Elevator Car Position Sensing With Partial Code Mark Detection
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Solution Overview
Problem
Existing position determination systems for elevator cars are costly and require significant material and installation space due to the large number of Hall sensors needed for reliable detection, especially when immediate position determination after restart is not necessary.
Innovation Solution
A position determination system using a code tape with a pseudo-random code mark pattern and a detection device with fewer sensors, allowing for cost-effective production and reduced installation space, where the detection device can only detect a part of a position mark at a time, and the evaluation unit assembles complete position marks from successively detected code marks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of Hall sensors are used to ensure reliable position determination, then measurement precision and reliability are improved, but device complexity, material cost, and installation space increase
Solution Approach 1:
The code mark pattern is divided into multiple code marks that form position marks in a pseudorandom sequence. The detection device scans these segmented code marks sequentially rather than requiring all sensors to detect the entire pattern simultaneously, reducing the number of sensors needed while maintaining measurement precision through the unique pseudorandom arrangement.
Solution Approach 2:
The detection device only needs to detect a portion of the code mark pattern at any given time rather than the entire pattern. By scanning sequentially through the pseudorandom sequence of position marks, the system achieves reliable position determination with fewer sensors than would be required to detect the complete pattern simultaneously.
2Loss of time
If the detection device scans the entire code mark pattern simultaneously, then position determination can be made immediately after restart, but device complexity and installation space requirements increase
Solution Approach 1:
The detection device transitions from a static simultaneous detection approach to a dynamic sequential scanning approach. The device moves along the code tape, scanning position marks in a pseudorandom sequence, which allows compact device design while maintaining the ability to quickly determine position after restart through the unique sequence arrangement.
Solution Approach 2:
The code mark pattern is pre-arranged in a pseudorandom sequence where position marks are uniquely arranged. This preliminary arrangement allows the detection device to quickly identify its position in the sequence during scanning, enabling fast position determination after restart without requiring the device to span the entire code mark length.
3Reliability
If Hall sensors are used to detect magnetic code marks, then detection reliability is improved, but material cost and device complexity increase
Solution Approach 1:
The patent extracts only the essential detection function from complex Hall sensor arrays. By using a simplified detection device with fewer sensors that scans a pseudorandom sequence of position marks, the system maintains detection reliability through the unique sequence arrangement while reducing material costs and simplifying manufacturing.
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 solution provides a cost-effective and space-efficient position determination system that can still achieve precise cabin position determination, suitable for monitoring applications where immediate restart determination is not critical, and can be used independently of existing elevator control systems.
Implementation Method 1
The code marks form magnetic poles, so that the code mark pattern is composed of a series of magnetic north and south poles
Implementation Method 2
This device incorporates a series of Hall sensors that scan the code marker pattern without contact
Data Source
Figure 1
Figure 2~3
AI summary
The invention relates to a position-determining system and a method for ascertaining a cab position of an elevator cab. The position-determining system (28) comprises a code tape (27) that is applied next to the elevator cab parallel to a displacement direction (22) and that comprises a code mark pattern constructed from individual code marks (50), a detection apparatus (32), attached to the elevator cab, for detecting code marks (50) of the code mark pattern on the code tape (27) and an evaluation unit (30) for determining the cab position on the basis of the code marks (50) detected by the detection apparatus (32). Here, n successive code marks (50) of the code mark pattern form a position mark (51), the position marks (51) are unambiguously arranged in an n-element pseudorandom sequence of various position marks (50), the position marks (51) form a single-track code mark pattern and each position mark (51) is assigned to a discrete cab position. According to the invention, a detection region (52) of the detection apparatus (32) has a detection length (LE) in the displacement direction that is smaller than a position mark length (LP) of a position mark (51) in the displacement direction (22).