Elevator Group Control Using Reference Trajectories
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Solution Overview
Problem
Conventional elevator group control systems fail to maintain equal time intervals between elevator cars, leading to inefficient hall call assignment and increased waiting times due to the unpredictability of hall call generation and the limitations of existing control methods.
Innovation Solution
The system prepares a reference trajectory for each elevator car to forecast future positions and adjusts car speed and stop times to align with this trajectory, ensuring equal time intervals by using car speed adjustments, door operation speed, and stop position adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional assignment methods based on forecasted waiting time are used, then hall calls are assigned to elevator cars, but the cars cannot be maintained at equal time intervals leading to inefficient service distribution
Solution Approach 1:
The system performs preliminary actions by predicting future positions of elevator cars and pre-adjusting their speeds before hall calls are generated. This allows the cars to be positioned optimally in advance, ensuring equal time intervals are maintained regardless of when calls occur, thereby reducing user waiting time while improving service efficiency
Solution Approach 2:
The system dynamically adjusts the speed of each elevator car based on predicted future positions and desired equal time intervals. By continuously modifying car speeds in real-time according to their trajectories, the system maintains optimal spacing between cars, improving both service efficiency and reducing waiting times
2Ease of operation
If elevator cars are not uniformly arranged at equal time intervals, then the system operates with flexible car positioning, but hall calls generated between cars with longer intervals experience longer waiting times
Solution Approach 1:
The system predicts future positions of all elevator cars and pre-adjusts their speeds to achieve equal time intervals before hall calls are generated. This preliminary positioning ensures that regardless of where calls occur, users experience minimal waiting times while the system maintains operational flexibility
Solution Approach 2:
The system continuously monitors the actual positions and timing of elevator cars, compares them with the predicted equal time interval trajectories, and makes real-time speed adjustments. This feedback mechanism ensures cars maintain optimal spacing, reducing waiting times while preserving positioning flexibility
3Adaptability or versatility
If hall call generation is left random and unpredictable, then the system operates without intervention, but the assignment of hall calls cannot optimize car spacing leading to uneven car arrangement
Solution Approach 1:
The system performs preliminary speed adjustments based on predicted future positions before random hall calls are generated. By pre-positioning cars at equal time intervals, the system can effectively handle random calls while maintaining optimal service distribution efficiency
Solution Approach 2:
The system dynamically responds to random hall call generation by continuously adjusting car speeds based on real-time position data and predicted trajectories. This dynamic adaptation ensures that even with random calls, the cars maintain equal time intervals and optimal service distribution
Data Source
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Figure 3(a)~3(b)
AI summary
In view of the limited effect of the elevator car (12A, 12B, 12C) interval control by hall call assignment alone, depending on generation of hall calls, an elevator group control system and a control method thereof are disclosed, in which the waiting time can be shortened more accurately in finely detailed fashion. A reference trajectory indicating a reference position of each elevator car (12A, 12B, 12C) within a predetermined future time is prepared for each elevator car (12A, 12B, 12C), and a forecasted trajectory corresponding to the reference trajectory is prepared by forecasting the position of each elevator car (12A, 12B, 12C). A hall call is assigned in such a manner that the forecasted trajectory approaches the reference trajectory. At the same time, the operation control factors other than assignment, including the car speed (car speed and acceleration) and the stop time (the door operation speed and the door opening time) of each elevator car (12A, 12B, 12C) are adjusted during the period lacking the assignment process.