distance and Plausibility Analysis
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Solution Overview
Problem
Conventional methods for determining the current location of an elevator car in a shaft are complex and expensive, often failing to meet safety-critical reliability requirements due to errors and disturbances, such as misalignment and environmental factors.
Innovation Solution
A method using a laser distance measuring device to measure the distance between a car reference position and a shaft reference position, combined with plausibility analysis from independent data sources like location sensors, acceleration sensors, and encoder signals, to enhance the reliability of the location determination without requiring additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Hall sensors and magnetic markers are used for precise position detection, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex mechanical/electromagnetic position detection systems (Hall sensors and magnetic markers) with a laser-based distance measurement system. The laser distance measuring device measures the distance between a laser transmitter in the shaft and a reflector on the car, providing precise position information through optical time-of-flight measurement rather than electromagnetic field detection, thereby reducing hardware complexity while maintaining measurement precision.
2Ease of manufacture
If laser transmitters and reflectors are used for position monitoring, then ease of manufacture is improved, but reliability deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the measured distance from the laser distance measuring device is continuously compared with expected distance values based on car position. When the measured distance deviates from the expected range, the system generates a plausibility indicator signal, allowing the control system to detect and respond to measurement errors, thereby improving reliability while maintaining the simple laser-based structure.
3Reliability
If multiple independent measurement systems are integrated for high reliability, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent introduces a plausibility evaluation mechanism that acts as an intermediary between the simple laser distance measurement and the control system. Instead of integrating multiple independent measurement systems, the system uses the laser measurement combined with plausibility checking against expected position ranges to achieve high reliability (SIL2/SIL3), avoiding the complexity of multiple redundant measurement systems while maintaining safety integrity.
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 reliable car location information with increased accuracy and reduced complexity, meeting safety integrity levels like SIL2 or SIL3, while minimizing additional hardware needs and energy consumption.
Implementation Method 1
measuring a distance between a car reference position at the car and a shaft reference position in the shaft using a laser distance measuring device
Data Source
AI summary
A method and a controller determine information about a current location of a car in a shaft of an elevator. The method includes the steps of: measuring a distance between a car reference position at the car and a shaft reference position in the shaft using a laser distance measuring device; analyzing a plausibility of the measured distance taking into account plausibility information correlating with the current location of the car independently from the distance measuring; and determining the information about the current location of the car based on the measured distance and the analyzed plausibility.