Dynamic Elevator Fleet Sizing via RTT and Arrival Rate
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Solution Overview
Problem
Optimizing the number of active elevator cars in a multi-car elevator system to efficiently handle both low and high traffic situations, ensuring optimal energy usage and car utilization.
Innovation Solution
Determining the number of active elevator cars using the formula N=RTT*arr*carsize, where RTT is the round trip time, arr is the arrival rate of passengers, and carsize is the car load factor, with options for determining arrival rate through load weighing devices, photocells, door light ray systems, or traffic forecast data, and calculating RTT in real-time using elevator control logic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the number of active elevator cars is increased to handle high traffic situations, then the system's ability to handle high traffic is improved, but energy consumption increases
Solution Approach 1:
The system dynamically adjusts the number of active elevator cars based on real-time traffic conditions. The control system continuously monitors arrival rates and round trip times, then optimizes the fleet size accordingly - activating more cars during high traffic periods and deactivating them during low traffic periods to reduce energy consumption.
Solution Approach 2:
The optimization method changes the operational parameters of the elevator system by adjusting the number of active cars based on calculated traffic metrics. The system uses the formula involving arrival rate, round trip time, and car size to determine optimal fleet configuration, thereby adapting energy usage to actual demand levels.
2Use of energy by moving object
If the number of active elevator cars is decreased to save energy, then energy consumption is reduced, but the system's ability to handle traffic deteriorates
Solution Approach 1:
The control system implements continuous feedback monitoring of traffic conditions including arrival rates and round trip times. This feedback loop enables the system to detect when traffic demand increases and respond by activating additional elevator cars, ensuring that energy is reduced only when traffic conditions actually permit such reduction.
Solution Approach 2:
The system performs preliminary calculations using the optimization formula to determine the optimal number of active cars before traffic conditions change. By proactively adjusting the fleet size based on predicted or measured traffic patterns, the system prevents both energy waste and service degradation.
3Device complexity
If fixed number of elevator cars are used, then system simplicity is maintained, but adaptability to varying traffic conditions deteriorates
Solution Approach 1:
The system changes operational parameters (number of active cars) based on traffic conditions without fundamentally altering the physical elevator infrastructure. The control system uses calculated metrics including arrival rate, round trip time, and car size to dynamically adjust fleet configuration, providing adaptability through software rather than hardware complexity.
Data Source
AI summary
According to an aspect, there is provided a method for determining the number of elevator cars in a two-shaft multi-car elevator system. The method comprises determining the number of active elevator cars N in the two-shaft multi-car elevator system byN=RTT*arra*carsize,wherein RTT is a round trip time of the two-shaft multi-car elevator system, arr is the arrival rate of passengers, a is a car load factor, and carsize is the number of passengers one elevator car is able to carry.