Elevator Car Positioning via Dual-Phase Offset Selection
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Solution Overview
Problem
Existing systems for determining the position of an elevator car in an elevator shaft face challenges in achieving accurate positioning while maintaining low costs and minimal installation effort, particularly due to limitations in the unambiguity portion of the modulation frequency used in time-of-flight methods.
Innovation Solution
The system employs a transmitter and sensor cell that emit and receive modulated electromagnetic radiation, with an evaluation unit that delays the original measurement signal, determines phase offsets, and selects either the first or second phase offset based on a selection condition to accurately determine the position of the elevator car within the elevator shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high modulation frequency is used in TOF methods to improve measurement accuracy, then the unambiguity portion length decreases, but the positioning accuracy within the unambiguity portion improves
Solution Approach 1:
The patent divides the elevator shaft into multiple unambiguity portions using a first modulation frequency, then uses a second modulation frequency to determine which portion the elevator car is in. This segmentation allows the system to achieve both high positioning accuracy within portions and overall range coverage across the entire shaft.
Solution Approach 2:
The patent adds a temporal dimension by using multiple modulation frequencies sequentially. The first frequency provides fine positioning within portions, while the second frequency provides coarse positioning to identify the current portion. This dimensional approach to frequency usage resolves the contradiction between accuracy and range.
2Length of moving object
If a low modulation frequency is used to increase the unambiguity portion length, then the measurement range increases, but the positioning accuracy decreases
Solution Approach 1:
The patent segments the measurement task into two stages: first determining the unambiguity portion using a low frequency, then determining the position within that portion using a high frequency. This segmentation allows the system to achieve both extended range and high accuracy.
Solution Approach 2:
The patent performs a preliminary measurement using a low modulation frequency to identify which unambiguity portion the elevator car is in, before performing the precise measurement using a high modulation frequency. This preliminary action enables the system to achieve both range and accuracy.
3Length of moving object
If multiple modulation frequencies are used to extend measurement range, then the unambiguity portion coverage increases, but the system complexity increases
Solution Approach 1:
The patent uses two modulation frequencies with complementary functions: the first frequency handles fine positioning within portions, while the second frequency handles coarse positioning to identify portions. Both frequencies work together in a unified system, avoiding the need for separate independent systems.
Solution Approach 2:
The patent performs a preliminary determination of the unambiguity portion using a low frequency, which simplifies the subsequent fine positioning measurement using a high frequency. This preliminary action reduces the complexity of the overall measurement process.
4Measurement precision
If phase offset determination is used for positioning, then positioning accuracy improves, but the unambiguity limitation restricts the measurement range
Solution Approach 1:
The patent segments the elevator shaft into multiple unambiguity portions using a first modulation frequency, then uses a second modulation frequency to determine which portion the elevator car is in. This segmentation allows the system to achieve both high positioning accuracy within portions and overall range coverage across the entire shaft.
Solution Approach 2:
The patent adds a temporal dimension by using multiple modulation frequencies sequentially. The first frequency provides fine positioning within portions, while the second frequency provides coarse positioning to identify the current portion. This dimensional approach to frequency usage resolves the contradiction between accuracy and range.
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 allows for accurate determination of the elevator car's position throughout the entire elevator shaft, avoiding the limitations of unambiguity portions and enhancing positioning accuracy without increasing costs or installation complexity.
Implementation Method 1
a transmitter (25) for emitting modulated electromagnetic radiation with a first modulation frequency as a first output signal, a sensor cell (28) for receiving electromagnetic radiation, reflected by an object detected by the sensor cell
Implementation Method 2
the evaluation unit (30) is configured so as to delay the original measurement signal by a delay time and thus generate a delayed measurement signal
Data Source
AI summary
A system determines the position of an elevator car movable in an elevator installation shaft. A transmitter emits modulated electromagnetic radiation with a first modulation frequency as a first output signal, a sensor cell receives electromagnetic radiation reflected by a detected object as an original measurement signal, and an evaluation unit, communicating with the transmitter and the sensor cell, delays the original measurement signal thus generating a delayed measurement signal, determines a first phase offset between the original measurement signal and the first output signal, determines a second phase offset between the delayed measurement signal and the first output signal, selects either the first phase offset or the second phase offset based upon a selection condition to determine a position of the elevator car within a portion of the elevator shaft, and determines the elevator car position based upon the elevator shaft portion and the position within the portion.