Elevator Rope Slip Estimation via Sensor Distance Comparison
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Solution Overview
Problem
Existing elevator systems face challenges in accurately estimating rope slip during normal operation, which can lead to poor stopping accuracy and insufficient braking during emergency stops due to decreased friction between hoisting ropes and traction sheaves.
Innovation Solution
A method and system for estimating rope slip in elevator systems by determining if predefined operational conditions are met during normal operation, and if so, using sensors to measure the distance traveled by the traction sheave and the elevator car, calculating the difference, and dividing it by the traction sheave distance to estimate the rope slip.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rope slip estimation is performed during normal operation mode, then manual tests are reduced and computing resources are conserved, but the complexity of determining operational conditions increases
Solution Approach 1:
The system pre-defines operational conditions (travel length threshold, load percentage ranges, direction constraints) that must be satisfied before rope slip estimation is performed. This preliminary setup allows the system to automatically determine whether normal operation mode conditions are met without complex real-time analysis, thereby reducing computational overhead while maintaining estimation accuracy.
Solution Approach 2:
The operational condition determination is divided into separate checkable parameters: travel length condition, load condition, and direction condition. Each parameter is independently evaluated against predefined thresholds, simplifying the overall complexity by breaking down the decision process into discrete, manageable segments that can be processed efficiently.
2Measurement precision
If rope slip is estimated using sensor measurements during normal operation, then stopping accuracy can be maintained, but the use of computing resources increases
Solution Approach 1:
The system performs rope slip estimation only partially - specifically, only when predefined operational conditions are satisfied during normal operation mode. This selective approach uses sensor data (traction sheave distance, elevator car distance) only when necessary, avoiding continuous computation and thereby reducing energy consumption while maintaining measurement precision when actually performed.
Solution Approach 2:
The system changes the operational parameters dynamically by adjusting whether estimation is performed based on satisfaction of predefined conditions (travel length, load, direction). This parameter-based control allows the system to maintain high measurement precision when needed while minimizing computing resource usage by switching estimation off during inappropriate conditions.
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 reliable and unaltered estimation of rope slip during normal operation, reducing the need for manual tests and conserving computing resources and storage space, while ensuring accurate monitoring of safety conditions and timely maintenance.
Implementation Method 1
measuring, by a first sensor positioned at an elevator hoisting machine, a distance that a traction sheave of an elevator hoisting machine travels
Implementation Method 2
measuring, by a second sensor positioned at the elevator car, a distance that the elevator car travels
Implementation Method 3
drive torque of the elevator car is generated by an electrical motor of the elevator hoisting machine
Implementation Method 4
the torque generated by the electrical motor of the elevator hoisting machine is transferred to the hoisting ropes via friction between the hoisting ropes and the traction sheave
Data Source
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AI summary
The present invention relates to a method for estimating rope slip in an elevator system, wherein the method (10,20) comprises the steps of: - During normal operation mode of the elevator system, determining whether one or more predefined operational conditions are fulfilled (11,21); and - If one or more of the predefined operational conditions are fulfilled, estimating rope slip in the elevator system during normal operation mode of the elevator system (12,22).